backend/file_manager.py

import os
import shutil
import time
import uuid
import asyncio
import json
from pathlib import Path

BASE_DIR = Path("/tmp/stem-sep")
MAX_AGE_SECONDS = 30 * 60  # 30 minutes
CLEANUP_INTERVAL = 5 * 60  # 5 minutes


def create_job() -> str:
    job_id = uuid.uuid4().hex[:12]
    job_dir = BASE_DIR / job_id
    job_dir.mkdir(parents=True, exist_ok=True)
    # Touch a marker so we can track creation time
    (job_dir / ".created").write_text(str(time.time()))
    return job_id


def get_job_dir(job_id: str) -> Path:
    return BASE_DIR / job_id


def save_upload(job_id: str, filename: str, content: bytes) -> Path:
    job_dir = get_job_dir(job_id)
    ext = Path(filename).suffix or ".wav"
    input_path = job_dir / f"input{ext}"
    input_path.write_bytes(content)
    return input_path


def save_imported_audio(job_id: str, source_filename: str, content: bytes) -> Path:
    return save_upload(job_id, source_filename, content)


def get_input_file(job_id: str) -> Path | None:
    job_dir = get_job_dir(job_id)
    if not job_dir.exists():
        return None

    for file in job_dir.iterdir():
        if file.is_file() and file.name.startswith("input"):
            return file
    return None


def get_metadata_path(job_id: str) -> Path:
    return get_job_dir(job_id) / "metadata.json"


def save_job_metadata(job_id: str, metadata: dict) -> Path:
    path = get_metadata_path(job_id)
    path.write_text(json.dumps(metadata, indent=2), encoding="utf-8")
    return path


def load_job_metadata(job_id: str) -> dict | None:
    path = get_metadata_path(job_id)
    if not path.exists():
        return None
    return json.loads(path.read_text(encoding="utf-8"))


def get_output_dir(job_id: str) -> Path:
    out = get_job_dir(job_id) / "stems"
    out.mkdir(parents=True, exist_ok=True)
    return out


def list_stem_files(job_id: str) -> dict[str, str]:
    """Find all stem audio files, checking stems subdir and job root."""
    result = {}
    audio_exts = {".wav", ".mp3", ".flac", ".aac"}
    for check_dir in [get_output_dir(job_id), get_job_dir(job_id)]:
        if not check_dir.exists():
            continue
        for f in check_dir.iterdir():
            if f.is_file() and f.suffix.lower() in audio_exts and not f.name.startswith("input") and f.stem not in result:
                result[f.stem] = f.name
    return result


def get_file_path(job_id: str, filename: str) -> Path | None:
    # Check stems dir first, then job root
    stem_path = get_output_dir(job_id) / filename
    if stem_path.exists():
        return stem_path
    root_path = get_job_dir(job_id) / filename
    if root_path.exists():
        return root_path
    return None


def delete_job(job_id: str):
    job_dir = get_job_dir(job_id)
    if job_dir.exists():
        shutil.rmtree(job_dir, ignore_errors=True)


async def cleanup_loop():
    """Background task: delete job dirs older than MAX_AGE_SECONDS."""
    while True:
        await asyncio.sleep(CLEANUP_INTERVAL)
        try:
            if not BASE_DIR.exists():
                continue
            now = time.time()
            for entry in BASE_DIR.iterdir():
                if not entry.is_dir():
                    continue
                marker = entry / ".created"
                if marker.exists():
                    created = float(marker.read_text().strip())
                    if now - created > MAX_AGE_SECONDS:
                        shutil.rmtree(entry, ignore_errors=True)
                else:
                    # No marker — use mtime
                    if now - entry.stat().st_mtime > MAX_AGE_SECONDS:
                        shutil.rmtree(entry, ignore_errors=True)
        except Exception:
            pass