#!/usr/bin/env python3
r"""
Thumbnail generation pipeline for photos database.
Reads photos with no thumbnail, generates 200x200 JPEG thumbnails, updates DB.

Cesty v DB se ukládají vždy v nativním Tower1 formátu:
  /mnt/user/ZalohaVsechObrazku/thumbnails/{year}/{month}/{sha256}.jpg

Fyzické zápisy probíhají přes cestu odpovídající aktuálnímu prostředí:
  - Tower1 (Unraid):  /mnt/user/ZalohaVsechObrazku/thumbnails/...
  - tower  (Unraid):  /mnt/remotes/TOWER1.LAN_ZalohaVsechObrazku/thumbnails/...
  - Windows:          \\Tower1\ZalohaVsechObrazku\thumbnails\...

Stejný princip platí pro čtení zdrojových fotek — cesty v DB jsou v Tower1
formátu a skript je přemapuje na lokální mount.

Usage:
    python generate_thumbnails.py [--batch-size 1000] [--dry-run]

Pro omezení počtu zpracovaných fotek nastav proměnnou MAX_PHOTOS níže (0 = všechny).
"""

import argparse
import logging
import os
import platform
import shutil
import socket
import sys
import time
from pathlib import Path, PurePosixPath

import psycopg2
import psycopg2.extras
from dotenv import load_dotenv
from PIL import Image, ImageOps

# .env hledáme nejprve vedle skriptu, pak v rodičovském adresáři (root projektu)
_here = Path(__file__).parent
for _env in (_here / ".env", _here.parent / ".env"):
    if _env.is_file():
        load_dotenv(_env)
        break

# ── Konfigurace ──────────────────────────────────────────────────────────────

# Maximální počet fotek ke zpracování (0 = všechny)
MAX_PHOTOS = 10

# Pokud True, na začátku skriptu se smažou všechny thumbnaily (DB i soubory)
RESET = True

# Pokud True, vedle každého thumbnailu se uloží i kopie originálu jako {sha256}_o.{ext}
# (pouze pro testování / vizuální srovnání)
SAVE_ORIGINAL = True

MAX_SIZE = (400, 400)
JPEG_QUALITY = 85
BATCH_SIZE = 1000

# Kanonický prefix pro DB (nativní Tower1 cesta)
DB_THUMBNAIL_BASE = "/mnt/user/ZalohaVsechObrazku/thumbnails"
DB_SOURCE_BASE = "/mnt/user/ZalohaVsechObrazku"

# Fyzické cesty podle prostředí
if platform.system() == "Windows":
    LOCAL_THUMBNAIL_BASE = Path(r"\\Tower1\ZalohaVsechObrazku\thumbnails")
    LOCAL_SOURCE_BASE = Path(r"\\Tower1\ZalohaVsechObrazku")
else:
    hostname = socket.gethostname()
    if hostname == "Tower1":
        LOCAL_THUMBNAIL_BASE = Path("/mnt/user/ZalohaVsechObrazku/thumbnails")
        LOCAL_SOURCE_BASE = Path("/mnt/user/ZalohaVsechObrazku")
    else:
        # tower nebo jiný Linux stroj — přes remote mount
        LOCAL_THUMBNAIL_BASE = Path("/mnt/remotes/TOWER1.LAN_ZalohaVsechObrazku/thumbnails")
        LOCAL_SOURCE_BASE = Path("/mnt/remotes/TOWER1.LAN_ZalohaVsechObrazku")

# ── Logging ──────────────────────────────────────────────────────────────────

LOG_FILE = Path(__file__).parent / "generate_thumbnails.log"

logging.basicConfig(
    level=logging.INFO,
    format="%(asctime)s [%(levelname)s] %(message)s",
    handlers=[
        logging.StreamHandler(sys.stdout),
        logging.FileHandler(LOG_FILE, encoding="utf-8"),
    ],
)
log = logging.getLogger(__name__)

