--------------------------------------------------------------------------------
--                              Module:Hatnote                                --
--                                                                            --
-- This module produces hatnote links and links to related articles. It       --
-- implements the {{hatnote}} and {{format link}} meta-templates and includes --
-- helper functions for other Lua hatnote modules.                            --
--------------------------------------------------------------------------------

local libraryUtil = require('libraryUtil')
local checkType = libraryUtil.checkType
local checkTypeForNamedArg = libraryUtil.checkTypeForNamedArg
local mArguments -- lazily initialise [[Module:Arguments]]
local yesno -- lazily initialise [[Module:Yesno]]
local formatLink -- lazily initialise [[Module:Format link]] ._formatLink

local p = {}

--------------------------------------------------------------------------------
-- Helper functions
--------------------------------------------------------------------------------

local function getArgs(frame)
	-- Fetches the arguments from the parent frame. Whitespace is trimmed and
	-- blanks are removed.
	mArguments = require('Module:Arguments')
	return mArguments.getArgs(frame, {parentOnly = true})
end

local function removeInitialColon(s)
	-- Removes the initial colon from a string, if present.
	return s:match('^:?(.*)')
end

function p.defaultClasses(inline)
	-- Provides the default hatnote classes as a space-separated string; useful
	-- for hatnote-manipulation modules like [[Module:Hatnote group]].
	return
		(inline == 1 and 'hatnote-inline' or 'hatnote') .. ' ' ..
		'navigation-not-searchable'
end

function p.disambiguate(page, disambiguator)
	-- Formats a page title with a disambiguation parenthetical,
	-- i.e. "Example" → "Example (disambiguation)".
	checkType('disambiguate', 1, page, 'string')
	checkType('disambiguate', 2, disambiguator, 'string', true)
	disambiguator = disambiguator or 'disambiguation'
	return mw.ustring.format('%s (%s)', page, disambiguator)
end

function p.findNamespaceId(link, removeColon)
	-- Finds the namespace id (namespace number) of a link or a pagename. This
	-- function will not work if the link is enclosed in double brackets. Colons
	-- are trimmed from the start of the link by default. To skip colon
	-- trimming, set the removeColon parameter to false.
	checkType('findNamespaceId', 1, link, 'string')
	checkType('findNamespaceId', 2, removeColon, 'boolean', true)
	if removeColon ~= false then
		link = removeInitialColon(link)
	end
	local namespace = link:match('^(.-):')
	if namespace then
		local nsTable = mw.site.namespaces[namespace]
		if nsTable then
			return nsTable.id
		end
	end
	return 0
end

function p.makeWikitextError(msg, helpLink, addTrackingCategory, title)
	-- Formats an error message to be returned to wikitext. If
	-- addTrackingCategory is not false after being returned from
	-- [[Module:Yesno]], and if we are not on a talk page, a tracking category
	-- is added.
	checkType('makeWikitextError', 1, msg, 'string')
	checkType('makeWikitextError', 2, helpLink, 'string', true)
	yesno = require('Module:Yesno')
	title = title or mw.title.getCurrentTitle()
	-- Make the help link text.
	local helpText
	if helpLink then
		helpText = ' ([[' .. helpLink .. '|help]])'
	else
		helpText = ''
	end
	-- Make the category text.
	local category
	if not title.isTalkPage -- Don't categorise talk pages
		and title.namespace ~= 2 -- Don't categorise userspace
		and yesno(addTrackingCategory) ~= false -- Allow opting out
	then
		category = 'Hatnote templates with errors'
		category = mw.ustring.format(
			'[[%s:%s]]',
			mw.site.namespaces[14].name,
			category
		)
	else
		category = ''
	end
	return mw.ustring.format(
		'<strong class="error">Error: %s%s.</strong>%s',
		msg,
		helpText,
		category
	)
end

local curNs = mw.title.getCurrentTitle().namespace
p.missingTargetCat =
	--Default missing target category, exported for use in related modules
	((curNs ==  0) or (curNs == 14)) and
	'Articles with hatnote templates targeting a nonexistent page' or nil

function p.quote(title)
	--Wraps titles in quotation marks. If the title starts/ends with a quotation
	--mark, kerns that side as with {{-'}}
	local quotationMarks = {
		["'"]=true, ['"']=true, ['“']=true, ["‘"]=true, ['”']=true, ["’"]=true
	}
	local quoteLeft, quoteRight = -- Test if start/end are quotation marks
		quotationMarks[string.sub(title,  1,  1)],
		quotationMarks[string.sub(title, -1, -1)]
	if quoteLeft or quoteRight then
		title = mw.html.create("span"):wikitext(title)
	end
	if quoteLeft  then title:css("padding-left",  "0.15em") end
	if quoteRight then title:css("padding-right", "0.15em") end
	return '"' .. tostring(title) .. '"'
end

--------------------------------------------------------------------------------
-- Hatnote
--
-- Produces standard hatnote text. Implements the {{hatnote}} template.
--------------------------------------------------------------------------------

function p.hatnote(frame)
	local args = getArgs(frame)
	local s = args[1]
	if not s then
		return p.makeWikitextError(
			'no text specified',
			'Template:Hatnote#Errors',
			args.category
		)
	end
	return p._hatnote(s, {
		extraclasses = args.extraclasses,
		selfref = args.selfref
	})
end

function p._hatnote(s, options)
	checkType('_hatnote', 1, s, 'string')
	checkType('_hatnote', 2, options, 'table', true)
	options = options or {}
	local inline = options.inline
	local hatnote = mw.html.create(inline == 1 and 'span' or 'div')
	local extraclasses
	if type(options.extraclasses) == 'string' then
		extraclasses = options.extraclasses
	end

	hatnote
		:attr('role', 'note')
		:addClass(p.defaultClasses(inline))
		:addClass(extraclasses)
		:addClass(options.selfref and 'selfref' or nil)
		:wikitext(s)

	return mw.getCurrentFrame():extensionTag{
		name = 'templatestyles', args = { src = 'Module:Hatnote/styles.css' }
	} .. tostring(hatnote)
end

return p