package cmdext

import (
	"bufio"
	"os/exec"
	"time"
)

type CommandResult struct {
	StdOut          string
	StdErr          string
	StdCombined     string
	ExitCode        int
	CommandTimedOut bool
}

func run(opt CommandRunner) (CommandResult, error) {
	cmd := exec.Command(opt.program, opt.args...)
	cmd.Env = append(cmd.Env, opt.env)

	stdoutPipe, err := cmd.StdoutPipe()
	if err != nil {
		return CommandResult{}, err
	}

	stderrPipe, err := cmd.StderrPipe()
	if err != nil {
		return CommandResult{}, err
	}

	err = cmd.Start()
	if err != nil {
		return CommandResult{}, err
	}

	errch := make(chan error, 1)
	go func() { errch <- cmd.Wait() }()

	combch := make(chan string, 32)
	stopCombch := make(chan bool)

	stdout := ""
	go func() {
		scanner := bufio.NewScanner(stdoutPipe)
		for scanner.Scan() {
			txt := scanner.Text()
			stdout += txt
			combch <- txt
		}
	}()

	stderr := ""
	go func() {
		scanner := bufio.NewScanner(stderrPipe)
		for scanner.Scan() {
			txt := scanner.Text()
			stderr += txt
			combch <- txt
		}
	}()

	defer func() {
		stopCombch <- true
	}()

	stdcombined := ""
	go func() {
		for {
			select {
			case txt := <-combch:
				stdcombined += txt
			case <-stopCombch:
				return
			}
		}
	}()

	var timeoutChan <-chan time.Time = make(chan time.Time, 1)
	if opt.timeout != nil {
		timeoutChan = time.After(*opt.timeout)
	}

	select {

	case <-timeoutChan:
		_ = cmd.Process.Kill()
		return CommandResult{
			StdOut:          stdout,
			StdErr:          stderr,
			StdCombined:     stdcombined,
			ExitCode:        -1,
			CommandTimedOut: true,
		}, nil

	case err := <-errch:
		if exiterr, ok := err.(*exec.ExitError); ok {
			return CommandResult{
				StdOut:          stdout,
				StdErr:          stderr,
				StdCombined:     stdcombined,
				ExitCode:        exiterr.ExitCode(),
				CommandTimedOut: false,
			}, nil
		} else if err != nil {
			return CommandResult{}, err
		} else {
			return CommandResult{
				StdOut:          stdout,
				StdErr:          stderr,
				StdCombined:     stdcombined,
				ExitCode:        0,
				CommandTimedOut: false,
			}, nil
		}
	}
}