<?php
namespace App\Models;

use PDO;
use PDOException;

class Database {
    private static $instance = null;
    private $connection;
    
    private function __construct() {
        $config = include __DIR__ . '/../../config/database.php';
        
        $dsn = "mysql:host={$config['host']};dbname={$config['database']};charset={$config['charset']}";
        
        try {
            $this->connection = new PDO(
                $dsn,
                $config['username'],
                $config['password'],
                [
                    PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION,
                    PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC,
                    PDO::ATTR_EMULATE_PREPARES => false,
                ]
            );
        } catch (PDOException $e) {
            die("Database connection failed: " . $e->getMessage());
        }
    }
    
    public static function getInstance() {
        if (self::$instance === null) {
            self::$instance = new self();
        }
        return self::$instance;
    }
    
    public function getConnection() {
        return $this->connection;
    }
    
    public function query($sql, $params = []) {
        $stmt = $this->connection->prepare($sql);
        $stmt->execute($params);
        return $stmt;
    }
    
    public function fetchAll($sql, $params = []) {
        return $this->query($sql, $params)->fetchAll();
    }
    
    public function fetch($sql, $params = []) {
        return $this->query($sql, $params)->fetch();
    }
    
    public function insert($table, $data) {
        $columns = implode(', ', array_keys($data));
        $placeholders = ':' . implode(', :', array_keys($data));
        
        $sql = "INSERT INTO {$table} ({$columns}) VALUES ({$placeholders})";
        $stmt = $this->connection->prepare($sql);
        $stmt->execute($data);
        
        return $this->connection->lastInsertId();
    }
    
    public function update($table, $data, $where) {
        $setParts = [];
        foreach ($data as $key => $value) {
            $setParts[] = "{$key} = :{$key}";
        }
        
        $whereParts = [];
        foreach ($where as $key => $value) {
            $whereParts[] = "{$key} = :where_{$key}";
            $data["where_{$key}"] = $value;
        }
        
        $sql = "UPDATE {$table} SET " . implode(', ', $setParts) . 
               " WHERE " . implode(' AND ', $whereParts);
        
        $stmt = $this->connection->prepare($sql);
        return $stmt->execute($data);
    }
    
    public function delete($table, $where) {
        $whereParts = [];
        $params = [];
        foreach ($where as $key => $value) {
            $whereParts[] = "{$key} = :{$key}";
            $params[$key] = $value;
        }
        
        $sql = "DELETE FROM {$table} WHERE " . implode(' AND ', $whereParts);
        return $this->query($sql, $params)->rowCount();
    }
}