# ── Pomocné funkce ───────────────────────────────────────────────────────────


def get_conn():
    return psycopg2.connect(
        host=os.getenv("DB_HOST") or os.getenv("PGHOST", "192.168.1.76"),
        port=int(os.getenv("DB_PORT") or os.getenv("PGPORT", 5432)),
        dbname=os.getenv("DB_NAME") or os.getenv("PGDATABASE", "fotky_buzalkovi"),
        user=os.getenv("DB_USER") or os.getenv("PGUSER", "vladimir.buzalka"),
        password=os.getenv("DB_PASSWORD") or os.getenv("PGPASSWORD", ""),
    )


def db_path_to_local(db_path: str) -> Path:
    """Převede cestu z DB (Tower1 nativní) na lokální cestu pro čtení/zápis."""
    if db_path.startswith(DB_SOURCE_BASE):
        relative = db_path[len(DB_SOURCE_BASE):]
        return LOCAL_SOURCE_BASE / relative.lstrip("/")
    return Path(db_path)


def thumbnail_db_path(sha256: str, taken_at) -> str:
    """Vrátí kanonickou cestu thumbnailu pro uložení do DB (Tower1 formát)."""
    if taken_at:
        year = str(taken_at.year)
        month = f"{taken_at.month:02d}"
    else:
        year = "unknown"
        month = "unknown"
    return f"{DB_THUMBNAIL_BASE}/{year}/{month}/{sha256.strip()}.jpg"


def thumbnail_local_path(sha256: str, taken_at) -> Path:
    """Vrátí lokální fyzickou cestu thumbnailu pro zápis souboru."""
    if taken_at:
        year = str(taken_at.year)
        month = f"{taken_at.month:02d}"
    else:
        year = "unknown"
        month = "unknown"
    return LOCAL_THUMBNAIL_BASE / year / month / f"{sha256.strip()}.jpg"


def generate_thumbnail(source_path: Path, dest_path: Path) -> bool:
    """Vygeneruje JPEG thumbnail se zachováním poměru stran.
    Pokud je SAVE_ORIGINAL=True, zkopíruje vedle i originál s sufixem _o."""
    dest_path.parent.mkdir(parents=True, exist_ok=True)
    with Image.open(source_path) as img:
        # Aplikuj EXIF Orientation, jinak vyjdou iPhone/foťák fotky otočené
        img = ImageOps.exif_transpose(img)
        if img.mode in ("RGBA", "P", "LA"):
            img = img.convert("RGB")
        img.thumbnail(MAX_SIZE, Image.LANCZOS)
        img.save(dest_path, "JPEG", quality=JPEG_QUALITY)

    # Kopie originálu vedle thumbnailu se sufixem _o (jen pro testovací účely)
    if SAVE_ORIGINAL:
        original_dest = dest_path.with_name(f"{dest_path.stem}_o{source_path.suffix}")
        shutil.copy2(source_path, original_dest)
    return True


def reset_thumbnails(conn, dry_run: bool) -> None:
    """Smaže všechny thumbnaily — soubory z disku a vynuluje thumbnail_path v DB."""
    log.warning("RESET=True — mažu existující thumbnaily.")

    # 1) Smazat adresář s thumbnaily
    if LOCAL_THUMBNAIL_BASE.exists():
        if dry_run:
            log.info("[DRY RUN] Would delete directory tree: %s", LOCAL_THUMBNAIL_BASE)
        else:
            log.info("Deleting directory tree: %s", LOCAL_THUMBNAIL_BASE)
            shutil.rmtree(LOCAL_THUMBNAIL_BASE, ignore_errors=True)
    else:
        log.info("Thumbnail dir does not exist, skipping FS delete: %s", LOCAL_THUMBNAIL_BASE)

    # 2) Vynulovat thumbnail_path v DB
    if dry_run:
        log.info("[DRY RUN] Would UPDATE photos SET thumbnail_path = NULL WHERE thumbnail_path IS NOT NULL")
    else:
        with conn.cursor() as cur:
            cur.execute("UPDATE photos SET thumbnail_path = NULL WHERE thumbnail_path IS NOT NULL")
            affected = cur.rowcount
            conn.commit()
        log.info("DB reset: cleared thumbnail_path on %d rows.", affected)


