local st = require "stanza";

local urlencode = require "net.http".urlencode;

local xmlns_xhtmlim = "http://jabber.org/protocol/xhtml-im";

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

local function replace_latex(data)

	module:log("debug", "Replacing latex...");

	local origin, stanza = data.origin, data.stanza;

	local body = stanza:child_with_name("body");

	if not body then return; end

	body = body:get_text();

	if not body:match("%$%$") then

		return;

	end

	local html = st.stanza("html", { xmlns = xmlns_xhtmlim })

		:tag("body", { xmlns = xmlns_xhtml });

	local in_latex, last_char;

	for snippet, up_to in body:gmatch("(.-)%$%$()") do

		last_char = up_to;

		if in_latex then

			-- Render latex and add image, next snippet is text

			in_latex = nil;

			html:tag("img", { src = "http://www.mathtran.org/cgi-bin/mathtran?D=2;tex="..urlencode(snippet), alt = snippet }):up();

		else

			-- Add text to HTML, next snippet is latex

			in_latex = true;

			html:tag("span"):text(snippet):up();

		end

	end

	if last_char < #body then

		html:tag("span"):text(body:sub(last_char, #body)):up();

	end

	for n, tag in ipairs(stanza.tags) do

		module:log("debug", "Tag: %s|%s", tag.attr.xmlns or "", tag.name or "");

		if tag.name == "html" and tag.attr.xmlns == xmlns_xhtmlim then

			stanza.tags[n] = html;

			for n, child in ipairs(stanza) do

				if child == tag then

					stanza[n] = html;

				end

			end

			return;

		end

	end

	stanza[#stanza+1] = html;

	stanza.tags[#stanza.tags+1] = html;

end

module:hook("message/bare", replace_latex, 30);

module:hook("message/full", replace_latex, 30);