/*
   Copyright 2020 Docker, Inc.

   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.
*/

package framework

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

	"github.com/onsi/gomega"
	"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
}

// 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()
	logrus.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)
	}
}

//WaitFor waits for a condition to be true
func WaitFor(interval, duration time.Duration, abort <-chan error, condition func() bool) error {
	ticker := time.NewTicker(interval)
	defer ticker.Stop()
	timeout := make(chan int)
	go func() {
		time.Sleep(duration)
		close(timeout)
	}()
	for {
		select {
		case err := <-abort:
			return err
		case <-timeout:
			return fmt.Errorf("timeout after %v", duration)
		case <-ticker.C:
			if condition() {
				return nil
			}
		}
	}
}

// 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)

	logrus.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 {
			logrus.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:
		logrus.Debugf("%s %s timed-out", cmd.Path, strings.Join(cmd.Args[1:], " "))
		if err := terminateProcess(cmd); err != nil {
			return "", err
		}
		return stdout.String(), fmt.Errorf(
			"timed out waiting for command %v:\nCommand stdout:\n%v\nstderr:\n%v",
			cmd.Args, stdout.String(), stderr.String())
	}
	if stderr.String() != "" {
		logrus.Debugf("stderr: %s", stderr.String())
	}
	return stdout.String(), nil
}

func terminateProcess(cmd *exec.Cmd) error {
	if runtime.GOOS == "windows" {
		return cmd.Process.Kill()
	}
	return cmd.Process.Signal(syscall.SIGTERM)
}

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
}