const autocannon = require("autocannon");
const { performance } = require("perf_hooks");

class LoadTester {
  constructor() {
    this.baseUrl = process.env.TEST_URL || "http://localhost:3049";
    this.results = [];
  }

  async runPurchaseLoadTest(eventId = 1, options = {}) {
    const defaultOptions = {
      url: `${this.baseUrl}/buy/${eventId}`,
      connections: 5000,
      duration: 30,
      method: "POST",
      headers: {
        "Content-Type": "application/json",
      },
      body: JSON.stringify({}),
      ...options,
    };

    console.log(`\n Starting load test for Event ${eventId}`);
    console.log(`Connections: ${defaultOptions.connections}`);
    console.log(`Duration: ${defaultOptions.duration}s`);
    console.log(`Target: ${defaultOptions.url}\n`);

    const startTime = performance.now();

    try {
      const result = await autocannon(defaultOptions);
      const endTime = performance.now();

      const testResult = {
        eventId,
        timestamp: new Date().toISOString(),
        duration: endTime - startTime,
        ...result,
      };

      this.results.push(testResult);
      this.printResults(testResult);

      return testResult;
    } catch (error) {
      console.error("❌ Load test failed:", error);
      throw error;
    }
  }

  async runMultiEventLoadTest(eventIds = [1, 2, 3], options = {}) {
    console.log(
      `\n Running multi-event load test for events: ${eventIds.join(", ")}`
    );

    const promises = eventIds.map((eventId) =>
      this.runPurchaseLoadTest(eventId, {
        connections: Math.floor(
          (options.connections || 5000) / eventIds.length
        ),
        duration: options.duration || 30,
      })
    );

    try {
      const results = await Promise.all(promises);
      this.printSummary(results);
      return results;
    } catch (error) {
      console.error("❌ Multi-event load test failed:", error);
      throw error;
    }
  }

  async runHealthCheckTest(options = {}) {
    const defaultOptions = {
      url: `${this.baseUrl}/health`,
      connections: 100,
      duration: 10,
      ...options,
    };

    console.log("\n Running health check load test...");

    try {
      const result = await autocannon(defaultOptions);
      console.log(`✅ Health check test completed`);
      console.log(`RPS: ${result.requests.average}`);
      console.log(`Latency: ${result.latency.average}ms`);

      return result;
    } catch (error) {
      console.error("❌ Health check test failed:", error);
      throw error;
    }
  }

  async runMetricsTest(options = {}) {
    const defaultOptions = {
      url: `${this.baseUrl}/metrics`,
      connections: 50,
      duration: 10,
      ...options,
    };

    console.log("\nRunning metrics endpoint test...");

    try {
      const result = await autocannon(defaultOptions);
      console.log(`✅ Metrics test completed`);
      console.log(`RPS: ${result.requests.average}`);
      console.log(`Latency: ${result.latency.average}ms`);

      return result;
    } catch (error) {
      console.error("Metrics test failed:", error);
      throw error;
    }
  }

  printResults(result) {
    console.log("LOAD TEST RESULTS");
    console.log("═".repeat(50));
    console.log(`Event ID: ${result.eventId}`);
    console.log(`Duration: ${(result.duration / 1000).toFixed(2)}s`);
    console.log(`Total Requests: ${result.requests.total}`);
    console.log(`Requests/sec: ${result.requests.average.toFixed(2)}`);
    console.log(`Avg Latency: ${result.latency.average.toFixed(2)}ms`);
    console.log(`Max Latency: ${result.latency.max}ms`);
    console.log(
      `✅ Success Rate: ${(
        ((result.requests.total - result.non2xx) / result.requests.total) *
        100
      ).toFixed(2)}%`
    );
    console.log(`❌ Errors: ${result.non2xx}`);
    console.log(`Connections: ${result.connections}`);
    console.log(
      `Throughput: ${(result.throughput.average / 1024 / 1024).toFixed(2)} MB/s`
    );
    console.log("═".repeat(50));
  }

  printSummary(results) {
    console.log("\nMULTI-EVENT TEST SUMMARY");
    console.log("═".repeat(60));

