import os
import uuid
import json
import tempfile
import logging
from datetime import datetime
from typing import Dict, Any, Optional, List
from pathlib import Path

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

# File processing imports
import PyPDF2
from docx import Document
import pandas as pd
from PIL import Image
import io

# 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 get_file_from_minio(object_key: str) -> bytes:
    """Download file from MinIO."""
    try:
        response = minio_client.get_object(MINIO_BUCKET_NAME, object_key)
        return response.read()
    except S3Error as e:
        logger.error("Failed to get file from MinIO", object_key=object_key, error=str(e))
        raise

def upload_file_to_minio(file_data: bytes, object_key: str) -> bool:
    """Upload file to MinIO."""
    try:
        minio_client.put_object(
            MINIO_BUCKET_NAME,
            object_key,
            file_data,
            length=len(file_data)
        )
        return True
    except S3Error as e:
        logger.error("Failed to upload file to MinIO", object_key=object_key, error=str(e))
        return False

def extract_text_from_pdf(file_data: bytes) -> str:
    """Extract text from PDF file."""
    try:
        pdf_reader = PyPDF2.PdfReader(io.BytesIO(file_data))
        text = ""
        for page in pdf_reader.pages:
            text += page.extract_text() + "\n"
        return text.strip()
    except Exception as e:
        logger.error("PDF text extraction failed", error=str(e))
        raise

def extract_text_from_docx(file_data: bytes) -> str:
    """Extract text from DOCX file."""
    try:
        doc = Document(io.BytesIO(file_data))
        text = ""
        for paragraph in doc.paragraphs:
            text += paragraph.text + "\n"
        return text.strip()
    except Exception as e:
        logger.error("DOCX text extraction failed", error=str(e))
        raise

def convert_csv_to_json(file_data: bytes) -> List[Dict[str, Any]]:
    """Convert CSV to JSON format."""
    try:
        df = pd.read_csv(io.BytesIO(file_data))
        return df.to_dict('records')
    except Exception as e:
        logger.error("CSV to JSON conversion failed", error=str(e))
        raise

def convert_excel_to_json(file_data: bytes) -> List[Dict[str, Any]]:
    """Convert Excel to JSON format."""
    try:
        df = pd.read_excel(io.BytesIO(file_data))
        return df.to_dict('records')
    except Exception as e:
        logger.error("Excel to JSON conversion failed", error=str(e))
        raise

def resize_image(file_data: bytes, width: int, height: int) -> bytes:
    """Resize image to specified dimensions."""
    try:
        image = Image.open(io.BytesIO(file_data))
        resized_image = image.resize((width, height), Image.Resampling.LANCZOS)
        
        output = io.BytesIO()
        resized_image.save(output, format=image.format or 'JPEG')
        return output.getvalue()
    except Exception as e:
        logger.error("Image resize failed", error=str(e))
        raise

def convert_image_format(file_data: bytes, target_format: str) -> bytes:
    """Convert image to different format."""
    try:
        image = Image.open(io.BytesIO(file_data))
        
        output = io.BytesIO()
        image.save(output, format=target_format.upper())
        return output.getvalue()
    except Exception as e:
        logger.error("Image format conversion failed", error=str(e))
        raise

def create_transformation_record(file_id: str, transformation_type: str, config: Dict[str, Any]) -> str:
    """Create transformation record in database."""
    conn = get_db_connection()
    try:
        with conn.cursor(cursor_factory=RealDictCursor) as cur:
            cur.execute("""
                INSERT INTO transformations (
                    file_id, transformation_type, input_path, status, config, created_at
                ) VALUES (%s, %s, %s, %s, %s, %s)
                RETURNING id
            """, (
                file_id,
                transformation_type,
                f"files/{file_id}",
                'pending',
                json.dumps(config),
                datetime.utcnow()
            ))
            
            transformation_id = cur.fetchone()['id']
            conn.commit()
            return str(transformation_id)
    except Exception as e:
        conn.rollback()
        logger.error("Failed to create transformation record", error=str(e))
        raise
    finally:
        conn.close()

