#!/usr/bin/env python3
"""
Database module for Multi-Personality Chat Bot
Handles SQLite database operations for chat history and analytics.
"""

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

logger = logging.getLogger(__name__)

class ChatDatabase:
    """Simple SQLite database for chat storage"""
    
    def __init__(self, db_path: str = None):
        """Initialize database connection"""
        # Determine database path from env or default to ./data/chat_data.db
        resolved_path = db_path or os.getenv("DB_PATH") or os.path.join(os.getcwd(), "data", "chat_data.db")
        # Ensure parent directory exists and is writable
        try:
            parent_dir = os.path.dirname(resolved_path) or "."
            os.makedirs(parent_dir, exist_ok=True)
        except Exception as e:
            logger.warning(f"Could not create DB directory '{resolved_path}': {e}")
        self.db_path = resolved_path
        self.initialize_database()
    
    def initialize_database(self):
        """Create database tables if they don't exist"""
        def _create_schema(conn: sqlite3.Connection):
                cursor = conn.cursor()
                
                # Create messages table
                cursor.execute("""
                    CREATE TABLE IF NOT EXISTS messages (
                        id INTEGER PRIMARY KEY AUTOINCREMENT,
                        username TEXT NOT NULL,
                        message TEXT NOT NULL,
                        personality_type TEXT NOT NULL,
                        sender_type TEXT NOT NULL CHECK(sender_type IN ('user', 'bot')),
                        timestamp DATETIME DEFAULT CURRENT_TIMESTAMP,
                        session_id TEXT,
                        response_time REAL
                    )
                """)
                
                # Lightweight migration: ensure expected columns exist on older DBs
                self._ensure_messages_columns(conn)
                
                # Create personality_stats table
                cursor.execute("""
                    CREATE TABLE IF NOT EXISTS personality_stats (
                        personality_type TEXT PRIMARY KEY,
                        total_messages INTEGER DEFAULT 0,
                        avg_response_time REAL DEFAULT 0.0,
                        last_used DATETIME DEFAULT CURRENT_TIMESTAMP
                    )
                """)
                
                conn.commit()
                logger.info("Database initialized successfully")
        
        # First attempt
        try:
            with sqlite3.connect(self.db_path) as conn:
                _create_schema(conn)
        except sqlite3.OperationalError as e:
            if "unable to open database file" in str(e).lower():
                # Fallback: try to recreate directory and retry
                try:
                    parent_dir = os.path.dirname(self.db_path) or "."
                    os.makedirs(parent_dir, exist_ok=True)
                    with sqlite3.connect(self.db_path) as conn:
                        _create_schema(conn)
                        return
                except Exception:
                    # Final fallback: use temp directory
                    tmp_dir = tempfile.gettempdir()
                    fallback_path = os.path.join(tmp_dir, "chat_data.db")
                    try:
                        os.makedirs(tmp_dir, exist_ok=True)
                    except Exception:
                        pass
                    try:
                        with sqlite3.connect(fallback_path) as conn:
                            self.db_path = fallback_path
                            _create_schema(conn)
                            logger.warning(f"DB path fallback in use: {fallback_path}")
                            return
                    except Exception as e2:
                        logger.error(f"Database initialization error (fallback failed): {e2}")
                        return
            else:
                logger.error(f"Database initialization error: {str(e)}")
        except Exception as e:
            logger.error(f"Database initialization error: {str(e)}")

    def _ensure_messages_columns(self, conn: sqlite3.Connection) -> None:
        """Ensure required columns exist in messages table for backward compatibility."""
        try:
            cursor = conn.cursor()
            cursor.execute("PRAGMA table_info(messages)")
            cols = {row[1]: row for row in cursor.fetchall()}  # name -> info

            # Columns to ensure exist: name -> SQL add column clause
            required_columns = {
                'personality_type': "ALTER TABLE messages ADD COLUMN personality_type TEXT",
                'sender_type': "ALTER TABLE messages ADD COLUMN sender_type TEXT",
                'session_id': "ALTER TABLE messages ADD COLUMN session_id TEXT",
                'response_time': "ALTER TABLE messages ADD COLUMN response_time REAL",
                'timestamp': "ALTER TABLE messages ADD COLUMN timestamp DATETIME DEFAULT CURRENT_TIMESTAMP",
            }

            for name, alter_sql in required_columns.items():
                if name not in cols:
                    try:
                        cursor.execute(alter_sql)
                        logger.info(f"Added missing column to messages table: {name}")
                    except Exception as e:
                        # If the column exists but PRAGMA didn't report it correctly or another race, log and continue
                        logger.warning(f"Could not add column '{name}' to messages: {e}")
            conn.commit()
        except Exception as e:
            logger.error(f"Error ensuring messages columns: {e}")
    
    def save_message(self, username: str, message: str, personality_type: str, 
                    sender_type: str, session_id: str = None, response_time: float = None) -> bool:
        """Save a message to the database"""
        try:
            with sqlite3.connect(self.db_path) as conn:
                cursor = conn.cursor()
                
