<?php
/**
 * HISTORY TOTAL KM API - Optimized Distance Calculation for Big Data
 * ==================================================================
 * 
 * DESKRIPSI:
 * ==========
 * API untuk menghitung total jarak tempuh kendaraan dengan optimasi khusus
 * untuk dataset besar (100+ miliar records). Menggunakan:
 * - Query optimization dengan indexing hints
 * - Memory-efficient processing
 * - Chunked data processing untuk dataset besar
 * - Caching mechanism untuk performa
 * - GROUP BY optimization untuk mengurangi duplicate coordinates
 * 
 * METHOD: GET
 * ENDPOINT: /api/history_total_km
 * AUTHENTICATION: Required (Bearer token atau session)
 * 
 * QUERY PARAMETERS:
 * =================
 * - awal: Start datetime (format: YYYY-MM-DD HH:MM:SS)
 * - akhir: End datetime (format: YYYY-MM-DD HH:MM:SS)
 * - tid: Tracking ID kendaraan
 * - chunk_size: Optional, default 1000 (untuk memory management)
 * 
 * CONTOH REQUEST:
 * ===============
 * GET /api/history_total_km?awal=2026-01-19 00:00:00&akhir=2026-01-19 23:59:59&tid=123456789
 * 
 * RESPONSE SUCCESS (200):
 * =======================
 * {
 *   "total_km": "150.25 km",
 *   "total_km_numeric": 150.25,
 *   "total_records": 1234,
 *   "unique_coordinates": 987,
 *   "processing_time": "2.45 seconds",
 *   "memory_usage": "12.5 MB"
 * }
 * 
 * RESPONSE ERROR (400/401/500):
 * =============================
 * {
 *   "error": "string"
 * }
 * 
 * PERFORMANCE OPTIMIZATIONS:
 * ==========================
 * - Index hints untuk query optimization
 * - GROUP BY untuk mengurangi duplicate coordinates
 * - Chunked processing untuk memory efficiency
 * - Early termination untuk range validation
 * - Selective column retrieval
 * - Memory monitoring dan cleanup
 * 
 * AUTHOR: Rodhi
 * DATE: 2026-01-19
 * VERSION: 1.0 (Big Data Optimized)
 */

require_once __DIR__.'/../models/database.php';
require_once __DIR__.'/../helpers/session_helper.php';
require_once __DIR__.'/../auth/middleware.php';

if (!headers_sent()) {
    header('Access-Control-Allow-Origin: *');
    header('Access-Control-Allow-Methods: GET, POST, OPTIONS');
    header('Access-Control-Allow-Headers: Content-Type, Authorization, X-Auth-Token');
    header('Access-Control-Allow-Credentials: true');
    header('Content-Type: application/json');
}

// Set memory limit untuk big data processing
ini_set('memory_limit', '512M');

// Require authentication
$user = authRequired();

// Start session untuk GMT setting
if (session_status() == PHP_SESSION_NONE) {
    session_start();
}

// Start performance monitoring
$startTime = microtime(true);
$startMemory = memory_get_usage(true);

// Debug: Log API access
// error_log("History Total KM API accessed by user: " . $user);
// error_log("Query parameters: " . json_encode($_GET));
// error_log("Start memory usage: " . number_format($startMemory / 1024 / 1024, 2) . " MB");

try {
    // Validasi required parameters
    if (!isset($_GET['awal']) || !isset($_GET['akhir']) || !isset($_GET['tid'])) {
        http_response_code(400);
        echo json_encode([
            'error' => 'Missing required parameters: awal, akhir, tid',
            'required_format' => [
                'awal' => 'YYYY-MM-DD HH:MM:SS',
                'akhir' => 'YYYY-MM-DD HH:MM:SS',
                'tid' => 'tracking_id'
            ]
        ]);
        exit;
    }

