from __future__ import annotations

from pathlib import Path
from typing import Any

from django.core.exceptions import ObjectDoesNotExist

from pobsync.config.schemas import GLOBAL_SCHEMA, HOST_SCHEMA
from pobsync.paths import PobsyncPaths
from pobsync.util import write_yaml_atomic
from pobsync.validate import validate_dict

from .models import GlobalConfig, HostConfig


class ConfigRepositoryError(RuntimeError):
    pass


def _global_yaml_data(global_config: GlobalConfig) -> dict[str, Any]:
    data = dict(global_config.data or {})
    data["backup_root"] = global_config.backup_root
    data["pobsync_home"] = global_config.pobsync_home
    return validate_dict(data, GLOBAL_SCHEMA, path="global")


def _host_yaml_data(host_config: HostConfig) -> dict[str, Any]:
    data = dict(host_config.config or {})
    data["host"] = host_config.host
    data["address"] = host_config.address
    return validate_dict(data, HOST_SCHEMA, path="host")


def export_global_config(prefix: Path, name: str = "default") -> Path:
    try:
        global_config = GlobalConfig.objects.get(name=name)
    except ObjectDoesNotExist as exc:
        raise ConfigRepositoryError(f"Missing GlobalConfig {name!r}") from exc

    paths = PobsyncPaths(home=prefix)
    write_yaml_atomic(paths.global_config_path, _global_yaml_data(global_config))
    return paths.global_config_path


def export_host_config(prefix: Path, host: str) -> Path:
    try:
        host_config = HostConfig.objects.get(host=host, enabled=True)
    except ObjectDoesNotExist as exc:
        raise ConfigRepositoryError(f"Missing enabled HostConfig {host!r}") from exc

    paths = PobsyncPaths(home=prefix)
    target = paths.hosts_dir / f"{host_config.host}.yaml"
    write_yaml_atomic(target, _host_yaml_data(host_config))
    return target


def export_runtime_configs(prefix: Path, host: str | None = None) -> list[Path]:
    written = [export_global_config(prefix)]
    hosts = HostConfig.objects.filter(enabled=True).order_by("host")
    if host is not None:
        hosts = hosts.filter(host=host)
    for host_config in hosts:
        written.append(export_host_config(prefix, host_config.host))
    return written