package main

import (
	"bytes"
	"fmt"
	"os/exec"
	"runtime"
)

type textClipboard interface {
	ReadText() (string, error)
	WriteText(string) error
}

type systemTextClipboard struct{}

func (systemTextClipboard) ReadText() (string, error) {
	command, args, err := clipboardCommand(false)
	if err != nil {
		return "", err
	}
	output, err := exec.Command(command, args...).Output()
	if err != nil {
		return "", fmt.Errorf("read system clipboard: %w", err)
	}
	return string(output), nil
}

func (systemTextClipboard) WriteText(value string) error {
	command, args, err := clipboardCommand(true)
	if err != nil {
		return err
	}
	process := exec.Command(command, args...)
	process.Stdin = bytes.NewBufferString(value)
	if output, err := process.CombinedOutput(); err != nil {
		if len(output) > 0 {
			return fmt.Errorf("write system clipboard: %w: %s", err, bytes.TrimSpace(output))
		}
		return fmt.Errorf("write system clipboard: %w", err)
	}
	return nil
}

func clipboardCommand(write bool) (string, []string, error) {
	switch runtime.GOOS {
	case "darwin":
		if write {
			return "pbcopy", nil, nil
		}
		return "pbpaste", nil, nil
	case "windows":
		script := "Get-Clipboard -Raw"
		if write {
			script = "$input | Set-Clipboard"
		}
		return "powershell.exe", []string{"-NoProfile", "-NonInteractive", "-Command", script}, nil
	default:
		type candidate struct {
			command string
			write   []string
			read    []string
		}
		candidates := []candidate{
			{command: "wl-copy", read: []string{"-n"}, write: nil},
			{command: "xclip", read: []string{"-selection", "clipboard", "-o"}, write: []string{"-selection", "clipboard", "-i"}},
			{command: "xsel", read: []string{"--clipboard", "--output"}, write: []string{"--clipboard", "--input"}},
		}
		for _, candidate := range candidates {
			command := candidate.command
			args := candidate.read
			if candidate.command == "wl-copy" && !write {
				command = "wl-paste"
			}
			if write {
				args = candidate.write
			}
			if _, err := exec.LookPath(command); err == nil {
				return command, args, nil
			}
		}
		return "", nil, fmt.Errorf("system clipboard unavailable: install wl-clipboard, xclip, or xsel")
	}
}