def update_transformation_status(transformation_id: str, status: str, result: Optional[Dict[str, Any]] = None, error_message: Optional[str] = None):
    """Update transformation status in database."""
    conn = get_db_connection()
    try:
        with conn.cursor() as cur:
            if status == 'processing':
                cur.execute("""
                    UPDATE transformations 
                    SET status = %s, started_at = %s 
                    WHERE id = %s
                """, (status, datetime.utcnow(), transformation_id))
            elif status == 'completed':
                cur.execute("""
                    UPDATE transformations 
                    SET status = %s, completed_at = %s, result = %s 
                    WHERE id = %s
                """, (status, datetime.utcnow(), json.dumps(result), transformation_id))
            elif status == 'failed':
                cur.execute("""
                    UPDATE transformations 
                    SET status = %s, completed_at = %s, error_message = %s 
                    WHERE id = %s
                """, (status, datetime.utcnow(), error_message, transformation_id))
            
            conn.commit()
    except Exception as e:
        conn.rollback()
        logger.error("Failed to update transformation status", error=str(e))
        raise
    finally:
        conn.close()

def get_file_info(file_id: str) -> Optional[Dict[str, Any]]:
    """Get file information from database."""
    conn = get_db_connection()
    try:
        with conn.cursor(cursor_factory=RealDictCursor) as cur:
            cur.execute("""
                SELECT id, filename, file_type, mime_type, object_key, status
                FROM files 
                WHERE id = %s
            """, (file_id,))
            
            file_record = cur.fetchone()
            return dict(file_record) if file_record else None
    except Exception as e:
        logger.error("Failed to get file info", error=str(e))
        return None
    finally:
        conn.close()

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

@app.route('/transform', methods=['POST'])
def transform_file():
    """Handle file transformation request."""
    try:
        data = request.get_json()
        if not data:
            return jsonify({'error': 'No data provided'}), 400
        
        file_id = data.get('file_id')
        transformation_type = data.get('transformation_type')
        config = data.get('config', {})
        
        if not file_id or not transformation_type:
            return jsonify({'error': 'file_id and transformation_type are required'}), 400
        
        # Get file information
        file_info = get_file_info(file_id)
        if not file_info:
            return jsonify({'error': 'File not found'}), 404
        
        if file_info['status'] == 'deleted':
            return jsonify({'error': 'File has been deleted'}), 400
        
        # Create transformation record
        transformation_id = create_transformation_record(file_id, transformation_type, config)
        
        # Update status to processing
        update_transformation_status(transformation_id, 'processing')
        
        logger.info("Starting transformation", 
                   file_id=file_id, 
                   transformation_id=transformation_id,
                   transformation_type=transformation_type)
        
        try:
            # Get file from MinIO
            file_data = get_file_from_minio(file_info['object_key'])
            
            # Perform transformation based on type
            result = None
            output_data = None
            
            if transformation_type == 'extract_text':
                if file_info['file_type'] == 'pdf':
                    result = extract_text_from_pdf(file_data)
                elif file_info['file_type'] in ['docx', 'doc']:
                    result = extract_text_from_docx(file_data)
                else:
                    raise ValueError(f"Text extraction not supported for file type: {file_info['file_type']}")
                
                # Save extracted text as new file
                output_filename = f"{Path(file_info['filename']).stem}_extracted.txt"
                output_object_key = f"transformations/{transformation_id}/{output_filename}"
                output_data = result.encode('utf-8')
                
            elif transformation_type == 'csv_to_json':
                if file_info['file_type'] != 'csv':
                    raise ValueError("CSV to JSON conversion only supports CSV files")
                
                result = convert_csv_to_json(file_data)
                output_filename = f"{Path(file_info['filename']).stem}.json"
                output_object_key = f"transformations/{transformation_id}/{output_filename}"
                output_data = json.dumps(result, indent=2).encode('utf-8')
                
            elif transformation_type == 'excel_to_json':
                if file_info['file_type'] not in ['xlsx', 'xls']:
                    raise ValueError("Excel to JSON conversion only supports Excel files")
                
                result = convert_excel_to_json(file_data)
                output_filename = f"{Path(file_info['filename']).stem}.json"
                output_object_key = f"transformations/{transformation_id}/{output_filename}"
                output_data = json.dumps(result, indent=2).encode('utf-8')
                
            elif transformation_type == 'resize_image':
                if not file_info['mime_type'].startswith('image/'):
                    raise ValueError("Image resize only supports image files")
                
                width = config.get('width', 800)
                height = config.get('height', 600)
                output_data = resize_image(file_data, width, height)
                
                output_filename = f"{Path(file_info['filename']).stem}_resized.{Path(file_info['filename']).suffix}"
                output_object_key = f"transformations/{transformation_id}/{output_filename}"
                
            elif transformation_type == 'convert_image':
                if not file_info['mime_type'].startswith('image/'):
                    raise ValueError("Image conversion only supports image files")
                
                target_format = config.get('format', 'JPEG')
                output_data = convert_image_format(file_data, target_format)
                
                output_filename = f"{Path(file_info['filename']).stem}.{target_format.lower()}"
                output_object_key = f"transformations/{transformation_id}/{output_filename}"
                
            else:
                raise ValueError(f"Unsupported transformation type: {transformation_type}")
            
