Module:Citation/CS1

Documentation for this module may be created at Module:Citation/CS1/doc

local z = {
    error_categories = {};
    error_ids = {};
    message_tail = {};
}

-- Include translation message hooks, ID and error handling configuration settings.
local cfg = mw.loadData( 'Module:Citation/CS1/Configuration' );

-- Contains a list of all recognized parameters
local whitelist = mw.loadData( 'Module:Citation/CS1/Whitelist' );

-- Whether variable is set or not
function is_set( var )
    return not (var == nil or var == '');
end

-- First set variable or nil if none
function first_set(...)
    local list = {...};
    for _, var in pairs(list) do
        if is_set( var ) then
            return var;
        end
    end
end

-- Whether needle is in haystack
function inArray( needle, haystack )
    if needle == nil then
        return false;
    end
    for n,v in ipairs( haystack ) do
        if v == needle then
            return n;
        end
    end
    return false;
end

-- Populates numbered arguments in a message string using an argument table.
function substitute( msg, args )
    return args and tostring( mw.message.newRawMessage( msg, args ) ) or msg;
end

-- Wraps a string using a message_list configuration taking one argument
function wrap( key, str, lower )
    if not is_set( str ) then
        return "";
    elseif inArray( key, { 'italic-title', 'trans-italic-title' } ) then
        str = safeforitalics( str );
    end
    if lower == true then
        return substitute( cfg.messages[key]:lower(), {str} );
    else
        return substitute( cfg.messages[key], {str} );
    end        
end

--[[
Argument wrapper.  This function provides support for argument 
mapping defined in the configuration file so that multiple names
can be transparently aliased to single internal variable.
]]
function argument_wrapper( args )
    local origin = {};
    
    return setmetatable({
        ORIGIN = function( self, k )
            local dummy = self[k]; --force the variable to be loaded.
            return origin[k];
        end
    },
    {
        __index = function ( tbl, k )
            if origin[k] ~= nil then
                return nil;
            end
            
            local args, list, v = args, cfg.aliases[k];
            
            if type( list ) == 'table' then
                v, origin[k] = selectone( args, list, 'redundant_parameters' );
                if origin[k] == nil then
                    origin[k] = ''; -- Empty string, not nil
                end
            elseif list ~= nil then
                v, origin[k] = args[list], list;
            else
                -- maybe let through instead of raising an error?
                -- v, origin[k] = args[k], k;
                error( cfg.messages['unknown_argument_map'] );
            end
            
            -- Empty strings, not nil;
            if v == nil then
                v = cfg.defaults[k] or '';
                origin[k] = '';
            end
            
            tbl = rawset( tbl, k, v );
            return v;
        end,
    });
end

-- Checks that parameter name is valid using the whitelist
function validate( name )
    name = tostring( name );
    
    -- Normal arguments
    if whitelist.basic_arguments[ name ] then
        return true;
    end
    
    -- Arguments with numbers in them
    name = name:gsub( "%d+", "#" );
    if whitelist.numbered_arguments[ name ] then
        return true;
    end
    
    -- Not found, argument not supported.
    return false
end

-- Formats a comment for error trapping
function errorcomment( content, hidden )
    return wrap( hidden and 'hidden-error' or 'visible-error', content );
end

--[[
Sets an error condition and returns the appropriate error message.  The actual placement
of the error message in the output is the responsibility of the calling function.
]]
function seterror( error_id, arguments, raw, prefix, suffix )
    local error_state = cfg.error_conditions[ error_id ];
    
    prefix = prefix or "";
    suffix = suffix or "";
    
    if error_state == nil then
        error( cfg.messages['undefined_error'] );
    elseif is_set( error_state.category ) then
        table.insert( z.error_categories, error_state.category );
    end
    
    local message = substitute( error_state.message, arguments );
    
    message = message .. " ([[" .. cfg.messages['help page link'] .. 
        "#" .. error_state.anchor .. "|" ..
        cfg.messages['help page label'] .. "]])";
    
    z.error_ids[ error_id ] = true;
    if inArray( error_id, { 'bare_url_missing_title', 'trans_missing_title' } )
            and z.error_ids['citation_missing_title'] then
        return '', false;
    end
    
    message = table.concat({ prefix, message, suffix });
    
    if raw == true then
        return message, error_state.hidden;
    end        
        
    return errorcomment( message, error_state.hidden );
end

-- Formats a wiki style external link
function externallinkid(options)
    local url_string = options.id;
    if options.encode == true or options.encode == nil then
        url_string = mw.uri.encode( url_string );
    end
    return mw.ustring.format( '[[%s|%s]]%s[%s%s%s %s]',
        options.link, options.label, options.separator or " ",
        options.prefix, url_string, options.suffix or "",
        mw.text.nowiki(options.id)
    );
end

-- Formats a wiki style internal link
function internallinkid(options)
    return mw.ustring.format( '[[%s|%s]]%s[[%s%s%s|%s]]',
        options.link, options.label, options.separator or " ",
        options.prefix, options.id, options.suffix or "",
        mw.text.nowiki(options.id)
    );
end

-- Format an external link with error checking
function externallink( URL, label, source )
    local error_str = "";
    if not is_set( label ) then
        label = URL;
        if is_set( source ) then
            error_str = seterror( 'bare_url_missing_title', { wrap( 'parameter', source ) }, false, " " );
        else
            error( cfg.messages["bare_url_no_origin"] );
        end            
    end
    if not checkurl( URL ) then
        error_str = seterror( 'bad_url', {}, false, " " ) .. error_str;
    end
    return table.concat({ "[", URL, " ", safeforurl( label ), "]", error_str });
end

-- Formats a link to Amazon
function amazon(id, domain)
    if not is_set(domain) then 
        domain = "com"
    elseif ( "jp" == domain or "uk" == domain ) then
        domain = "co." .. domain
    end
    local handler = cfg.id_handlers['ASIN'];
    return externallinkid({link = handler.link,
        label=handler.label , prefix="//www.amazon."..domain.."/dp/",id=id,
        encode=handler.encode, separator = handler.separator})
end

--[[
Formats a PMC and checks for embargoed articles.  The embargo parameter takes a date for a value. If the embargo date is in the futue
the PMC identifier will not be linked to the article.  If the embargo specifies a date in the past, or if it is empty or omitted, then
the PMC identifier is linked to the article through the link at cfg.id_handlers['PMC'].link.

The {{citation/core}} version of {{cite journal}} links the citation title (if url parameter is empty) when embargo date is in the past
or when embargo parameter is missing or empty. That behavior is inconsistent with the behavior of other identifiers used in CS1 and is
not supported here.
]]
function pmc(id, embargo)
	local handler = cfg.id_handlers['PMC'];
    
	local text;
	
	if is_set(embargo) then
		local lang = mw.getContentLanguage();
		local good1, embargo_date, good2, todays_date;
		good1, embargo_date = pcall( lang.formatDate, lang, 'U', embargo );
		good2, todays_date = pcall( lang.formatDate, lang, 'U' );

		if good1 and good2 and tonumber( embargo_date ) < tonumber( todays_date ) then	--if embargo date is in the past then
			text = externallinkid({link = handler.link, label = handler.label,			--ok to link to article
				prefix=handler.prefix,id=id,separator=handler.separator, encode=handler.encode})
		else
			text="[[" .. handler.link .. "|" .. handler.label .. "]]:" .. handler.separator .. id;	--still embargoed so no external link
		end
	else
		text = externallinkid({link = handler.link, label = handler.label,			--no embargo date, ok to link to article
			prefix=handler.prefix,id=id,separator=handler.separator, encode=handler.encode})
	end
	return text
end

