"""photo-pipeline: photo-ingest flow (v2 — batched + checkpointed).

Hashes incoming images, checks against the persistent fingerprint DB
(exact + near dupes), and registers new ones.

Batching: processes in chunks of `batch_size` (default 1000), committing to
the DB after each chunk. Checkpointing is DB-native: files already in the DB
(by sha256) are skipped on resume — an interrupted run continues where it
stopped, never redoing work.

For very large trees (e.g. 58K files), scan_directory can be slow to walk;
use walk_files for a streaming generator when batch_size is set.
"""

from pathlib import Path

from prefect import flow, task
from PIL import Image

import photo_db as db

EXT_IMAGES = {".jpg", ".jpeg", ".png", ".heic", ".webp", ".gif", ".tif", ".tiff", ".bmp"}


def _is_image(p: Path) -> bool:
    return p.is_file() and p.suffix.lower() in EXT_IMAGES


def walk_files(base_dir: str):
    """Stream image files under base_dir (generator — memory-safe for 50K+ files)."""
    root = Path(base_dir)
    if not root.exists():
        raise FileNotFoundError(f"{root} does not exist")
    for p in root.rglob("*"):
        if _is_image(p):
            yield str(p)


@task
def find_unprocessed(base_dir: str, batch_size: int, source: str = None) -> list[str]:
    """Find the next batch of files NOT yet in the fingerprint DB."""
    db.init_db()
    conn = db.get_db()
    conn.execute(
        "CREATE TABLE IF NOT EXISTS known_paths (path TEXT PRIMARY KEY, sha256 TEXT NOT NULL)"
    )
    batch = []
    for p_str in walk_files(base_dir):
        # cheap check: path already seen (image_hashes OR known_paths)
        known = conn.execute(
            "SELECT 1 FROM image_hashes WHERE path=? UNION SELECT 1 FROM known_paths WHERE path=?",
            (p_str, p_str),
        ).fetchone()
        if known:
            continue
        # content check: sha256 already registered (catches same photo at other paths)
        sha = db.sha256_file(p_str)
        sha_known = conn.execute(
            "SELECT 1 FROM image_hashes WHERE sha256=?", (sha,)
        ).fetchone()
        if sha_known:
            # record this path in known_paths so we don't re-hash it every loop
            conn.execute(
                "INSERT OR IGNORE INTO known_paths (path, sha256) VALUES (?,?)",
                (p_str, sha))
            continue
        batch.append(p_str)
        if len(batch) >= batch_size:
            break
    conn.commit()
    conn.close()
    print(f"find_unprocessed: {len(batch)} new files (batch_size={batch_size})")
    return batch


@task
def check_and_register(image_paths: list[str], source: str) -> dict:
    """Hash + dedup-check + register a batch. Returns verdict counts."""
    db.init_db()
    conn = db.get_db()
    exact_dups = []
    near_dups = []
    new_images = []
    for p_str in image_paths:
        p = Path(p_str)
        try:
            # exact dup by sha
            sha = db.sha256_file(p)
            match = conn.execute(
                "SELECT path, source FROM image_hashes WHERE sha256=?", (sha,)
            ).fetchone()
            if match:
                exact_dups.append((p_str, match[0]))
                continue
            # near dup by perceptual hash
            hx = db.hash_image(p)
            near, dist = db._near_dup_lookup(conn, hx)
            if near and dist <= 10:
                near_dups.append((p_str, near, dist))
                continue
            # new — register
            with Image.open(p) as im:
                w, h = im.size
            conn.execute(
                "INSERT INTO image_hashes (sha256, phash, dhash, file_size, width, height, path, source) "
                "VALUES (?,?,?,?,?,?,?,?)",
                (sha, hx["phash"], hx["dhash"], p.stat().st_size, w, h, str(p), source),
            )
            new_images.append(p_str)
        except Exception as e:
            print(f"  SKIP {p.name}: {type(e).__name__}: {e}")
    conn.commit()
    conn.close()
    return {
        "total": len(image_paths),
        "exact_dups": len(exact_dups),
        "near_dups": len(near_dups),
        "new": len(new_images),
        "exact_dup_list": exact_dups[:20],
        "near_dup_list": near_dups[:20],
        "new_list": new_images,
    }


@flow(name="photo-ingest")
def photo_ingest(base_dir: str, source: str = "takeout", batch_size: int = 1000,
                 max_batches: int | None = None):
    """Hash + dedup-check a folder against the persistent library, in batches.

    Args:
        base_dir: folder to scan
        source: label for the batch (e.g. takeout, archive-pictures)
        batch_size: files per batch/checkpoint (default 1000)
        max_batches: stop after N batches (useful for testing) — None = all
    """
    db.init_db()
    processed_batches = 0
    totals = {"exact_dups": 0, "near_dups": 0, "new": 0}

    while True:
        batch = find_unprocessed(base_dir, batch_size, source)
        if not batch:
            print("No more unprocessed files — done.")
            break
        result = check_and_register(batch, source)
        totals["exact_dups"] += result["exact_dups"]
        totals["near_dups"] += result["near_dups"]
        totals["new"] += result["new"]
        processed_batches += 1
        print(f"batch {processed_batches} done: {result['total']} files, "
              f"{result['new']} new, {result['exact_dups']} exact, {result['near_dups']} near")
        if max_batches and processed_batches >= max_batches:
            print(f"Stopped after {processed_batches} batches (max_batches={max_batches})")
            break

    totals["batches"] = processed_batches
    return totals


if __name__ == "__main__":
    import sys

    d = sys.argv[1] if len(sys.argv) > 1 else "/tmp/sample"
    src = sys.argv[2] if len(sys.argv) > 2 else "cli-test"
    bs = int(sys.argv[3]) if len(sys.argv) > 3 else 1000
    mb = int(sys.argv[4]) if len(sys.argv) > 4 else None
    r = photo_ingest(d, source=src, batch_size=bs, max_batches=mb)
    print(r)