import json
import os
import subprocess
import sys
from pathlib import Path
from tempfile import NamedTemporaryFile
from typing import Optional

from fastapi import HTTPException

from clan_cli.dirs import get_clan_flake_toplevel, nixpkgs_source
from clan_cli.git import commit_file, find_git_repo_root
from clan_cli.machines.folders import machine_folder, machine_settings_file
from clan_cli.nix import nix_eval


def verify_machine_config(
    machine_name: str, config: Optional[dict] = None, flake: Optional[Path] = None
) -> Optional[str]:
    """
    Verify that the machine evaluates successfully
    Returns a tuple of (success, error_message)
    """
    if config is None:
        config = config_for_machine(machine_name)
    if flake is None:
        flake = get_clan_flake_toplevel()
    with NamedTemporaryFile(mode="w") as clan_machine_settings_file:
        json.dump(config, clan_machine_settings_file, indent=2)
        clan_machine_settings_file.seek(0)
        env = os.environ.copy()
        env["CLAN_MACHINE_SETTINGS_FILE"] = clan_machine_settings_file.name
        proc = subprocess.run(
            nix_eval(
                flags=[
                    "--impure",
                    "--show-trace",
                    "--show-trace",
                    "--impure",  # needed to access CLAN_MACHINE_SETTINGS_FILE
                    f".#nixosConfigurations.{machine_name}.config.system.build.toplevel.outPath",
                ],
            ),
            capture_output=True,
            text=True,
            cwd=flake,
            env=env,
        )
    if proc.returncode != 0:
        return proc.stderr
    return None


def config_for_machine(machine_name: str) -> dict:
    # read the config from a json file located at {flake}/machines/{machine_name}/settings.json
    if not machine_folder(machine_name).exists():
        raise HTTPException(
            status_code=404,
            detail=f"Machine {machine_name} not found. Create the machine first`",
        )
    settings_path = machine_settings_file(machine_name)
    if not settings_path.exists():
        return {}
    with open(settings_path) as f:
        return json.load(f)


def set_config_for_machine(machine_name: str, config: dict) -> Optional[str]:
    # write the config to a json file located at {flake}/machines/{machine_name}/settings.json
    if not machine_folder(machine_name).exists():
        raise HTTPException(
            status_code=404,
            detail=f"Machine {machine_name} not found. Create the machine first`",
        )
    error = verify_machine_config(machine_name, config)
    if error is not None:
        return error
    settings_path = machine_settings_file(machine_name)
    settings_path.parent.mkdir(parents=True, exist_ok=True)
    with open(settings_path, "w") as f:
        json.dump(config, f)
    repo_dir = find_git_repo_root()

    if repo_dir is not None:
        commit_file(settings_path, repo_dir)
    return None


def schema_for_machine(
    machine_name: str, config: Optional[dict] = None, flake: Optional[Path] = None
) -> dict:
    if flake is None:
        flake = get_clan_flake_toplevel()
    # use nix eval to lib.evalModules .#nixosConfigurations.<machine_name>.options.clan
    with NamedTemporaryFile(mode="w") as clan_machine_settings_file:
        env = os.environ.copy()
        inject_config_flags = []
        if config is not None:
            json.dump(config, clan_machine_settings_file, indent=2)
            clan_machine_settings_file.seek(0)
            env["CLAN_MACHINE_SETTINGS_FILE"] = clan_machine_settings_file.name
            inject_config_flags = [
                "--impure",  # needed to access CLAN_MACHINE_SETTINGS_FILE
            ]
        proc = subprocess.run(
            nix_eval(
                flags=inject_config_flags
                + [
                    "--impure",
                    "--show-trace",
                    "--expr",
                    f"""
                    let
                        flake = builtins.getFlake (toString {flake});
                        lib = import {nixpkgs_source()}/lib;
                        options = flake.nixosConfigurations.{machine_name}.options;
                        clanOptions = options.clan;
                        jsonschemaLib = import {Path(__file__).parent / "jsonschema"} {{ inherit lib; }};
                        jsonschema = jsonschemaLib.parseOptions clanOptions;
                    in
                        jsonschema
                    """,
                ],
            ),
            capture_output=True,
            text=True,
            cwd=flake,
            env=env,
        )
    if proc.returncode != 0:
        print(proc.stderr, file=sys.stderr)
        raise Exception(
            f"Failed to read schema for machine {machine_name}:\n{proc.stderr}"
        )
    return json.loads(proc.stdout)