"""
Database Manager for EmotionMirror Application

This module provides functionality for database operations, including:
- Creating and initializing the SQLite database
- Storing analysis results
- Retrieving historical data
- Managing database connections

All database operations are encapsulated in this module to ensure clean separation
of concerns and modularity.
"""

import os
import json
import sqlite3
import logging
from datetime import datetime
from typing import Dict, List, Any, Optional, Tuple

# Configure logging
logger = logging.getLogger(__name__)

class DatabaseManager:
    """
    Manages database operations for the EmotionMirror application.
    
    This class handles all interactions with the SQLite database, providing
    a clean interface for the rest of the application to store and retrieve data.
    """
    
    def __init__(self, db_path: str):
        """
        Initialize the database manager.
        
        Args:
            db_path: Path to the SQLite database file
        """
        self.db_path = db_path
        self._initialize_db()
    
    def _initialize_db(self) -> None:
        """
        Initialize the database by creating necessary tables if they don't exist.
        """
        os.makedirs(os.path.dirname(self.db_path), exist_ok=True)
        
        conn = None
        try:
            conn = sqlite3.connect(self.db_path)
            cursor = conn.cursor()
            
            # Create analyses table
            cursor.execute('''
            CREATE TABLE IF NOT EXISTS analyses (
                id INTEGER PRIMARY KEY AUTOINCREMENT,
                session_id TEXT NOT NULL,
                timestamp TEXT NOT NULL,
                image_path TEXT NOT NULL,
                face_count INTEGER NOT NULL,
                results TEXT NOT NULL,
                tags TEXT
            )
            ''')
            
            # Create faces table
            cursor.execute('''
            CREATE TABLE IF NOT EXISTS faces (
                id INTEGER PRIMARY KEY AUTOINCREMENT,
                analysis_id INTEGER NOT NULL,
                face_index INTEGER NOT NULL,
                emotion TEXT NOT NULL,
                confidence REAL NOT NULL,
                features TEXT NOT NULL,
                emotions TEXT NOT NULL,
                FOREIGN KEY (analysis_id) REFERENCES analyses (id)
            )
            ''')
            
            conn.commit()
            logger.info("Database initialized successfully")
        except sqlite3.Error as e:
            logger.error(f"Database initialization error: {e}")
        finally:
            if conn:
                conn.close()
    
    def save_analysis(self, 
                     session_id: str, 
                     image_path: str, 
                     results: Dict[str, Any],
                     tags: Optional[List[str]] = None) -> int:
        """
        Save analysis results to the database.
        
        Args:
            session_id: Current session identifier
            image_path: Path to the analyzed image
            results: Analysis results dictionary
            tags: Optional list of tags for the analysis
            
        Returns:
            The ID of the newly inserted analysis record
        """
        conn = None
        try:
            conn = sqlite3.connect(self.db_path)
            cursor = conn.cursor()
            
            # Convert tags list to JSON string if provided
            tags_json = json.dumps(tags) if tags else None
            
            # Insert analysis record
            cursor.execute(
                '''
                INSERT INTO analyses 
                (session_id, timestamp, image_path, face_count, results, tags)
                VALUES (?, ?, ?, ?, ?, ?)
                ''',
                (
                    session_id,
                    datetime.now().isoformat(),
                    image_path,
                    results.get('face_count', 0),
                    json.dumps(results),
                    tags_json
                )
            )
            
            analysis_id = cursor.lastrowid
            
            # Insert face records if present
            faces = results.get('faces', [])
            for i, face in enumerate(faces):
                cursor.execute(
                    '''
                    INSERT INTO faces
                    (analysis_id, face_index, emotion, confidence, features, emotions)
                    VALUES (?, ?, ?, ?, ?, ?)
                    ''',
                    (
                        analysis_id,
                        i,
                        face.get('emotion', 'unknown'),
                        face.get('confidence', 0.0),
                        json.dumps(face.get('features', {})),
                        json.dumps(face.get('emotions', {}))
                    )
                )
            
            conn.commit()
            logger.info(f"Saved analysis with ID {analysis_id} and {len(faces)} faces")
            return analysis_id
            
        except sqlite3.Error as e:
            logger.error(f"Error saving analysis: {e}")
            if conn:
                conn.rollback()
            return -1
        finally:
            if conn:
                conn.close()
    
    def get_analysis_history(self, 
                           session_id: Optional[str] = None, 
                           limit: int = 10) -> List[Dict[str, Any]]:
        """
        Retrieve analysis history from the database.
        
        Args:
            session_id: Optional session ID to filter by
            limit: Maximum number of records to return
            
        Returns:
            List of analysis records as dictionaries
        """
        conn = None
        try:
            conn = sqlite3.connect(self.db_path)
            conn.row_factory = sqlite3.Row  # This enables name-based access to columns
            cursor = conn.cursor()
            
            query = '''
            SELECT 
                id, 
                session_id, 
                timestamp, 
                image_path, 
                face_count, 
                results,
                tags
            FROM analyses
            '''
            
            params = []
            if session_id:
                query += ' WHERE session_id = ?'
                params.append(session_id)
                
            query += '''
            ORDER BY timestamp DESC
            LIMIT ?
            '''
            params.append(limit)
            
            cursor.execute(query, params)
            
            # Convert row objects to dictionaries
            analyses = []
            for row in cursor.fetchall():
                analysis = dict(row)
                
                # Parse JSON fields
                analysis['results'] = json.loads(analysis['results'])
                if analysis['tags']:
                    analysis['tags'] = json.loads(analysis['tags'])
                
                # Get faces for this analysis
                face_cursor = conn.cursor()
                face_cursor.execute(
                    '''
                    SELECT 
                        id,
                        face_index,
                        emotion,
                        confidence,
                        features,
                        emotions
                    FROM faces
                    WHERE analysis_id = ?
                    ORDER BY face_index
                    ''',
                    (analysis['id'],)
                )
                
                faces = []
                for face_row in face_cursor.fetchall():
                    face = dict(face_row)
                    
                    # Parse JSON fields
                    face['features'] = json.loads(face['features'])
                    face['emotions'] = json.loads(face['emotions'])
                    
                    faces.append(face)
                
                analysis['faces'] = faces
                analyses.append(analysis)
                
            return analyses
            
        except sqlite3.Error as e:
            logger.error(f"Error retrieving analysis history: {e}")
            return []
        finally:
            if conn:
                conn.close()
    
    def get_analysis_by_id(self, analysis_id: int) -> Optional[Dict[str, Any]]:
        """
        Retrieve a specific analysis by ID.
        
