local z = {

	error_cats_t = {};															-- for categorizing citations that contain errors

	error_ids_t = {};															-- list of error identifiers; used to prevent duplication of certain errors; local to this module

	error_msgs_t = {};															-- sequence table of error messages

	maint_cats_t = {};															-- for categorizing citations that aren't erroneous per se, but could use a little work

	prop_cats_t = {};															-- for categorizing citations based on certain properties, language of source for instance

	prop_keys_t = {};															-- for adding classes to the citation's <cite> tag

};





--[[--------------------------< F O R W A R D   D E C L A R A T I O N S >--------------------------------------

]]



local cfg;																		-- table of tables imported from selected Module:Citation/CS1/Configuration





--[[--------------------------< I S _ S E T >------------------------------------------------------------------



Returns true if argument is set; false otherwise. Argument is 'set' when it exists (not nil) or when it is not an empty string.



]]



local function is_set (var)

	return not (var == nil or var == '');

end





--[[--------------------------< I N _ A R R A Y >--------------------------------------------------------------



Whether needle is in haystack



]]



local function in_array (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





--[[--------------------------< H A S _ A C C E P T _ A S _ W R I T T E N >------------------------------------



When <str> is wholly wrapped in accept-as-written markup, return <str> without markup and true; return <str> and false else



with allow_empty = false, <str> must have at least one character inside the markup

with allow_empty = true, <str> the markup frame can be empty like (()) to distinguish an empty template parameter from the specific condition "has no applicable value" in citation-context.



After further evaluation the two cases might be merged at a later stage, but should be kept separated for now.



]]



local function has_accept_as_written (str, allow_empty)

	if not is_set (str) then

		return str, false;

	end



	local count;



	if true == allow_empty then

		str, count = str:gsub ('^%(%((.*)%)%)$', '%1'); 						-- allows (()) to be an empty set

	else

		str, count = str:gsub ('^%(%((.+)%)%)$', '%1');

	end

	return str, 0 ~= count;

end





--[[--------------------------< S U B S T I T U T E >----------------------------------------------------------



Populates numbered arguments in a message string using an argument table. <args> may be a single string or a

sequence table of multiple strings.



]]



local function substitute (msg, args)

	return args and mw.message.newRawMessage (msg, args):plain() or msg;

end





--[[--------------------------< E R R O R _ C O M M E N T >----------------------------------------------------



Wraps error messages with CSS markup according to the state of hidden. <content> may be a single string or a

sequence table of multiple strings.



]]



local function error_comment (content, hidden)

	return substitute (hidden and cfg.presentation'hidden-error' or cfg.presentation'visible-error'], content);

end





--[[--------------------------< H Y P H E N _ T O _ D A S H >--------------------------------------------------



Converts a hyphen to a dash under certain conditions.  The hyphen must separate

like items; unlike items are returned unmodified.  These forms are modified:

	letter - letter (A - B)

	digit - digit (4-5)

	digit separator digit - digit separator digit (4.1-4.5 or 4-1-4-5)

	letterdigit - letterdigit (A1-A5) (an optional separator between letter and

		digit is supported – a.1-a.5 or a-1-a-5)

	digitletter - digitletter (5a - 5d) (an optional separator between letter and

		digit is supported – 5.a-5.d or 5-a-5-d)



any other forms are returned unmodified.



str may be a comma- or semicolon-separated list



]]



local function hyphen_to_dash (str)

	if not is_set (str) then

		return str;

	end



	local accept;																-- boolean



	str = str:gsub ("(%(%(.-%)%))", function(m) return m:gsub(",", "，"):gsub(";", "；") end) -- replace commas and semicolons in accept-as-written markup with similar unicode characters so they'll be ignored during the split	

	str = str:gsub ('&[nm]dash;', {['&ndash;' = '–', '&mdash;' = '—'});		-- replace &mdash; and &ndash; entities with their characters; semicolon mucks up the text.split

	str = str:gsub ('&#45;', '-'); -- replace HTML numeric entity with hyphen character

	str = str:gsub ('&nbsp;', ' '); -- replace &nbsp; entity with generic keyboard space character

