from __future__ import annotations

import hashlib
import json
import time
from pathlib import Path

from pydantic import BaseModel, Field


class FetchCacheEntry(BaseModel):
    text: str
    headers: dict[str, str] = Field(default_factory=dict)


def build_fetch_cache_key(*, name: str, url: str) -> str:
    raw = f"{name}|{url}"
    return hashlib.sha256(raw.encode("utf-8")).hexdigest()


def load_fetch_cache(*, cache_dir: Path, cache_key: str, ttl_seconds: int) -> FetchCacheEntry | None:
    text_path = cache_dir / f"{cache_key}.txt"
    meta_path = cache_dir / f"{cache_key}.json"
    if not text_path.is_file() or not meta_path.is_file():
        return None

    expires_at = meta_path.stat().st_mtime + ttl_seconds
    if expires_at < time.time():
        return None

    try:
        metadata = json.loads(meta_path.read_text(encoding="utf-8"))
    except json.JSONDecodeError:
        return None

    headers = metadata.get("headers")
    if not isinstance(headers, dict):
        headers = {}

    return FetchCacheEntry(
        text=text_path.read_text(encoding="utf-8"),
        headers={str(k): str(v) for k, v in headers.items()},
    )


def save_fetch_cache(*, cache_dir: Path, cache_key: str, text: str, headers: dict[str, str]) -> Path:
    cache_dir.mkdir(parents=True, exist_ok=True)
    text_path = cache_dir / f"{cache_key}.txt"
    meta_path = cache_dir / f"{cache_key}.json"
    text_path.write_text(text, encoding="utf-8")
    meta_path.write_text(json.dumps({"headers": headers}, ensure_ascii=False, indent=2), encoding="utf-8")
    return text_path