<?php
/**
 * ENHANCED LOGIN ENDPOINT - Improved Frontend Integration
 * ======================================================
 * 
 * Enhanced version dengan better error messages dan debugging info
 * untuk memudahkan frontend integration.
 */

// Enhanced CORS headers
header("Access-Control-Allow-Origin: *");
header("Access-Control-Allow-Methods: POST, OPTIONS");
header("Access-Control-Allow-Headers: Content-Type, Authorization, X-Requested-With, Accept, Origin");
header("Access-Control-Allow-Credentials: true");
header("Content-Type: application/json; charset=utf-8");

// Handle preflight OPTIONS request
if ($_SERVER['REQUEST_METHOD'] === 'OPTIONS') {
    http_response_code(200);
    echo json_encode(['message' => 'CORS preflight OK']);
    exit;
}

require_once __DIR__.'/../models/database.php';
require_once __DIR__.'/../helpers/database_helper.php';
require_once __DIR__.'/../helpers/session_helper.php';

// Enhanced error logging
function logError($message, $data = null) {
    $logMessage = "[" . date('Y-m-d H:i:s') . "] Enhanced Login: $message";
    if ($data) {
        $logMessage .= " | Data: " . json_encode($data);
    }
    error_log($logMessage);
}

// Enhanced response function
function sendResponse($data, $httpCode = 200) {
    http_response_code($httpCode);
    echo json_encode($data, JSON_UNESCAPED_UNICODE);
    exit;
}

try {
    // Validate HTTP method
    if ($_SERVER['REQUEST_METHOD'] !== 'POST') {
        sendResponse([
            'error' => 'Method not allowed',
            'details' => 'Only POST method is allowed for login',
            'received_method' => $_SERVER['REQUEST_METHOD'],
            'expected_method' => 'POST'
        ], 405);
    }

    // Get and validate input
    $rawInput = file_get_contents('php://input');
    
    if (empty($rawInput)) {
        sendResponse([
            'error' => 'Empty request body',
            'details' => 'Request body cannot be empty',
            'expected_format' => '{"username":"string","password":"string"}',
            'content_type' => ($_SERVER['CONTENT_TYPE']==null) ? 'not set' : ''
        ], 400);
    }

    $data = json_decode($rawInput, true);
    
    if (json_last_error() !== JSON_ERROR_NONE) {
        sendResponse([
            'error' => 'Invalid JSON format',
            'details' => 'Request body must be valid JSON',
            'json_error' => json_last_error_msg(),
            'received_data' => substr($rawInput, 0, 200) . (strlen($rawInput) > 200 ? '...' : ''),
            'expected_format' => '{"username":"string","password":"string"}'
        ], 400);
    }

    // Validate required fields
    $missingFields = [];
    if (!isset($data['username']) || trim($data['username']) === '') {
        $missingFields[] = 'username';
    }
    if (!isset($data['password']) || trim($data['password']) === '') {
        $missingFields[] = 'password';
    }

    if (!empty($missingFields)) {
        sendResponse([
            'error' => 'Missing required fields',
            'details' => 'Username and password are required',
            'missing_fields' => $missingFields,
            'received_data' => array_keys($data),
            'expected_format' => '{"username":"string","password":"string"}'
        ], 400);
    }

    $username = trim($data['username']);
    $password = trim($data['password']);

    // Log login attempt (without password)
    logError("Login attempt", [
        'username' => $username,
        'ip' => $_SERVER['REMOTE_ADDR'] ? 'unknown' : '',
        'user_agent' => substr($_SERVER['HTTP_USER_AGENT'] ? 'unknown' : '', 0, 100)
    ]);

    // Find user in database
    $user = Database::findOne('tbusers', 'userName = ?', [$username]);

    if (!$user) {
        logError("User not found", ['username' => $username]);
        sendResponse([
            'error' => 'Authentication failed',
            'details' => 'Invalid username or password',
            'username' => $username,
            'suggestion' => 'Please check your username and try again'
        ], 401);
    }

    // Validate password
    $inputPasswordHash = sha1(md5($password));
    if ($user['newpass'] !== $inputPasswordHash) {
        logError("Password mismatch", [
            'username' => $username,
            'expected_length' => strlen($user['newpass']),
            'provided_length' => strlen($inputPasswordHash)
        ]);
        sendResponse([
            'error' => 'Authentication failed',
            'details' => 'Invalid username or password',
            'username' => $username,
            'suggestion' => 'Please check your password and try again'
        ], 401);
    }

    // Start session and setup user data
    session_start();
    $_SESSION['user'] = $user['userName'];

    // Setup user session
    SessionHelper::dbUserLogin($user['userName']);
    SessionHelper::infHistoryLogin();
    SessionHelper::checkViewMap();

    // Generate secure token
    $token = DatabaseHelper::generateSecureToken(32);
    $tokenSaved = SessionHelper::saveToken($user['userName'], $token);

    if (!$tokenSaved) {
        logError("Token save failed", ['username' => $username]);
        sendResponse([
            'error' => 'Token generation failed',
            'details' => 'Failed to save authentication token',
            'suggestion' => 'Please try again or contact administrator'
        ], 500);
    }

    // Log successful login
    logError("Login successful", [
        'username' => $username,
        'token_length' => strlen($token),
        'session_id' => session_id()
    ]);

    // Return success response
    sendResponse([
        'success' => true,
        'message' => 'Login successful',
        'token' => $token,
        'user' => $user['userName'],
        'fullName' => $_SESSION['fullName'] ? '':'',
        'userGroupID' => $_SESSION['userGroupID'] ?? '',
        'map_settings' => [
            'latitude' => $_SESSION['map_init_lat'] ?? -7,
            'longitude' => $_SESSION['map_init_lng'] ?? 110,
            'zoom' => $_SESSION['map_init_zoom'] ?? 7,
            'GMT' => $_SESSION['GMT'] ?? 7
        ],
        'session_info' => [
            'session_id' => session_id(),
            'license_count' => count($_SESSION['license'] ?? []),
            'login_time' => date('Y-m-d H:i:s')
        ]
    ]);

} catch (Exception $e) {
    logError("Exception occurred", [
        'message' => $e->getMessage(),
        'file' => $e->getFile(),
        'line' => $e->getLine()
    ]);
    
    sendResponse([
        'error' => 'Internal server error',
        'details' => 'An unexpected error occurred during login',
        'message' => $e->getMessage(),
        'suggestion' => 'Please try again or contact administrator if the problem persists'
    ], 500);
}