local mod_muc = module:depends("muc")

local http = require "net.http"

local st = require "util.stanza"

local url_pattern = [[https?://%S+]]

local domain_pattern = '^%w+://([^/]+)'

local xmlns_fasten = "urn:xmpp:fasten:0"

local xmlns_xhtml = "http://www.w3.org/1999/xhtml"

local whitelist = module:get_option_set("ogp_domain_whitelist", {})

local function is_whitelisted(url)

	if whitelist:empty() then

		return true

	end

	local domain = url:match(domain_pattern)

	if whitelist:contains(domain) then

		return true;

	end

	return false

end

local function fetch_ogp_data(room, url, origin_id)

	if not url or not is_whitelisted(url) then

		return;

	end

	http.request(

		url,

		nil,

		function(response_body, response_code, _)

			if response_code ~= 200 then

				return

			end

			local to = room.jid

			local from = room and room.jid or module.host

			local fastening = st.message({to = to, from = from, type = 'groupchat'}):tag("apply-to", {xmlns = xmlns_fasten, id = origin_id})

			local found_metadata = false

			local message_body = ""

			local meta_pattern = [[<meta (.-)/?>]]

			for match in response_body:gmatch(meta_pattern) do

				local property = match:match([[property=%s*["']?(og:.-)["']?%s]])

				if not property then

					property = match:match([[property=["']?(og:.-)["']$]])

				end

				local content = match:match([[content=%s*["'](.-)["']%s]])

				if not content then

					content = match:match([[content=["']?(.-)["']$]])

				end

				if not content then

					content = match:match([[content=(.-) property]])

				end

				if not content then

					content = match:match([[content=(.-)$]])

				end

				if property and content then

					fastening:tag(

						"meta",

						{

							xmlns = xmlns_xhtml,

							property = property,

							content = content

						}

					):up()

					found_metadata = true

					message_body = message_body .. property .. "\t" .. content .. "\n"

				end

			end

			if found_metadata then

				mod_muc.get_room_from_jid(room.jid):broadcast_message(fastening)

			end

		end

	)

end

local function ogp_handler(event)

	local room, stanza = event.room, st.clone(event.stanza)

	local body = stanza:get_child_text("body")

	if not body then return; end

	local origin_id = stanza:find("{urn:xmpp:sid:0}origin-id@id")

	if not origin_id then return; end

	for url in body:gmatch(url_pattern) do

		fetch_ogp_data(room, url, origin_id);

	end

end

module:hook("muc-occupant-groupchat", ogp_handler)

module:hook("muc-message-is-historic", function (event)

	local fastening = event.stanza:get_child('apply-to', xmlns_fasten)

	if fastening and fastening:get_child('meta', xmlns_xhtml) then

		return true

	end

end);