package main

import (
	"bufio"
	"bytes"
	"flag"
	"fmt"
	"io"
	"os"
	"os/exec"
	"strings"
	"time"
)

const (
	// PackageSummary is the format string for the result summary of packages.
	// [ok|FAIL]    github.com/metacpp/parallel-go-test    100.00s
	PackageSummary = "%s    %s    %.3fs\n"
)

func usage() string {
	return `Usage:
  parallel-go-test -f <binary> [-p n] [-t timeout]

  Test names must be listed one per line on stdin.
  Timeout is measured in seconds.
`
}

func main() {
	binaryPath := flag.String("f", "", "file path of test package")
	parallelism := flag.Int("p", 1, "number of tests to execute in parallel")
	timeout := flag.String("t", "3600s", "Panit test binary after specific duration(seconds).")
	flag.Parse()

	if binaryPath == nil || *binaryPath == "" {
		fmt.Fprint(os.Stderr, usage())
		os.Exit(1)
	}

	if _, err := os.Stat(*binaryPath); err != nil {
		fmt.Fprintf(os.Stderr, "Not valid file path: %s\n", *binaryPath)
		os.Exit(1)
	}

	testNames := make([]string, 0, 0)
	stdInReader := bufio.NewReader(os.Stdin)

	for {
		line, err := stdInReader.ReadString('\n')
		if err != nil {
			if err == io.EOF {
				if strings.TrimSpace(line) != "" {
					testNames = append(testNames, line)
				}
				break
			}
			fmt.Fprintf(os.Stderr, "error reading stdin: %s", err)
			os.Exit(1)
		}

		if strings.TrimSpace(line) != "" {
			testNames = append(testNames, line)
		}
	}

	testQueue := make(chan string)
	messages := make(chan string)
	completed := make(chan struct{})

	startTime := time.Now()
	for i := 0; i < *parallelism; i++ {
		go runWorker(testQueue, messages, completed, *binaryPath, *timeout)
	}

	go func() {
		for _, testName := range testNames {
			testQueue <- strings.TrimSpace(testName)
		}
	}()

	failsCount := 0
	resultsCount := 0
	for {
		select {
		case message := <-messages:
			if strings.Contains(message, "--- FAIL") {
				failsCount++
			}
			fmt.Printf("%s", message)
		case <-completed:
			resultsCount++
		}

		if resultsCount == len(testNames) {
			break
		}
	}

	endTime := time.Now()
	elapsed := endTime.Sub(startTime)

	status := "ok"
	if failsCount > 0 {
		status = "FAIL"
	}

	fmt.Printf(PackageSummary, status, *binaryPath, elapsed.Seconds())

}

func runWorker(inputQueue <-chan string, messages chan<- string,
	done chan<- struct{}, binaryName string, timeout string) {
	for {
		select {
		case testName := <-inputQueue:
			messages <- runTest(testName, binaryName, timeout)
			done <- struct{}{}
		}
	}
}

func runTest(testName string, binaryPath string, timeout string) string {
	var stdResult bytes.Buffer
	cmd := exec.Command(binaryPath,
		"-test.v",
		"-test.timeout", timeout,
		"-test.run", fmt.Sprintf("^%s$", testName))
	cmd.Stdout = &stdResult
	cmd.Stderr = &stdResult

	if err := cmd.Run(); err != nil {
		stdResult.WriteString(fmt.Sprintf("%s\n", err.Error()))
	}

	return stdResult.String()
}