package gui

import (
	"fmt"
	"io/fs"
	"net"
	"net/http"
	"runtime"
	"strings"
	"sync"

	"github.com/zserge/lorca"
)

// service 图形用户界面服务.
type service struct {
	listener net.Listener
	htmls    map[string]string
	binds    map[string]interface{}
	handler  http.Handler
	wg       sync.WaitGroup
}

// NewGui 新建图形用户界面服务.
func NewGui() GUI {
	l, err := net.Listen("tcp", "127.0.0.1:0")
	if err != nil {
		panic(err)
	}

	s := &service{
		htmls:    make(map[string]string),
		binds:    make(map[string]interface{}),
		listener: l,
		wg:       sync.WaitGroup{},
	}
	// nolint: errcheck
	go http.Serve(s.listener, s)

	return s
}

// Bind 事件绑定.
func (p *service) Bind(name string, f interface{}) {
	p.binds[name] = f
}

// Close 关闭.
func (p *service) Close() error {
	if p.listener != nil {
		return p.listener.Close()
	}

	return nil
}

// FS 设置文件系统.
func (p *service) FS(dir string, fsys fs.FS) {
	if dir != "" {
		fsys, _ = fs.Sub(fsys, dir)
	}

	p.handler = http.FileServer(http.FS(fsys))
}

// Handler 设置回调.
func (p *service) Handler(handler http.Handler) {
	p.handler = handler
}

// HTML 设置HTML页面.
func (p *service) HTML(url, html string) {
	p.htmls[url] = html
}

func getArgs() []string {
	args := []string{}

	if runtime.GOOS == "linux" {
		args = append(args, "--class=Lorca")
	}

	return args
}

// Open 打开窗口，返回UI对象.
func (p *service) Open(url string, width, height int) (lorca.UI, error) {
	if strings.HasPrefix(url, "/") {
		url = fmt.Sprintf("http://%s%s", p.listener.Addr(), url)
	}

	ui, err := lorca.New(url, "", width, height, getArgs()...)
	if err != nil {
		return ui, err
	}

	if len(p.binds) > 0 {
		for name, f := range p.binds {
			_ = ui.Bind(name, f)
		}

		err = ui.Load(url)
		if err != nil {
			return ui, err
		}
	}

	p.wg.Add(1)

	go func() {
		<-ui.Done()
		p.wg.Done()
	}()

	return ui, nil
}

// Run 运行.
func (p *service) Run() {
	p.wg.Wait()
}

// ServeHTTP web服务.
func (p *service) ServeHTTP(w http.ResponseWriter, req *http.Request) {
	if html, has := p.htmls[req.URL.Path]; has {
		fmt.Fprint(w, html)

		return
	}

	if p.handler != nil {
		p.handler.ServeHTTP(w, req)

		return
	}

	w.WriteHeader(http.StatusNotFound)
	fmt.Fprintf(w, "no such page: %s\n", req.URL)
}