#!/usr/bin/env python3

import argparse
import dataclasses
import enum
import json
import logging
import pathlib
import subprocess
from typing import Any
import yaml

import dialog


class NoMatchingProfile(ValueError):
    pass


class LogLevel:
    def __init__(self, value: str) -> None:
        try:
            self.numerical_level = logging.getLevelNamesMapping()[value.upper()]
        except KeyError:
            raise ValueError("invalid value")


class GraphicalServer(enum.StrEnum):
    XORG = enum.auto()
    WAYLAND = enum.auto()


@dataclasses.dataclass
class Monitor:
    output: str

    xrandr_opts: list[str] = dataclasses.field(default_factory=list)
    wlr_randr_opts: list[str] = dataclasses.field(default_factory=list)
    position: str | None = None
    background: str | None = None
    primary: bool = False

    @classmethod
    def from_json_dict(cls, json_dict: dict[str, Any]) -> "Monitor":
        def convert_key_name(name: str) -> str:
            return name.replace("-", "_")

        return cls(**{convert_key_name(key): value for key, value in json_dict.items()})


@dataclasses.dataclass
class Profile:
    name: str
    monitors: list[Monitor] = dataclasses.field(default_factory=list)

    identifier: str | None = None
    xrandr_opts: list[str] = dataclasses.field(default_factory=list)
    wlr_randr_opts: list[str] = dataclasses.field(default_factory=list)

    @classmethod
    def from_json_dict(cls, json_dict: dict[str, Any]) -> "Profile":
        def convert_key_name(name: str) -> str:
            return name.replace("-", "_")

        kwargs = {}
        for key, value in json_dict.items():
            key = convert_key_name(key)
            if key == "monitors":
                value = [Monitor.from_json_dict(item) for item in value]
            kwargs[key] = value
        return cls(**kwargs)

    def apply(self, graphical_server: GraphicalServer | None):
        match graphical_server:
            case GraphicalServer.XORG:
                self.apply_xorg()
            case GraphicalServer.WAYLAND:
                self.apply_wayland()
            case None:
                try:
                    subprocess.run(["xrandr"], check=True, stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)
                except (subprocess.CalledProcessError, FileNotFoundError):
                    self.apply_wayland()
                else:
                    self.apply_xorg()

    def apply_xorg(self):
        # We build the command line starting from just "xrandr" and adding
        # arguments.
        xrandr_cmd = ['xrandr']
        feh_cmd = ['feh', '--bg-fill']

        try:
            xrandr_cmd += self.xrandr_opts
        except KeyError:
            pass

        for monitor in self.monitors:
            xrandr_cmd.extend(monitor.xrandr_opts)

            if monitor.background is not None:
                feh_cmd.append(monitor.background)

        logging.debug("Executing: %s", xrandr_cmd)
        subprocess.run(xrandr_cmd, check=False)
        logging.debug("Executing: %s", feh_cmd)
        subprocess.run(feh_cmd, check=False)

    def apply_wayland(self):
        # We build the command line starting from just "xrandr" and adding
        # arguments.
        wlr_randr_cmd = ['wlr-randr']

        try:
            wlr_randr_cmd += self.wlr_randr_opts
        except KeyError:
            pass

        for monitor in self.monitors:
            wlr_randr_cmd.extend(monitor.wlr_randr_opts)

        logging.debug("Executing: %s", wlr_randr_cmd)
        subprocess.run(wlr_randr_cmd, check=False)


class MonitorMenu:
    def __init__(self, profiles: list[Profile]) -> None:
        self.profiles = profiles
        self.d = dialog.Dialog(autowidgetsize=True)

    def run(self, *, graphical_server: GraphicalServer | None = None, apply_exit=False):
        choices = []

        i = 0
        for p in self.profiles:
            choices.append((str(i), p.name))
            i += 1

        while True:
            code, profile_idx = self.d.menu(
                    'Select the profile you want to use.',
                    choices=choices)

            if code in (self.d.ESC, self.d.CANCEL):
                return

            try:
                self.profiles[int(profile_idx)].apply(graphical_server=graphical_server)
                if apply_exit:
                    return
            except IndexError:
                raise NoMatchingProfile from None


def load_profiles_config(path: pathlib.Path | None):
    if path is not None:
        with path.open() as fh:
            if path.suffix == ".json":
                return json.load(fh)
            # Expect YAML by default
            return yaml.safe_load(fh)

    # Try monitor-profiles.yaml and revert to monitor-profiles.json if the
    # first one does not exist.
    try:
        with pathlib.Path("~/.config/monitor-profiles.yaml").expanduser().open() as fh:
            return yaml.safe_load(fh)
    except FileNotFoundError:
        with pathlib.Path("~/.config/monitor-profiles.json").expanduser().open() as fh:
            return json.load(fh)


def main():
    parser = argparse.ArgumentParser()
    parser.add_argument("--log-level", "--loglevel", type=LogLevel, default="info")
    parser.add_argument("--graphical-server", choices=list(GraphicalServer),
                        type=GraphicalServer)
    parser.add_argument(
            "--profiles-config",
            metavar="PATH",
            type=pathlib.Path,
            help="Configuration file to use."
            " By default $HOME/.config/monitor-profiles.yaml (preferred)"
            " or $HOME/.config/monitor-profiles.json")
    subparser = parser.add_subparsers(dest="command")
    run_parser = subparser.add_parser("run")
    run_parser.add_argument("--apply-exit", action="store_true")
    apply_parser = subparser.add_parser("apply")
    identifier_group = apply_parser.add_mutually_exclusive_group(required=True)
    identifier_group.add_argument("--index", type=int)
    identifier_group.add_argument("--id", type=str)

    args = parser.parse_args()
    logging.basicConfig(level=args.log_level.numerical_level)

    data = load_profiles_config(args.profiles_config)

    profiles = [Profile.from_json_dict(item) for item in data]

    match args.command:
        case None:
            MonitorMenu(profiles).run(graphical_server=args.graphical_server)
        case "run":
            MonitorMenu(profiles).run(apply_exit=args.apply_exit, graphical_server=args.graphical_server)
        case "apply":
            if args.index is not None:
                try:
                    profiles[args.index].apply(graphical_server=args.graphical_server)
                except IndexError:
                    raise NoMatchingProfile from None
            else:
                try:
                    next(filter(lambda p: p.identifier == args.id, profiles)).apply(graphical_server=args.graphical_server)
                except StopIteration:
                    raise NoMatchingProfile from None


if __name__ == '__main__':
    main()