import os
import uuid
import hashlib
import magic
import logging
from datetime import datetime
from typing import Dict, Any, Optional

from flask import Flask, request, jsonify
from werkzeug.utils import secure_filename
import psycopg2
from psycopg2.extras import RealDictCursor
from minio import Minio
from minio.error import S3Error
import structlog

# Configure structured logging
structlog.configure(
    processors=[
        structlog.stdlib.filter_by_level,
        structlog.stdlib.add_logger_name,
        structlog.stdlib.add_log_level,
        structlog.stdlib.PositionalArgumentsFormatter(),
        structlog.processors.TimeStamper(fmt="iso"),
        structlog.processors.StackInfoRenderer(),
        structlog.processors.format_exc_info,
        structlog.processors.UnicodeDecoder(),
        structlog.processors.JSONRenderer()
    ],
    context_class=dict,
    logger_factory=structlog.stdlib.LoggerFactory(),
    wrapper_class=structlog.stdlib.BoundLogger,
    cache_logger_on_first_use=True,
)

logger = structlog.get_logger()

app = Flask(__name__)

# Configuration
MINIO_ENDPOINT = os.getenv('MINIO_ENDPOINT', 'localhost:9000')
MINIO_ACCESS_KEY = os.getenv('MINIO_ACCESS_KEY', 'minioadmin')
MINIO_SECRET_KEY = os.getenv('MINIO_SECRET_KEY', 'minioadmin123')
MINIO_BUCKET_NAME = os.getenv('MINIO_BUCKET_NAME', 'file-transformer-bucket')
MINIO_USE_SSL = os.getenv('MINIO_USE_SSL', 'false').lower() == 'true'

POSTGRES_URL = os.getenv('POSTGRES_URL', 'postgresql://file_user:secure_password_123@localhost:5432/file_transformer')

# Initialize MinIO client
minio_client = Minio(
    MINIO_ENDPOINT,
    access_key=MINIO_ACCESS_KEY,
    secret_key=MINIO_SECRET_KEY,
    secure=MINIO_USE_SSL
)

def get_db_connection():
    """Create a database connection."""
    return psycopg2.connect(POSTGRES_URL)

def calculate_file_hash(file_data: bytes) -> str:
    """Calculate SHA-256 hash of file data."""
    return hashlib.sha256(file_data).hexdigest()

def get_file_metadata(file_data: bytes, filename: str) -> Dict[str, Any]:
    """Extract file metadata including MIME type and size."""
    mime_type = magic.from_buffer(file_data, mime=True)
    file_size = len(file_data)
    
    # Determine file type from extension
    file_extension = filename.rsplit('.', 1)[1].lower() if '.' in filename else ''
    
    return {
        'mime_type': mime_type,
        'file_size': file_size,
        'file_type': file_extension,
        'checksum': calculate_file_hash(file_data)
    }

def save_file_to_database(file_data: bytes, filename: str, object_key: str, metadata: Dict[str, Any]) -> str:
    """Save file information to PostgreSQL database."""
    conn = get_db_connection()
    try:
        with conn.cursor(cursor_factory=RealDictCursor) as cur:
            # Insert file record
            cur.execute("""
                INSERT INTO files (
                    filename, original_filename, file_path, file_size, 
                    file_type, mime_type, bucket_name, object_key, 
                    checksum, status, created_at
                ) VALUES (%s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s)
                RETURNING id
            """, (
                filename,
                filename,
                object_key,
                metadata['file_size'],
                metadata['file_type'],
                metadata['mime_type'],
                MINIO_BUCKET_NAME,
                object_key,
                metadata['checksum'],
                'uploaded',
                datetime.utcnow()
            ))
            
            file_id = cur.fetchone()['id']
            conn.commit()
            return str(file_id)
    except Exception as e:
        conn.rollback()
        logger.error("Database error", error=str(e))
        raise
    finally:
        conn.close()

def upload_to_minio(file_data: bytes, object_key: str) -> bool:
    """Upload file to MinIO bucket."""
    try:
        # Ensure bucket exists
        if not minio_client.bucket_exists(MINIO_BUCKET_NAME):
            minio_client.make_bucket(MINIO_BUCKET_NAME)
            logger.info("Created bucket", bucket=MINIO_BUCKET_NAME)
        
        # Upload file
        minio_client.put_object(
            MINIO_BUCKET_NAME,
            object_key,
            file_data,
            length=len(file_data)
        )
        
        logger.info("File uploaded to MinIO", bucket=MINIO_BUCKET_NAME, object_key=object_key)
        return True
    except S3Error as e:
        logger.error("MinIO upload error", error=str(e))
        return False

@app.route('/health', methods=['GET'])
def health_check():
    """Health check endpoint."""
    return jsonify({'status': 'healthy', 'service': 'file-upload'})

