#!/usr/bin/env python3

# https://en.wikipedia.org/wiki/Extended_Display_Identification_Data

# TODO: This is a real mess, it's a transition from the setup-desktop.sh shell
#       script to something a little more flexible. But it mostly doesn't work
#       yet and is just subbing in for parse-edid.

# TODO: List screens if none are known

# TODO: Zooming
# xrandr --output eDP-1 --mode 2880x1620 --panning 2880x1620
#bigmodes=( 3840x2160 3200x1800 )
#modes=( 2560x1440 2048x1152 1920x1080 1600x900 1368x768
#        1360x768 1280x720 1024x576 960x540 864x486
#        720x405 640x360 )

import re
import os
import sys
import struct
from collections import namedtuple
from subprocess import check_output, call

BUILTIN_DISPLAY_RESOLUTIONS = [
    "1600x900", "1920x1080", "2048x1152", "2880x1620"]
BEST_RESOLUTION = BUILTIN_DISPLAY_RESOLUTIONS[2]

DRM_PATH = "/sys/class/drm"
EDID_MAGIC = b'\x00\xff\xff\xff\xff\xff\xff\x00'
EDID_14 = b'\x01\x04'
UNSPEC_TEXT = 0xFE
SERIAL = 0xFF
NAME = 0xFC


MonitorData = namedtuple(
    "MonitorData", ("card", "port", "name", "serial", "text"))


def parse_xrandr_query():
    monitors = {}
    monitor = None

    for line in check_output(("xrandr", "-q")).split(b"\n"):
        line = line.decode("us-ascii")

        if " connected " in line:
            monitor = line.split(" ")[0]
            monitors[monitor] = []
        elif monitor and line.startswith("  "):
            monitors[monitor].append(line.strip().split(" ")[0])

    return monitors


def parse_card_port(p):
    card, port = p.split("/")[-1].split("-", 1)
    return int(card[len("card"):]), port


def parse_descriptor(card, port, md):
    name, serial, text = None, None, None

    for i in range(54, 108, 18):
        d = md[i:i+18]
        dtype, data = d[3], d[5:]

        prep = lambda dd: dd.decode("us-ascii", errors="ignore").strip()

        if dtype == UNSPEC_TEXT:
            text = prep(data)
        elif dtype == SERIAL:
            serial = prep(data)
        elif dtype == NAME:
            name = prep(data)

    return MonitorData(card, port, name, serial, text)


def parse_edid(data, path):
    if data[0:8] != EDID_MAGIC:
        raise Exception("Not EDID")

    if data[18:20] != EDID_14:
        raise Exception("Not EDID 1.4")

    card, port = parse_card_port(path)
    return parse_descriptor(card, port, data)


def get_monitor_edid(path):
    edid = os.path.join(path, "edid")
    if not os.path.exists(edid):
        raise Exception("No card with that name {!r}".format(path))

    with open(edid, "rb") as fp:
        data = fp.read()

    return parse_edid(data, path)


def enumerate_monitors():
    monitors = []

    for path in os.listdir(DRM_PATH):
        if not re.match("^card\d+-", path):
            continue

        drm_path = os.path.join(DRM_PATH, path)
        monitors.append(get_monitor_edid(drm_path))

    return monitors


def script_main(args):
    all_resolutions = parse_xrandr_query() # Do first to refresh /sys
    all_monitors = enumerate_monitors()

    for monitor in all_monitors:
        resolutions = all_resolutions[monitor.port]

        # 27" Dell monitors
        if monitor == "DELL U2715H":
            call(["xrandr",
                  "--output", "DP-1","--auto",
                  "--output", "DP-2", "--auto", "--right-of", "DP-1",
                  "--output", "eDP-1", "--off"])
            break
        elif monitor == "AMX_HDMI1_A2":
            call(["xrandr",
                  "--output", "eDP-1", "--mode", BEST_RESOLUTION,
                  "--output", monitor.card, "--auto", "--right-of", "eDP-1"])
            break
        elif monitor == "DELL U3415W":
            call(["xrandr",
                  "--output", "eDP-1", "--mode", BEST_RESOLUTION,
                  "--output", monitor.card, "--mode", "3440x1440",
                  "--right-of", "eDP-1"])
            break
        elif monitor == "CS-CODECPLUS":
            call(["xrandr",
                  "--output", "eDP-1", "--mode", BEST_RESOLUTION,
                  "--output", monitor.card, "--auto", "--right-of", "eDP-1"])
            break
        else:
            call(["xrandr",
                  "--output", "eDP-1", "--mode", BEST_RESOLUTION,
                  "--output", "DP-1", "--off",
                  "--output", "DP-2", "--off"])
            break


def main(args):
    print(get_monitor_edid(args[1]).name)

if __name__ == "__main__":
    #sys.exit(main(sys.argv))
    sys.stdin.mode = "rb"
    print(parse_edid(sys.stdin.buffer.read(), "/card1-eDP-1").text)