        Args:
            analysis_id: ID of the analysis to retrieve
            
        Returns:
            Analysis record as a dictionary, or None if not found
        """
        conn = None
        try:
            conn = sqlite3.connect(self.db_path)
            conn.row_factory = sqlite3.Row
            cursor = conn.cursor()
            
            cursor.execute(
                '''
                SELECT 
                    id, 
                    session_id, 
                    timestamp, 
                    image_path, 
                    face_count, 
                    results,
                    tags
                FROM analyses
                WHERE id = ?
                ''',
                (analysis_id,)
            )
            
            row = cursor.fetchone()
            if not row:
                return None
                
            analysis = dict(row)
            
            # Parse JSON fields
            analysis['results'] = json.loads(analysis['results'])
            if analysis['tags']:
                analysis['tags'] = json.loads(analysis['tags'])
            
            # Get faces for this analysis
            face_cursor = conn.cursor()
            face_cursor.execute(
                '''
                SELECT 
                    id,
                    face_index,
                    emotion,
                    confidence,
                    features,
                    emotions
                FROM faces
                WHERE analysis_id = ?
                ORDER BY face_index
                ''',
                (analysis_id,)
            )
            
            faces = []
            for face_row in face_cursor.fetchall():
                face = dict(face_row)
                
                # Parse JSON fields
                face['features'] = json.loads(face['features'])
                face['emotions'] = json.loads(face['emotions'])
                
                faces.append(face)
            
            analysis['faces'] = faces
            return analysis
            
        except sqlite3.Error as e:
            logger.error(f"Error retrieving analysis by ID: {e}")
            return None
        finally:
            if conn:
                conn.close()
    
    def get_emotion_statistics(self, 
                             session_id: Optional[str] = None, 
                             limit: int = 50) -> Dict[str, float]:
        """
        Compute emotion statistics across multiple analyses.
        
        Args:
            session_id: Optional session ID to filter by
            limit: Maximum number of records to analyze
            
        Returns:
            Dictionary of emotion frequencies
        """
        conn = None
        try:
            conn = sqlite3.connect(self.db_path)
            cursor = conn.cursor()
            
            query = '''
            SELECT emotion, COUNT(*) as count
            FROM faces
            '''
            
            params = []
            if session_id:
                query += '''
                JOIN analyses ON faces.analysis_id = analyses.id
                WHERE analyses.session_id = ?
                '''
                params.append(session_id)
            
            query += '''
            GROUP BY emotion
            ORDER BY count DESC
            '''
            
            cursor.execute(query, params)
            rows = cursor.fetchall()
            
            # Calculate emotion frequencies
            total = sum(count for _, count in rows)
            stats = {emotion: count / total for emotion, count in rows} if total > 0 else {}
            
            return stats
            
        except sqlite3.Error as e:
            logger.error(f"Error computing emotion statistics: {e}")
            return {}
        finally:
            if conn:
                conn.close()
                
    def delete_analysis(self, analysis_id: int) -> bool:
        """
        Delete an analysis and its associated faces.
        
        Args:
            analysis_id: ID of the analysis to delete
            
        Returns:
            True if deletion was successful, False otherwise
        """
        conn = None
        try:
            conn = sqlite3.connect(self.db_path)
            cursor = conn.cursor()
            
            # Delete associated faces first (due to foreign key constraint)
            cursor.execute('DELETE FROM faces WHERE analysis_id = ?', (analysis_id,))
            
            # Delete the analysis
            cursor.execute('DELETE FROM analyses WHERE id = ?', (analysis_id,))
            
            conn.commit()
            return cursor.rowcount > 0
            
        except sqlite3.Error as e:
            logger.error(f"Error deleting analysis: {e}")
            if conn:
                conn.rollback()
            return False
        finally:
            if conn:
                conn.close()
    
    def export_analysis_data(self, 
                           analysis_id: Optional[int] = None, 
                           session_id: Optional[str] = None,
                           limit: int = 100) -> Dict[str, Any]:
        """
        Export analysis data in a structured format suitable for JSON/CSV export.
        
        Args:
            analysis_id: Optional specific analysis ID to export
            session_id: Optional session ID to filter by
            limit: Maximum number of records to export
            
        Returns:
            Dictionary containing the exported data
        """
        if analysis_id:
            # Export a single analysis
            analysis = self.get_analysis_by_id(analysis_id)
            if not analysis:
                return {'error': f'Analysis with ID {analysis_id} not found'}
            
            return {
                'metadata': {
                    'exported_at': datetime.now().isoformat(),
                    'record_count': 1
                },
                'analyses': [analysis]
            }
        else:
            # Export multiple analyses
            analyses = self.get_analysis_history(session_id, limit)
            
            return {
                'metadata': {
                    'exported_at': datetime.now().isoformat(),
                    'record_count': len(analyses),
                    'session_id': session_id
                },
                'analyses': analyses
            }