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--[[
History of changes since last sync: 2020-01-11

2020-07-30: unify handling of error and maint messaging; see Help_talk:Citation_Style_1#Some_maintenance_items_to_upgrade_to_errors
2020-09-26: create has_accept_as_written(); see Help_talk:Citation_Style_1#Replacing_ignore-isbn-error%3D_and_doi-broken%3D_by_isbn%2Fdoi%3D%28%28invalid-value%29%29_syntax
2020-09-26: add_prop_cat() moved here from Module:Citation/CS1/sandbox; see Help_talk:Citation_Style_1#Request_for_new_maintenance_category_for_abbreviated_year_ranges_in_the_date%3D_parameter

]]


local z = {
	error_categories = {};														-- for categorizing citations that contain errors
	error_ids = {};
	message_tail = {};
	maintenance_cats = {};														-- for categorizing citations that aren't erroneous per se, but could use a little work
	properties_cats = {};														-- for categorizing citations based on certain properties, language of source for instance
};


--[[--------------------------< 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


--[[--------------------------< 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 futher 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)
	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


--[[--------------------------< 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


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

Populates numbered arguments in a message string using an argument table.

]]

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.

]]

local function error_comment( content, hidden )
	return substitute( hidden and cfg.presentation['hidden-error'] or cfg.presentation['visible-error'], content );
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, 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 is_set (link) then
		if is_set (display) then
			return table.concat ({'[[', link, '|', display, ']]'});
		else
			return table.concat ({'[[', link, ']]'});
		end
	else
		return '';
	end
end


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

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.

TODO: change z.error_categories and z.maintenance_cats to have the form cat_name = true; to avoid dups without having to have an extra cat

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

local function set_message (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'] .. ': ' .. 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_categories, error_state.category );
		else
			if not added_maint_cats[error_id] then
				added_maint_cats[error_id] = true;								-- note that we've added this category
				table.insert (z.maintenance_cats, 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[error_id] = true;
	if z.error_ids['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 raw == true then
		return message, error_state.hidden;
	end		

	return error_comment (message, error_state.hidden);
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(args[alias]) 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 = args[alias];												-- 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.maintenance_cats 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.maintenance_cats.

]]

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.maintenance_cats, 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.properties_cats 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.properties_cats

local function add_prop_cat (key, arguments)
	if not added_prop_cats [key] then
		added_prop_cats [key] = true;											-- note that we've added this category
		key = key:gsub ('(foreign_lang_source_?2?)%a%a%a?[%a%-]*', '%1');		-- strip lang code from keyname
		table.insert( z.properties_cats, substitute (cfg.prop_cats [key], arguments));	-- make name then add to table
	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;
	else
		if str:sub(1,1) == "'" then str = "<span></span>" .. str; end
		if str:sub(-1,-1) == "'" then str = str .. "<span></span>"; end
		
		-- Remove newlines as they break italics.
		return str:gsub( '\n', ' ' );
	end
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.presentation[key], {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_seq[count]}, 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_list[i] = wrap_style ('parameter', v);
		end
		table.insert (error_list, wrap_style ('parameter', selected));
		table.insert (z.message_tail, {set_message (error_condition, {make_sep_list (#error_list, error_list)}, true)});
	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,
	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
	}