	

	local out = {};

	local list = mw.text.split (str, '%s*[,;]%s*');								-- split str at comma or semicolon separators if there are any



	for _, item in ipairs (list) do												-- for each item in the list

		item, accept = has_accept_as_written (item);							-- remove accept-this-as-written markup when it wraps all of item

		if not accept and mw.ustring.match (item, '^%w*[%.%-]?%w+%s*[%-–—]%s*%w*[%.%-]?%w+$') then	-- if a hyphenated range or has endash or emdash separators

			if item:match ('^%a+[%.%-]?%d+%s*%-%s*%a+[%.%-]?%d+$') or			-- letterdigit hyphen letterdigit (optional separator between letter and digit)

				item:match ('^%d+[%.%-]?%a+%s*%-%s*%d+[%.%-]?%a+$') or			-- digitletter hyphen digitletter (optional separator between digit and letter)

				item:match ('^%d+[%.%-]%d+%s*%-%s*%d+[%.%-]%d+$') or			-- digit separator digit hyphen digit separator digit

				item:match ('^%d+%s*%-%s*%d+$') or								-- digit hyphen digit

				item:match ('^%a+%s*%-%s*%a+$') then							-- letter hyphen letter

					item = item:gsub ('(%w*[%.%-]?%w+)%s*%-%s*(%w*[%.%-]?%w+)', '%1–%2');	-- replace hyphen, remove extraneous space characters

			else

				item = mw.ustring.gsub (item, '%s*[–—]%s*', '–');				-- for endash or emdash separated ranges, replace em with en, remove extraneous whitespace

			end

		end

		table.insert (out, item);												-- add the (possibly modified) item to the output table

	end



	local temp_str = '';														-- concatenate the output table into a comma separated string

	temp_str, accept = has_accept_as_written (table.concat (out, ', '));		-- remove accept-this-as-written markup when it wraps all of concatenated out

	if accept then

		temp_str = has_accept_as_written (str);									-- when global markup removed, return original str; do it this way to suppress boolean second return value

		return temp_str:gsub("，", ","):gsub("；", ";");

	else

		return temp_str:gsub("，", ","):gsub("；", ";");						-- else, return assembled temp_str

	end

end





--[=[-------------------------< M A K E _ W I K I L I N K >----------------------------------------------------



Makes a wikilink; when both link and display text is provided, returns a wikilink in the form [[L|D]]; if only

link is provided (or link and display are the same), returns a wikilink in the form [[L]]; if neither are

provided or link is omitted, returns an empty string.



]=]



local function make_wikilink (link, display)

	if not is_set (link) then return '' end



	if is_set (display) and link ~= display then			

		return table.concat ({'[[', link, '|', display, ']]'});			

	else

		return table.concat ({'[[', link, ']]'});

	end

end





--[[--------------------------< S E T _ M E S S A G E >----------------------------------------------------------



Sets an error message using the ~/Configuration error_conditions{} table along with arguments supplied in the function

call, inserts the resulting message in z.error_msgs_t{} sequence table, and returns the error message.



<error_id> – key value for appropriate error handler in ~/Configuration error_conditions{} table 

<arguments> – may be a single string or a sequence table of multiple strings to be subsititued into error_conditions[error_id].message

<raw> – boolean

	true –	causes this function to return the error message not wrapped in visible-error, hidden-error span tag;

			returns error_conditions[error_id].hidden as a second return value

			does not add message to z.error_msgs_t sequence table

	false, nil – adds message wrapped in visible-error, hidden-error span tag to z.error_msgs_t

			returns the error message wrapped in visible-error, hidden-error span tag; there is no second return value

<prefix> – string to be prepended to <message>									-- TODO: remove support for these unused(?) arguments?

<suffix> – string to be appended to <message>



TODO: change z.error_cats_t and z.maint_cats_t to have the form cat_name = true?  this to avoid dups without having to have an extra table



]]



local added_maint_cats = {}														-- list of maintenance categories that have been added to z.maint_cats_t; TODO: figure out how to delete this table



local function set_message (error_id, arguments, raw, prefix, suffix)

	local error_state = cfg.error_conditionserror_id];

	

	prefix = prefix or '';

	suffix = suffix or '';

	

	if error_state == nil then

		error (cfg.messages'undefined_error' .. ': ' .. error_id);			-- because missing error handler in Module:Citation/CS1/Configuration



	elseif is_set (error_state.category) then

		if error_state.message then												-- when error_state.message defined, this is an error message

			table.insert (z.error_cats_t, error_state.category);

		else

			if not added_maint_catserror_id then

				added_maint_catserror_id = true;								-- note that we've added this category

				table.insert (z.maint_cats_t, substitute (error_state.category, arguments));	-- make cat name then add to table

			end

			return;																-- because no message, nothing more to do

		end

	end



	local message = substitute (error_state.message, arguments);



	message = table.concat (

		{

		message,

		' (',

		make_wikilink (

			table.concat (

				{

				cfg.messages'help page link'],

				'#',

				error_state.anchor

				}),

			cfg.messages'help page label']),

		')'