    const totalRequests = results.reduce((sum, r) => sum + r.requests.total, 0);
    const avgRPS = results.reduce((sum, r) => sum + r.requests.average, 0);
    const avgLatency =
      results.reduce((sum, r) => sum + r.latency.average, 0) / results.length;
    const totalErrors = results.reduce((sum, r) => sum + r.non2xx, 0);

    console.log(`Events Tested: ${results.length}`);
    console.log(`Total Requests: ${totalRequests}`);
    console.log(`Combined RPS: ${avgRPS.toFixed(2)}`);
    console.log(`Avg Latency: ${avgLatency.toFixed(2)}ms`);
    console.log(
      `✅ Overall Success Rate: ${(
        ((totalRequests - totalErrors) / totalRequests) *
        100
      ).toFixed(2)}%`
    );
    console.log(`❌ Total Errors: ${totalErrors}`);
    console.log("═".repeat(60));

    // Individual event breakdown
    results.forEach((result, index) => {
      console.log(`\nEvent ${result.eventId}:`);
      console.log(`  RPS: ${result.requests.average.toFixed(2)}`);
      console.log(`  Latency: ${result.latency.average.toFixed(2)}ms`);
      console.log(
        `  ✅ Success: ${(
          ((result.requests.total - result.non2xx) / result.requests.total) *
          100
        ).toFixed(2)}%`
      );
    });
  }

  async runFullTestSuite() {
    console.log("STARTING FULL LOAD TEST SUITE");
    console.log("═".repeat(60));

    try {
      // 1. Health check test
      await this.runHealthCheckTest();

      // 2. Metrics test
      await this.runMetricsTest();

      // 3. Single event high-load test
      await this.runPurchaseLoadTest(1, {
        connections: 5000,
        duration: 30,
      });

      // 4. Multi-event test
      await this.runMultiEventLoadTest([1, 2, 3], {
        connections: 6000,
        duration: 30,
      });

      console.log("\n FULL TEST SUITE COMPLETED!");
      console.log(` Total tests run: ${this.results.length + 2}`);
    } catch (error) {
      console.error("❌ Test suite failed:", error);
      process.exit(1);
    }
  }

  getResults() {
    return this.results;
  }

  exportResults(filename = "load-test-results.json") {
    const fs = require("fs");
    const data = {
      timestamp: new Date().toISOString(),
      testSuite: "Ticket Microservice Load Test",
      results: this.results,
    };

    fs.writeFileSync(filename, JSON.stringify(data, null, 2));
    console.log(`📄 Results exported to: ${filename}`);
  }
}

// CLI execution
if (require.main === module) {
  const args = process.argv.slice(2);
  const tester = new LoadTester();

  async function main() {
    try {
      if (args.includes("--full")) {
        await tester.runFullTestSuite();
      } else if (args.includes("--event")) {
        const eventId = parseInt(args[args.indexOf("--event") + 1]) || 1;
        const connections =
          parseInt(args[args.indexOf("--connections") + 1]) || 5000;
        const duration = parseInt(args[args.indexOf("--duration") + 1]) || 30;

        await tester.runPurchaseLoadTest(eventId, { connections, duration });
      } else if (args.includes("--multi")) {
        const eventIds = args.includes("--events")
          ? args[args.indexOf("--events") + 1].split(",").map(Number)
          : [1, 2, 3];
        const connections =
          parseInt(args[args.indexOf("--connections") + 1]) || 6000;
        const duration = parseInt(args[args.indexOf("--duration") + 1]) || 30;

        await tester.runMultiEventLoadTest(eventIds, { connections, duration });
      } else {
        console.log("Ticket Microservice Load Tester");
        console.log("Usage:");
        console.log(
          "  node tests/load-test.js --full                    # Run full test suite"
        );
        console.log(
          "  node tests/load-test.js --event 1 --connections 5000 --duration 30"
        );
        console.log(
          "  node tests/load-test.js --multi --events 1,2,3 --connections 6000"
        );
        console.log("");
        console.log("Running default single event test...");
        await tester.runPurchaseLoadTest(1);
      }

      if (args.includes("--export")) {
        tester.exportResults();
      }
    } catch (error) {
      console.error("Test execution failed:", error);
      process.exit(1);
    }
  }

  main();
}

module.exports = LoadTester;