package framework

import (
	"bytes"
	"fmt"
	"io"
	"os/exec"
	"runtime"
	"strings"
	"time"

	"github.com/onsi/gomega"
	log "github.com/sirupsen/logrus"
)

func (b CmdContext) makeCmd() *exec.Cmd {
	return exec.Command(b.command, b.args...)
}

// CmdContext is used to build, customize and execute a command.
// Add more functions to customize the context as needed.
type CmdContext struct {
	command string
	args    []string
	envs    []string
	dir     string
	stdin   io.Reader
	timeout <-chan time.Time
	retries RetriesContext
}

// RetriesContext is used to tweak retry loop.
type RetriesContext struct {
	count    int
	interval time.Duration
}

// NewCommand creates a command context.
func NewCommand(command string, args ...string) *CmdContext {
	return &CmdContext{
		command: command,
		args:    args,
		retries: RetriesContext{interval: time.Second},
	}
}

func dockerExecutable() string {
	if runtime.GOOS == "windows" {
		return "./bin/windows/docker.exe"
	}
	return "./bin/docker"
}

// NewDockerCommand creates a docker builder.
func NewDockerCommand(args ...string) *CmdContext {
	return NewCommand(dockerExecutable(), args...)
}

// WithinDirectory tells Docker the cwd.
func (b *CmdContext) WithinDirectory(path string) *CmdContext {
	b.dir = path
	return b
}

// WithEnvs set envs in context.
func (b *CmdContext) WithEnvs(envs []string) *CmdContext {
	b.envs = envs
	return b
}

// WithTimeout controls maximum duration.
func (b *CmdContext) WithTimeout(t <-chan time.Time) *CmdContext {
	b.timeout = t
	return b
}

// WithRetries sets how many times to retry the command before issuing an error
func (b *CmdContext) WithRetries(count int) *CmdContext {
	b.retries.count = count
	return b
}

// Every interval between 2 retries
func (b *CmdContext) Every(interval time.Duration) *CmdContext {
	b.retries.interval = interval
	return b
}

// WithStdinData feeds via stdin.
func (b CmdContext) WithStdinData(data string) *CmdContext {
	b.stdin = strings.NewReader(data)
	return &b
}

// WithStdinReader feeds via stdin.
func (b CmdContext) WithStdinReader(reader io.Reader) *CmdContext {
	b.stdin = reader
	return &b
}

// ExecOrDie runs a docker command.
func (b CmdContext) ExecOrDie() string {
	str, err := b.Exec()
	log.Debugf("stdout: %s", str)
	gomega.Expect(err).NotTo(gomega.HaveOccurred())
	return str
}

// Exec runs a docker command.
func (b CmdContext) Exec() (string, error) {
	retry := b.retries.count
	for ; ; retry-- {
		cmd := b.makeCmd()
		cmd.Dir = b.dir
		cmd.Stdin = b.stdin
		if b.envs != nil {
			cmd.Env = b.envs
		}
		stdout, err := Execute(cmd, b.timeout)
		if err == nil || retry < 1 {
			return stdout, err
		}
		time.Sleep(b.retries.interval)
	}
}

// Execute executes a command.
// The command cannot be re-used afterwards.
func Execute(cmd *exec.Cmd, timeout <-chan time.Time) (string, error) {
	var stdout, stderr bytes.Buffer
	cmd.Stdout = mergeWriter(cmd.Stdout, &stdout)
	cmd.Stderr = mergeWriter(cmd.Stderr, &stderr)

	log.Infof("Execute '%s %s'", cmd.Path, strings.Join(cmd.Args[1:], " ")) // skip arg[0] as it is printed separately
	if err := cmd.Start(); err != nil {
		return "", fmt.Errorf("error starting %v:\nCommand stdout:\n%v\nstderr:\n%v\nerror:\n%v", cmd, stdout.String(), stderr.String(), err)
	}
	errCh := make(chan error, 1)
	go func() {
		errCh <- cmd.Wait()
	}()
	select {
	case err := <-errCh:
		if err != nil {
			log.Debugf("%s %s failed: %v", cmd.Path, strings.Join(cmd.Args[1:], " "), err)
			return stderr.String(), fmt.Errorf("error running %v:\nCommand stdout:\n%v\nstderr:\n%v\nerror:\n%v", cmd, stdout.String(), stderr.String(), err)
		}
	case <-timeout:
		log.Debugf("%s %s timed-out", cmd.Path, strings.Join(cmd.Args[1:], " "))
		if err := cmd.Process.Kill(); err != nil {
			return "", err
		}
		return "", fmt.Errorf(
			"timed out waiting for command %v:\nCommand stdout:\n%v\nstderr:\n%v",
			cmd.Args, stdout.String(), stderr.String())
	}
	if stderr.String() != "" {
		log.Debugf("stderr: %s", stderr.String())
	}
	return stdout.String(), nil
}

func mergeWriter(other io.Writer, buf io.Writer) io.Writer {
	if other != nil {
		return io.MultiWriter(other, buf)
	}
	return buf
}

// Powershell runs a powershell command.
func Powershell(input string) (string, error) {
	output, err := Execute(exec.Command("powershell", "-NoProfile", "-NonInteractive", "-ExecutionPolicy", "Unrestricted", "-Command", input), nil)
	if err != nil {
		return "", fmt.Errorf("fail to execute %s: %s", input, err)
	}
	return strings.TrimSpace(output), nil
}