                cursor.execute("""
                    INSERT INTO messages (username, message, personality_type, sender_type, session_id, response_time)
                    VALUES (?, ?, ?, ?, ?, ?)
                """, (username, message, personality_type, sender_type, session_id, response_time))
                
                conn.commit()
                return True
                
        except sqlite3.OperationalError as e:
            # Auto-migrate if schema is missing expected columns, then retry once
            if "no column named" in str(e).lower():
                logger.warning(f"Schema issue detected ('{e}'). Attempting to migrate and retry insert...")
                try:
                    with sqlite3.connect(self.db_path) as conn:
                        self._ensure_messages_columns(conn)
                        cursor = conn.cursor()
                        cursor.execute(
                            """
                            INSERT INTO messages (username, message, personality_type, sender_type, session_id, response_time)
                            VALUES (?, ?, ?, ?, ?, ?)
                            """,
                            (username, message, personality_type, sender_type, session_id, response_time),
                        )
                        conn.commit()
                        logger.info("Insert succeeded after schema migration")
                        return True
                except Exception as e2:
                    logger.error(f"Retry after migration failed: {e2}")
                    return False
            else:
                logger.error(f"Operational DB error saving message: {e}")
                return False
        except Exception as e:
            logger.error(f"Unexpected DB error saving message: {str(e)}")
            return False
    
    def get_recent_messages(self, personality_type: str = None, limit: int = 50) -> List[Dict[str, Any]]:
        """Get recent messages, optionally filtered by personality type"""
        try:
            with sqlite3.connect(self.db_path) as conn:
                cursor = conn.cursor()
                
                if personality_type:
                    cursor.execute("""
                        SELECT username, message, personality_type, sender_type, timestamp
                        FROM messages 
                        WHERE personality_type = ?
                        ORDER BY timestamp DESC 
                        LIMIT ?
                    """, (personality_type, limit))
                else:
                    cursor.execute("""
                        SELECT username, message, personality_type, sender_type, timestamp
                        FROM messages 
                        ORDER BY timestamp DESC 
                        LIMIT ?
                    """, (limit,))
                
                messages = []
                for row in cursor.fetchall():
                    messages.append({
                        'username': row[0],
                        'message': row[1],
                        'personality_type': row[2],
                        'sender_type': row[3],
                        'timestamp': row[4]
                    })
                
                return messages
                
        except Exception as e:
            logger.error(f"Error retrieving messages: {str(e)}")
            return []
    
    def clear_personality_chat(self, personality_type: str, username: str = None) -> bool:
        """Clear chat history for a personality (optionally for a specific user)"""
        try:
            with sqlite3.connect(self.db_path) as conn:
                cursor = conn.cursor()
                
                if username:
                    cursor.execute("""
                        DELETE FROM messages 
                        WHERE personality_type = ? AND username = ?
                    """, (personality_type, username))
                else:
                    cursor.execute("""
                        DELETE FROM messages 
                        WHERE personality_type = ?
                    """, (personality_type,))
                
                conn.commit()
                return True
                
        except Exception as e:
            logger.error(f"Error clearing chat: {str(e)}")
            return False
    
    def get_personality_stats(self, personality_type: str) -> Dict[str, Any]:
        """Get statistics for a specific personality"""
        try:
            with sqlite3.connect(self.db_path) as conn:
                cursor = conn.cursor()
                
                # Get message count
                cursor.execute("""
                    SELECT COUNT(*) FROM messages 
                    WHERE personality_type = ? AND sender_type = 'bot'
                """, (personality_type,))
                
                message_count = cursor.fetchone()[0]
                
                # Get average response time
                cursor.execute("""
                    SELECT AVG(response_time) FROM messages 
                    WHERE personality_type = ? AND sender_type = 'bot' AND response_time IS NOT NULL
                """, (personality_type,))
                
                avg_response_time = cursor.fetchone()[0] or 0.0
                
                return {
                    'personality_type': personality_type,
                    'total_messages': message_count,
                    'avg_response_time': round(avg_response_time, 2)
                }
                
        except Exception as e:
            logger.error(f"Error getting personality stats: {str(e)}")
            return {
                'personality_type': personality_type,
                'total_messages': 0,
                'avg_response_time': 0.0
            }
    
    def get_all_stats(self) -> Dict[str, Any]:
        """Get overall statistics"""
        try:
            with sqlite3.connect(self.db_path) as conn:
                cursor = conn.cursor()
                
                # Total messages
                cursor.execute("SELECT COUNT(*) FROM messages")
                total_messages = cursor.fetchone()[0]
                
                # Messages by personality
                cursor.execute("""
                    SELECT personality_type, COUNT(*) 
                    FROM messages 
                    GROUP BY personality_type
                """)
                
                personality_breakdown = dict(cursor.fetchall())
                
                return {
                    'total_messages': total_messages,
                    'personality_breakdown': personality_breakdown
                }
                
        except Exception as e:
            logger.error(f"Error getting all stats: {str(e)}")
            return {
                'total_messages': 0,
                'personality_breakdown': {}
            }