"""photo-pipeline: process-staging flow.

After review (dashboard = DB-only decisions), this flow materializes the
decisions: moves approved files to /mnt/data/01_keep, rejected to 03_delete.

Separating decisions (instant, in dashboard) from moves (here) keeps review
fast — cross-filesystem moves are the slow part and happen in one efficient pass.
"""

import shutil
from pathlib import Path

from prefect import flow, task

import photo_db as db

STAGING = Path("/mnt/data")
STATUS_TO_DIR = {
    "approved": "01_keep",
    "rejected": "03_delete",
}


@task
def materialize_decisions(status: str = None) -> dict:
    """Move files according to their DB status. Idempotent (skips already-moved)."""
    db.init_db()
    conn = db.get_db()
    if status:
        rows = conn.execute(
            "SELECT sha256, path, status FROM image_hashes WHERE status=?", (status,)
        ).fetchall()
    else:
        rows = conn.execute(
            "SELECT sha256, path, status FROM image_hashes WHERE status IN ('approved','rejected')"
        ).fetchall()
    conn.close()

    moved = 0
    already = 0
    errors = []
    for sha, path, st in rows:
        target_dir = STATUS_TO_DIR.get(st)
        if not target_dir:
            continue
        src = Path(path)
        dest_dir = STAGING / target_dir
        dest_dir.mkdir(parents=True, exist_ok=True)
        dest = dest_dir / src.name

        # already in the right place?
        if src.parent == dest_dir:
            already += 1
            continue
        if not src.exists():
            errors.append(f"{path}: missing source")
            continue
        # avoid collision: append suffix if dest exists
        if dest.exists():
            dest = dest_dir / f"{src.stem}_{sha[:8]}{src.suffix}"
        try:
            shutil.move(str(src), str(dest))
            conn = db.get_db()
            conn.execute(
                "UPDATE image_hashes SET path=?, status=? WHERE sha256=?", (str(dest), st, sha)
            )
            conn.commit()
            conn.close()
            moved += 1
        except Exception as e:
            errors.append(f"{path}: {e}")

    return {"moved": moved, "already": already, "errors": errors}


@flow(name="process-staging")
def process_staging(status: str = None):
    """Materialize review decisions: move approved/rejected files to staging."""
    result = materialize_decisions(status)
    print(f"process-staging: {result}")
    return result


if __name__ == "__main__":
    process_staging()