"""
MeshBay Node — TMDB metadata and thumbnail cache for the Videos group app.

Node-wide (not per-group, `data_dir/media_cache.db`), same rationale as
`tmdb_enabled`/`tmdb_api_token` living in `group_settings` under the
`group_id=""` sentinel (docs/mediacenter.md §5.5): TMDB is one operator's
budget and credential, and a thumbnail is the same bytes regardless of which
group happens to share the file.

Disposable and rebuildable, like the rest of the file index (§1, §2) — never
a second identity for a file. Every row here is keyed off a value the node
can already derive (a file's own blake3 id, or a TMDB id), so losing this
database costs re-probing/re-fetching, not data.
"""

import json
import logging
import time
from pathlib import Path

import aiosqlite

log = logging.getLogger(__name__)

_SCHEMA = """
CREATE TABLE IF NOT EXISTS file_tmdb (
    file_id     TEXT PRIMARY KEY,
    tmdb_id     TEXT NOT NULL,
    media_type  TEXT NOT NULL
);
CREATE TABLE IF NOT EXISTS tmdb_meta (
    tmdb_id     TEXT NOT NULL,
    media_type  TEXT NOT NULL,
    json        TEXT NOT NULL,
    fetched_at  REAL NOT NULL,
    PRIMARY KEY (tmdb_id, media_type)
);
CREATE TABLE IF NOT EXISTS thumbs (
    thumb_hash  TEXT PRIMARY KEY,
    file_id     TEXT NOT NULL,
    jpeg        BLOB NOT NULL
);
CREATE INDEX IF NOT EXISTS idx_thumbs_file ON thumbs(file_id);
"""

# TMDB overviews/ratings do drift; a file's own resolved tmdb_id does not
# need re-checking on this schedule, only the metadata blob (§5.4, V3).
TMDB_META_TTL_SECS = 30 * 86400


class MediaCache:
    """Async SQLite cache for TMDB lookups and generated thumbnails."""

    def __init__(self, db_path: Path):
        self._db_path = db_path
        self._db: aiosqlite.Connection | None = None

    async def open(self) -> None:
        self._db_path.parent.mkdir(parents=True, exist_ok=True)
        self._db = await aiosqlite.connect(str(self._db_path))
        await self._db.executescript(_SCHEMA)
        await self._db.commit()

    async def close(self) -> None:
        if self._db:
            await self._db.close()
            self._db = None

    # ── file -> tmdb id mapping ──────────────────────────────────────────────

    async def get_file_tmdb(self, file_id: str) -> tuple[str, str] | None:
        """Returns (tmdb_id, media_type), or None if this file was never resolved."""
        async with self._db.execute(
            "SELECT tmdb_id, media_type FROM file_tmdb WHERE file_id = ?",
            (file_id,),
        ) as cur:
            row = await cur.fetchone()
        return (row[0], row[1]) if row else None

    async def set_file_tmdb(self, file_id: str, tmdb_id: str, media_type: str) -> None:
        await self._db.execute(
            "INSERT OR REPLACE INTO file_tmdb (file_id, tmdb_id, media_type) "
            "VALUES (?, ?, ?)",
            (file_id, tmdb_id, media_type),
        )
        await self._db.commit()

    # ── tmdb id -> metadata json ─────────────────────────────────────────────

    async def get_tmdb_meta(self, tmdb_id: str, media_type: str) -> dict | None:
        """Returns None on a miss or on an entry older than TMDB_META_TTL_SECS."""
        async with self._db.execute(
            "SELECT json, fetched_at FROM tmdb_meta WHERE tmdb_id = ? AND media_type = ?",
            (tmdb_id, media_type),
        ) as cur:
            row = await cur.fetchone()
        if not row:
            return None
        raw_json, fetched_at = row
        if time.time() - fetched_at > TMDB_META_TTL_SECS:
            return None
        return json.loads(raw_json)

    async def set_tmdb_meta(self, tmdb_id: str, media_type: str, meta: dict) -> None:
        await self._db.execute(
            "INSERT OR REPLACE INTO tmdb_meta (tmdb_id, media_type, json, fetched_at) "
            "VALUES (?, ?, ?, ?)",
            (tmdb_id, media_type, json.dumps(meta), time.time()),
        )
        await self._db.commit()

    # ── thumbnails ────────────────────────────────────────────────────────────

    async def get_thumb(self, thumb_hash: str) -> bytes | None:
        async with self._db.execute(
            "SELECT jpeg FROM thumbs WHERE thumb_hash = ?", (thumb_hash,),
        ) as cur:
            row = await cur.fetchone()
        return bytes(row[0]) if row else None

    async def get_thumb_hash_by_file_id(self, file_id: str) -> str | None:
        """
        A TMDB poster/backdrop is stored under a synthetic file_id
        (`tmdb:{poster_path}`, stable across requests for the same image) —
        this is how `_fetch_and_cache_poster` recognizes "already fetched"
        without knowing the content hash up front (that's only known once
        the bytes are downloaded).
        """
        async with self._db.execute(
            "SELECT thumb_hash FROM thumbs WHERE file_id = ?", (file_id,),
        ) as cur:
            row = await cur.fetchone()
        return row[0] if row else None

    async def put_thumb(self, thumb_hash: str, file_id: str, jpeg: bytes) -> None:
        await self._db.execute(
            "INSERT OR REPLACE INTO thumbs (thumb_hash, file_id, jpeg) VALUES (?, ?, ?)",
            (thumb_hash, file_id, jpeg),
        )
        await self._db.commit()

    # ── pruning ───────────────────────────────────────────────────────────────

    async def prune_file(self, file_id: str) -> None:
        """
        Called when a file leaves the index (deletion, unshared root). Removes
        its thumbnail and its file->tmdb mapping. `tmdb_meta` rows are left
        alone — they're keyed by tmdb_id, not file_id, and other files (other
        episodes of the same show) may still reference the same entry.
        """
        await self._db.execute("DELETE FROM thumbs WHERE file_id = ?", (file_id,))
        await self._db.execute("DELETE FROM file_tmdb WHERE file_id = ?", (file_id,))
        await self._db.commit()