module:set_global();

local loggingmanager = require "core.loggingmanager";

local format = require "util.format".format;

local pposix = require "util.pposix";

local rb = require "util.ringbuffer";

local queue = require "util.queue";

local default_timestamp = "%b %d %H:%M:%S ";

local max_chunk_size = module:get_option_number("log_ringbuffer_chunk_size", 16384);

local os_date = os.date;

local default_filename_template = "{paths.data}/ringbuffer-logs-{pid}-{count}.log";

local render_filename = require "util.interpolation".new("%b{}", function (s) return s; end, {

	yyyymmdd = function (t)

		return os_date("%Y%m%d", t);

	end;

	hhmmss = function (t)

		return os_date("%H%M%S", t);

	end;

});

local dump_count = 0;

local function dump_buffer(dump, filename)

	dump_count = dump_count + 1;

	local f, err = io.open(filename, "a+");

	if not f then

		module:log("error", "Unable to open output file: %s", err);

		return;

	end

	f:write(("-- Dumping log buffer at %s --\n"):format(os_date(default_timestamp)));

	dump(f);

	f:write("-- End of dump --\n\n");

	f:close();

end

local function get_filename(filename_template)

	filename_template = filename_template or default_filename_template;

	return render_filename(filename_template, {

		paths = prosody.paths;

		pid = pposix.getpid();

		count = dump_count;

		time = os.time();

	});

end

local function new_buffer(config)

	local write, dump;

	if config.lines then

		local buffer = queue.new(config.lines, true);

		function write(line)

			buffer:push(line);

		end

		function dump(f)

			-- COMPAT w/0.11 - update to use :consume()

			for line in buffer.pop, buffer do

				f:write(line);

			end

		end

	else

		local buffer_size = config.size or 100*1024;

		local buffer = rb.new(buffer_size);

		function write(line)

			if not buffer:write(line) then

				if #line > buffer_size then

					buffer:discard(buffer_size);

					buffer:write(line:sub(-buffer_size));

				else

					buffer:discard(#line);

					buffer:write(line);

				end

			end

		end

		function dump(f)

			local bytes_remaining = buffer:length();

			while bytes_remaining > 0 do

				local chunk_size = math.min(bytes_remaining, max_chunk_size);

				local chunk = buffer:read(chunk_size);

				if not chunk then

					return;

				end

				f:write(chunk);

				bytes_remaining = bytes_remaining - chunk_size;

			end

		end

	end

	return write, dump;

end

local function ringbuffer_log_sink_maker(sink_config)

	local write, dump = new_buffer(sink_config);

	local timestamps = sink_config.timestamps;

	if timestamps == true or timestamps == nil then

		timestamps = default_timestamp; -- Default format

	elseif timestamps then

		timestamps = timestamps .. " ";

	end

	local function handler()

		dump_buffer(dump, sink_config.filename or get_filename(sink_config.filename_template));

	end

	if sink_config.signal then

		module:hook_global("signal/"..sink_config.signal, handler);

	elseif sink_config.event then

		module:hook_global(sink_config.event, handler);

	end

	return function (name, level, message, ...)

		local line = format("%s%s\t%s\t%s\n", timestamps and os_date(timestamps) or "", name, level, format(message, ...));

		write(line);

	end;

end

loggingmanager.register_sink_type("ringbuffer", ringbuffer_log_sink_maker);