            # Upload transformed file to MinIO
            if output_data:
                if not upload_file_to_minio(output_data, output_object_key):
                    raise Exception("Failed to upload transformed file")
            
            # Update transformation as completed
            update_transformation_status(transformation_id, 'completed', {
                'output_object_key': output_object_key,
                'output_filename': output_filename,
                'result': result if isinstance(result, (str, list, dict)) else None
            })
            
            # Update file status
            conn = get_db_connection()
            with conn.cursor() as cur:
                cur.execute("""
                    UPDATE files 
                    SET status = 'transformed', transformation_type = %s, processed_at = %s
                    WHERE id = %s
                """, (transformation_type, datetime.utcnow(), file_id))
                conn.commit()
            conn.close()
            
            response_data = {
                'transformation_id': transformation_id,
                'file_id': file_id,
                'transformation_type': transformation_type,
                'status': 'completed',
                'output_object_key': output_object_key,
                'output_filename': output_filename,
                'completed_at': datetime.utcnow().isoformat()
            }
            
            logger.info("Transformation completed", 
                       transformation_id=transformation_id,
                       file_id=file_id)
            
            return jsonify(response_data), 200
            
        except Exception as e:
            error_message = str(e)
            logger.error("Transformation failed", 
                        transformation_id=transformation_id,
                        file_id=file_id,
                        error=error_message)
            
            # Update transformation as failed
            update_transformation_status(transformation_id, 'failed', error_message=error_message)
            
            return jsonify({
                'transformation_id': transformation_id,
                'file_id': file_id,
                'status': 'failed',
                'error': error_message
            }), 500
            
    except Exception as e:
        logger.error("Transform request error", error=str(e))
        return jsonify({'error': 'Internal server error'}), 500

@app.route('/transformations/<transformation_id>', methods=['GET'])
def get_transformation_status(transformation_id: str):
    """Get transformation status and details."""
    try:
        conn = get_db_connection()
        with conn.cursor(cursor_factory=RealDictCursor) as cur:
            cur.execute("""
                SELECT id, file_id, transformation_type, input_path, output_path,
                       status, config, result, error_message, started_at, completed_at, created_at
                FROM transformations 
                WHERE id = %s
            """, (transformation_id,))
            
            transformation = cur.fetchone()
            if not transformation:
                return jsonify({'error': 'Transformation not found'}), 404
            
            return jsonify(dict(transformation)), 200
            
    except Exception as e:
        logger.error("Error fetching transformation", error=str(e))
        return jsonify({'error': 'Internal server error'}), 500
    finally:
        conn.close()

@app.route('/transformations/<transformation_id>/retry', methods=['POST'])
def retry_transformation(transformation_id: str):
    """Retry a failed transformation."""
    try:
        conn = get_db_connection()
        with conn.cursor(cursor_factory=RealDictCursor) as cur:
            # Get transformation details
            cur.execute("""
                SELECT file_id, transformation_type, config
                FROM transformations 
                WHERE id = %s
            """, (transformation_id,))
            
            transformation = cur.fetchone()
            if not transformation:
                return jsonify({'error': 'Transformation not found'}), 404
            
            if transformation['status'] != 'failed':
                return jsonify({'error': 'Only failed transformations can be retried'}), 400
            
            # Reset transformation status
            cur.execute("""
                UPDATE transformations 
                SET status = 'pending', started_at = NULL, completed_at = NULL, 
                    error_message = NULL, result = NULL
                WHERE id = %s
            """, (transformation_id,))
            conn.commit()
        
        # Trigger new transformation
        transform_data = {
            'file_id': transformation['file_id'],
            'transformation_type': transformation['transformation_type'],
            'config': transformation['config'] or {}
        }
        
        # Call transform endpoint internally
        with app.test_client() as client:
            response = client.post('/transform', json=transform_data)
            return response.get_json(), response.status_code
            
    except Exception as e:
        logger.error("Error retrying transformation", 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)