import hashlib
import os
from pathlib import Path
import sqlite3
import sys
import tempfile

root = Path.home() / 'Library/Application Support/KJamsClone/DJ'
media = root / 'Media'
def digest(path):
    h = hashlib.sha256()
    with path.open('rb') as stream:
        for chunk in iter(lambda: stream.read(1024 * 1024), b''):
            h.update(chunk)
    return h.hexdigest()
with sqlite3.connect(f'file:{root / "Library.sqlite"}?mode=ro', uri=True) as db:
    originals = [Path(row[0]) for row in db.execute('select original_path from songs') if row[0]]
# Include the failed, unregistered source only within the same explicitly imported folder.
folders = {p.parent for p in originals}
sources = set(originals)
for folder in folders:
    sources.update(p for p in folder.iterdir() if p.is_file() and p.suffix.lower() == '.mp3')
repairs = []
for source in sorted(sources):
    if not source.is_file() or source.stat().st_size == 0:
        continue
    expected = digest(source)
    target = media / (expected + source.suffix.lower())
    if target.is_file() and target.stat().st_size == 0:
        repairs.append((source, target, expected))
print(f'Verified {len(repairs)} empty DJ copies with matching original audio.')
if '--apply' in sys.argv:
    for source, target, expected in repairs:
        descriptor, temporary = tempfile.mkstemp(prefix='.kjmix-repair-', dir=media)
        try:
            with os.fdopen(descriptor, 'wb') as output, source.open('rb') as input_stream:
                for chunk in iter(lambda: input_stream.read(1024 * 1024), b''):
                    output.write(chunk)
                output.flush()
                os.fsync(output.fileno())
            assert digest(Path(temporary)) == expected
            assert target.stat().st_size == 0, 'Destination changed; refusing to replace it'
            os.chmod(temporary, 0o644)
            os.replace(temporary, target)
            print(f'Repaired verified audio: {target.name} ({target.stat().st_size} bytes)')
        finally:
            if os.path.exists(temporary):
                os.unlink(temporary)