feeds.lua

local io, string = io, string;

local error = error;

local print = print;

local t_insert = table.insert;

local ipairs = ipairs;

local http = require "socket.http";

local st = require "stanza";

local new_stream = require "xmlstream".new;

local xmlns_atom = "http://www.w3.org/2005/Atom";

--[[

By popular request; a fluffy bunny:

 (\ /)

 (. .)

c(")(")

--]]

module "feeds"

local translate_entry = {};

function translate_entry.atom(feed, stanza)

	if stanza.name == "entry" then

		feed[#feed+1] = stanza;

	elseif stanza.name == "author" then

		feed.author = {};

		for i,a in ipairs(stanza) do

			if a.name and a[1] then

				feed.author[a.name] = a[1];

			end

		end

	elseif stanza.name == "link" then

		if not feed.links then feed.links = {}; end

		if stanza.attr.href then

			if stanza.attr.rel then

				feed.links[stanza.attr.rel] = stanza.attr.href;

			else

				t_insert(feed.links, stanza.attr.href)

			end

		end

	else

		feed[stanza.name] = stanza:get_text();

	end

end

-- RSS->Atom translator

-- 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.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

function translate_entry.rss(feed, stanza)

	if stanza.name == "item" then

		local atom_entry = st.stanza("entry", { xmlns = xmlns_atom });

		for tag in stanza:childtags() do

			local translator = rss2atom[tag.name];

			if translator then

				translator(atom_entry, tag);

			end

		end

		translate_entry.atom(feed, atom_entry:reset());

	else

		translate_entry.atom(feed, stanza);

	end

end

local function new_feed_stream(feed)

	local callbacks = {

		streamopened = function (feed, attr, name)

			if name == "feed" and attr.xmlns == xmlns_atom then

				feed.type = "atom";

				feed.xmlns = xmlns_atom;

				feed.notopen = nil;

			elseif name == "rss" and attr.xmlns == "" then

				feed.type = "rss";

				feed.xmlns = "";

				-- Don't open until channel

			elseif feed.type == "rss" and name == "channel" and attr.xmlns == feed.xmlns then

				feed.notopen = nil;

			else

				error("Unsupported feed type: <"

					..name

					..(attr.xmlns and (" xmlns='"..attr.xmlns.."'") or "")

					..">"

				);

			end

		end;

		streamclosed = function (feed)

		end;

		handlestanza = function (feed, stanza)

			-- Skip tags not in the feed's default namespace

			if stanza.attr.xmlns ~= feed.xmlns then

				return;

			end

			translate_entry[feed.type](feed, stanza);

		end;

		error = function (feed, err, d)

			error(err..": "..d);

		end;

	};

	return new_stream(feed, callbacks);

end

function feed_from_string(data)

	local feed = {notopen = true};

	local stream = new_feed_stream(feed);

	stream:feed(data);

	return feed;

end

function open(url)

	if url:match("^file://") then

		return open_file(url);

	elseif url:match("^https?://") then

		return open_http(url);

	else

		return false, "Could not understand URL: "..url;

	end

end

function open_file(filename)

	local file, err = io.open((filename:gsub("^file://", "")));

	if not file then

		return file, err;

	end

	local feed = feed_from_string(file:read("*a"));

	file:close();

	return feed;

end

function open_http(url)

	local data, err = http.request(url);

	if not data then

		return data, err;

	end

	local feed = feed_from_string(data);

	return feed;

end