		});



	z.error_ids_terror_id = true;

	if z.error_ids_t'err_citation_missing_title' and							-- if missing-title error already noted

		in_array (error_id, {'err_bare_url_missing_title', 'err_trans_missing_title'}) then		-- and this error is one of these

			return '', false;													-- don't bother because one flavor of missing title is sufficient

	end

	

	message = table.concat ({prefix, message, suffix});



	if true == raw then

		return message, error_state.hidden;										-- return message not wrapped in visible-error, hidden-error span tag

	end		



	message = error_comment (message, error_state.hidden);						-- wrap message in visible-error, hidden-error span tag

	table.insert (z.error_msgs_t, message);										-- add it to the messages sequence table

	return message;																-- and done; return value generally not used but is used as a flag in various functions of ~/Identifiers

end





--[[-------------------------< I S _ A L I A S _ U S E D >-----------------------------------------------------



This function is used by select_one() to determine if one of a list of alias parameters is in the argument list

provided by the template.



Input:

	args – pointer to the arguments table from calling template

	alias – one of the list of possible aliases in the aliases lists from Module:Citation/CS1/Configuration

	index – for enumerated parameters, identifies which one

	enumerated – true/false flag used to choose how enumerated aliases are examined

	value – value associated with an alias that has previously been selected; nil if not yet selected

	selected – the alias that has previously been selected; nil if not yet selected

	error_list – list of aliases that are duplicates of the alias already selected



Returns:

	value – value associated with alias we selected or that was previously selected or nil if an alias not yet selected

	selected – the alias we selected or the alias that was previously selected or nil if an alias not yet selected



]]



local function is_alias_used (args, alias, index, enumerated, value, selected, error_list)

	if enumerated then															-- is this a test for an enumerated parameters?

		alias = alias:gsub ('#', index);										-- replace '#' with the value in index

	else

		alias = alias:gsub ('#', '');											-- remove '#' if it exists

	end



	if is_set (argsalias]) then												-- alias is in the template's argument list

		if value ~= nil and selected ~= alias then								-- if we have already selected one of the aliases

			local skip;

			for _, v in ipairs (error_list) do									-- spin through the error list to see if we've added this alias

				if v == alias then

					skip = true;

					break;														-- has been added so stop looking 

				end

			end

			if not skip then													-- has not been added so

				table.insert (error_list, alias);								-- add error alias to the error list

			end

		else

			value = argsalias];												-- not yet selected an alias, so select this one

			selected = alias;

		end

	end

	return value, selected;														-- return newly selected alias, or previously selected alias

end





--[[--------------------------< A D D _ M A I N T _ C A T >------------------------------------------------------



Adds a category to z.maint_cats_t using names from the configuration file with additional text if any.

To prevent duplication, the added_maint_cats table lists the categories by key that have been added to z.maint_cats_t.



]]



local function add_maint_cat (key, arguments)

	if not added_maint_cats key then

		added_maint_cats key = true;											-- note that we've added this category

		table.insert (z.maint_cats_t, substitute (cfg.maint_cats key], arguments));	-- make name then add to table

	end

end





--[[--------------------------< A D D _ P R O P _ C A T >--------------------------------------------------------



Adds a category to z.prop_cats_t using names from the configuration file with additional text if any.



foreign_lang_source and foreign_lang_source_2 keys have a language code appended to them so that multiple languages

may be categorized but multiples of the same language are not categorized.



added_prop_cats is a table declared in page scope variables above



]]



local added_prop_cats = {};														-- list of property categories that have been added to z.prop_cats_t



local function add_prop_cat (key, arguments, key_modifier)

	local key_modified = key .. ((key_modifier and key_modifier) or '');		-- modify <key> with <key_modifier> if present and not nil

	

	if not added_prop_cats key_modified then

		added_prop_cats key_modified = true;									-- note that we've added this category

		table.insert (z.prop_cats_t, substitute (cfg.prop_cats key], arguments));	-- make name then add to table

		table.insert (z.prop_keys_t, 'cs1-prop-' .. key);						-- convert key to class for use in the citation's <cite> tag

	end

end





--[[--------------------------< S A F E _ F O R _ I T A L I C S >----------------------------------------------



Protects a string that will be wrapped in wiki italic markup '' ... ''



Note: We cannot 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.