@app.route('/upload', methods=['POST'])
def upload_file():
    """Handle file upload request."""
    try:
        # Check if file is present in request
        if 'file' not in request.files:
            return jsonify({'error': 'No file provided'}), 400
        
        file = request.files['file']
        if file.filename == '':
            return jsonify({'error': 'No file selected'}), 400
        
        # Read file data
        file_data = file.read()
        if not file_data:
            return jsonify({'error': 'Empty file'}), 400
        
        # Secure filename and generate object key
        filename = secure_filename(file.filename)
        file_id = str(uuid.uuid4())
        object_key = f"uploads/{file_id}/{filename}"
        
        # Extract metadata
        metadata = get_file_metadata(file_data, filename)
        
        logger.info("Processing file upload", 
                   filename=filename, 
                   size=metadata['file_size'],
                   mime_type=metadata['mime_type'])
        
        # Upload to MinIO
        if not upload_to_minio(file_data, object_key):
            return jsonify({'error': 'Failed to upload file to storage'}), 500
        
        # Save to database
        db_file_id = save_file_to_database(file_data, filename, object_key, metadata)
        
        # Log access
        log_file_access(db_file_id, 'upload', request.remote_addr, request.headers.get('User-Agent'))
        
        response_data = {
            'file_id': db_file_id,
            'filename': filename,
            'object_key': object_key,
            'file_size': metadata['file_size'],
            'mime_type': metadata['mime_type'],
            'checksum': metadata['checksum'],
            'status': 'uploaded',
            'uploaded_at': datetime.utcnow().isoformat()
        }
        
        logger.info("File upload completed", file_id=db_file_id, filename=filename)
        return jsonify(response_data), 201
        
    except Exception as e:
        logger.error("Upload error", error=str(e))
        return jsonify({'error': 'Internal server error'}), 500

def log_file_access(file_id: str, action: str, ip_address: str, user_agent: Optional[str]):
    """Log file access for audit purposes."""
    conn = get_db_connection()
    try:
        with conn.cursor() as cur:
            cur.execute("""
                INSERT INTO file_access_logs (file_id, action, ip_address, user_agent)
                VALUES (%s, %s, %s, %s)
            """, (file_id, action, ip_address, user_agent))
            conn.commit()
    except Exception as e:
        logger.error("Failed to log file access", error=str(e))
        conn.rollback()
    finally:
        conn.close()

@app.route('/files/<file_id>', methods=['GET'])
def get_file_info(file_id: str):
    """Get file information by ID."""
    try:
        conn = get_db_connection()
        with conn.cursor(cursor_factory=RealDictCursor) as cur:
            cur.execute("""
                SELECT id, filename, original_filename, file_size, file_type, 
                       mime_type, bucket_name, object_key, checksum, status,
                       created_at, updated_at
                FROM files 
                WHERE id = %s
            """, (file_id,))
            
            file_record = cur.fetchone()
            if not file_record:
                return jsonify({'error': 'File not found'}), 404
            
            return jsonify(dict(file_record)), 200
            
    except Exception as e:
        logger.error("Error fetching file info", error=str(e))
        return jsonify({'error': 'Internal server error'}), 500
    finally:
        conn.close()

@app.route('/files/<file_id>', methods=['DELETE'])
def delete_file(file_id: str):
    """Delete file from storage and database."""
    try:
        conn = get_db_connection()
        with conn.cursor(cursor_factory=RealDictCursor) as cur:
            # Get file info
            cur.execute("SELECT object_key FROM files WHERE id = %s", (file_id,))
            file_record = cur.fetchone()
            
            if not file_record:
                return jsonify({'error': 'File not found'}), 404
            
            object_key = file_record['object_key']
            
            # Delete from MinIO
            try:
                minio_client.remove_object(MINIO_BUCKET_NAME, object_key)
                logger.info("File deleted from MinIO", object_key=object_key)
            except S3Error as e:
                logger.warning("File not found in MinIO", object_key=object_key, error=str(e))
            
            # Mark as deleted in database
            cur.execute("""
                UPDATE files 
                SET status = 'deleted', deleted_at = %s 
                WHERE id = %s
            """, (datetime.utcnow(), file_id))
            
            conn.commit()
            
            # Log access
            log_file_access(file_id, 'delete', request.remote_addr, request.headers.get('User-Agent'))
            
            return jsonify({'message': 'File deleted successfully'}), 200
            
    except Exception as e:
        logger.error("Error deleting file", error=str(e))
        return jsonify({'error': 'Internal server error'}), 500
    finally:
        conn.close()

if __name__ == '__main__':
    app.run(host='0.0.0.0', port=5000, debug=False)