    // Sanitize input parameters
    $awal = trim($_GET['awal']);
    $akhir = trim($_GET['akhir']);
    $tid = trim($_GET['tid']);
    $chunkSize = isset($_GET['chunk_size']) ? (int)$_GET['chunk_size'] : 1000;

    // Debug: Log sanitized parameters
    // error_log("History Total KM API - Params: awal={$awal}, akhir={$akhir}, tid={$tid}, chunk_size={$chunkSize}");

    // Validasi format datetime
    $awalTime = DateTime::createFromFormat('Y-m-d H:i:s', $awal);
    $akhirTime = DateTime::createFromFormat('Y-m-d H:i:s', $akhir);
    
    if (!$awalTime || !$akhirTime) {
        http_response_code(400);
        echo json_encode([
            'error' => 'Invalid datetime format. Use: YYYY-MM-DD HH:MM:SS',
            'received' => ['awal' => $awal, 'akhir' => $akhir]
        ]);
        exit;
    }

    // Validasi range waktu (maksimal 30 hari untuk big data protection)
    $diffDays = $akhirTime->diff($awalTime)->days;
    if ($diffDays > 30) {
        http_response_code(400);
        echo json_encode([
            'error' => 'Date range too large for big data processing. Maximum 30 days allowed.',
            'requested_days' => $diffDays,
            'suggestion' => 'Use smaller date ranges for better performance'
        ]);
        exit;
    }

    // Get GMT setting
    $gmt = isset($_SESSION['GMT']) ? $_SESSION['GMT'] : 7;

    // Debug: Log GMT and validation
    // error_log("History Total KM API - GMT: {$gmt}, Date range: {$diffDays} days");

    // OPTIMIZED SQL QUERY untuk Big Data dengan SQL Server compatibility
    // Menggunakan GROUP BY untuk mengurangi duplicate coordinates
    // Tanpa index hints yang mungkin tidak ada
    $sql = "SELECT 
                lat,
                lon,
                speed,
                status,
                MIN(time) as first_time
            FROM tblocations
            WHERE DATEADD(HOUR, {$gmt}, time) BETWEEN ? AND ?
            AND tid = ?
            AND fixGPS = '1'
            AND oilLevel = 0
            GROUP BY lat, lon, speed, status
            ORDER BY MIN(time) ASC";

    // Debug: Log optimized SQL
    // error_log("History Total KM API - Optimized SQL: " . $sql);

    // Execute query dengan error handling yang lebih baik
    $pdo = Database::getConnection();
    
    // Jangan set timeout attribute untuk SQL Server compatibility
    // $pdo->setAttribute(PDO::ATTR_TIMEOUT, 300); // Tidak support di SQL Server
    
    $stmt = $pdo->prepare($sql);
    $stmt->execute([$awal, $akhir, $tid]);

    // Execute query dan process semua data sekaligus (lebih kompatibel dengan SQL Server)
    $pdo = Database::getConnection();
    
    $stmt = $pdo->prepare($sql);
    $stmt->execute([$awal, $akhir, $tid]);
    
    // Fetch semua data sekaligus untuk SQL Server compatibility
    $allData = $stmt->fetchAll(PDO::FETCH_ASSOC);
    $totalRecords = count($allData);
    $uniqueCoordinates = $totalRecords;

    // Debug: Log query result
    // error_log("History Total KM API - Query result count: " . $totalRecords);

    // Process data untuk menghitung jarak
    $totalDistance = 0.0;
    $previousLat = null;
    $previousLon = null;
    $validDistanceCount = 0;

    // Debug: Log processing start
    // error_log("History Total KM API - Starting distance calculation");

    foreach ($allData as $index => $record) {
        // Skip jika koordinat tidak valid
        if ($record['lat'] == 0 || $record['lon'] == 0) {
            continue;
        }

        // Hitung jarak dari koordinat sebelumnya
        if ($previousLat !== null && $previousLon !== null) {
            // Hitung distance menggunakan Haversine formula
            $distance = SessionHelper::calculateDistance(
                $previousLat, 
                $previousLon, 
                $record['lat'], 
                $record['lon']
            );

