library/cmd/manage/main.go

package main

import (
	"fmt"
	"log"

	"git.yetaga.in/alazyreader/library/config"
	"github.com/gdamore/tcell"
	"github.com/kelseyhightower/envconfig"
)

func main() {
	var c config.Config
	err := envconfig.Process("library", &c)
	if err != nil {
		log.Fatalln(err)
	}

	screen, err := tcell.NewScreen()
	if err != nil {
		log.Fatalln(err)
	}
	err = screen.Init()
	if err != nil {
		log.Fatalln(err)
	}
	screen.Clear()
	w, h := screen.Size()
	l := &list{
		w: w - 4, h: h - 4,
		x: 2, y: 1,
		selected:  2,
		listItems: []string{"foo", "bar", "baz"},
	}
	b := &box{
		w: w, h: h,
		x: 0, y: 0,
		title:     "library",
		menuItems: []string{"(e)dit", "(q)uit"},
		contents:  l,
	}
	for {
		e := screen.PollEvent()
		switch v := e.(type) {
		case *tcell.EventError:
			screen.Clear()
			screen.Beep()
			b.draw(screen)
			screen.SetContent(1, 1, 'E', nil, tcell.StyleDefault)
		case *tcell.EventKey:
			screen.Clear()
			if v.Key() == tcell.KeyUp && l.selected > 0 {
				l.selected = l.selected - 1
			}
			if v.Key() == tcell.KeyDown && l.selected < len(l.listItems)-1 {
				l.selected = l.selected + 1
			}
			if v.Rune() == 'q' {
				screen.Fini()
				fmt.Printf("Thank you for playing Wing Commander!\n\n")
				return
			}
			b.draw(screen)
		case *tcell.EventResize:
			screen.Clear()
			w, h := screen.Size()
			b.w, b.h = w, h
			b.draw(screen)
		case *tcell.EventInterrupt:
		case *tcell.EventMouse:
		case *tcell.EventTime:
		default:
		}
		screen.Sync()
	}
}

type drawable interface {
	draw(tcell.Screen)
}

type box struct {
	x, y      int
	h, w      int
	title     string
	menuItems []string
	contents  drawable
}

func (b *box) draw(s tcell.Screen) {
	for m := 1; m < b.w-1; m++ {
		s.SetContent(m, b.y, tcell.RuneHLine, nil, tcell.StyleDefault)
		s.SetContent(m, b.h-1, tcell.RuneHLine, nil, tcell.StyleDefault)
	}
	for m := 1; m < b.h-1; m++ {
		s.SetContent(b.x, m, tcell.RuneVLine, nil, tcell.StyleDefault)
		s.SetContent(b.w-1, m, tcell.RuneVLine, nil, tcell.StyleDefault)
	}
	s.SetContent(b.x, b.y, tcell.RuneULCorner, nil, tcell.StyleDefault)
	s.SetContent(b.w-1, b.y, tcell.RuneURCorner, nil, tcell.StyleDefault)
	s.SetContent(b.x, b.h-1, tcell.RuneLLCorner, nil, tcell.StyleDefault)
	s.SetContent(b.w-1, b.h-1, tcell.RuneLRCorner, nil, tcell.StyleDefault)

	if b.title != "" {
		t := b.x + 2
		s.SetContent(t, b.y, ' ', nil, tcell.StyleDefault)
		t++
		for _, r := range b.title {
			s.SetContent(t, b.y, r, nil, tcell.StyleDefault)
			t++
		}
		s.SetContent(t, b.y, ' ', nil, tcell.StyleDefault)
	}
	if len(b.menuItems) != 0 {
		t := b.x + 2
		s.SetContent(t, b.h-1, ' ', nil, tcell.StyleDefault)
		t++
		for i := range b.menuItems {
			for _, r := range b.menuItems[i] {
				s.SetContent(t, b.h-1, r, nil, tcell.StyleDefault)
				t++
			}
			s.SetContent(t, b.h-1, ' ', nil, tcell.StyleDefault)
			t++
		}
	}
	if b.contents != nil {
		b.contents.draw(s)
	}
}

type list struct {
	x, y      int
	h, w      int
	selected  int
	listItems []string
}

func (l *list) draw(s tcell.Screen) {
	for i := range l.listItems {
		for j, r := range l.listItems[i] {
			s.SetContent(l.x+j, l.y+i, r, nil, tcell.StyleDefault)
		}
		if i == l.selected {
			s.SetContent(l.x+len(l.listItems[i])+1, l.y+i, '<', nil, tcell.StyleDefault)
		}
	}
}