-- Formats a DOI and checks for DOI errors.
function doi(id, inactive)
    local cat = ""
    local handler = cfg.id_handlers['DOI'];
    
    local text;
    if is_set(inactive) then
        text = "[[" .. handler.link .. "|" .. handler.label .. "]]:" .. id;
        table.insert( z.error_categories, "Pages with DOIs inactive since " .. selectyear(inactive) );        
        inactive = " (" .. cfg.messages['inactive'] .. " " .. inactive .. ")" 
    else 
        text = externallinkid({link = handler.link, label = handler.label,
            prefix=handler.prefix,id=id,separator=handler.separator, encode=handler.encode})
        inactive = "" 
    end
    if ( string.sub(id,1,3) ~= "10." ) then      
        cat = seterror( 'bad_doi' );
    end
    return text .. inactive .. cat 
end

-- Formats an OpenLibrary link, and checks for associated errors.
function openlibrary(id)
    local code = id:sub(-1,-1)
    local handler = cfg.id_handlers['OL'];
    if ( code == "A" ) then
        return externallinkid({link=handler.link, label=handler.label,
            prefix="http://openlibrary.org/authors/OL",id=id, separator=handler.separator,
            encode = handler.encode})
    elseif ( code == "M" ) then
        return externallinkid({link=handler.link, label=handler.label,
            prefix="http://openlibrary.org/books/OL",id=id, separator=handler.separator,
            encode = handler.encode})
    elseif ( code == "W" ) then
        return externallinkid({link=handler.link, label=handler.label,
            prefix= "http://openlibrary.org/works/OL",id=id, separator=handler.separator,
            encode = handler.encode})
    else
        return externallinkid({link=handler.link, label=handler.label,
            prefix= "http://openlibrary.org/OL",id=id, separator=handler.separator,
            encode = handler.encode}) .. 
            ' ' .. seterror( 'bad_ol' );
    end
end

--[[
Validate and format an issn.  This code fixes the case where an editor has included an ISSN in the citation but has separated the two groups of four
digits with a space.  When that condition occurred, the resulting link looked like this:

	|issn=0819 4327 gives: [http://www.worldcat.org/issn/0819 4327 0819 4327]  -- can't have spaces in an external link
	
This code now prevents that by inserting a hyphen at the issn midpoint.  It also validates the issn for length and makes sure that the checkdigit agrees
with the calculated value.  Incorrect length (8 digits), characters other than 0-9 and X, or checkdigit / calculated value mismatch will all cause a check issn
error message.  The issn is always displayed with a hyphen, even if the issn was given as a single group of 8 digits.
]]
function issn(id)
	local clean_issn;
	local issn_copy = id;		-- save a copy of unadulterated issn; use this version for display if issn does not validate
	local handler = cfg.id_handlers['ISSN'];
	local temp = 0;
	local text;
	local valid_issn = true;

	id=id:gsub( "[%s-–]", "" );									-- strip spaces, hyphens, and ndashes from the issn
	clean_issn=string.sub( id, 1, 4 ) .. "-" .. string.sub( id, 5 );	-- make a copy with a hyphen after 4 digits; use this version for display if issn validates

	if 8 ~= id:len() or nil == id:match( "^%d*X?$" ) then		-- validate the issn: 8 didgits long, containing only 0-9 or X in the last position
		valid_issn=false;										-- wrong length or improper character
	else
		id = { id:byte(1, 8) };									-- table of individual bytes
		for i, v in ipairs( id ) do								-- loop through all of the byte an calculate the checksum
			if v == string.byte( "X" ) then						-- if checkdigit is X
				temp = temp + 10*( 9 - i );						-- it represents 10 decimal
			else
				temp = temp + tonumber( string.char(v) )*(9-i);	
			end
		end
		valid_issn = temp % 11 == 0;							-- checksum must be zero for valid issn
	end

	if true == valid_issn then
		id = clean_issn;										-- if valid, use the cleaned-up version for the display			
	else
		id = issn_copy;											-- if not valid, use the show the invalid issn with error message
	end
	
	text = externallinkid({link = handler.link, label = handler.label,
		prefix=handler.prefix,id=id,separator=handler.separator, encode=handler.encode})
 
	if false == valid_issn then
		text = text .. ' ' .. seterror( 'bad_issn' )			-- add an error message if the issn is invalid
	end 
	
	return text
end


--[[
Determines whether an URL string is valid

At present the only check is whether the string appears to 
be prefixed with a URI scheme.  It is not determined whether 
the URI scheme is valid or whether the URL is otherwise well 
formed.
]]
function checkurl( url_str )
    -- Protocol-relative or URL scheme
    return url_str:sub(1,2) == "//" or url_str:match( "^[^/]*:" ) ~= nil;
end

-- Removes irrelevant text and dashes from ISBN number
-- Similar to that used for Special:BookSources
function cleanisbn( isbn_str )
    return isbn_str:gsub( "[^-0-9X]", "" );
end

-- Determines whether an ISBN string is valid
function checkisbn( isbn_str )
    isbn_str = cleanisbn( isbn_str ):gsub( "-", "" );
    local len = isbn_str:len();
 
    if len ~= 10 and len ~= 13 then
        return false;
    end
 
    local temp = 0;
    if len == 10 then
        if isbn_str:match( "^%d*X?$" ) == nil then return false; end
        isbn_str = { isbn_str:byte(1, len) };
        for i, v in ipairs( isbn_str ) do
            if v == string.byte( "X" ) then
                temp = temp + 10*( 11 - i );
            else
                temp = temp + tonumber( string.char(v) )*(11-i);
            end
        end
        return temp % 11 == 0;
    else
        if isbn_str:match( "^%d*$" ) == nil then return false; end
        isbn_str = { isbn_str:byte(1, len) };
        for i, v in ipairs( isbn_str ) do
            temp = temp + (3 - 2*(i % 2)) * tonumber( string.char(v) );
        end
        return temp % 10 == 0;
    end
end

-- Gets the display text for a wikilink like [[A|B]] or [[B]] gives B
function removewikilink( str )
    return (str:gsub( "%[%[([^%[%]]*)%]%]", function(l)
        return l:gsub( "^[^|]*|(.*)$", "%1" ):gsub("^%s*(.-)%s*$", "%1");
    end));
end

-- Escape sequences for content that will be used for URL descriptions
function safeforurl( str )
    if str:match( "%[%[.-%]%]" ) ~= nil then 
        table.insert( z.message_tail, { seterror( 'wikilink_in_url', {}, true ) } );
    end
    
    return str:gsub( '[%[%]\n]', {    
        ['['] = '&#91;',
        [']'] = '&#93;',
        ['\n'] = ' ' } );
end

-- Converts a hyphen to a dash
function hyphentodash( str )
    if not is_set(str) or str:match( "[%[%]{}<>]" ) ~= nil then
        return str;
    end    
    return str:gsub( '-', '–' );
end

-- Protects a string that will be wrapped in wiki italic markup '' ... ''
function safeforitalics( str )
    --[[ Note: We can not use <i> for italics, as the expected behavior for
    italics specified by ''...'' in the title is that they will be inverted
    (i.e. unitalicized) in the resulting references.  In addition, <i> and ''
    tend to interact poorly under Mediawiki's HTML tidy. ]]
    
    if not is_set(str) then
        return str;
    else
        if str:sub(1,1) == "'" then str = "<span />" .. str; end
        if str:sub(-1,-1) == "'" then str = str .. "<span />"; end
        
        -- Remove newlines as they break italics.
        return str:gsub( '\n', ' ' );
    end
end

--[[
Joins a sequence of strings together while checking for duplicate separation
characters.
]]
function safejoin( tbl, duplicate_char )
    --[[
    Note: we use string functions here, rather than ustring functions.
    
