from __future__ import annotations

import os
import tempfile
from dataclasses import dataclass
from pathlib import Path
from typing import Any

import yaml


@dataclass(frozen=True, slots=True)
class HermesModelRoute:
    model: str
    endpoint: str
    api_key: str = ""
    provider_label: str = ""


@dataclass(frozen=True, slots=True)
class HermesConfigSnapshot:
    path: Path
    existed: bool
    content: bytes


def get_hermes_home() -> Path:
    configured_home = str(os.getenv("HERMES_HOME", "")).strip()
    if configured_home:
        return Path(configured_home).expanduser()
    return Path.home() / ".hermes"


def get_hermes_config_path() -> Path:
    return get_hermes_home() / "config.yaml"


def capture_hermes_config_snapshot(config_path: Path | None = None) -> HermesConfigSnapshot:
    target_path = config_path or get_hermes_config_path()
    if not target_path.exists():
        return HermesConfigSnapshot(path=target_path, existed=False, content=b"")
    return HermesConfigSnapshot(path=target_path, existed=True, content=target_path.read_bytes())


def restore_hermes_config_snapshot(snapshot: HermesConfigSnapshot) -> None:
    snapshot.path.parent.mkdir(parents=True, exist_ok=True)
    if snapshot.existed:
        snapshot.path.write_bytes(snapshot.content)
        return
    if snapshot.path.exists():
        snapshot.path.unlink()


def sync_hermes_model_settings(
    primary_route: HermesModelRoute,
    fallback_route: HermesModelRoute | None = None,
    config_path: Path | None = None,
) -> Path:
    target_path = config_path or get_hermes_config_path()
    target_path.parent.mkdir(parents=True, exist_ok=True)

    config = _load_existing_config(target_path)
    config["model"] = _build_primary_model_config(primary_route)

    if fallback_route is None:
        config.pop("fallback_model", None)
    else:
        config["fallback_model"] = _build_fallback_model_config(fallback_route)

    _atomic_yaml_write(target_path, config)
    return target_path


def _load_existing_config(config_path: Path) -> dict[str, Any]:
    if not config_path.exists():
        return {}

    raw_content = config_path.read_text(encoding="utf-8")
    if not raw_content.strip():
        return {}

    loaded = yaml.safe_load(raw_content)
    if loaded is None:
        return {}
    if not isinstance(loaded, dict):
        raise ValueError(f"Hermes 配置文件格式无效: {config_path}")
    return dict(loaded)


def _build_primary_model_config(route: HermesModelRoute) -> dict[str, Any]:
    normalized_model = route.model.strip()
    normalized_endpoint = route.endpoint.strip().rstrip("/")
    if not normalized_model or not normalized_endpoint:
        raise ValueError("Hermes 主模型同步失败：模型名称或接口地址为空。")

    api_mode = _infer_api_mode(route)
    payload: dict[str, Any] = {
        "provider": "custom",
        "default": normalized_model,
        "base_url": normalized_endpoint,
    }
    if route.api_key.strip():
        payload["api_key"] = route.api_key.strip()
    else:
        payload.pop("api_key", None)
    if api_mode != "chat_completions":
        payload["api_mode"] = api_mode
    else:
        payload.pop("api_mode", None)
    return payload


def _build_fallback_model_config(route: HermesModelRoute) -> dict[str, Any]:
    normalized_model = route.model.strip()
    normalized_endpoint = route.endpoint.strip().rstrip("/")
    if not normalized_model or not normalized_endpoint:
        raise ValueError("Hermes 备份模型同步失败：模型名称或接口地址为空。")

    api_mode = _infer_api_mode(route)
    payload: dict[str, Any] = {
        "provider": "custom",
        "model": normalized_model,
        "base_url": normalized_endpoint,
    }
    if route.api_key.strip():
        payload["api_key"] = route.api_key.strip()
    else:
        payload.pop("api_key", None)
    if api_mode != "chat_completions":
        payload["api_mode"] = api_mode
    else:
        payload.pop("api_mode", None)
    return payload


def _infer_api_mode(route: HermesModelRoute) -> str:
    provider_label = route.provider_label.strip().casefold()
    endpoint = route.endpoint.strip().lower().rstrip("/")

    if provider_label == "claude" or "anthropic.com" in endpoint or endpoint.endswith("/anthropic"):
        return "anthropic_messages"
    if "api.openai.com" in endpoint or "api.x.ai" in endpoint:
        return "codex_responses"
    return "chat_completions"


def _atomic_yaml_write(target_path: Path, payload: dict[str, Any]) -> None:
    serialized = yaml.safe_dump(payload, sort_keys=False, allow_unicode=True)
    with tempfile.NamedTemporaryFile(
        mode="w",
        encoding="utf-8",
        dir=str(target_path.parent),
        prefix=f".{target_path.name}.",
        delete=False,
    ) as temp_file:
        temp_file.write(serialized)
        temp_path = Path(temp_file.name)

    temp_path.replace(target_path)