# ── Zpracování ───────────────────────────────────────────────────────────────


def process_batch(conn, batch_size: int, dry_run: bool) -> int:
    with conn.cursor(cursor_factory=psycopg2.extras.DictCursor) as cur:
        cur.execute(
            """
            SELECT id, sha256_file, file_path, taken_at
            FROM photos
            WHERE thumbnail_path IS NULL
            ORDER BY
                -- 1) reálné fotky (>= 1 MB) jdou před drobky/testy
                (file_size < 1048576),
                -- 2) Apple + DateTimeOriginal jdou úplně první
                NOT (exif_raw->>'Image Make' = 'Apple'
                     AND exif_raw ? 'EXIF DateTimeOriginal'),
                -- 3) pak ostatní s DateTimeOriginal
                NOT (exif_raw ? 'EXIF DateTimeOriginal'),
                -- 4) pak cokoli s exif_raw
                (exif_raw IS NULL),
                id
            LIMIT %s
            """,
            (batch_size,),
        )
        rows = cur.fetchall()

    if not rows:
        return 0

    processed = 0
    for row in rows:
        photo_id = row["id"]
        sha256 = row["sha256_file"]
        source_db = row["file_path"]
        taken_at = row["taken_at"]

        db_path = thumbnail_db_path(sha256, taken_at)
        local_dest = thumbnail_local_path(sha256, taken_at)
        local_source = db_path_to_local(source_db)

        # Thumbnail už existuje na disku — jen zapsat cestu do DB
        if local_dest.exists():
            if not dry_run:
                with conn.cursor() as cur:
                    cur.execute(
                        "UPDATE photos SET thumbnail_path = %s WHERE id = %s",
                        (db_path, photo_id),
                    )
                    conn.commit()
            processed += 1
            continue

        # Zdrojový soubor neexistuje
        if not local_source.is_file():
            log.warning("Source missing, skipping id=%d: %s (local: %s)", photo_id, source_db, local_source)
            continue

        try:
            if dry_run:
                log.info("[DRY RUN] Would generate: %s -> %s (DB: %s)", local_source, local_dest, db_path)
            else:
                generate_thumbnail(local_source, local_dest)
                with conn.cursor() as cur:
                    cur.execute(
                        "UPDATE photos SET thumbnail_path = %s WHERE id = %s",
                        (db_path, photo_id),
                    )
                    conn.commit()
            processed += 1
        except Exception:
            log.exception("Failed to generate thumbnail for id=%d: %s", photo_id, source_db)
            conn.rollback()

    return processed


def main():
    parser = argparse.ArgumentParser(description="Generate photo thumbnails")
    parser.add_argument("--batch-size", type=int, default=BATCH_SIZE)
    parser.add_argument("--dry-run", action="store_true", help="Don't write files or update DB")
    args = parser.parse_args()

    limit = MAX_PHOTOS

    log.info("=" * 60)
    log.info("Starting thumbnail generation")
    log.info("  batch_size=%d, dry_run=%s, limit=%s", args.batch_size, args.dry_run, limit or "all")
    log.info("  hostname=%s, platform=%s", socket.gethostname(), platform.system())
    log.info("  source base (local): %s", LOCAL_SOURCE_BASE)
    log.info("  thumbnail base (local): %s", LOCAL_THUMBNAIL_BASE)
    log.info("  thumbnail base (DB): %s", DB_THUMBNAIL_BASE)

    conn = get_conn()
    total_processed = 0
    batch_num = 0

    try:
        if RESET:
            reset_thumbnails(conn, args.dry_run)

        while True:
            # Pokud je limit nastavený, omezíme velikost dávky na zbývající počet
            remaining = args.batch_size
            if limit > 0:
                remaining = min(args.batch_size, limit - total_processed)
                if remaining <= 0:
                    log.info("Limit %d reached. Done.", limit)
                    break

            batch_num += 1
            t0 = time.time()
            count = process_batch(conn, remaining, args.dry_run)
            elapsed = time.time() - t0

            if count == 0:
                log.info("No more photos to process. Done.")
                break

            total_processed += count
            log.info(
                "Batch %d: processed %d thumbnails in %.1fs (total: %d)",
                batch_num, count, elapsed, total_processed,
            )
    except KeyboardInterrupt:
        log.info("Interrupted by user. Total processed: %d", total_processed)
    finally:
        conn.close()

    log.info("Finished. Total thumbnails: %d", total_processed)


if __name__ == "__main__":
    main()