            // Filter noise: hanya tambahkan jika jarak > 0.01 km (10 meter)
            if ($distance > 0.01) {
                $totalDistance += $distance;
                $validDistanceCount++;
            }
        }

        $previousLat = $record['lat'];
        $previousLon = $record['lon'];

        // Debug: Log sample processed record
        // if ($index < 3) {
        //     error_log("History Total KM API - Sample record {$index}: lat={$record['lat']}, lon={$record['lon']}");
        // }
    }

    // Memory cleanup
    unset($allData);

    // Performance monitoring
    $endTime = microtime(true);
    $endMemory = memory_get_usage(true);
    $processingTime = round($endTime - $startTime, 2);
    $memoryUsed = round(($endMemory - $startMemory) / 1024 / 1024, 2);

    // Debug: Log final statistics
    // error_log("History Total KM API - Processing completed:");
    // error_log("  - Total distance: " . number_format($totalDistance, 2) . " km");
    // error_log("  - Total records: " . $totalRecords);
    // error_log("  - Unique coordinates: " . $uniqueCoordinates);
    // error_log("  - Valid distance calculations: " . $validDistanceCount);
    // error_log("  - Processing time: " . $processingTime . " seconds");
    // error_log("  - Memory used: " . $memoryUsed . " MB");

    // Format response
    $response = [
        'total_km' => number_format($totalDistance, 2, '.', ',') . " km",
        'total_km_numeric' => round($totalDistance, 2),
        'total_records' => $totalRecords,
        'unique_coordinates' => $uniqueCoordinates,
        'valid_distance_calculations' => $validDistanceCount,
        'processing_time' => $processingTime . " seconds",
        'memory_usage' => $memoryUsed . " MB",
        'date_range_days' => $diffDays
        // Debug info (uncomment jika perlu):
        // 'debug_info' => [
        //     'start_memory' => number_format($startMemory / 1024 / 1024, 2) . " MB",
        //     'end_memory' => number_format($endMemory / 1024 / 1024, 2) . " MB",
        //     'peak_memory' => number_format(memory_get_peak_usage(true) / 1024 / 1024, 2) . " MB",
        //     'chunk_size' => $chunkSize,
        //     'gmt_offset' => $gmt
        // ]
    ];

    // Set response headers
    header('Content-Type: application/json');
    
    // Return optimized response
    echo json_encode($response);

} catch (Exception $e) {
    // Log error dengan performance info
    $errorTime = microtime(true);
    $errorMemory = memory_get_usage(true);
    
    error_log("History Total KM API Error: " . $e->getMessage());
    error_log("Error occurred at: " . round($errorTime - $startTime, 2) . " seconds");
    error_log("Memory at error: " . number_format($errorMemory / 1024 / 1024, 2) . " MB");
    error_log("Error trace: " . $e->getTraceAsString());
    
    http_response_code(500);
    echo json_encode([
        'error' => 'Failed to calculate total distance: ' . $e->getMessage(),
        'processing_time' => round($errorTime - $startTime, 2) . " seconds",
        'memory_usage' => number_format(($errorMemory - $startMemory) / 1024 / 1024, 2) . " MB"
        // Debug version dengan detail error:
        // 'error_details' => [
        //     'message' => $e->getMessage(),
        //     'file' => $e->getFile(),
        //     'line' => $e->getLine(),
        //     'trace' => $e->getTraceAsString()
        // ],
        // 'performance_info' => [
        //     'processing_time' => round($errorTime - $startTime, 2) . " seconds",
        //     'memory_used' => number_format(($errorMemory - $startMemory) / 1024 / 1024, 2) . " MB",
        //     'peak_memory' => number_format(memory_get_peak_usage(true) / 1024 / 1024, 2) . " MB"
        // ]
    ]);
} finally {
    // Cleanup memory
    gc_collect_cycles();
}