    This has considerably faster performance and should work correctly as 
    long as the duplicate_char is strict ASCII.  The strings
    in tbl may be ASCII or UTF8.
    ]]
    
    local str = '';
    local comp = '';
    local end_chr = '';
    local trim;
    for _, value in ipairs( tbl ) do
        if value == nil then value = ''; end
        
        if str == '' then
            str = value;
        elseif value ~= '' then
            if value:sub(1,1) == '<' then
                -- Special case of values enclosed in spans and other markup.
                comp = value:gsub( "%b<>", "" );
            else
                comp = value;
            end
            
            if comp:sub(1,1) == duplicate_char then
                trim = false;
                end_chr = str:sub(-1,-1);
                -- str = str .. "<HERE(enchr=" .. end_chr.. ")"
                if end_chr == duplicate_char then
                    str = str:sub(1,-2);
                elseif end_chr == "'" then
                    if str:sub(-3,-1) == duplicate_char .. "''" then
                        str = str:sub(1, -4) .. "''";
                    elseif str:sub(-5,-1) == duplicate_char .. "]]''" then
                        trim = true;
                    elseif str:sub(-4,-1) == duplicate_char .. "]''" then
                        trim = true;
                    end
                elseif end_chr == "]" then
                    if str:sub(-3,-1) == duplicate_char .. "]]" then
                        trim = true;
                    elseif str:sub(-2,-1) == duplicate_char .. "]" then
                        trim = true;
                    end
                elseif end_chr == " " then
                    if str:sub(-2,-1) == duplicate_char .. " " then
                        str = str:sub(1,-3);
                    end
                end

                if trim then
                    if value ~= comp then 
                        local dup2 = duplicate_char;
                        if dup2:match( "%A" ) then dup2 = "%" .. dup2; end
                        
                        value = value:gsub( "(%b<>)" .. dup2, "%1", 1 )
                    else
                        value = value:sub( 2, -1 );
                    end
                end
            end
            str = str .. value;
        end
    end
    return str;
end  

--[[
Return the year portion of a date string, if possible.  
Returns empty string if the argument can not be interpreted
as a year.
]]
function selectyear( str )
    -- Is the input a simple number?
    local num = tonumber( str ); 
    if num ~= nil and num > 0 and num < 2100 and num == math.floor(num) then
        return str;
    else
        -- Use formatDate to interpret more complicated formats
        local lang = mw.getContentLanguage();
        local good, result;
        good, result = pcall( lang.formatDate, lang, 'Y', str );
        if good then 
            return result;
        else
            -- extract year if the date uses seasons
            str=string.lower (str);
            local seasons={"winter", "spring", "summer", "fall", "autumn"};
            local date_string_split=mw.text.split (str, "[%s%-/–]");      -- split date string into parts; white space, hyphen, forward slash, and ndash are allowed separators
            local has_season=false;
            
            for n,season_value in ipairs(seasons) do                -- for each season ...
                for n,split_value in ipairs(date_string_split) do   -- ... loop through date string values 
                    if split_value == season_value then             -- does the split value match the season value?
                        if has_season==false then                   -- found one. if this one is the first we've found ...
                            has_season=true;                        -- ... remember that we found a season
                        end
                    elseif has_season==true then                    -- if split_value isn't a season, and we've previously found a season ...
                        num = tonumber( split_value );              -- ... convert current split value to a number if we can
                        if num ~= nil and num > 0 and num < 2100 and num == math.floor(num) then    -- if it's a suitable number
                            return tostring( num );                                                 -- return it as a string
                        end -- if num
                    end -- if string.find
                end -- for split value loop
            end -- season value loop
        end -- if good
    end -- if num
end -- selectyear

-- Attempts to convert names to initials.
function reducetoinitials(first)
    local initials = {}
    for word in string.gmatch(first, "%S+") do
        table.insert(initials, string.sub(word,1,1)) -- Vancouver format does not include full stops.
    end
    return table.concat(initials) -- Vancouver format does not include spaces.
end

-- Formats a list of people (e.g. authors / editors) 
function listpeople(control, people)
    local sep = control.sep;
    local namesep = control.namesep
    local format = control.format
    local maximum = control.maximum
    local lastauthoramp = control.lastauthoramp;
    local text = {}
    local etal = false;
    
    if sep:sub(-1,-1) ~= " " then sep = sep .. " " end
    if maximum ~= nil and maximum < 1 then return "", 0; end
    
    for i,person in ipairs(people) do
        if is_set(person.last) then
            local mask = person.mask
            local one
            local sep_one = sep;
            if maximum ~= nil and i > maximum then
                etal = true;
                break;
            elseif (mask ~= nil) then
                local n = tonumber(mask)
                if (n ~= nil) then
                    one = string.rep("&mdash;",n)
                else
                    one = mask;
                    sep_one = " ";
                end
            else
                one = person.last
                local first = person.first
                if is_set(first) then 
                    if ( "vanc" == format ) then first = reducetoinitials(first) end
                    one = one .. namesep .. first 
                end
                if is_set(person.link) then one = "[[" .. person.link .. "|" .. one .. "]]" end
            end
            table.insert( text, one )
            table.insert( text, sep_one )
        end
    end

    local count = #text / 2;
    if count > 0 then 
        if count > 1 and is_set(lastauthoramp) and not etal then
            text[#text-2] = " & ";
        end
        text[#text] = nil; 
    end
    
    local result = table.concat(text) -- construct list
    if etal then 
        local etal_text = cfg.messages['et al'];
        result = result .. " " .. etal_text;
    end
    
    -- if necessary wrap result in <span> tag to format in Small Caps
    if ( "scap" == format ) then result = 
        '<span class="smallcaps" style="font-variant:small-caps">' .. result .. '</span>';
    end 
    return result, count
end

-- Generates a CITEREF anchor ID.
function anchorid( options )
    return "CITEREF" .. table.concat( options );
end

-- Gets name list from the input arguments
function extractnames(args, list_name)
    local names = {};
    local i = 1;
    local last;
    
    while true do
        last = selectone( args, cfg.aliases[list_name .. '-Last'], 'redundant_parameters', i );
        if not is_set(last) then
            -- just in case someone passed in an empty parameter
            break;
        end
        names[i] = {
            last = last,
            first = selectone( args, cfg.aliases[list_name .. '-First'], 'redundant_parameters', i ),
            link = selectone( args, cfg.aliases[list_name .. '-Link'], 'redundant_parameters', i ),
            mask = selectone( args, cfg.aliases[list_name .. '-Mask'], 'redundant_parameters', i )
        };
        i = i + 1;
    end
    return names;
end

-- Populates ID table from arguments using configuration settings
function extractids( args )
    local id_list = {};
    for k, v in pairs( cfg.id_handlers ) do    
        v = selectone( args, v.parameters, 'redundant_parameters' );
        if is_set(v) then id_list[k] = v; end
    end
    return id_list;
end

