# scripts/make_checksums.py
import argparse, csv, hashlib, pathlib, sys, os
from collections import defaultdict

def sha256(p, buf=1024*1024):
    h = hashlib.sha256()
    with open(p, "rb") as f:
        while chunk := f.read(buf):
            h.update(chunk)
    return h.hexdigest()

def norm_header(h: str) -> str:
    return (h or "").strip().lstrip("\ufeff").lower().replace(" ", "_")

def norm_path_for_match(p: str) -> str:
    # Normalize separators and remove leading .\ or ./, make POSIX-ish
    q = p.replace("\\", "/")
    while q.startswith("./") or q.startswith(".\\"):
        q = q[2:]
    return q

def main():
    ap = argparse.ArgumentParser()
    ap.add_argument("--meta", default="data/metadata/metadata.csv",
                    help="Path to metadata.csv")
    ap.add_argument("--audio-root", default="data/audio",
                    help="Root folder containing audio files")
    ap.add_argument("--path-col", default=None,
                    help="Column name that holds paths (default: auto-detect; prefers 'file_path')")
    ap.add_argument("--checksum-col", default="checksum_sha256",
                    help="Column name to write sha256 into")
    args = ap.parse_args()

    root = pathlib.Path(__file__).resolve().parents[1]
    audio_root = (root / args.audio_root).resolve()
    meta_path = (root / args.meta).resolve()

    if not meta_path.exists():
        sys.exit(f"[ERR] metadata file not found: {meta_path}")
    if not audio_root.exists():
        print(f"[WARN] audio root not found yet: {audio_root}")

    # Build map: relative path (POSIX) -> sha256
    print("[INFO] Scanning audio files for checksums…")
    hashmap = {}
    for p in audio_root.rglob("*"):
        if p.suffix.lower() not in {".wav", ".flac"} or not p.is_file():
            continue
        rel = p.relative_to(root).as_posix()
        hashmap[norm_path_for_match(rel)] = sha256(p)

    # Read CSV with dialect sniffing and normalized headers
    print(f"[INFO] Reading metadata: {meta_path}")
    raw = meta_path.read_text(encoding="utf-8", errors="replace")
    try:
        dialect = csv.Sniffer().sniff(raw.splitlines()[0] if raw else ",")
    except Exception:
        dialect = csv.excel  # fallback to comma

    rows = []
    with open(meta_path, newline="", encoding="utf-8", errors="replace") as f:
        reader = csv.reader(f, dialect)
        try:
            headers = next(reader)
        except StopIteration:
            sys.exit("[ERR] metadata.csv appears empty.")

        norm_headers = [norm_header(h) for h in headers]
        hdr_map = {norm_header(h): i for i, h in enumerate(headers)}

        # Choose the path column
        candidate_names = [norm_header(args.path_col)] if args.path_col else [
            "file_path", "filepath", "path", "relative_path", "audio_path", "wav", "rir_path"
        ]
        path_col_norm = next((c for c in candidate_names if c in hdr_map), None)
        if not path_col_norm:
            msg = (f"[ERR] Could not find a path column. Looked for any of: "
                   f"{candidate_names}. Available columns: {norm_headers}")
            sys.exit(msg)

        checksum_col_norm = norm_header(args.checksum_col)
        # If checksum column absent, append it
        if checksum_col_norm not in hdr_map:
            headers.append(args.checksum_col)
            norm_headers.append(checksum_col_norm)
            checksum_idx = len(headers) - 1
        else:
            checksum_idx = hdr_map[checksum_col_norm]

        path_idx = hdr_map[path_col_norm]

        # Process rows
        rows.append(headers)  # header row for writing back
        for i, row in enumerate(reader, start=1):
            # pad short rows
            if len(row) < len(headers):
                row += [""] * (len(headers) - len(row))
            # Normalize the path for lookup
            csv_path_raw = (row[path_idx] or "").strip()
            if not csv_path_raw:
                print(f"[WARN] row {i}: empty path cell; leaving checksum blank")
                rows.append(row)
                continue

            # Try multiple lookup strategies
            candidates = []

            # 1) CSV path as given (normalized)
            candidates.append(norm_path_for_match(csv_path_raw))

            # 2) If CSV path is absolute, try making it relative to project root
            p = pathlib.Path(csv_path_raw)
            if p.is_absolute():
                try:
                    rel = p.relative_to(root).as_posix()
                    candidates.append(norm_path_for_match(rel))
                except Exception:
                    pass

            # 3) If CSV path is relative to audio_root
            try:
                rel2 = (audio_root / csv_path_raw).resolve().relative_to(root).as_posix()
                candidates.append(norm_path_for_match(rel2))
            except Exception:
                pass

            # 4) Fallback: match by basename if unique
            basename = pathlib.Path(csv_path_raw).name
            if basename:
                # build once a reverse index by basename
                pass

            # deduplicate candidates
            candidates = list(dict.fromkeys(candidates))

            sha = ""
            for cand in candidates:
                sha = hashmap.get(cand, "")
                if sha:
                    break

            # As a last resort, basename matching (unique)
            if not sha and basename:
                matches = [v for k, v in hashmap.items() if pathlib.Path(k).name == basename]
                if len(matches) == 1:
                    sha = matches[0]

            row[checksum_idx] = sha
            if not sha:
                print(f"[WARN] row {i}: no match for '{csv_path_raw}' (tried {len(candidates)} candidates)")
            rows.append(row)

    # Write back CSV (same dialect; UTF-8)
    print(f"[INFO] Writing updated metadata with checksums → {meta_path}")
    with open(meta_path, "w", newline="", encoding="utf-8") as f:
        writer = csv.writer(f, dialect)
        writer.writerows(rows)

    print("[DONE] Checksums inserted. "
          f"Found hashes for ~{sum(1 for r in rows[1:] if r[checksum_idx])} rows.")

if __name__ == "__main__":
    main()