// Backend/tests/k6/login-load-test.js
// Load test สำหรับ Login API โดยใช้ test credentials ที่สร้างไว้
import http from 'k6/http';
import { check, sleep } from 'k6';
import { Rate, Trend, Counter } from 'k6/metrics';
import { SharedArray } from 'k6/data';

// Load test credentials
const students = new SharedArray('students', function () {
    return JSON.parse(open('./test-credentials.json')).students;
});

// Custom metrics
const errorRate = new Rate('errors');
const loginDuration = new Trend('login_duration');
const successfulLogins = new Counter('successful_logins');
const failedLogins = new Counter('failed_logins');

// Test configuration
export const options = {
    // Ramp-up pattern
    stages: [
        { duration: '10s', target: 10 },  // Ramp up to 10 users
        { duration: '30s', target: 10 },  // Stay at 10 users
        { duration: '10s', target: 25 },  // Ramp up to 25 users
        { duration: '30s', target: 25 },  // Stay at 25 users
        { duration: '10s', target: 50 },  // Ramp up to 50 users
        { duration: '30s', target: 50 },  // Stay at 50 users
        { duration: '10s', target: 0 },   // Ramp down
    ],
    thresholds: {
        http_req_duration: ['p(95)<2000'],  // 95% of requests < 2s
        errors: ['rate<0.1'],               // Error rate < 10%
        login_duration: ['p(95)<2000'],     // 95% pof logins < 2s
    },
};

const BASE_URL = __ENV.BASE_URL || 'http://192.168.1.137:4000';

export default function () {
    // เลือก student แบบ random จาก credentials
    const student = students[Math.floor(Math.random() * students.length)];

    const payload = JSON.stringify({
        email: student.email,
        password: student.password,
    });

    const params = {
        headers: {
            'Content-Type': 'application/json',
        },
    };

    // Test Login
    const startTime = new Date();
    const res = http.post(`${BASE_URL}/api/auth/login`, payload, params);
    const duration = new Date() - startTime;

    // Record metrics
    loginDuration.add(duration);
    
    const isSuccess = res.status === 200;
    errorRate.add(!isSuccess);

    if (isSuccess) {
        successfulLogins.add(1);
    } else {
        failedLogins.add(1);
        console.log(`Login failed for ${student.email}: ${res.status} - ${res.body}`);
    }

    // Assertions
    check(res, {
        'status is 200': (r) => r.status === 200,
        'has access token': (r) => {
            try {
                const body = JSON.parse(r.body);
                return body.data && body.data.accessToken;
            } catch (e) {
                return false;
            }
        },
        'has refresh token': (r) => {
            try {
                const body = JSON.parse(r.body);
                return body.data && body.data.refreshToken;
            } catch (e) {
                return false;
            }
        },
        'response time < 2s': (r) => r.timings.duration < 2000,
    });

    // Think time between requests (simulate real user behavior)
    sleep(Math.random() * 2 + 1); // 1-3 seconds
}

// Summary handler
export function handleSummary(data) {
    return {
        'stdout': textSummary(data, { indent: ' ', enableColors: true }),
        'login-load-test-summary.json': JSON.stringify(data, null, 2),
    };
}

function textSummary(data, options) {
    const metrics = data.metrics;
    
    let summary = '\n========== LOGIN LOAD TEST SUMMARY ==========\n\n';
    
    // Request stats
    if (metrics.http_reqs) {
        summary += `Total Requests: ${metrics.http_reqs.values.count}\n`;
    }
    if (metrics.successful_logins) {
        summary += `Successful Logins: ${metrics.successful_logins.values.count}\n`;
    }
    if (metrics.failed_logins) {
        summary += `Failed Logins: ${metrics.failed_logins.values.count}\n`;
    }
    
    // Duration stats
    if (metrics.http_req_duration) {
        summary += `\nResponse Time:\n`;
        summary += `  - Avg: ${metrics.http_req_duration.values.avg.toFixed(2)}ms\n`;
        summary += `  - Min: ${metrics.http_req_duration.values.min.toFixed(2)}ms\n`;
        summary += `  - Max: ${metrics.http_req_duration.values.max.toFixed(2)}ms\n`;
        summary += `  - p(95): ${metrics.http_req_duration.values['p(95)'].toFixed(2)}ms\n`;
    }
    
    // Error rate
    if (metrics.errors) {
        summary += `\nError Rate: ${(metrics.errors.values.rate * 100).toFixed(2)}%\n`;
    }
    
    summary += '\n==============================================\n';
    
    return summary;
}