package clipboard

import (
	"os/exec"
	"strings"
	"bytes"
)

type ShellClipboard struct {
	copyCommand string
	pasteCommand string
	testCommand string
}

var try = []ShellClipboard {
	ShellClipboard {"wl-copy", "wl-paste -n", "wl-copy -h"},
	ShellClipboard {
		"xclip -selection clipboard", "xclip -selection clipboard -o",
		"xclip -h",
	},
	ShellClipboard {"pbcopy", "pbpaste", "pbcopy -help"},
}

func command(command string) *exec.Cmd {
	args := strings.Split(command, " ")
	return exec.Command(args[0], args[1:]...)
}

func (c ShellClipboard) Test() bool {
	cmd := command(c.testCommand)
	return cmd.Run() == nil
}

func (c ShellClipboard) Copy(text string) {
	cmd := command(c.copyCommand)
	pipe, err := cmd.StdinPipe()
	cmd.Start()
	go func() {
		if err != nil {
			return
		}
		defer pipe.Close()

		buf := bytes.NewBuffer([]byte(text))
		buf.WriteTo(pipe)
	}()
}

func (c ShellClipboard) Paste() <-chan string {
	cmd := command(c.pasteCommand)
	pipe, err := cmd.StdoutPipe()
	cmd.Start()
	ch := make(chan string, 1)
	go func() {
		if err != nil {
			return
		}
		defer pipe.Close()

		buf := bytes.NewBuffer(nil)
		_, err = buf.ReadFrom(pipe)
		if err != nil {
			return
		}
		ch <- buf.String()
		close(ch)
	}()
	return ch
}

func DiscoverCommand() {
	for _, c := range try {
		if c.Test() {
			Set(c)
			break
		}
	}
}