import hashlib
import logging
import time
from pathlib import Path

from flask import Flask, request

from app.config import LOG_LEVEL

logging.basicConfig(
    level=getattr(logging, LOG_LEVEL.upper(), logging.INFO),
    format="%(asctime)s [%(levelname)s] %(name)s: %(message)s",
    datefmt="%Y-%m-%d %H:%M:%S",
)

app = Flask(__name__)


# ── Static asset versioning ────────────────────────────────────────
# Each /static/<file> reference gets a ?v=<hash> query string so we can serve
# it with `Cache-Control: immutable` and still bust the cache when bytes change.
_FALLBACK_TOKEN = hashlib.sha1(str(time.time()).encode()).hexdigest()[:8]
_static_hashes: dict[str, str] = {}


def _hash_file(path: Path) -> str:
    h = hashlib.sha1()
    with path.open("rb") as fh:
        for chunk in iter(lambda: fh.read(65536), b""):
            h.update(chunk)
    return h.hexdigest()[:8]


def static_hash(filename: str) -> str:
    if filename in _static_hashes:
        return _static_hashes[filename]
    path = Path(app.static_folder) / filename
    try:
        token = _hash_file(path)
    except OSError:
        logging.getLogger(__name__).warning(
            "static_hash: cannot hash %s, using fallback token", filename
        )
        return _FALLBACK_TOKEN
    _static_hashes[filename] = token
    return token


def static_v(filename: str) -> str:
    return f"/static/{filename}?v={static_hash(filename)}"


_static_dir = Path(app.static_folder)
if _static_dir.is_dir():
    for _path in sorted(_static_dir.iterdir()):
        if _path.is_file():
            try:
                _static_hashes[_path.name] = _hash_file(_path)
            except OSError:
                continue

APP_VERSION = (
    hashlib.sha1(
        "|".join(f"{n}:{h}" for n, h in sorted(_static_hashes.items())).encode()
    ).hexdigest()[:8]
    if _static_hashes
    else _FALLBACK_TOKEN
)

app.jinja_env.globals["static_v"] = static_v


@app.after_request
def _add_cache_headers(response):
    if response.mimetype == "text/html":
        response.headers["Cache-Control"] = "no-cache, must-revalidate"
        return response
    if request.path.startswith("/static/") and request.args.get("v"):
        response.headers["Cache-Control"] = "public, max-age=31536000, immutable"
    return response


from app import routes  # noqa: E402, F401