-- Takes a table of IDs and turns it into a table of formatted ID outputs.
function buildidlist( id_list, options )
    local new_list, handler = {};
    
    function fallback(k) return { __index = function(t,i) return cfg.id_handlers[k][i] end } end;
    
    for k, v in pairs( id_list ) do
        -- fallback to read-only cfg
        handler = setmetatable( { ['id'] = v }, fallback(k) );
        
        if handler.mode == 'external' then
            table.insert( new_list, {handler.label, externallinkid( handler ) } );
        elseif handler.mode == 'internal' then
            table.insert( new_list, {handler.label, internallinkid( handler ) } );
        elseif handler.mode ~= 'manual' then
            error( cfg.messages['unknown_ID_mode'] );
        elseif k == 'DOI' then
            table.insert( new_list, {handler.label, doi( v, options.DoiBroken ) } );
        elseif k == 'ASIN' then
            table.insert( new_list, {handler.label, amazon( v, options.ASINTLD ) } ); 
        elseif k == 'OL' then
            table.insert( new_list, {handler.label, openlibrary( v ) } );
        elseif k == 'PMC' then
            table.insert( new_list, {handler.label, pmc( v, options.Embargo ) } );
        elseif k == 'ISSN' then
        	table.insert( new_list, {handler.label, issn( v ) } );
        elseif k == 'ISBN' then
            local ISBN = internallinkid( handler );
            if not checkisbn( v ) and not is_set(options.IgnoreISBN) then
                ISBN = ISBN .. seterror( 'bad_isbn', {}, false, " ", "" );
            end
            table.insert( new_list, {handler.label, ISBN } );                
        else
            error( cfg.messages['unknown_manual_ID'] );
        end
    end
    
    function comp( a, b )
        return a[1] < b[1];
    end
    
    table.sort( new_list, comp );
    for k, v in ipairs( new_list ) do
        new_list[k] = v[2];
    end
    
    return new_list;
end
  
-- Chooses one matching parameter from a list of parameters to consider
-- Generates an error if more than one match is present.
function selectone( args, possible, error_condition, index )
    local value = nil;
    local selected = '';
    local error_list = {};
    
    if index ~= nil then index = tostring(index); end
    
    -- Handle special case of "#" replaced by empty string
    if index == '1' then
        for _, v in ipairs( possible ) do
            v = v:gsub( "#", "" );
            if is_set(args[v]) then
                if value ~= nil and selected ~= v then
                    table.insert( error_list, v );
                else
                    value = args[v];
                    selected = v;
                end
            end
        end        
    end
    
    for _, v in ipairs( possible ) do
        if index ~= nil then
            v = v:gsub( "#", index );
        end
        if is_set(args[v]) then
            if value ~= nil and selected ~=  v then
                table.insert( error_list, v );
            else
                value = args[v];
                selected = v;
            end
        end
    end
    
    if #error_list > 0 then
        local error_str = "";
        for _, k in ipairs( error_list ) do
            if error_str ~= "" then error_str = error_str .. cfg.messages['parameter-separator'] end
            error_str = error_str .. wrap( 'parameter', k );
        end
        if #error_list > 1 then
            error_str = error_str .. cfg.messages['parameter-final-separator'];
        else
            error_str = error_str .. cfg.messages['parameter-pair-separator'];
        end
        error_str = error_str .. wrap( 'parameter', selected );
        table.insert( z.message_tail, { seterror( error_condition, {error_str}, true ) } );
    end
    
    return value, selected;
end

-- COinS metadata (see <http://ocoins.info/>) allows automated tools to parse
-- the citation information.
function COinS(data)
    if 'table' ~= type(data) or nil == next(data) then
        return '';
    end
    
    local ctx_ver = "Z39.88-2004";
    
    -- treat table strictly as an array with only set values.
    local OCinSoutput = setmetatable( {}, {
        __newindex = function(self, key, value)
            if is_set(value) then
                rawset( self, #self+1, table.concat{ key, '=', mw.uri.encode( removewikilink( value ) ) } );
            end
        end
    });
    
    if is_set(data.Chapter) then
        OCinSoutput.rft_val_fmt = "info:ofi/fmt:kev:mtx:book";
        OCinSoutput["rft.genre"] = "bookitem";
        OCinSoutput["rft.btitle"] = data.Chapter;
        OCinSoutput["rft.atitle"] = data.Title;
    elseif is_set(data.Periodical) then
        OCinSoutput.rft_val_fmt = "info:ofi/fmt:kev:mtx:journal";
        OCinSoutput["rft.genre"] = "article";
        OCinSoutput["rft.jtitle"] = data.Periodical;
        OCinSoutput["rft.atitle"] = data.Title;
    else
        OCinSoutput.rft_val_fmt = "info:ofi/fmt:kev:mtx:book";
        OCinSoutput["rft.genre"] = "book"
        OCinSoutput["rft.btitle"] = data.Title;
    end
    
    OCinSoutput["rft.place"] = data.PublicationPlace;
    OCinSoutput["rft.date"] = data.Date;
    OCinSoutput["rft.series"] = data.Series;
    OCinSoutput["rft.volume"] = data.Volume;
    OCinSoutput["rft.issue"] = data.Issue;
    OCinSoutput["rft.pages"] = data.Pages;
    OCinSoutput["rft.edition"] = data.Edition;
    OCinSoutput["rft.pub"] = data.PublisherName;
    
    for k, v in pairs( data.ID_list ) do
        local id, value = cfg.id_handlers[k].COinS;
        if k == 'ISBN' then value = cleanisbn( v ); else value = v; end
        if string.sub( id or "", 1, 4 ) == 'info' then
            OCinSoutput["rft_id"] = table.concat{ id, "/", v };
        else
            OCinSoutput[ id ] = value;
        end
    end
    
    local last, first;
    for k, v in ipairs( data.Authors ) do
        last, first = v.last, v.first;
        if k == 1 then
            if is_set(last) then
                OCinSoutput["rft.aulast"] = last;
            end
            if is_set(first) then 
                OCinSoutput["rft.aufirst"] = first;
            end
        end
        if is_set(last) and is_set(first) then
            OCinSoutput["rft.au"] = table.concat{ last, ", ", first };
        elseif is_set(last) then
            OCinSoutput["rft.au"] = last;
        end
    end
    
    OCinSoutput.rft_id = data.URL;
    OCinSoutput.rfr_id = table.concat{ "info:sid/", mw.site.server:match( "[^/]*$" ), ":", data.RawPage };
    OCinSoutput = setmetatable( OCinSoutput, nil );
    
    -- sort with version string always first, and combine.
    table.sort( OCinSoutput );
    table.insert( OCinSoutput, 1, "ctx_ver=" .. ctx_ver );  -- such as "Z39.88-2004"
    return table.concat(OCinSoutput, "&");
end

--[[
This is the main function foing the majority of the citation
formatting.
]]
function citation0( config, args)
    --[[ 
    Load Input Parameters
    The argment_wrapper facillitates the mapping of multiple
    aliases to single internal variable.
    ]]
    local A = argument_wrapper( args );

    local i 
    local PPrefix = A['PPrefix']
    local PPPrefix = A['PPPrefix']
    if is_set( A['NoPP'] ) then PPPrefix = "" PPrefix = "" end
    
    -- Pick out the relevant fields from the arguments.  Different citation templates
    -- define different field names for the same underlying things.    
    local Authors = A['Authors'];
    local a = extractnames( args, 'AuthorList' );

    local Coauthors = A['Coauthors'];
    local Others = A['Others'];
    local Editors = A['Editors'];
    local e = extractnames( args, 'EditorList' );

    local Year = A['Year'];
    local PublicationDate = A['PublicationDate'];
    local OrigYear = A['OrigYear'];
    local Date = A['Date'];
    local LayDate = A['LayDate'];
    ------------------------------------------------- Get title data
    local Title = A['Title'];
    local BookTitle = A['BookTitle'];
    local Conference = A['Conference'];
    local TransTitle = A['TransTitle'];
    local TitleNote = A['TitleNote'];
    local TitleLink = A['TitleLink'];
    local Chapter = A['Chapter'];
    local ChapterLink = A['ChapterLink'];
    local TransChapter = A['TransChapter'];
    local TitleType = A['TitleType'];
    local ArchiveURL = A['ArchiveURL'];
    local URL = A['URL']
    local URLorigin = A:ORIGIN('URL');
    local ChapterURL = A['ChapterURL'];
    local ChapterURLorigin = A:ORIGIN('ChapterURL');
    local ConferenceURL = A['ConferenceURL'];
    local ConferenceURLorigin = A:ORIGIN('ConferenceURL');
    local Periodical = A['Periodical'];
    
    if ( config.CitationClass == "encyclopaedia" ) then
        if not is_set(Chapter) then
            if not is_set(Title) then
                Title = Periodical;
                Periodical = '';
            else
                Chapter = Title
                TransChapter = TransTitle
                Title = '';
                TransTitle = '';
            end
        end
    end

    local Series = A['Series'];
    local Volume = A['Volume'];
    local Issue = A['Issue'];
    local Position = '';
    local Page, Pages, At, page_type;
    
