#!/usr/bin/python

import serial
import mpd
import time
import sys
import logging

logger = logging.getLogger()
logging.basicConfig(format="%(asctime)s - %(name)s - %(levelname)s - %(message)s")
logger.setLevel(logging.DEBUG)

class Config:
    display_lines = 2
    display_width = 16
    display_length = display_lines * display_width

class Daemon:
    line = ""
    playing = False

    def __init__(self):
        self.ser = serial.Serial(sys.argv[1], 9600, timeout=1)

        # raise timeout to let arduino start up
        self.ser.timeout = 15
        incoming = self.readline()

        # arduino sometimes has a dirty buffer
        # and sends junk before the ready message
        if not incoming.endswith("ready"):
            sys.stderr.write("Got unexpected reply: "+incoming)
            raise Exception("Wrong client greeting")
        self.ser.timeout = 1

        self.client = mpd.MPDClient()
        self.client.connect("localhost", 6600)
        logger.debug("connected")

    def readline(self):
        return self.ser.readline().decode("ascii").strip()

    def update(self):
        old_line = self.line
        old_playing = self.playing
        changed = False

        incoming = self.client.currentsong()

        self.line = incoming["artist"] + " - " + incoming["title"]
        if self.line != old_line:
            changed = True

        self.playing = self.client.status()["state"] == "play"
        if self.playing != old_playing:
            changed = True

        return changed

    def run(self):
        self.update()

        last_display_update = 0.0
        last_song_update = 0.0
        now = 0.0
        time_diff = 0.0
        current_position = 0

        while 1:
            now = time.time()

            # check for incoming commands from arduino
            if self.ser.inWaiting() > 0:
                incoming = self.readline()

                logger.info("got serial command: '%s'", incoming)

                functions = {
                    "next": self.client.next,
                    "previous": self.client.previous,
                    "pause": self.client.pause,
                }
                try:
                    func = functions[incoming]
                    func()

                    # force redraw if anything changed
                    if self.update():
                        last_display_update = 0
                        current_position = 0

                except KeyError:
                    logger.warning("ignoring unknown serial command '%s'", incoming)
                    pass

            # check if song changed
            # TODO: use idle and poll (more often)?
            time_diff = now - last_song_update
            if time_diff > 2.5 or time_diff < -60.0:
                last_song_update = now
                if self.update():
                    last_display_update = 0
                    current_position = 0

            # update arduino display
            time_diff = now - last_display_update
            if time_diff > 0.8 or time_diff < -60.0:
                last_display_update = now
                if self.playing:
                    i = current_position

                    if i - 1 + Config.display_length == len(self.line):
                        i = 0

                    if i == 0:
                        # allow people to start reading
                        last_display_update += 2

                    if len(self.line) > Config.display_length:
                        buf = self.line[i:i+Config.display_length]
                    else:
                        buf = self.line.ljust(Config.display_length, " ")

                    i += 1
                    current_position = i
                else:
                    buf = "-- PAUSED --".center(Config.display_width, " ").ljust(Config.display_length, " ")

                    # always start at the beginning if we unpause
                    current_position = 0

                logger.debug("current_position = %s, buf = '%s'", str(current_position).rjust(3), buf)
                self.ser.write(bytes(buf, "ascii", "replace"))

            time.sleep(0.05)

if __name__ == '__main__':
    d = Daemon()
    d.run()