//go:build linux

package main

import (
	"errors"
	"fmt"
	"os"
	"sync"
)

type dialogToolType int

const (
	toolNone dialogToolType = iota
	toolNotifySend
	toolKdialogPassive
	toolZenity
	toolKdialogError
	toolXmessage
)

var (
	dialogTools     map[string]bool
	dialogToolOnce  sync.Once
	dialogToolNames = []string{"notify-send", "kdialog", "zenity", "xmessage"}
)

func init() {
	dialogToolOnce.Do(func() { detectDialogTools(defaultCommandRunner{}) })
}

func platformStartupChannels(runner commandRunner) []promptChannel {
	return []promptChannel{
		linuxCommandChannel("notify-send", toolNotifySend, runner, linuxHasGraphicalSessionAndDBus, func(req promptRequest) []string {
			return []string{"-u", "critical", "-a", appName, "-i", "nex", req.title, req.message}
		}),
		linuxCommandChannel("kdialog", toolKdialogPassive, runner, linuxHasGraphicalSession, func(req promptRequest) []string {
			return []string{"--title", req.title, "--passivepopup", req.message, "10"}
		}),
		linuxCommandChannel("zenity", toolZenity, runner, linuxHasGraphicalSession, func(req promptRequest) []string {
			return []string{"--error", fmt.Sprintf("--title=%s", req.title), fmt.Sprintf("--text=%s", req.message)}
		}),
		linuxCommandChannel("kdialog", toolKdialogError, runner, linuxHasGraphicalSession, func(req promptRequest) []string {
			return []string{"--title", req.title, "--error", req.message}
		}),
		linuxCommandChannel("xmessage", toolXmessage, runner, linuxHasX11Display, func(req promptRequest) []string {
			return []string{"-center", "-buttons", "OK:0", "-default", "OK", fmt.Sprintf("%s: %s", req.title, req.message)}
		}),
	}
}

func detectDialogTools(runner commandRunner) {
	dialogTools = make(map[string]bool, len(dialogToolNames))
	for _, name := range dialogToolNames {
		_, err := runner.LookPath(name)
		dialogTools[name] = err == nil
	}
}

func linuxCommandChannel(name string, typ dialogToolType, runner commandRunner, environmentOK func() error, args func(promptRequest) []string) promptChannel {
	return promptChannel{
		name: fmt.Sprintf("linux-%s-%d", name, typ),
		available: func() error {
			if err := linuxCommandAvailable(runner, name); err != nil {
				return err
			}
			return environmentOK()
		},
		run: func(req promptRequest) error {
			return runner.Run(promptCommandTimeout, nil, name, args(req)...)
		},
	}
}

func linuxCommandAvailable(runner commandRunner, name string) error {
	if _, ok := runner.(defaultCommandRunner); ok {
		dialogToolOnce.Do(func() { detectDialogTools(runner) })
		if dialogTools[name] {
			return nil
		}
		return fmt.Errorf("%s 不可用", name)
	}

	_, err := runner.LookPath(name)
	return err
}

func linuxHasGraphicalSession() error {
	if os.Getenv("DISPLAY") == "" && os.Getenv("WAYLAND_DISPLAY") == "" {
		return errors.New("缺少图形会话")
	}
	return nil
}

func linuxHasGraphicalSessionAndDBus() error {
	if err := linuxHasGraphicalSession(); err != nil {
		return err
	}
	if os.Getenv("DBUS_SESSION_BUS_ADDRESS") == "" {
		return errors.New("缺少 DBus session bus")
	}
	return nil
}

func linuxHasX11Display() error {
	if os.Getenv("DISPLAY") == "" {
		return errors.New("缺少 X11 DISPLAY")
	}
	return nil
}