"""Celery tasks for Nexus POS background jobs."""

import os
import sys
import time

# Ensure pos/ is on path for imports when Celery worker runs standalone
sys.path.insert(0, os.path.dirname(os.path.abspath(__file__)))

from celery_app import celery
import psycopg2
import redis as redis_lib

MASTER_DB_URL = os.environ.get('MASTER_DB_URL', 'postgresql://postgres@/nexus_autoparts')
REDIS_URL = os.environ.get('REDIS_URL', 'redis://localhost:6379/0')


def _get_db():
    return psycopg2.connect(MASTER_DB_URL)


def _get_redis():
    return redis_lib.from_url(REDIS_URL, decode_responses=True)


@celery.task(bind=True, max_retries=3)
def warm_vehicle_cache_task(self, batch_size=5000, ttl=3600):
    """Warm Redis cache for vehicle info from part_vehicle_preview."""
    conn = _get_db()
    cur = conn.cursor()
    r = _get_redis()
    r.ping()

    cur.execute("SELECT id_part FROM parts WHERE oem_part_number IS NOT NULL ORDER BY id_part")
    all_ids = [row[0] for row in cur.fetchall()]
    total = len(all_ids)

    processed = 0
    cached = 0
    start = time.time()

    for i in range(0, total, batch_size):
        batch = all_ids[i:i + batch_size]
        cur.execute("""
            SELECT part_id, name_brand, name_model, year_car
            FROM part_vehicle_preview
            WHERE part_id = ANY(%s)
        """, (batch,))

        pipe = r.pipeline()
        batch_cached = 0
        for row in cur.fetchall():
            info = f"{row[1]} {row[2]} {row[3]}"
            pipe.setex(f'nexus:vehicle:{row[0]}', ttl, info)
            batch_cached += 1
        pipe.execute()

        processed += len(batch)
        cached += batch_cached
        self.update_state(
            state='PROGRESS',
            meta={'current': processed, 'total': total, 'cached': cached}
        )

    cur.close()
    conn.close()
    elapsed = time.time() - start
    return {'total': total, 'cached': cached, 'elapsed': int(elapsed)}


@celery.task(bind=True, max_retries=2)
def bulk_import_inventory_task(self, csv_path, tenant_id, branch_id=None):
    """Bulk import inventory from CSV in background."""
    from services.inventory_engine import bulk_import_csv
    conn = _get_db()
    try:
        result = bulk_import_csv(conn, csv_path, tenant_id, branch_id)
        conn.commit()
        return result
    except Exception as exc:
        conn.rollback()
        raise self.retry(exc=exc)
    finally:
        conn.close()


@celery.task(bind=True, max_retries=1)
def generate_report_task(self, report_type, params, tenant_id):
    """Generate heavy reports asynchronously."""
    # Placeholder: implement actual report generation per type
    self.update_state(state='PROGRESS', meta={'step': 'collecting_data'})
    time.sleep(2)  # Simulate work
    return {
        'report_type': report_type,
        'tenant_id': tenant_id,
        'status': 'completed',
        'url': f'/pos/static/reports/{report_type}_{tenant_id}.pdf',
    }