import sqlite3
import logging
from contextlib import contextmanager
from datetime import datetime

class DBHandler:
    def __init__(self, db_path='qr_codes.db'):
        self.db_path = db_path
        self.logger = logging.getLogger(__name__)
        self.setup_database()

    @contextmanager
    def get_connection(self):
        """Administra la conexión a la base de datos"""
        conn = None
        try:
            conn = sqlite3.connect(self.db_path)
            yield conn
        except sqlite3.Error as e:
            self.logger.error(f"Error de conexión a la base de datos: {e}")
            raise
        finally:
            if conn:
                conn.close()

    def setup_database(self):
        """Crea la tabla si no existe"""
        create_table_sql = '''
        CREATE TABLE IF NOT EXISTS qr_codes (
            id INTEGER PRIMARY KEY AUTOINCREMENT,
            qr_data TEXT NOT NULL UNIQUE,
            camera_name TEXT NOT NULL,
            created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
        );
        '''
        try:
            with self.get_connection() as conn:
                cursor = conn.cursor()
                cursor.execute(create_table_sql)
                conn.commit()
                self.logger.info("Base de datos inicializada correctamente")
        except sqlite3.Error as e:
            self.logger.error(f"Error creando la tabla: {e}")
            raise

    def check_qr_exists(self, qr_data: str) -> bool:
        """Verifica si un código QR ya existe en la base de datos"""
        query = 'SELECT COUNT(*) FROM qr_codes WHERE qr_data = ?'
        try:
            with self.get_connection() as conn:
                cursor = conn.cursor()
                cursor.execute(query, (qr_data,))
                (count,) = cursor.fetchone()
                return count > 0
        except sqlite3.Error as e:
            self.logger.error(f"Error verificando QR: {e}")
            return False

    def save_qr(self, qr_data: str,camera_name: str) -> bool:
        """Guarda un nuevo código QR en la base de datos"""
        if self.check_qr_exists(qr_data):
            return False

        insert_sql = 'INSERT INTO qr_codes (qr_data,camera_name) VALUES (?, ?)'
        try:
            with self.get_connection() as conn:
                cursor = conn.cursor()
                cursor.execute(insert_sql, (qr_data,camera_name))
                conn.commit()
                self.logger.info(f"QR guardado en DB: {qr_data}")
                return True
        except sqlite3.Error as e:
            self.logger.error(f"Error guardando QR: {e}")
            return False

    def get_all_qrs(self) -> list:
        """Obtiene todos los códigos QR almacenados"""
        query = 'SELECT qr_data, created_at FROM qr_codes ORDER BY created_at DESC'
        try:
            with self.get_connection() as conn:
                cursor = conn.cursor()
                cursor.execute(query)
                return cursor.fetchall()
        except sqlite3.Error as e:
            self.logger.error(f"Error obteniendo QRs: {e}")
            return []