import sqlite3
import os
from datetime import datetime, timedelta
from contextlib import contextmanager

DATABASE_PATH = 'files.db'

def init_database():
    """Inicializar la base de datos y crear las tablas necesarias"""
    with get_db_connection() as conn:
        cursor = conn.cursor()
        
        # Crear tabla de archivos
        cursor.execute('''
            CREATE TABLE IF NOT EXISTS files (
                id TEXT PRIMARY KEY,
                original_filename TEXT NOT NULL,
                stored_filename TEXT NOT NULL,
                file_size INTEGER NOT NULL,
                created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
                expires_at TIMESTAMP NOT NULL,
                download_count INTEGER DEFAULT 0,
                is_deleted BOOLEAN DEFAULT FALSE
            )
        ''')
        
        conn.commit()

@contextmanager
def get_db_connection():
    """Context manager para conexiones a la base de datos"""
    conn = sqlite3.connect(DATABASE_PATH)
    conn.row_factory = sqlite3.Row  # Permite acceder a las columnas por nombre
    try:
        yield conn
    finally:
        conn.close()

def save_file(file_id, original_filename, stored_filename, file_size, expires_hours=24):
    """Guardar información de un archivo en la base de datos"""
    expires_at = datetime.now() + timedelta(hours=expires_hours)
    
    with get_db_connection() as conn:
        cursor = conn.cursor()
        cursor.execute('''
            INSERT INTO files (id, original_filename, stored_filename, file_size, expires_at)
            VALUES (?, ?, ?, ?, ?)
        ''', (file_id, original_filename, stored_filename, file_size, expires_at.isoformat()))
        conn.commit()

def get_file_by_id(file_id):
    """Obtener información de un archivo por su ID"""
    with get_db_connection() as conn:
        cursor = conn.cursor()
        cursor.execute('''
            SELECT * FROM files 
            WHERE id = ? AND is_deleted = FALSE
        ''', (file_id,))
        return cursor.fetchone()

def get_all_files():
    """Obtener todos los archivos no eliminados"""
    with get_db_connection() as conn:
        cursor = conn.cursor()
        cursor.execute('''
            SELECT * FROM files 
            WHERE is_deleted = FALSE 
            ORDER BY created_at DESC
        ''')
        return cursor.fetchall()

def get_active_files():
    """Obtener solo archivos activos (no expirados y no eliminados)"""
    with get_db_connection() as conn:
        cursor = conn.cursor()
        cursor.execute('''
            SELECT * FROM files 
            WHERE is_deleted = FALSE AND expires_at > ?
            ORDER BY created_at DESC
        ''', (datetime.now().isoformat(),))
        return cursor.fetchall()

def delete_file(file_id):
    """Marcar un archivo como eliminado (soft delete)"""
    with get_db_connection() as conn:
        cursor = conn.cursor()
        cursor.execute('''
            UPDATE files 
            SET is_deleted = TRUE 
            WHERE id = ?
        ''', (file_id,))
        conn.commit()
        return cursor.rowcount > 0

def hard_delete_file(file_id):
    """Eliminar completamente un archivo de la base de datos"""
    with get_db_connection() as conn:
        cursor = conn.cursor()
        cursor.execute('DELETE FROM files WHERE id = ?', (file_id,))
        conn.commit()
        return cursor.rowcount > 0

def increment_download_count(file_id):
    """Incrementar el contador de descargas de un archivo"""
    with get_db_connection() as conn:
        cursor = conn.cursor()
        cursor.execute('''
            UPDATE files 
            SET download_count = download_count + 1 
            WHERE id = ?
        ''', (file_id,))
        conn.commit()

def cleanup_expired_files():
    """Eliminar archivos expirados de la base de datos"""
    with get_db_connection() as conn:
        cursor = conn.cursor()
        cursor.execute('''
            UPDATE files 
            SET is_deleted = TRUE 
            WHERE expires_at <= ? AND is_deleted = FALSE
        ''', (datetime.now().isoformat(),))
        conn.commit()
        return cursor.rowcount

def get_file_stats():
    """Obtener estadísticas de archivos"""
    with get_db_connection() as conn:
        cursor = conn.cursor()
        
        # Total de archivos
        cursor.execute('SELECT COUNT(*) FROM files WHERE is_deleted = FALSE')
        total_files = cursor.fetchone()[0]
        
        # Archivos activos
        cursor.execute('''
            SELECT COUNT(*) FROM files 
            WHERE is_deleted = FALSE AND expires_at > ?
        ''', (datetime.now().isoformat(),))
        active_files = cursor.fetchone()[0]
        
        # Total de descargas
        cursor.execute('SELECT SUM(download_count) FROM files WHERE is_deleted = FALSE')
        total_downloads = cursor.fetchone()[0] or 0
        
        return {
            'total_files': total_files,
            'active_files': active_files,
            'total_downloads': total_downloads
        }