    Page = A['Page'];
    Pages = hyphentodash( A['Pages'] );
    At = A['At'];
    
    if is_set(Page) then
        if is_set(Pages) or is_set(At) then
            Page = Page .. " " .. seterror('extra_pages');
            Pages = '';
            At = '';
        end
    elseif is_set(Pages) then
        if is_set(At) then
            Pages = Pages .. " " .. seterror('extra_pages');
            At = '';
        end
    end    
    
    local Edition = A['Edition'];
    local PublicationPlace = A['PublicationPlace']
    local Place = A['Place'];
    
    if not is_set(PublicationPlace) and is_set(Place) then
        PublicationPlace = Place;
    end
    
    if PublicationPlace == Place then Place = ''; end
    
    local PublisherName = A['PublisherName'];
    local RegistrationRequired = A['RegistrationRequired'];
    local SubscriptionRequired = A['SubscriptionRequired'];
    local Via = A['Via'];
    local AccessDate = A['AccessDate'];
    local ArchiveDate = A['ArchiveDate'];
    local Agency = A['Agency'];
    local DeadURL = A['DeadURL']
    local Language = A['Language'];
    local Format = A['Format'];
    local Ref = A['Ref'];
    
    local DoiBroken = A['DoiBroken'];
    local ID = A['ID'];
    local ASINTLD = A['ASINTLD'];
    local IgnoreISBN = A['IgnoreISBN'];
    local Embargo = A['Embargo'];

    local ID_list = extractids( args );
    
    local Quote = A['Quote'];
    local PostScript = A['PostScript'];
    local LayURL = A['LayURL'];
    local LaySource = A['LaySource'];
    local Transcript = A['Transcript'];
    local TranscriptURL = A['TranscriptURL'] 
    local TranscriptURLorigin = A:ORIGIN('TranscriptURL');
    local sepc = A['Separator'];
    local LastAuthorAmp = A['LastAuthorAmp'];
    local no_tracking_cats = A['NoTracking'];

    local use_lowercase = ( sepc ~= '.' );
    local this_page = mw.title.getCurrentTitle();  --Also used for COinS and for language
    
    if not is_set(no_tracking_cats) then
        for k, v in pairs( cfg.uncategorized_namespaces ) do
            if this_page.nsText == v then
                no_tracking_cats = "true";
                break;
            end
        end
    end

    -- At this point fields may be nil if they weren't specified in the template use.  We can use that fact.
    
    -- Account for the oddity that is {{cite conference}}, before generation of COinS data.
    if is_set(BookTitle) then
        Chapter = Title;
        ChapterLink = TitleLink;
        TransChapter = TransTitle;
        Title = BookTitle;
        TitleLink = '';
        TransTitle = '';
    end
    -- Account for the oddity that is {{cite episode}}, before generation of COinS data.
    if config.CitationClass == "episode" then
        local AirDate = A['AirDate'];
        local SeriesLink = A['SeriesLink'];
        local Season = A['Season'];
        local SeriesNumber = A['SeriesNumber'];
        local Network = A['Network'];
        local Station = A['Station'];
        local s, n = {}, {};
        local Sep = (first_set(A["SeriesSeparator"], A["Separator"]) or "") .. " ";
        
        if is_set(Issue) then table.insert(s, cfg.messages["episode"] .. " " .. Issue); Issue = ''; end
        if is_set(Season) then table.insert(s, cfg.messages["season"] .. " " .. Season); end
        if is_set(SeriesNumber) then table.insert(s, cfg.messages["series"] .. " " .. SeriesNumber); end
        if is_set(Network) then table.insert(n, Network); end
        if is_set(Station) then table.insert(n, Station); end
        
        Date = Date or AirDate;
        Chapter = Title;
        ChapterLink = TitleLink;
        TransChapter = TransTitle;
        Title = Series;
        TitleLink = SeriesLink;
        TransTitle = '';
        
        Series = table.concat(s, Sep);
        ID = table.concat(n, Sep);
    end
    
    -- COinS metadata (see <http://ocoins.info/>) for
    -- automated parsing of citation information.
    local OCinSoutput = COinS{
        ['Periodical'] = Periodical,
        ['Chapter'] = Chapter,
        ['Title'] = Title,
        ['PublicationPlace'] = PublicationPlace,
        ['Date'] = first_set(Date, Year, PublicationDate),
        ['Series'] = Series,
        ['Volume'] = Volume,
        ['Issue'] = Issue,
        ['Pages'] = first_set(Page, Pages, At),
        ['Edition'] = Edition,
        ['PublisherName'] = PublisherName,
        ['URL'] = first_set( URL, ChapterURL ),
        ['Authors'] = a,
        ['ID_list'] = ID_list,
        ['RawPage'] = this_page.prefixedText,
    };

    if is_set(Periodical) and not is_set(Chapter) and is_set(Title) then
        Chapter = Title;
        ChapterLink = TitleLink;
        TransChapter = TransTitle;
        Title = '';
        TitleLink = '';
        TransTitle = '';
    end

    -- Now perform various field substitutions.
    -- We also add leading spaces and surrounding markup and punctuation to the
    -- various parts of the citation, but only when they are non-nil.
    if not is_set(Authors) then
        local Maximum = tonumber( A['DisplayAuthors'] );
        
        -- Preserve old-style implicit et al.
        if not is_set(Maximum) and #a == 9 then 
            Maximum = 8;
            table.insert( z.message_tail, { seterror('implict_etal_author', {}, true ) } );
        elseif not is_set(Maximum) then
            Maximum = #a + 1;
        end
            
        local control = { 
            sep = A["AuthorSeparator"] .. " ",
            namesep = (first_set(A["AuthorNameSeparator"], A["NameSeparator"]) or "") .. " ",
            format = A["AuthorFormat"],
            maximum = Maximum,
            lastauthoramp = LastAuthorAmp
        };
        
        -- If the coauthor field is also used, prevent ampersand and et al. formatting.
        if is_set(Coauthors) then
            control.lastauthoramp = nil;
            control.maximum = #a + 1;
        end
        
        Authors = listpeople(control, a) 
    end

	if not is_set(Authors) and is_set(Coauthors) then	-- coauthors aren't displayed if one of authors=, authorn=, or lastn= isn't specified
		table.insert( z.message_tail, { seterror('coauthors_missing_author', {}, true) } );	-- emit error message
	end

    local EditorCount
    if not is_set(Editors) then
        local Maximum = tonumber( A['DisplayEditors'] );
        -- Preserve old-style implicit et al.
        if not is_set(Maximum) and #e == 4 then 
            Maximum = 3;
            table.insert( z.message_tail, { seterror('implict_etal_editor', {}, true) } );
        elseif not is_set(Maximum) then
            Maximum = #e + 1;
        end

        local control = { 
            sep = A["EditorSeparator"] .. " ",
            namesep = (first_set(A["EditorNameSeparator"], A["NameSeparator"]) or "") .. " ",
            format = A['EditorFormat'],
            maximum = Maximum,
            lastauthoramp = LastAuthorAmp
        };

