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
    data["ssh"] = {
        "user": global_config.ssh_user,
        "port": global_config.ssh_port,
        "options": list(global_config.ssh_options or []),
    }
    data["rsync"] = {
        "binary": global_config.rsync_binary,
        "args": list(global_config.rsync_args or []),
        "timeout_seconds": global_config.rsync_timeout_seconds,
        "bwlimit_kbps": global_config.rsync_bwlimit_kbps,
        "extra_args": list(global_config.rsync_extra_args or []),
    }
    data["defaults"] = {
        "source_root": global_config.default_source_root,
        "destination_subdir": global_config.default_destination_subdir,
    }
    data["excludes_default"] = list(global_config.excludes_default or [])
    data["retention_defaults"] = {
        "daily": global_config.retention_daily,
        "weekly": global_config.retention_weekly,
        "monthly": global_config.retention_monthly,
        "yearly": global_config.retention_yearly,
    }
    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
    if host_config.ssh_user or host_config.ssh_port:
        data["ssh"] = {}
        if host_config.ssh_user:
            data["ssh"]["user"] = host_config.ssh_user
        if host_config.ssh_port is not None:
            data["ssh"]["port"] = host_config.ssh_port
    else:
        data.pop("ssh", None)
    if host_config.source_root:
        data["source_root"] = host_config.source_root
    else:
        data.pop("source_root", None)
    data["includes"] = list(host_config.includes or [])
    if host_config.excludes_replace is not None:
        data["excludes_replace"] = list(host_config.excludes_replace or [])
        data.pop("excludes_add", None)
    else:
        data["excludes_add"] = list(host_config.excludes_add or [])
        data.pop("excludes_replace", None)
    if host_config.rsync_extra_args:
        data["rsync"] = {"extra_args": list(host_config.rsync_extra_args or [])}
    else:
        data.pop("rsync", None)
    data["retention"] = {
        "daily": host_config.retention_daily,
        "weekly": host_config.retention_weekly,
        "monthly": host_config.retention_monthly,
        "yearly": host_config.retention_yearly,
    }
    return validate_dict(data, HOST_SCHEMA, path="host")


def global_config_data(name: str = "default") -> dict[str, Any]:
    try:
        global_config = GlobalConfig.objects.get(name=name)
    except ObjectDoesNotExist as exc:
        raise ConfigRepositoryError(f"Missing GlobalConfig {name!r}") from exc
    return _global_yaml_data(global_config)


def host_config_data(host: str) -> dict[str, Any]:
    try:
        host_config = HostConfig.objects.get(host=host, enabled=True)
    except ObjectDoesNotExist as exc:
        raise ConfigRepositoryError(f"Missing enabled HostConfig {host!r}") from exc
    return _host_yaml_data(host_config)


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