import os
import json
import time
import hashlib
from db.config import DATA_DIR

CACHE_DIR = os.path.join(DATA_DIR, "cache")
CACHE_TTL = 86400


def _ensure_dir():
    os.makedirs(CACHE_DIR, exist_ok=True)


def _page_to_filename(page_name):
    safe = page_name.replace("/", "_").replace("?", "_").replace("&", "_").replace("%", "_")
    if len(safe) > 120:
        safe = hashlib.md5(page_name.encode()).hexdigest()
    return os.path.join(CACHE_DIR, safe + ".html")


def cache_get(page_name):
    fpath = _page_to_filename(page_name)
    if not os.path.exists(fpath):
        return None
    mtime = os.path.getmtime(fpath)
    if time.time() - mtime > CACHE_TTL:
        return None
    with open(fpath, "r", encoding="utf-8", errors="replace") as f:
        return f.read()


def cache_put(page_name, content):
    _ensure_dir()
    fpath = _page_to_filename(page_name)
    with open(fpath, "w", encoding="utf-8", errors="replace") as f:
        f.write(content)


PROGRESS_FILE = os.path.join(DATA_DIR, "crawl_progress.json")


def load_progress():
    if not os.path.exists(PROGRESS_FILE):
        return {"last_page": 0, "max_pages": 0}
    try:
        with open(PROGRESS_FILE, "r", encoding="utf-8") as f:
            return json.load(f)
    except Exception:
        return {"last_page": 0, "max_pages": 0}


def save_progress(last_page, max_pages):
    _ensure_dir()
    with open(PROGRESS_FILE, "w", encoding="utf-8") as f:
        json.dump({"last_page": last_page, "max_pages": max_pages}, f)


def clear_progress():
    if os.path.exists(PROGRESS_FILE):
        os.remove(PROGRESS_FILE)


def cache_clear(older_than=None):
    _ensure_dir()
    now = time.time()
    for fname in os.listdir(CACHE_DIR):
        fpath = os.path.join(CACHE_DIR, fname)
        if fname.endswith(".html"):
            age = now - os.path.getmtime(fpath)
            if older_than is None or age > older_than:
                os.remove(fpath)