local st = require "util.stanza";

-- RSS->Atom translator

-- http://code.matthewwild.co.uk/lua-feeds/

-- Helpers to translate item child elements

local rss2atom = {};

function rss2atom.title(atom_entry, tag)

	atom_entry:tag("title"):text(tag:get_text()):up();

end

function rss2atom.link(atom_entry, tag)

	atom_entry:tag("link", { href = tag:get_text() }):up();

end

function rss2atom.enclosure(atom_entry, tag)

	atom_entry:tag("link", { rel = "enclosure", href = tag.attr.url, type = tag.attr.type, length = tag.attr.length }):up();

end

function rss2atom.author(atom_entry, tag)

	atom_entry:tag("author")

		:tag("email"):text(tag:get_text()):up()

	:up();

end

function rss2atom.guid(atom_entry, tag)

	atom_entry:tag("id"):text(tag:get_text()):up();

end

function rss2atom.category(atom_entry, tag)

	atom_entry:tag("category", { term = tag:get_text(), scheme = tag.attr.domain }):up();

end

function rss2atom.description(atom_entry, tag)

	atom_entry:tag("summary"):text(tag:get_text()):up();

end

local months = {

	jan = "01", feb = "02", mar = "03", apr = "04", may = "05", jun = "06";

	jul = "07", aug = "08", sep = "09", oct = "10", nov = "11", dec = "12";

};

function rss2atom.pubDate(atom_entry, tag)

	local pubdate = tag:get_text():gsub("^%a+,", ""):gsub("^%s*", "");

	local date, month, year, hour, minute, second, zone =

		pubdate:match("^(%d%d?) (%a+) (%d+) (%d+):(%d+):?(%d*) ?(.*)$");

	if not date then return; end

	if #date == 1 then

		date = "0"..date;

	end

	month = months[month:sub(1,3):lower()];

	if #year == 2 then -- GAH!

		if tonumber(year) > 80 then

			year = "19"..year;

		else

			year = "20"..year;

		end

	end

	if zone == "UT" or zone == "GMT" then zone = "Z"; end

	if #second == 0 then

		second = "00";

	end

	local date_string = string.format("%s-%s-%sT%s:%s:%s%s", year, month, date, hour, minute, second, zone);

	atom_entry:tag("published"):text(date_string):up();

end

-- Translate a single item to atom

local function translate_rss(rss_feed)

	local feed = st.stanza("feed", { xmlns = "http://www.w3.org/2005/Atom" });

	local channel = rss_feed:get_child("channel");

	-- TODO channel properties

	for item in channel:childtags("item") do

		feed:tag("entry");

		for tag in item:childtags() do

			local translator = rss2atom[tag.name];

			if translator then

				translator(feed, tag);

			end

		end

		-- Preserve Atom-namespaced items

		for atomtag in item:childtags(nil, "http://www.w3.org/2005/Atom") do

			feed:add_child(st.clone(atomtag));

		end

		feed:reset();

	end

	return feed;

end

return { translate_rss = translate_rss }