        Editors, EditorCount = listpeople(control, e);
    else
        EditorCount = 1;
    end

    local Cartography = "";
    local Scale = "";
    if config.CitationClass == "map" then
        if not is_set( Authors ) and is_set( PublisherName ) then
            Authors = PublisherName;
            PublisherName = "";
        end
        Cartography = A['Cartography'];
        if is_set( Cartography ) then
            Cartography = sepc .. " " .. wrap( 'cartography', Cartography, use_lowercase );
        end        
        Scale = A['Scale'];
        if is_set( Scale ) then
            Scale = sepc .. " " .. Scale;
        end        
    end
    
    if not is_set(Date) then
        Date = Year;
        if is_set(Date) then
            local Month = A['Month'];
            if is_set(Month) then 
                Date = Month .. " " .. Date;
                local Day = A['Day']
                if is_set(Day) then Date = Day .. " " .. Date end
            end
        end
    end
    
    if inArray(PublicationDate, {Date, Year}) then PublicationDate = ''; end
    if not is_set(Date) and is_set(PublicationDate) then
        Date = PublicationDate;
        PublicationDate = '';
    end

    -- Captures the value for Date prior to adding parens or other textual transformations
    local DateIn = Date;
    
    if  not is_set(URL) and
        not is_set(ChapterURL) and
        not is_set(ArchiveURL) and
        not is_set(ConferenceURL) and
        not is_set(TranscriptURL) then
        
        -- Test if cite web is called without giving a URL
        if ( config.CitationClass == "web" ) then
            table.insert( z.message_tail, { seterror( 'cite_web_url', {}, true ) } );
        end
        
        -- Test if accessdate is given without giving a URL
        if is_set(AccessDate) then
            table.insert( z.message_tail, { seterror( 'accessdate_missing_url', {}, true ) } );
            AccessDate = '';
        end
        
        -- Test if format is given without giving a URL
        if is_set(Format) then
            Format = Format .. seterror( 'format_missing_url' );
        end
    end
    
    -- Test if citation has no title
    if  not is_set(Chapter) and
        not is_set(Title) and
        not is_set(Periodical) and
        not is_set(Conference) and
        not is_set(TransTitle) and
        not is_set(TransChapter) then
        table.insert( z.message_tail, { seterror( 'citation_missing_title', {}, true ) } );
    end
    
    Format = is_set(Format) and " (" .. Format .. ")" or "";
    
    local OriginalURL = URL
    DeadURL = DeadURL:lower();
    if is_set( ArchiveURL ) then
        if ( DeadURL ~= "no" ) then
            URL = ArchiveURL
            URLorigin = A:ORIGIN('ArchiveURL')
        end
    end
    
    -- Format chapter / article title
    if is_set(Chapter) and is_set(ChapterLink) then 
        Chapter = "[[" .. ChapterLink .. "|" .. Chapter .. "]]";
    end
    if is_set(Periodical) and is_set(Title) then
        Chapter = wrap( 'italic-title', Chapter );
        TransChapter = wrap( 'trans-italic-title', TransChapter );
    else
        Chapter = wrap( 'quoted-title', Chapter );
        TransChapter = wrap( 'trans-quoted-title', TransChapter );
    end
    
    local TransError = ""
    if is_set(TransChapter) then
        if not is_set(Chapter) then
            TransError = " " .. seterror( 'trans_missing_chapter' );
        else
            TransChapter = " " .. TransChapter;
        end
    end
    
    Chapter = Chapter .. TransChapter;
    
    if is_set(Chapter) then
        if not is_set(ChapterLink) then
            if is_set(ChapterURL) then
                Chapter = externallink( ChapterURL, Chapter ) .. TransError;
                if not is_set(URL) then
                    Chapter = Chapter .. Format;
                    Format = "";
                end
            elseif is_set(URL) then 
                Chapter = externallink( URL, Chapter ) .. TransError .. Format;
                URL = "";
                Format = "";
            else
                Chapter = Chapter .. TransError;
            end            
        elseif is_set(ChapterURL) then
            Chapter = Chapter .. " " .. externallink( ChapterURL, nil, ChapterURLorigin ) .. 
                TransError;
        else
            Chapter = Chapter .. TransError;
        end
        Chapter = Chapter .. sepc .. " " -- with end-space
    elseif is_set(ChapterURL) then
        Chapter = " " .. externallink( ChapterURL, nil, ChapterURLorigin ) .. sepc .. " ";
    end        
    
    -- Format main title.
    if is_set(TitleLink) and is_set(Title) then
        Title = "[[" .. TitleLink .. "|" .. Title .. "]]"
    end
    
    if is_set(Periodical) then
        Title = wrap( 'quoted-title', Title );
        TransTitle = wrap( 'trans-quoted-title', TransTitle );
    elseif inArray(config.CitationClass, {"web","news","pressrelease","conference"}) and
            not is_set(Chapter) then
        Title = wrap( 'quoted-title', Title );
        TransTitle = wrap( 'trans-quoted-title', TransTitle );
    else
        Title = wrap( 'italic-title', Title );
        TransTitle = wrap( 'trans-italic-title', TransTitle );
    end
    
    TransError = "";
    if is_set(TransTitle) then
        if not is_set(Title) then
            TransError = " " .. seterror( 'trans_missing_title' );
        else
            TransTitle = " " .. TransTitle;
        end
    end
    
    Title = Title .. TransTitle;
    
    if is_set(Title) then
        if not is_set(TitleLink) and is_set(URL) then 
            Title = externallink( URL, Title ) .. TransError .. Format       
            URL = "";
            Format = "";
        else
            Title = Title .. TransError;
        end
    end
    
    if is_set(Place) then
        Place = " " .. wrap( 'written', Place, use_lowercase ) .. sepc .. " ";
    end
    
    if is_set(Conference) then
        if is_set(ConferenceURL) then
            Conference = externallink( ConferenceURL, Conference );
        end
        Conference = sepc .. " " .. Conference
    elseif is_set(ConferenceURL) then
        Conference = sepc .. " " .. externallink( ConferenceURL, nil, ConferenceURLorigin );
    end
    
    if not is_set(Position) then
        local Minutes = A['Minutes'];
        if is_set(Minutes) then
            Position = " " .. Minutes .. " " .. cfg.messages['minutes'];
        else
            local Time = A['Time'];
            if is_set(Time) then
                local TimeCaption = A['TimeCaption']
                if not is_set(TimeCaption) then
                    TimeCaption = cfg.messages['event'];
                    if sepc ~= '.' then
                        TimeCaption = TimeCaption:lower();
                    end
                end
                Position = " " .. TimeCaption .. " " .. Time;
            end
        end
    else
        Position = " " .. Position;
        At = '';
    end
    
    if not is_set(Page) then
        if is_set(Pages) then
            if is_set(Periodical) and
                not inArray(config.CitationClass, {"encyclopaedia","web","book","news"}) then
                Pages = ": " .. Pages;
            elseif tonumber(Pages) ~= nil then
                Pages = sepc .." " .. PPrefix .. Pages;
            else
                Pages = sepc .." " .. PPPrefix .. Pages;
            end
        end
    else
        if is_set(Periodical) and
            not inArray(config.CitationClass, {"encyclopaedia","web","book","news"}) then
            Page = ": " .. Page;
        else
            Page = sepc .." " .. PPrefix .. Page;
        end
    end
    
    At = is_set(At) and (sepc .. " " .. At) or "";
    Position = is_set(Position) and (sepc .. " " .. Position) or "";
    if config.CitationClass == 'map' then
        local Section = A['Section'];
        local Inset = A['Inset'];
        if first_set( Pages, Page, At ) ~= nil or sepc ~= '.' then
            if is_set( Section ) then
                Section = ", " .. wrap( 'section', Section, true );
            end
            if is_set( Inset ) then
                Inset = ", " .. wrap( 'inset', Inset, true );
            end
        else
            if is_set( Section ) then
                Section = sepc .. " " .. wrap( 'section', Section, use_lowercase );
                if is_set( Inset ) then
                    Inset = ", " .. wrap( 'inset', Inset, true );
                end
            elseif is_set( Inset ) then
                Inset = sepc .. " " .. wrap( 'inset', Inset, use_lowercase );
            end            
        end            
        At = At .. Section .. Inset;        
    end    

	--[[Look in the list of iso639-1 language codes to see if the value provided in the language parameter matches one of them.  If a match is found, 
	use that value; if not, then use the value that was provided with the language parameter.
	