]]



local function safe_for_italics (str)

	if not is_set (str) then return str end



	if str:sub (1, 1) == "'" then str = "<span></span>" .. str; end

	if str:sub (-1, -1) == "'" then str = str .. "<span></span>"; end

	

	return str:gsub ('\n', ' ');												-- Remove newlines as they break italics.

end





--[[--------------------------< W R A P _ S T Y L E >----------------------------------------------------------



Applies styling to various parameters.  Supplied string is wrapped using a message_list configuration taking one

argument; protects italic styled parameters.  Additional text taken from citation_config.presentation - the reason

this function is similar to but separate from wrap_msg().



]]



local function wrap_style (key, str)

	if not is_set (str) then

		return "";

	elseif in_array (key, {'italic-title', 'trans-italic-title'}) then

		str = safe_for_italics (str);

	end



	return substitute (cfg.presentationkey], {str});

end





--[[--------------------------< M A K E _ S E P _ L I S T >------------------------------------------------------------



make a separated list of items using provided separators.

	<sep_list> - typically '<comma><space>'

	<sep_list_pair> - typically '<space>and<space>'

	<sep_list_end> - typically '<comma><space>and<space>' or '<comma><space>&<space>'



defaults to cfg.presentation['sep_list'], cfg.presentation['sep_list_pair'], and cfg.presentation['sep_list_end']

if <sep_list_end> is specified, <sep_list> and <sep_list_pair> must also be supplied



]]



local function make_sep_list (count, list_seq, sep_list, sep_list_pair, sep_list_end)

	local list = '';



	if not sep_list then														-- set the defaults

		sep_list = cfg.presentation'sep_list'];

		sep_list_pair = cfg.presentation'sep_list_pair'];

		sep_list_end = cfg.presentation'sep_list_end'];

	end

	

	if 2 >= count then

		list = table.concat (list_seq, sep_list_pair);							-- insert separator between two items; returns list_seq[1] then only one item

	elseif 2 < count then

		list = table.concat (list_seq, sep_list, 1, count - 1);					-- concatenate all but last item with plain list separator

		list = table.concat ({list, list_seqcount]}, sep_list_end);			-- concatenate last item onto end of <list> with final separator

	end

	

	return list;

end





--[[--------------------------< S E L E C T _ O N E >----------------------------------------------------------



Chooses one matching parameter from a list of parameters to consider.  The list of parameters to consider is just

names.  For parameters that may be enumerated, the position of the numerator in the parameter name is identified

by the '#' so |author-last1= and |author1-last= are represented as 'author-last#' and 'author#-last'.



Because enumerated parameter |<param>1= is an alias of |<param>= we must test for both possibilities.





Generates an error if more than one match is present.



]]



local function select_one (args, aliases_list, error_condition, index)

	local value = nil;															-- the value assigned to the selected parameter

	local selected = '';														-- the name of the parameter we have chosen

	local error_list = {};



	if index ~= nil then index = tostring(index); end



	for _, alias in ipairs (aliases_list) do									-- for each alias in the aliases list

		if alias:match ('#') then												-- if this alias can be enumerated

			if '1' == index then												-- when index is 1 test for enumerated and non-enumerated aliases

				value, selected = is_alias_used (args, alias, index, false, value, selected, error_list);	-- first test for non-enumerated alias

			end

			value, selected = is_alias_used (args, alias, index, true, value, selected, error_list);	-- test for enumerated alias

		else

			value, selected = is_alias_used (args, alias, index, false, value, selected, error_list);	-- test for non-enumerated alias

		end

	end



	if #error_list > 0 and 'none' ~= error_condition then						-- for cases where this code is used outside of extract_names()

		for i, v in ipairs (error_list) do

			error_listi = wrap_style ('parameter', v);

		end

		table.insert (error_list, wrap_style ('parameter', selected));

		set_message (error_condition, {make_sep_list (#error_list, error_list)});

	end

	

	return value, selected;

end





--[=[-------------------------< R E M O V E _ W I K I _ L I N K >----------------------------------------------



Gets the display text from a wikilink like [[A|B]] or [[B]] gives B



The str:gsub() returns either A|B froma [[A|B]] or B from [[B]] or B from B (no wikilink markup).



In l(), l:gsub() removes the link and pipe (if they exist); the second :gsub() trims whitespace from the label

if str was wrapped in wikilink markup.  Presumably, this is because without wikimarkup in str, there is no match

in the initial gsub, the replacement function l() doesn't get called.



