-- This implements Template:Template link general and various other templates in its family
local getArgs = require('Module:Arguments').getArgs
local p = {}

-- Is a string non-empty?
local function _ne(s) 
	return s ~= nil and s ~= ""
end

local nw = mw.text.nowiki

local function addTemplate(s)
	local i, _ = s:find(':', 1, true)
	if i == nil then
		return 'Template:' .. s
	end
	local ns = s:sub(1, i - 1)
	if ns == '' or mw.site.namespaces[ns] then
		return s
	else
		return 'Template:' .. s
	end
end

local function trimTemplate(s)
	local needle = 'template:'
	if s:sub(1, needle:len()):lower() == needle then
		return s:sub(needle:len() + 1)	
	else
		return s
	end
end

-- Builds the link part
local function linkTitle(args)
	local titleObj
	if args['1'] then
		-- This handles :Page and other NS
		titleObj = mw.title.new(args['1'], 'Template')
	else
		titleObj = mw.title.getCurrentTitle()
	end

	local textPart = args.alttext
	if not _ne(textPart) then
		if titleObj ~= nil then
			textPart = titleObj:inNamespace("Template") and args['1'] or titleObj.fullText
		else
			-- redlink
			textPart = args['1']
		end
	end
	
	if _ne(args.subst) then
		-- HACK: the ns thing above is probably broken
		textPart = 'subst:' .. textPart
	end
	
	if _ne(args.brace) then
		textPart = nw('{{') .. textPart .. nw('}}')
	elseif _ne(args.braceinside) then
		textPart = nw('{') .. textPart .. nw('}')
	end

	local titlePart
	if _ne(args.nolink) then
		titlePart = textPart
	else
		titlePart = '[[' .. (titleObj ~= nil and titleObj.fullText or addTemplate(args['1'])) ..
			'|' .. textPart .. ']]'
	end
	if _ne(args.braceinside) then
		titlePart = nw('{') .. titlePart .. nw('}')
	end
	local bold = _ne(args.bold) or _ne(args.boldlink) or _ne(args.boldname)
	if bold then
		titlePart = "'''" .. titlePart .. "'''"
	end
	if _ne(args.nowrapname) then
		titlePart = '<span class="nowrap">' .. titlePart .. '</span>'
	end
	return titlePart
end

function p.main(frame)
	local args = getArgs(frame, {
		trim = true,
		removeBlanks = false
	})
	return p._main(args)
end

function p._main(args)
	local italic = _ne(args.italic) or _ne(args.italics)
	local dontBrace = _ne(args.brace) or _ne(args.braceinside)
	local code = _ne(args.code) or _ne(args.tt)
	local show_result = _ne(args._show_result)
	local expand = _ne(args._expand)
	
	local titlePart = linkTitle(args)
	
	-- Build the arguments
	local textPart = ""
	local textPartBuffer = "&#124;"
	local codeArguments = {}
	local codeArgumentsString = ""
	local i = 2
	local j = 1
	while args[i] do
		local val = args[i]
		if val ~= "" then
			if _ne(args.nowiki) then
				-- Unstrip nowiki tags first because calling nw on something that already contains nowiki tags will
				-- mangle the nowiki strip marker and result in literal UNIQ...QINU showing up
				val = nw(mw.text.unstripNoWiki(val))
			end
			local k, v = string.match(val, "(.*)=(.*)")
			if not k then
				codeArguments[j] = val
				j = j + 1
			else
				codeArguments[k] = v
			end
			codeArgumentsString = codeArgumentsString .. textPartBuffer .. val
			if italic then
				val = '<span style="font-style:italic;">' .. val .. '</span>'
			end
			textPart = textPart .. textPartBuffer .. val
		end
		i = i + 1
	end

	-- final wrap
	local ret = titlePart .. textPart
	if not dontBrace then ret = nw('{{') .. ret .. nw('}}') end
	if _ne(args.a) then ret = nw('*') .. '&nbsp;' .. ret end
	if _ne(args.kbd) then ret = '<kbd>' .. ret .. '</kbd>' end
	if code then
		ret = '<code>' .. ret .. '</code>'
	elseif _ne(args.plaincode) then
		ret = '<code style="border:none;background:transparent;color:inherit">' .. ret .. '</code>'
	end
	if _ne(args.nowrap) then ret = '<span class="nowrap">' .. ret .. '</span>' end
	
	--[[ Wrap as html?? 
	local span = mw.html.create('span')
	span:wikitext(ret)
	--]]
	if _ne(args.debug) then ret = ret .. '\n<pre>' .. mw.text.encode(mw.dumpObject(args)) .. '</pre>' end

	if show_result then
		if _ne(args.nocat) then codeArguments['nocat'] = true end
		local result = mw.getCurrentFrame():expandTemplate{title = addTemplate(args[1]), args = codeArguments}
		ret = ret .. " → " .. result
	end

	if expand then
		local query = mw.text.encode('{{' .. addTemplate(args[1]) .. string.gsub(codeArgumentsString, textPartBuffer, "|") .. '}}')
		local url = mw.uri.fullUrl('special:ExpandTemplates', 'wpInput=' .. query)
		mw.log()
		ret = ret .. " [" .. tostring(url) .. "]"
	end

	return ret
end

return p