	Categories are assigned in a manner similar to the {{xx icon}} templates - categorizes only mainspace citations and only when the language code is not 'en' (English).
	]]
	if is_set (Language) then
		local name = cfg.iso639_1[Language:lower()];		-- get the language name if Language parameter has a valid iso 639-1 code
		if nil == name then
			Language=" " .. wrap( 'language', Language );	-- no match, use parameter's value
		else
			if 0 == this_page.namespace and 'en' ~= Language:lower() then	--found a match; is this page main / article space and English not the language?
				Language=" " .. wrap( 'language', name .. '[[Category:Articles with ' .. name .. '-language external links]]' );	-- in main space and not English: categorize
			else
				Language=" " .. wrap( 'language', name );	--not in mainspace or language is English so don't categorize
			end
		end
	else
		Language="";	-- language not specified so make sure this is an empty string;
	end

    Others = is_set(Others) and (sepc .. " " .. Others) or "";
    TitleType = is_set(TitleType) and (" (" .. TitleType .. ")") or "";
    TitleNote = is_set(TitleNote) and (sepc .. " " .. TitleNote) or "";
    Edition = is_set(Edition) and (" " .. wrap( 'edition', Edition )) or "";
    Issue = is_set(Issue) and (" (" .. Issue .. ")") or "";
    Series = is_set(Series) and (sepc .. " " .. Series) or "";
    OrigYear = is_set(OrigYear) and (" [" .. OrigYear .. "]") or "";
    Agency = is_set(Agency) and (sepc .. " " .. Agency) or "";
    
    if is_set(Volume) then
        if ( mw.ustring.len(Volume) > 4 )
          then Volume = sepc .." " .. Volume;
          else Volume = " <b>" .. hyphentodash(Volume) .. "</b>";
        end
    end
    
    ------------------------------------ totally unrelated data
    --[[ Loosely mimic {{subscription required}} template; Via parameter identifies a delivery source that is not the publisher; these sources often, but not always, exist
    behind a registration or paywall.  So here, we've chosen to decouple via from subscription (via has never been part of the registration required template).
    
    Subscription implies paywall; Registration does not.  If both are used in a citation, the subscription required link note is displayed. There are no error messages for this condition.
    ]]
    if is_set(Via) then
        Via = " " .. wrap( 'via', Via );
    end

	if is_set(SubscriptionRequired) then
        SubscriptionRequired = sepc .. " " .. cfg.messages['subscription']; --here when 'via' parameter not used but 'subscription' is
    elseif is_set(RegistrationRequired) then
        SubscriptionRequired = sepc .. " " .. cfg.messages['registration']; --here when 'via' and 'subscription' parameters not used but 'registration' is
    end

    if is_set(AccessDate) then
        local retrv_text = " " .. cfg.messages['retrieved']
        if (sepc ~= ".") then retrv_text = retrv_text:lower() end
        AccessDate = '<span class="reference-accessdate">' .. sepc
            .. substitute( retrv_text, {AccessDate} ) .. '</span>'
    end
    
    if is_set(ID) then ID = sepc .." ".. ID; end
    
    ID_list = buildidlist( ID_list, {DoiBroken = DoiBroken, ASINTLD = ASINTLD, IgnoreISBN = IgnoreISBN, Embargo=Embargo} );

    if is_set(URL) then
        URL = " " .. externallink( URL, nil, URLorigin );
    end

    if is_set(Quote) then
        if Quote:sub(1,1) == '"' and Quote:sub(-1,-1) == '"' then
            Quote = Quote:sub(2,-2);
        end
        Quote = sepc .." " .. wrap( 'quoted-text', Quote ); 
        PostScript = "";
    elseif PostScript:lower() == "none" then
        PostScript = "";
    end
    
    local Archived
    if is_set(ArchiveURL) then
        if not is_set(ArchiveDate) then
            ArchiveDate = seterror('archive_missing_date');
        end
        if "no" == DeadURL then
            local arch_text = cfg.messages['archived'];
            if sepc ~= "." then arch_text = arch_text:lower() end
            Archived = sepc .. " " .. substitute( cfg.messages['archived-not-dead'],
                { externallink( ArchiveURL, arch_text ), ArchiveDate } );
            if not is_set(OriginalURL) then
                Archived = Archived .. " " .. seterror('archive_missing_url');                               
            end
        elseif is_set(OriginalURL) then
            local arch_text = cfg.messages['archived-dead'];
            if sepc ~= "." then arch_text = arch_text:lower() end
            Archived = sepc .. " " .. substitute( arch_text,
                { externallink( OriginalURL, cfg.messages['original'] ), ArchiveDate } );
        else
            local arch_text = cfg.messages['archived-missing'];
            if sepc ~= "." then arch_text = arch_text:lower() end
            Archived = sepc .. " " .. substitute( arch_text, 
                { seterror('archive_missing_url'), ArchiveDate } );
        end
    else
        Archived = ""
    end
    
    local Lay
    if is_set(LayURL) then
        if is_set(LayDate) then LayDate = " (" .. LayDate .. ")" end
        if is_set(LaySource) then 
            LaySource = " &ndash; ''" .. safeforitalics(LaySource) .. "''";
        else
            LaySource = "";
        end
        if sepc == '.' then
            Lay = sepc .. " " .. externallink( LayURL, cfg.messages['lay summary'] ) .. LaySource .. LayDate
        else
            Lay = sepc .. " " .. externallink( LayURL, cfg.messages['lay summary']:lower() ) .. LaySource .. LayDate
        end            
    else
        Lay = "";
    end
    
    if is_set(Transcript) then
        if is_set(TranscriptURL) then Transcript = externallink( TranscriptURL, Transcript ); end
    elseif is_set(TranscriptURL) then
        Transcript = externallink( TranscriptURL, nil, TranscriptURLorigin );
    end
    
    local Publisher;
    if is_set(Periodical) and
        not inArray(config.CitationClass, {"encyclopaedia","web","pressrelease"}) then
        if is_set(PublisherName) then
            if is_set(PublicationPlace) then
                Publisher = PublicationPlace .. ": " .. PublisherName;
            else
                Publisher = PublisherName;  
            end
        elseif is_set(PublicationPlace) then
            Publisher= PublicationPlace;
        else 
            Publisher = "";
        end
        if is_set(PublicationDate) then
            if is_set(Publisher) then
                Publisher = Publisher .. ", " .. wrap( 'published', PublicationDate );
            else
                Publisher = PublicationDate;
            end
        end
        if is_set(Publisher) then
            Publisher = " (" .. Publisher .. ")";
        end
    else
        if is_set(PublicationDate) then
            PublicationDate = " (" .. wrap( 'published', PublicationDate ) .. ")";
        end
        if is_set(PublisherName) then
            if is_set(PublicationPlace) then
                Publisher = sepc .. " " .. PublicationPlace .. ": " .. PublisherName .. PublicationDate;
            else
                Publisher = sepc .. " " .. PublisherName .. PublicationDate;  
            end            
        elseif is_set(PublicationPlace) then 
            Publisher= sepc .. " " .. PublicationPlace .. PublicationDate;
        else 
            Publisher = PublicationDate;
        end
    end
    
    -- Several of the above rely upon detecting this as nil, so do it last.
    if is_set(Periodical) then
        if is_set(Title) or is_set(TitleNote) then 
            Periodical = sepc .. " " .. wrap( 'italic-title', Periodical ) 
        else 
            Periodical = wrap( 'italic-title', Periodical )
        end
    end

    -- Piece all bits together at last.  Here, all should be non-nil.
    -- We build things this way because it is more efficient in LUA
    -- not to keep reassigning to the same string variable over and over.

