-- statusd for MPD (Music Player Daemon) using a single persistent connection
--
-- bugs/requests/comments: Leandro Lucarella <llucax@gmail.com>
--
-- Based on statusd_exec.lua from Antti Vähäkotamäki (the async code) and
-- statusd_mpd.lua from delirium@hackish.org (the mpd glue code).
--
-- Usage is self documented in the default settings section. It provides the
-- same functionality from statusd_mpd.luam from delirium@hackish.org but it
-- uses a single persistent connection to MPD and does better usage from hints
-- (the status is "hinted important" when mpd status or volume change (and
-- optionally, up to important_time seconds from the begining of each song).
--
-- This is free software; you can redistribute it and/or modify it under
-- the terms of the GNU Lesser General Public License as published by
-- the Free Software Foundation; either version 2.1 of the License, or
-- (at your option) any later version.

local defaults={
    -- netcat path
    netcat = 'netcat',

    -- 500 or less makes seconds increment relatively smoothly while playing
    update_interval = 1000,

    -- mpd server info (localhost:6600 are mpd defaults)
    address = "localhost",
    port = 6600,

    -- mpd password (if any)
    password = nil,

    -- seconds to consider the mpd in 'important' hint (0 never, -1 always)
    important_time = 10, -- seconds

    -- display template
    -- ---
    -- can use the following:
    --   track metadata: %artist, %title, %num, %album, %year, %len
    --   current track position: %pos
    --   volume: %volume
    --   escape for the percent character: %%

    -- a default template
    template = "%artist - %num - %title (%pos / %len)"
}

local settings = table.join(statusd.get_config("mpd"), defaults)

local timer
local last_volume
local last_state

-- Function for starting and restarting execution of a process

local function start_execution()

    -- Set up a function for receiving the data
    -- and informing the statusbar

    local function process_input(data)

        -- At first, we are not initialized
        local inited = false

        -- When we get new data, output the last complete line

        while data do

            if not inited then
                -- welcome msg
                if string.sub(data, 1, 6) ~= "OK MPD" then
                    statusd.inform("mpd_hint", "critical")
                    statusd.inform("mpd", "bad mpd response on init")
                end

                -- 'password' response (if necessary)
                if settings.password ~= nil then
                    if string.sub(data, 1, 2) ~= "OK" then
                        statusd.inform("mpd_hint", "critical")
                        statusd.inform("mpd_hint", "bad mpd password")
                    end
                end

                -- everything ok, receive more data
                inited = true
                data = coroutine.yield()
            end

            local info = {}
            local hint = "normal"

            for attrib, val in string.gfind(data, "([^\n]-): ([^\n]*)") do

                if attrib == "time" then
                    _, _, info.pos, info.len = string.find(val, "(%d+):(%d+)")
                    if settings.important_time == -1
                                    or info.pos+0 <= settings.important_time
                                        and settings.important_time ~= 0 then
                        hint = "important"
                    end
                    info.pos = string.format("%d:%02d", math.floor(info.pos / 60),
                            math.mod(info.pos, 60))
                    info.len = string.format("%d:%02d", math.floor(info.len / 60),
                            math.mod(info.len, 60))
                elseif attrib == "state" then
                    info.state = val
                    if info.state ~= last_state then
                        hint = "important"
                    end
                    last_state = info.state
                elseif attrib == "volume" then
                    info.volume = val .. "%"
                    if info.volume ~= last_volume then
                        hint = "important"
                    end
                    last_volume = info.volume
                elseif attrib == "Artist" then
                    info.artist = val
                elseif attrib == "Title" then
                    info.title = val
                elseif attrib == "Album" then
                    info.album = val
                elseif attrib == "Track" then
                    info.num = val
                elseif attrib == "Date" then
                    info.year = val
                end
            end

            -- done querying; now build the string
            statusd.inform("mpd_hint", hint)
            if info.state == "play" then
                local mpd_st = settings.template
                -- fill in %values
                mpd_st = string.gsub(mpd_st, "%%([%w%_]+)",
                        function (x) return(info[x]  or "") end)
                mpd_st = string.gsub(mpd_st, "%%%%", "%%")
                statusd.inform("mpd", mpd_st)
            elseif info.state == "pause" then
                statusd.inform("mpd", "Paused")
            else
                statusd.inform("mpd", "No song playing")
            end

            -- Wait for bgread to signal that more data
            -- is available or the program has exited

            data = coroutine.yield()
        end

        -- Program has exited.
        -- Start a timer for a new execution if set.

        timer:set(settings.update_interval,
                  function() start_execution() end)
    end

    -- Set up a simple function for printing errors

    local function process_error(data)
        while data do
            io.stderr:write("ion-statusd [statusd_mpd]: " .. data)
            io.stderr:flush()
            data = coroutine.yield()
        end
    end

    -- Execute the program in the background and create
    -- coroutine functions to handle input and error data
    local sleep = settings.update_interval / 1000
    sleep = string.gsub(sleep, '(%d+),(%d+)', '%1.%2')
    local cmd = 'while sleep ' .. sleep .. '; do ' ..
                'echo "status\ncurrentsong"; done | ' ..
                settings.netcat .. ' ' .. settings.address .. ' ' ..
                settings.port
    if settings.password ~= nil then
        cmd = "echo 'password " .. settings.password .. "'; " .. cmd
    end
    statusd.popen_bgread(cmd, coroutine.wrap(process_input),
                              coroutine.wrap(process_error))

end

-- Now start execution of all defined processes

timer = statusd.create_timer()
start_execution()

-- vim: set et sts=4 sw=4 :