package main

import (
	"encoding/json"
	"log"
	"os"
	"strings"
	"syscall"

	"github.com/BurntSushi/xgb"
	"github.com/BurntSushi/xgb/xproto"
)

const stateEnv = "WM_STATE"

type savedClient struct {
	Win      xproto.Window
	Floating bool
	Tags     BitMask
}

type savedState struct {
	Clients    []savedClient
	GlobalTags BitMask
	Layout     string
	Focused    xproto.Window
}

func restart() {
	st := savedState{GlobalTags: GlobalTags, Layout: layout, Focused: focused}
	for _, c := range clientList {
		st.Clients = append(st.Clients, savedClient{c.Win, c.Floating, c.Tags})
	}
	data, err := json.Marshal(st)
	if err != nil {
		log.Println("restart: failed to save state:", err)
		return
	}

	exe, err := os.Executable()
	if err != nil {
		exe = os.Args[0]
	}
	exe = strings.TrimSuffix(exe, " (deleted)")

	env := append(os.Environ(), stateEnv+"="+string(data))
	log.Println("restarting", exe)
	if err := syscall.Exec(exe, os.Args, env); err != nil {
		log.Println("restart: exec failed:", err)
	}
}

func restoreState(conn *xgb.Conn) bool {
	raw, ok := os.LookupEnv(stateEnv)
	if !ok {
		return false
	}
	os.Unsetenv(stateEnv)

	var st savedState
	if err := json.Unmarshal([]byte(raw), &st); err != nil {
		log.Println("restore: bad state:", err)
		return false
	}

	GlobalTags = st.GlobalTags
	if st.Layout != "" {
		layout = st.Layout
	}

	for _, sc := range st.Clients {
		geom, err := xproto.GetGeometry(conn, xproto.Drawable(sc.Win)).Reply()
		if err != nil {
			continue
		}
		client := &Client{
			Win:      sc.Win,
			X:        geom.X,
			Y:        geom.Y,
			Width:    geom.Width,
			Height:   geom.Height,
			Floating: sc.Floating,
			Tags:     sc.Tags,
		}
		clients[sc.Win] = client
		clientList = append(clientList, client)

		xproto.ChangeWindowAttributes(conn, sc.Win,
			xproto.CwEventMask,
			[]uint32{
				xproto.EventMaskEnterWindow |
					xproto.EventMaskFocusChange |
					xproto.EventMaskPropertyChange,
			})
	}

	if _, ok := clients[st.Focused]; ok {
		focused = st.Focused
	}

	for _, c := range clients {
		xproto.UnmapWindow(conn, c.Win)
	}
	updateWindows(conn)
	drawBar(conn)
	return true
}