-- This module implements [[Template:WebCite]].

local p = {}

-- Lazily load a mw.language object.
local lang

-- NS_MAIN holds the namespace number for the Main namespace.
local NS_MAIN = 0
-- NS_FILE holds the namespace number for the File namespace.
local NS_FILE = 6
--NS_INDEX holds the namespace number for the Index namespace.
local NS_INDEX = 120
-- NS_USER holds the namespace number for the User namespace. TESTING ONLY
--local NS_USER = 2
-- NS_MODULE holds the namespace number for the Module namespace. TESTING ONLY
--local NS_MODULE = 828

-- get the current page
local currentPageTitle = mw.title.getCurrentTitle()
	
-- get the current page's namespace
local namespace = currentPageTitle.namespace
	
-- Avoid rendering tracking categories outside of main or file namespaces
local isAllowedNamespace = (namespace == NS_MAIN or namespace == NS_FILE or namespace == NS_INDEX) and true

-- Formats all error messages and adds appropriate tracking category
local function makeWikitextError(msg, missing)
	-- styling for the error message
	local ret = '<span style="color: red;">[[Template:WebCite]] error: '..msg..'.</span>'
	-- add appropriate tracking category
	if isAllowedNamespace then
		if missing then
			ret = ret..'[[Category:Template usages with missing parameters]]'
		else
			ret = ret..'[[Category:Template usages with invalid parameter values]]'
		end
	end
	return ret
end

-- Formats all dates including wookieepedia linking
local function makeDateLink(date)
	lang = lang or mw.language.getContentLanguage()
	local success, dateLink
	if date and #date == 7 then 
		-- YYYY-MM
		success, dateLink = pcall(
			lang.formatDate, lang,
			'[[F]], [[Y]]',
			date .. '-01'
		)
	elseif date and #date == 4 then
		-- YYYY
		success, dateLink = pcall(
			lang.formatDate, lang,
			'[[Y]]',
			date .. '-01-01'
		)
	else
		-- YYYY-MM-DD
		success, dateLink = pcall(
			lang.formatDate, lang,
			'[[F j]], [[Y]]',
			date
		)
	end
	
	return dateLink
end

function p._main(args)
	-- Capture variables
	local url = args.url
	local text = args.text
	if not text then
		text = args.title
	end
	
	-- Validate input
	if not url then
		-- missing url parameter
		return makeWikitextError("missing '''url''' parameter must be specified", true)
	end
	
	if not text then
		-- missing title parameter
		return makeWikitextError("missing '''text''' parameter must be specified", true)
	end
	
	-- Capture remaing variables
	local author = args.author
	local citeDate = args.date
	local citeFormat = args.format
	local work = args.work
	local publisher = args.publisher
	local pages = args.pages
	local language = args.language
	local quote = args.quote
	local archiveDate = args.archivedate
	local archiveUrl = args.archiveurl
	local archiveFile = args.archivefile
	local noBackup = args.nobackup
	local noLive = args.nolive
	
	local ret = {}
    
	-- URL
	
	-- check for any badly formatted urls
	if not mw.ustring.find(url, 'http://') and not mw.ustring.find(url, 'https://')  then
		ret[#ret + 1] = makeWikitextError("badly formatted '''url''' parameter", false)
		if isAllowedNamespace then
			ret[#ret + 1] = '[[Category:Templates with invalid URL parameters]]'
			return table.concat(ret)
		end
	end
	
	-- build the left-most url/archive links
	if url and text then
		if archiveUrl then
			-- use archiveUrl
			ret[#ret + 1] = '['..archiveUrl..' '..text..']'
        elseif archiveDate then
			-- use archiveDate to build a Wayback url
			ret[#ret + 1] = '[https://web.archive.org/web/'..archiveDate..'/'..url..' '..text..']'
        elseif url then
			-- if no archive links, then just use the url
			ret[#ret + 1] = '['..url..' '..text..']'
		end
	end

	-- Language
	if language then
		ret[#ret + 1] = '&#32;('..language..')'
	end

	-- Format or Pages
	if citeFormat or pages then
		-- opening (
		ret[#ret + 1] = '&#32;('
		
		-- Format
		if citeFormat then
			ret[#ret + 1] = citeFormat
		end
		
		-- add a space if both
		if citeFormat and pages then
			ret[#ret + 1] = '&#32;'
		end
		
