import os
import json
import uuid
import time
import threading
import asyncio
from typing import Dict, Optional

# Note: job processing will call into async functions from main via asyncio.run

JOBS_DIR = os.path.join(os.path.dirname(__file__), "jobs")
os.makedirs(JOBS_DIR, exist_ok=True)


class JobManager:
    """Simple persistent job queue and worker.

    Jobs are stored as JSON files in `jobs/` so they survive restarts.
    Worker runs in a dedicated thread and processes jobs sequentially.
    """

    def __init__(self):
        self._lock = threading.Lock()
        self._stop_event = threading.Event()
        self._thread: Optional[threading.Thread] = None

    def start(self):
        if self._thread and self._thread.is_alive():
            return
        self._thread = threading.Thread(target=self._run, daemon=True)
        self._thread.start()

    def stop(self):
        self._stop_event.set()
        if self._thread:
            self._thread.join(timeout=2)

    def _run(self):
        # Continuously look for queued jobs and process them
        while not self._stop_event.is_set():
            job = self._pop_next_job()
            if job:
                try:
                    self._process_job(job)
                except Exception as e:
                    # Mark job failed
                    job['status'] = 'failed'
                    job['error'] = str(e)
                    job['finished_at'] = time.time()
                    self._save_job(job)
            else:
                time.sleep(0.5)

    def _job_path(self, job_id: str) -> str:
        return os.path.join(JOBS_DIR, f"{job_id}.json")

    def _save_job(self, job: Dict):
        with open(self._job_path(job['id']), 'w', encoding='utf-8') as f:
            json.dump(job, f, indent=2)

    def _load_job(self, job_id: str) -> Optional[Dict]:
        p = self._job_path(job_id)
        if not os.path.exists(p):
            return None
        with open(p, 'r', encoding='utf-8') as f:
            return json.load(f)

    def _pop_next_job(self) -> Optional[Dict]:
        # Find oldest job with status 'queued'
        files = [f for f in os.listdir(JOBS_DIR) if f.endswith('.json')]
        files.sort()
        for fname in files:
            path = os.path.join(JOBS_DIR, fname)
            try:
                with open(path, 'r', encoding='utf-8') as f:
                    job = json.load(f)
                if job.get('status') == 'queued':
                    job['status'] = 'processing'
                    job['started_at'] = time.time()
                    self._save_job(job)
                    return job
            except Exception:
                continue
        return None

    def create_job(self, user_id: str, filename: str, file_path: str, username: Optional[str] = None) -> Dict:
        job_id = uuid.uuid4().hex
        job = {
            'id': job_id,
            'user_id': user_id,
            'username': username,
            'filename': filename,
            'file_path': file_path,
            'status': 'queued',
            'created_at': time.time()
        }
        self._save_job(job)
        return job

    def get_job(self, job_id: str) -> Optional[Dict]:
        return self._load_job(job_id)

    def _process_job(self, job: Dict):
        # Import heavy modules lazily to avoid startup cost
        from main import rag_manager, hf_storage

        job_id = job['id']
        user_id = job['user_id']
        filename = job['filename']
        file_path = job['file_path']

        try:
            # Read content
            with open(file_path, 'rb') as f:
                content = f.read()

            # Ensure RAG engine is ready (async call)
            engine = asyncio.run(rag_manager.get_engine(user_id))

            # Run upload_document in thread to avoid blocking event loop
            result = asyncio.run(asyncio.to_thread(engine.upload_document, filename, content, 'auto'))

            if result.get('status') != 'success':
                job['status'] = 'failed'
                job['error'] = result.get('message', 'processing error')
                job['finished_at'] = time.time()
                self._save_job(job)
                return

            # Save pdf to user's uploaded_pdfs folder
            base_dir = os.path.dirname(os.path.abspath(__file__))
            user_pdfs_dir = os.path.join(base_dir, 'users', user_id, 'uploaded_pdfs')
            os.makedirs(user_pdfs_dir, exist_ok=True)
            pdf_path = os.path.join(user_pdfs_dir, filename)
            with open(pdf_path, 'wb') as f:
                f.write(content)

            # Push to HF (perform in thread)
            asyncio.run(asyncio.to_thread(hf_storage.push_storage_to_hf, user_id, f"Upload {filename}"))

            job['status'] = 'success'
            job['result'] = {
                'document_id': result.get('doc_id', ''),
                'filename': filename,
                'pages': result.get('pages'),
                'chunks': result.get('chunks')
            }
            job['finished_at'] = time.time()
            self._save_job(job)

        except Exception as e:
            job['status'] = 'failed'
            job['error'] = str(e)
            job['finished_at'] = time.time()
            self._save_job(job)


job_manager = JobManager()