#!/usr/bin/env python3
from subprocess import call, check_call, check_output
from time import sleep
import os
import sys
import json

CONTAINER_NAME = "otherworld"
IMAGE_NAME = "debian:stable"

def create_x11_mapping ():
    home = os.environ["HOME"]
    xdg_dir = os.environ["XDG_RUNTIME_DIR"]
    display = os.environ["DISPLAY"]
    inner_user = home
    Xauthority = os.environ["XAUTHORITY"]

    return ["-e", f"DISPLAY={display}", 
            "-v", "/tmp/.X11-unix/:/tmp/.X11-unix",
            "-v", "/dev/snd:/dev/snd",
            "-v", f"{xdg_dir}/pulse:/run/pulse:ro",
            "-v", f"{home}/.gtkrc-2.0:{inner_user}/.gtkrc-2.0",
            "-v", f"{home}/.config/gtk-3.0/:{inner_user}/.config/gtk-3.0",
            "-v", f"{home}/.guix-profile/share/fonts/truetype:/user/share/fonts/truetype-guix",
            "-v", f"{home}/.guix-profile/share/fonts/opentype:/usr/share/fonts/opentype-guix",
            "-v", f"{Xauthority}:{inner_user}/.Xauthority",
            "-w", inner_user,
            "--shm-size", "2g",
            "--privileged"]

DOCKER_CREATE_OPTIONS = ["-t"] + create_x11_mapping()
USER_VOLUMES = ["~/otherworld"]
BACKGROUND_COMMAND = None
DEFAULT_COMMAND = ["bash"]

def docker_inspect (container):
    return json.loads(check_output(["docker", "inspect", container]))

def docker_create (image, container, options, command):
    docker_command = ["docker", "create", "--name", container] + options + [image]
    if command:
        docker_command = docker_command + command
    call(docker_command)

def docker_get_user (container, user):
    return check_output(["docker", "exec", container, "groups", user])

def docker_create_user (container, user, uid=None):
    command = ["docker", "exec", container, "adduser", user, "--gecos", ",,,", "--disabled-password"]
    if uid is not None:
        command = command + ["--uid", str(uid)]
    call(command)
    call(["docker", "exec", container, "chown", user, f"/home/{user}"])

def docker_start (container):
    call(["docker", "start", container])

def docker_exec (container, command, user):
    call(["docker", "exec", "--user", user, "-ti", container] + command)

def docker_rm (container):
    call(["docker", "rm", "-f", container])

def docker_build (build_path, options, image_name):
    check_call(["docker", "build"] + options + ["-t", image_name, build_path])
    return image_name

def docker_pull (image_name):
    check_call(["docker", "pull", image_name])

def resolve_build_path (build_path):
    if build_path is not None and build_path.startswith("~/"):
        build_path = f"{os.environ['HOME']}/{build_path[1:]}"

    return build_path

def expand_user_volumes (volumes):
    outer_home = os.environ["HOME"]
    inner_home = outer_home
    mappings = []
    for volume in volumes:
        source = volume
        target = volume
        if ":" in source:
            (source, target) = source.split(":")
        
        if source.startswith("~/"):
            source = f"{outer_home}/{source[1:]}"

        if source.startswith(outer_home) and not os.path.exists(source):
            os.makedirs(source)

        if target.startswith("~/"):
            target = f"{inner_home}/{target[1:]}"

        mappings = mappings + ["-v", f"{source}:{target}"]

    return mappings

user = os.environ["USER"]
uid = int(check_output(["id", "-u"]).strip())
image_name = os.environ.get("OW_IMAGE", IMAGE_NAME)
container_name = os.environ.get("OW_CONTAINER", f"{CONTAINER_NAME}_{user}")
build_path = None

command = sys.argv[1:]
command_user = user
user_volumes = USER_VOLUMES
pull = False

quiet = False
while len(command) > 0:
    arg = command[0]
    if arg == "--quiet":
        command = command[1:]
        quiet = True
    elif arg == "--rm":
        if not quiet:
            print(f">> Removing container: {container_name}")
        docker_rm(container_name)
        sys.exit(0)
    elif arg == "--sudo":
        command_user = "root"
        command = command[1:]
    elif arg.startswith("--container="):
        container_name = arg[len("--container="):]
        command = command[1:]
    elif arg.startswith("--image="):
        image_name = arg[len("--image="):]
        command = command[1:]
    elif arg.startswith("--build="):
        build_path = arg[len("--build="):]
        command = command[1:]
    elif arg.startswith("--volume="):
        user_volumes.append(arg[len("--volume="):])
        command = command[1:]
    elif arg == "--pull":
        command = command[1:]
        pull = True
    else:
        break

if len(command) == 0:
    command = DEFAULT_COMMAND

container = None
try:
    container = docker_inspect(container_name)[0]
except Exception:
    build_path = resolve_build_path(build_path)
    if build_path is not None:
        image_name = docker_build(build_path, ["--pull"] if pull else [], f"image_{container_name}")
    elif pull:
        docker_pull(image_name)

    if not quiet:
        print(f">> Creating container: {container_name} (using image: {image_name})")
    docker_create(
        image_name,
        container_name,
        DOCKER_CREATE_OPTIONS + expand_user_volumes(user_volumes),
        BACKGROUND_COMMAND
    )
    container = docker_inspect(container_name)[0]

if not container["State"]["Running"]:
    if not quiet:
        print(f">> Starting container: {container_name}")
    docker_start(container_name)
    container = docker_inspect(container_name)[0]

try:
    docker_get_user(container_name, user)
except Exception:
    if not quiet:
        print(f">> Creating container user: {user}")
    docker_create_user(container_name, user, uid)

if not quiet:
    print(f">> Welcome to {container_name} (IP {container['NetworkSettings']['IPAddress']})")
docker_exec(container_name, command, command_user)