		-- Pages
		if pages then
			ret[#ret + 1] = pages
		end
		
		-- closing )
		ret[#ret + 1] = ')'
	end
	
	-- Author
	if author then
		ret[#ret + 1] = '&#32;by '..author
	end

	-- Publisher
	if publisher then
		ret[#ret + 1] = ',&#32;published by '..publisher
	end
	
	-- Work
	if work then
		ret[#ret + 1] = "&#32;on "..work
    else
    	-- if work parameter hasn't been provided, we can create a link to the website's homepage automatically
    	-- grab the website's homepage - including http(s)://
        local website = url:match('^(%w+://[^/]+)')
        -- grab the website's domain name which we'll use for the website title
        local domain = url:match('^%w+://([^/]+)')
        -- create a link to the website's homepage
        ret[#ret + 1] = "&#32;on ["..website..' '..domain.."]"
	end
	
	-- Date
	if citeDate then
		-- add a formatted data
		ret[#ret + 1] = '&#32;('..makeDateLink(citeDate)..')'
		-- check if date contains letters
		-- we only want dates formatted as YYYY-MM-DD e.g. 2020-11-23)
		if mw.ustring.find(citeDate, 'a') or mw.ustring.find(citeDate, 'e') or mw.ustring.find(citeDate, 'u') then
    		-- any dates containing the above letters, e.g. Jan 12, 2019
    		-- add the appropriate tracking category
    		if isAllowedNamespace then
				ret[#ret + 1] = '[[Category:WebCite date argument usages with incorrect date formats]]'
			end
        end
	end
	
	-- Quote
	if quote then
		ret[#ret + 1] = '&#58;&#32;"'..quote..'"'
	end

	-- Start of the right-most url/archive links
    ret[#ret + 1] = '&#32;<small>('

    if noBackup then
    	-- noBackup i.e. when an archive link cannot be produced because the original content is no longer available
       ret[#ret + 1] = 'content obsolete and backup link not available'
    else
        if noLive then
        	-- original content is no longer available (but archive link may exist)
             ret[#ret + 1] = 'content now obsolete;&#32;'
        end
        
        if archiveFile then
        	ret[#ret + 1] =	'[[:' .. archiveFile .. '|screenshot]]'
        elseif archiveUrl or archiveDate then
			-- add url link to output
			ret[#ret + 1] =	'archived from ['..url..' the original]'
        elseif mw.ustring.find(url, '//archive.org/') or mw.ustring.find(url, '.archive.org/') then
			ret[#ret + 1] = 'archived on Archive.org'
		else
			-- format unverifie backup link message
	        local verifyBackupLink = '[[Template:WebCite|<span style="color: red;">\'\'\'not verified!\'\'\'</span>]]'
	        -- create a temporary Wayback link from the url
	        ret[#ret + 1] = '[https://web.archive.org/web/'..url..' backup link]&#32;'..verifyBackupLink
	        -- add a tracking category for the missing archival links
    		if isAllowedNamespace then
				ret[#ret + 1] = '[[Category:Pages with missing permanent archival links]]'
			end
		end
		
		-- Full Wayback URL given
    	if archiveUrl and mw.ustring.find(archiveUrl, 'web.archive.org/web') then
    		-- so return it with appropriate tracking categories
    		if isAllowedNamespace then
				ret[#ret + 1] = '[[Category:Archiveurl usages with Wayback URLs]]'
			end
    		-- grab the date value from the Wayback url
			local waybackDate = archiveUrl:match('https://web.archive.org/web/(%d+)/http')
			-- add Wayback date to output
			ret[#ret + 1] =	'&#32;on '..makeDateLink(waybackDate)
		elseif archiveDate then
			-- add archiveDate to output
			ret[#ret + 1] =	'&#32;on '..makeDateLink(archiveDate)
		end
    end
    
	-- End of the right-most url/archive links
    ret[#ret + 1] = ')</small>'
	
	-- final output
	return table.concat(ret)
end

-- this has slightly slower performance than the next function
--local getArgs = require('Module:Arguments').getArgs
--function p.main(frame)
--	local args = getArgs(frame)
--	return p._main(args)
--end

function p.main(frame)
	local args = {}
	for k, v in pairs(frame:getParent().args) do
		v = v:match('^%s*(.-)%s*$') -- trim whitespace
		if v ~= '' then
			args[k] = v
		end
	end
	return p._main(args)
end

return p