"""Migration script to create messages for existing files without message_id

This script:
1. Finds all files in tr_room_files that have no message_id
2. Creates an associated message (image_ref or file_ref) for each
3. Updates the file record with the new message_id

Run from project root:
    python scripts/migrate_orphan_files.py
"""
import sys
import os

# Add project root to path
sys.path.insert(0, os.path.dirname(os.path.dirname(os.path.abspath(__file__))))

from datetime import datetime
from sqlalchemy import create_engine
from sqlalchemy.orm import sessionmaker

from app.core.config import get_settings
from app.modules.file_storage.models import RoomFile
from app.modules.realtime.models import Message, MessageType
from app.modules.file_storage.services.minio_service import generate_presigned_url

settings = get_settings()


def get_db_session():
    """Create database session"""
    engine = create_engine(settings.DATABASE_URL)
    Session = sessionmaker(bind=engine)
    return Session()


def migrate_orphan_files():
    """Migrate orphan files by creating associated messages"""
    db = get_db_session()

    try:
        # Find files without message_id
        orphan_files = db.query(RoomFile).filter(
            RoomFile.message_id.is_(None),
            RoomFile.deleted_at.is_(None)
        ).all()

        if not orphan_files:
            print("No orphan files found. Nothing to migrate.")
            return

        print(f"Found {len(orphan_files)} orphan files to migrate.")

        migrated = 0
        failed = 0

        for file in orphan_files:
            try:
                # Generate presigned URL for file
                download_url = generate_presigned_url(
                    bucket=file.minio_bucket,
                    object_path=file.minio_object_path,
                    expiry_seconds=3600
                )

                # Determine message type
                if file.file_type == "image":
                    msg_type = MessageType.IMAGE_REF
                    content = f"[Image] {file.filename}"
                else:
                    msg_type = MessageType.FILE_REF
                    content = f"[File] {file.filename}"

                # Get next sequence number for the room
                max_seq = db.query(Message.sequence_number).filter(
                    Message.room_id == file.room_id
                ).order_by(Message.sequence_number.desc()).first()
                next_seq = (max_seq[0] + 1) if max_seq else 1

                # Create metadata
                metadata = {
                    "file_id": file.file_id,
                    "file_url": download_url,
                    "filename": file.filename,
                    "file_type": file.file_type,
                    "mime_type": file.mime_type,
                    "file_size": file.file_size,
                }

                # Add thumbnail_url for images
                if file.file_type == "image":
                    metadata["thumbnail_url"] = download_url

                # Create message
                message = Message(
                    room_id=file.room_id,
                    sender_id=file.uploader_id,
                    content=content,
                    message_type=msg_type,
                    message_metadata=metadata,
                    created_at=file.uploaded_at,  # Use original upload time
                    sequence_number=next_seq,
                )

                db.add(message)
                db.flush()  # Get the message_id

                # Update file with message_id
                file.message_id = message.message_id

                migrated += 1
                print(f"  Migrated: {file.filename} -> message {message.message_id}")

            except Exception as e:
                failed += 1
                print(f"  Failed: {file.filename} - {e}")

        # Commit all changes
        db.commit()
        print(f"\nMigration complete: {migrated} migrated, {failed} failed")

    except Exception as e:
        db.rollback()
        print(f"Migration failed: {e}")
        raise
    finally:
        db.close()


if __name__ == "__main__":
    print("Starting orphan files migration...")
    print("=" * 50)
    migrate_orphan_files()
    print("=" * 50)
    print("Done.")