Module:collation

local export = {}

local compare_module = "Module:compare"
local functions_module = "Module:fun"
local memoize_module = "Module:memoize"
local string_utilities_module = "Module:string utilities"
local utilities_module = "Module:utilities"

local concat = table.concat
local find = string.find
local format = string.format
local make_sort_function -- defined below
local match = string.match
local remove = table.remove
local require = require
local sort = table.sort
local sub = string.sub
local type = type

local function get_plaintext(...)
	get_plaintext = require(utilities_module).get_plaintext
	return get_plaintext(...)
end

local function is_callable(...)
	is_callable = require(functions_module).is_callable
	return is_callable(...)
end

local function memoize(...)
	memoize = require(memoize_module)
	return memoize(...)
end

local function trim(...)
	trim = require(string_utilities_module).trim
	return trim(...)
end

-- Custom functions for generating a sortkey that will achieve the desired sort
-- order.
local custom_funcs
local function get_custom_funcs()
	custom_funcs, get_custom_funcs = {
		ahk = "Mymr-sortkey",
		aio = "Mymr-sortkey",
		blk = "Mymr-sortkey",
		egy = "egy-utilities",
		kac = "Mymr-sortkey",
		kht = "Mymr-sortkey",
		ksw = "Mymr-sortkey",
		kyu = "Mymr-sortkey",
		 = "Mymr-sortkey",
		mnw = "Mymr-sortkey",
		my  = "Mymr-sortkey",
		phk = "Mymr-sortkey",
		pwo = "Mymr-sortkey",
		omx = "Mymr-sortkey",
		shn = "Mymr-sortkey",
		tjl = "Mymr-sortkey",
	}, nil
	return custom_funcs
end

local function is_lang_object(lang)
	return lang and type(lang) == "table" and type(lang.getCanonicalName) == "function"
end

local function check_function(funcName, argIdx, func)
	return is_callable(func) or error(format("bad argument #%d to %s: expected function or callable table; got %s", argIdx, funcName, type(func)), 2)
end

function export.make_lang_sortkey_function(lang, make_sortbase)
	local makeDisplayText, makeSortKey = lang.makeDisplayText
	local custom = (custom_funcs or get_custom_funcs())

	if custom then
		local _makeSortKey = require("Module:" .. custom).makeSortKey
		function makeSortKey(_, text)
			return _makeSortKey(text, lang, lang:findBestScript(text))
		end
	else
		makeSortKey = lang.makeSortKey
	end

	return make_sortbase and check_function("make_sort_function", 3, make_sortbase) and function(element)
		return (makeSortKey(
			lang,
			(makeDisplayText(
				lang,
				get_plaintext(make_sortbase(element))
			))
		))
	end or function(element)
		return (makeSortKey(
			lang,
			(makeDisplayText(
				lang,
				get_plaintext(element)
			))
		))
	end
end

do
	local compare
	local function get_compare()
		compare, get_compare = require(compare_module), nil
		return compare
	end

	function export.make_sort_function(lang, make_sortbase)
		local compare_func, make_sortkey = compare or get_compare()
		if is_lang_object(lang) then
			make_sortkey = memoize(export.make_lang_sortkey_function(lang, make_sortbase), true)
		elseif make_sortbase and check_function("make_sort_function", 2, make_sortbase) then
			make_sortkey = memoize(make_sortbase, true)
		else
			return compare_func
		end
		return function(elem1, elem2)
			return compare_func(make_sortkey(elem1), make_sortkey(elem2))
		end
	end
	make_sort_function = export.make_sort_function
end

function export.sort(elems, lang, make_sortbase)
	return sort(elems, make_sort_function(lang, make_sortbase))
end

function export.sort_template(frame)
	if not mw.isSubsting() then
		error("This template must be substed.")
	end

	local args
	if frame.args.parent then
		args = frame:getParent().args
	else
		args = frame.args
	end

	local m_table = require("Module:table")
	local elems = m_table.shallowCopy(args)
	local m_languages = require("Module:languages")
	local lang
	if args.lang then
		lang = m_languages.getByCode(args.lang) or m_languages.err(args.lang, "lang")
	else
		local code = remove(elems, 1)
		code = code and trim(code)
		lang = m_languages.getByCode(code) or m_languages.err(code, 1)
	end

	local i = 1
	while true do
		local elem = elems
		while elem do
			elem = trim(elem, "%s")
			if elem ~= "" then
				break
			end
			remove(elems, i)
			elem = elems
		end
		if not elem then
			break
		elseif not ( -- Strip redundant wikilinks.
			not match(elem, "^()%[%[") or
			find(elem, "[[", 3, true) or
			find(elem, "]]", 3, true) ~= #elem - 1 or
			find(elem, "|", 3, true)
		) then
			elem = sub(elem, 3, -3)
			elem = trim(elem, "%s")
		end
		elems = elem .. "\n"
		i = i + 1
	end

	elems = m_table.removeDuplicates(elems)
	export.sort(elems, lang)

	return concat(elems, args.sep or "|")
end

return export