]=]



local function remove_wiki_link (str)

	return (str:gsub ("%[%[([^%[%]]*)%]%]", function(l)

		return l:gsub ("^[^|]*|(.*)$", "%1" ):gsub ("^%s*(.-)%s*$", "%1");

	end));

end





--[=[-------------------------< I S _ W I K I L I N K >--------------------------------------------------------



Determines if str is a wikilink, extracts, and returns the wikilink type, link text, and display text parts.

If str is a complex wikilink ([[L|D]]):

	returns wl_type 2 and D and L from [[L|D]];

if str is a simple wikilink ([[D]])

	returns wl_type 1 and D from [[D]] and L as empty string;

if not a wikilink:

	returns wl_type 0, str as D, and L as empty string.



trims leading and trailing whitespace and pipes from L and D ([[L|]] and [[|D]] are accepted by MediaWiki and

treated like [[D]]; while [[|D|]] is not accepted by MediaWiki, here, we accept it and return D without the pipes).



]=]



local function is_wikilink (str)

	local D, L

	local wl_type = 2;															-- assume that str is a complex wikilink [[L|D]]



	if not str:match ('^%[%[[^%]]+%]%]$') then									-- is str some sort of a wikilink (must have some sort of content)

		return 0, str, '';														-- not a wikilink; return wl_type as 0, str as D, and empty string as L

	end

	

	L, D = str:match ('^%[%[([^|]+)|([^%]]+)%]%]$');							-- get L and D from [[L|D]] 



	if not is_set (D) then														-- if no separate display

		D = str:match ('^%[%[([^%]]*)|*%]%]$');									-- get D from [[D]] or [[D|]]

		wl_type = 1; 

	end

	

	D = mw.text.trim (D, '%s|');												-- trim white space and pipe characters 

	return wl_type, D, L or '';

end





--[[--------------------------< S T R I P _ A P O S T R O P H E _ M A R K U P >--------------------------------



Strip wiki italic and bold markup from argument so that it doesn't contaminate COinS metadata.

This function strips common patterns of apostrophe markup.  We presume that editors who have taken the time to

markup a title have, as a result, provided valid markup. When they don't, some single apostrophes are left behind.



Returns the argument without wiki markup and a number; the number is more-or-less meaningless except as a flag

to indicate that markup was replaced; do not rely on it as an indicator of how many of any kind of markup was

removed; returns the argument and nil when no markup removed



]]



local function strip_apostrophe_markup (argument)

	if not is_set (argument) then

		return argument, nil;													-- no argument, nothing to do

	end



	if nil == argument:find ( "''", 1, true ) then								-- Is there at least one double apostrophe?  If not, exit.

		return argument, nil;

	end



	local flag;

	while true do

		if argument:find ("'''''", 1, true) then								-- bold italic (5)

			argument, flag = argument:gsub ("%'%'%'%'%'", "");					-- remove all instances of it

		elseif argument:find ("''''", 1, true) then								-- italic start and end without content (4)

			argument, flag=argument:gsub ("%'%'%'%'", "");

		elseif argument:find ("'''", 1, true) then								-- bold (3)

			argument, flag=argument:gsub ("%'%'%'", "");

		elseif argument:find ("''", 1, true) then								-- italic (2)

			argument, flag = argument:gsub ("%'%'", "");

		else

			break;

		end

	end



	return argument, flag;														-- done

end





--[[--------------------------< S E T _ S E L E C T E D _ M O D U L E S >--------------------------------------



Sets local cfg table to same (live or sandbox) as that used by the other modules.



]]



local function set_selected_modules (cfg_table_ptr)

	cfg = cfg_table_ptr;

	

end





--[[--------------------------< E X P O R T S >----------------------------------------------------------------

]]



return {

	add_maint_cat = add_maint_cat,												-- exported functions

	add_prop_cat = add_prop_cat,

	error_comment = error_comment,

	has_accept_as_written = has_accept_as_written,

	hyphen_to_dash = hyphen_to_dash,

	in_array = in_array,

	is_set = is_set,

	is_wikilink = is_wikilink,

	make_sep_list = make_sep_list,

	make_wikilink = make_wikilink,

	remove_wiki_link = remove_wiki_link,

	safe_for_italics = safe_for_italics,

	select_one = select_one,

	set_message = set_message,

	set_selected_modules = set_selected_modules,

	strip_apostrophe_markup = strip_apostrophe_markup,

	substitute = substitute,

	wrap_style = wrap_style,



	z = z,																		-- exported table

	}