    local tcommon
    if inArray(config.CitationClass, {"journal","citation"}) and is_set(Periodical) then
        if is_set(Others) then Others = Others .. sepc .. " " end
        tcommon = safejoin( {Others, Title, TitleNote, Conference, Periodical, Format, TitleType, Scale, Series, 
            Language, Cartography, Edition, Publisher, Agency, Volume, Issue}, sepc );
    else 
        tcommon = safejoin( {Title, TitleNote, Conference, Periodical, Format, TitleType, Scale, Series, Language, 
            Volume, Issue, Others, Cartography, Edition, Publisher, Agency}, sepc );
    end
    
    if #ID_list > 0 then
        ID_list = safejoin( { sepc .. " ",  table.concat( ID_list, sepc .. " " ), ID }, sepc );
    else
        ID_list = ID;
    end
    
    local idcommon = safejoin( { ID_list, URL, Archived, AccessDate, Via, SubscriptionRequired, Lay, Quote }, sepc );
    local text;
    local pgtext = Position .. Page .. Pages .. At;
    
    if is_set(Authors) then
        if is_set(Coauthors) then
            Authors = Authors .. A['AuthorSeparator'] .. " " .. Coauthors
        end
        if is_set(Date) then
            Date = " ("..Date..")" .. OrigYear .. sepc .. " "
        elseif string.sub(Authors,-1,-1) == sepc then
            Authors = Authors .. " "
        else
            Authors = Authors .. sepc .. " "
        end
        if is_set(Editors) then
            local in_text = " ";
            local post_text = "";
            if is_set(Chapter) then
                in_text = in_text .. cfg.messages['in'] .. " "
            else
                if EditorCount <= 1 then
                    post_text = ", " .. cfg.messages['editor'];
                else
                    post_text = ", " .. cfg.messages['editors'];
                end
            end 
            if (sepc ~= '.') then in_text = in_text:lower() end
            Editors = in_text .. Editors .. post_text;
            if (string.sub(Editors,-1,-1) == sepc)
                then Editors = Editors .. " "
                else Editors = Editors .. sepc .. " "
            end
        end
        text = safejoin( {Authors, Date, Chapter, Place, Editors, tcommon }, sepc );
        text = safejoin( {text, pgtext, idcommon}, sepc );
    elseif is_set(Editors) then
        if is_set(Date) then
            if EditorCount <= 1 then
                Editors = Editors .. ", " .. cfg.messages['editor'];
            else
                Editors = Editors .. ", " .. cfg.messages['editors'];
            end
            Date = " (" .. Date ..")" .. OrigYear .. sepc .. " "
        else
            if EditorCount <= 1 then
                Editors = Editors .. " (" .. cfg.messages['editor'] .. ")" .. sepc .. " "
            else
                Editors = Editors .. " (" .. cfg.messages['editors'] .. ")" .. sepc .. " "
            end
        end
        text = safejoin( {Editors, Date, Chapter, Place, tcommon}, sepc );
        text = safejoin( {text, pgtext, idcommon}, sepc );
    else
        if is_set(Date) then
            if ( string.sub(tcommon,-1,-1) ~= sepc )
              then Date = sepc .." " .. Date .. OrigYear
              else Date = " " .. Date .. OrigYear
            end
        end
        if config.CitationClass=="journal" and is_set(Periodical) then
            text = safejoin( {Chapter, Place, tcommon}, sepc );
            text = safejoin( {text, pgtext, Date, idcommon}, sepc );
        else
            text = safejoin( {Chapter, Place, tcommon, Date}, sepc );
            text = safejoin( {text, pgtext, idcommon}, sepc );
        end
    end
    
    if is_set(PostScript) and PostScript ~= sepc then
        text = safejoin( {text, sepc}, sepc );  --Deals with italics, spaces, etc.
        text = text:sub(1,-2); --Remove final seperator    
    end    
    
    text = safejoin( {text, PostScript}, sepc );

    -- Now enclose the whole thing in a <span/> element
    if not is_set(Year) then
        if is_set(DateIn) then
            Year = selectyear( DateIn );
        elseif is_set(PublicationDate) then
            Year = selectyear( PublicationDate );
        end
    end
    
    local options = {};
    
    if is_set(config.CitationClass) and config.CitationClass ~= "citation" then
        options.class = "citation " .. config.CitationClass;
    else
        options.class = "citation";
    end
    
    if is_set(Ref) and Ref:lower() ~= "none" then
        local id = Ref
        if ( "harv" == Ref ) then
            local names = {} --table of last names & year
            if #a > 0 then
                for i,v in ipairs(a) do 
                    names[i] = v.last 
                    if i == 4 then break end
                end
            elseif #e > 0 then
                for i,v in ipairs(e) do 
                    names[i] = v.last 
                    if i == 4 then break end                
                end
            end
            names[ #names + 1 ] = Year;
            id = anchorid(names)
        end
        options.id = id;
    end
    
    if string.len(text:gsub("<span[^>/]*>.-</span>", ""):gsub("%b<>","")) <= 2 then
        z.error_categories = {};
        text = seterror('empty_citation');
        z.message_tail = {};
    end
    
    if is_set(options.id) then 
        text = '<span id="' .. mw.uri.anchorEncode(options.id) ..'" class="' .. mw.text.nowiki(options.class) .. '">' .. text .. "</span>";
    else
        text = '<span class="' .. mw.text.nowiki(options.class) .. '">' .. text .. "</span>";
    end        

    local empty_span = '<span style="display:none;">&nbsp;</span>';
    
    -- Note: Using display: none on then COinS span breaks some clients.
    local OCinS = '<span title="' .. OCinSoutput .. '" class="Z3988">' .. empty_span .. '</span>';
    text = text .. OCinS;
    
    if #z.message_tail ~= 0 then
        text = text .. " ";
        for i,v in ipairs( z.message_tail ) do
            if is_set(v[1]) then
                if i == #z.message_tail then
                    text = text .. errorcomment( v[1], v[2] );
                else
                    text = text .. errorcomment( v[1] .. "; ", v[2] );
                end
            end
        end
    end
    
    no_tracking_cats = no_tracking_cats:lower();
    if inArray(no_tracking_cats, {"", "no", "false", "n"}) then
        for _, v in ipairs( z.error_categories ) do
            text = text .. '[[Category:' .. v ..']]';
        end
    end
    
    return text
end

-- This is used by templates such as {{cite book}} to create the actual citation text.
function z.citation(frame)
    local pframe = frame:getParent()
    
    local args = {};
    local suggestions = {};
    local error_text, error_state;

    local config = {};
    for k, v in pairs( frame.args ) do
        config[k] = v;
        args[k] = v;       
    end    

    for k, v in pairs( pframe.args ) do
        if v ~= '' then
            if not validate( k ) then            
                error_text = "";
                if type( k ) ~= 'string' then
                    -- Exclude empty numbered parameters
                    if v:match("%S+") ~= nil then
                        error_text, error_state = seterror( 'text_ignored', {v}, true );
                    end
                elseif validate( k:lower() ) then 
                    error_text, error_state = seterror( 'parameter_ignored_suggest', {k, k:lower()}, true );
                else
                    if #suggestions == 0 then
                        suggestions = mw.loadData( 'Module:Citation/CS1/Suggestions' );
                    end
                    if suggestions[ k:lower() ] ~= nil then
                        error_text, error_state = seterror( 'parameter_ignored_suggest', {k, suggestions[ k:lower() ]}, true );
                    else
                        error_text, error_state = seterror( 'parameter_ignored', {k}, true );
                    end
                end                  
                if error_text ~= '' then
                    table.insert( z.message_tail, {error_text, error_state} );
                end                
            end
            args[k] = v;
        elseif args[k] ~= nil or (k == 'postscript') then
            args[k] = v;
        end        
    end    
    
    return citation0( config, args)
end

return z