local yesno = require('Module:Yesno')
local delink = require('Module:Delink')._delink

local p = {}

function p.main(frame)
	local getArgs = require('Module:Arguments').getArgs
	local args = getArgs(frame)
	return p._main(args)
end

function p._main(args)
	-- If first arg or a url is not provided,
	-- but we have a second arg, make a button.
	-- Otherwise, return nothing.
	args.originalInput = args[1]
	args[1] = delink({args[1]})
	if args[1] == "" then
		args[1] = nil
	end

	if not args[1] and not args.url then
		if args[2] then
			p.nolink = true
		else
			return ''
		end
	end

	local data = p.makeLinkData(args)
	local link = p.renderLink
	local trackingCategories = p.renderTrackingCategories(args)
	return link .. trackingCategories
end

function p.makeLinkData(args)
	local data = {}

	-- Get the link and display values,
	-- and find whether we are outputting
	-- a wikilink or a URL.
	if args.url then
		data.isUrl = true
		data.link = args.url
		if args[1] then
			data.display = args[1]
		elseif args[2] then
			data.display = args[2]
		else
			data.display = args.url
			p.urlisdisplay = true
		end
	else
		data.isUrl = false
		p.urlisdisplay = false
		data.link = args[1]
		if args[2] then
			data.display = args[2]
		else
			data.display = args[1]
		end
		if args[1] and args[1]:find('http') then
			data.isUrl = true
		end
	end
	
	if yesno(args.link) == false then
		p.nolink = true
	end

	-- Colours
	-- For the merge with 
	local colour = args.color and args.color:lower

	-- Classes
	local class = args.class and args.class:lower
	data.classes = {}
	if class == 'ui-button-green'
		or class == 'ui-button-blue'
		or class == 'ui-button-red'
	then
		table.insert
	else
		table.insert
	end
	
	--If class is unset,
	--then let color determine class
	if not class then
		if colour == 'blue' then
			class = 'mw-ui-progressive'
		elseif colour == 'red' then
			class = 'mw-ui-destructive'
		elseif colour == 'green' then
			class = 'mw-ui-constructive'
		end
	end
	
	if class then
		table.insert
	end

	-- Styles
	do
		--[[
		-- Check whether we are on the same page as we have specified in
		-- args[1], but not if we are using a URL link, as then args[1] is only
		-- a display value. If we are currently on the page specified in
		-- args[1] make the button colour darker so that it stands out from
		-- other buttons on the page.
		--]]
		local success, linkTitle, currentTitle
		if not data.isUrl then
			currentTitle = mw.title.getCurrentTitle
			success, linkTitle = pcall
		elseif p.urlisdisplay then
			currentTitle = mw.title.getCurrentTitle
		end
		if success
			and linkTitle
			and mw.title.equals
			and not p.urlisdisplay
		then
			if class == 'ui-button-blue'
				or class == 'mw-ui-progressive'
				or class == 'mw-ui-constructive'
			then
				data.backgroundColor = '#2962CB'
				data.color = '#fff'
			elseif class == 'ui-button-green' then
				data.backgroundColor = '#008B6D'
			elseif class == 'ui-button-red' or class == 'mw-ui-destructive' then
				data.backgroundColor = '#A6170F'
			else
				data.backgroundColor = '#CCC'
				data.color = '#666'
			end
		elseif p.urlisdisplay then
			data.dummyLink = tostring(currentTitle)
		end
		-- Add user-specified styles.
		data.style = args.style
	end
	return data
end

function p.renderLink
	-- Render the display span tag.
	local display
	do
		local displaySpan = mw.html.create('span')
		for i, class in ipairs(data.classes or {}) do
			displaySpan:addClass(class)
		end

		displaySpan
				['background-color'] = data.backgroundColor,
				color = data.color
		if data.style then
			displaySpan:cssText(data.style)
		end
		displaySpan:wikitext(data.display)
		display = tostring(displaySpan)
	end

	-- Render the link
	local link
	if originalInput and originalInput:find('|') then
		link = string.format('%s', delink, display)
	elseif p.nolink then
		if p.urlisdisplay then
			link = string.format
		else
			link = string.format
		end
	else
		if data.isUrl then
			link = string.format
		else
			link = string.format
		end
	end

	return string.format
end

function p.renderTrackingCategories(args)
	if yesno(args.category) == false then
		return ''
	end
	local class = args.class and args.class:lower
	if class == 'ui-button-green'
		or class == 'ui-button-blue'
		or class == 'ui-button-red'
	then
		return ''
	else
		return ''
	end
end