piframe-go/cmd/ui/ui.go

package main

import (
	"io"
	"log"
	"os/exec"
	"time"

	"github.com/eiannone/keyboard"

	"github.com/gdamore/tcell"
	"github.com/rivo/tview"
)

const (
	CMD_FIM            = "/usr/local/bin/pf-fim.sh"
	SLIDESHOW_INTERVAL = 300 * time.Second
)

func main() {
	// fim placeholder so we can operate on it when a exit slideshow is received
	var fim *exec.Cmd = nil

	// Run slideshow
	fim = exec.Command(CMD_FIM)

	// Setup stdin for fim to control slideshow
	stdin, err := fim.StdinPipe()
	if err != nil {
		log.Fatalf("Error getting fim stdin : %s", err)
	}

	// Advance slideshow every interval as defined in const()
	ticker := time.NewTicker(SLIDESHOW_INTERVAL)
	stop_ticker := make(chan struct{})
	go func() {
		for {
			select {
			case <-ticker.C:
				_, err = io.WriteString(stdin, "n")
				if err != nil {
					log.Fatalf("Error advancing slides : %s", err)
				}
			case <-stop_ticker:
				ticker.Stop()
				stdin.Close()
				return
			}
		}
	}()

	// Start watching for key strokes and echo them back to stdout
	keysEvents, err := keyboard.GetKeys(10)
	if err != nil {
		panic(err)
	}
	defer func() {
		_ = keyboard.Close()
	}()

	// Goroutine for tracking which keys are pressed and controlling fim if appropriate
	go func() {
		for {
			event := <-keysEvents
			if event.Err != nil {
				panic(event.Err)
			}
			log.Printf("You pressed: key %X\n", event.Key)

			// Keys for fim event management (previous/next in particular)
			fimKey := ""
			if event.Key == keyboard.KeyArrowLeft || event.Key == keyboard.KeyArrowDown {
				fimKey = "p"
			}
			if event.Key == keyboard.KeyArrowRight || event.Key == keyboard.KeyArrowUp {
				fimKey = "n"
			}

			// Exit fim and move to the config UI
			if event.Key == keyboard.KeyEsc || event.Key == keyboard.KeyEnter || event.Key == keyboard.KeySpace {
				if fim != nil { // Just in case someone lays on exit key or similar during startup
					if err := fim.Process.Kill(); err != nil {
						log.Fatalf("failed to kill fim : %s", err)
					}
				}
				break
			}

			// Control fim if we received a valid key for next/previous slide
			if fimKey != "" {
				log.Printf("Sending key to fim : %s", fimKey)
				_, err = io.WriteString(stdin, fimKey)
				if err != nil {
					log.Fatalf("Error controlling fim : %s", err)
				}
				ticker.Reset(SLIDESHOW_INTERVAL)
			}
		}
	}()

	// Run fim
	if err := fim.Run(); err != nil {
		// Unwrap the error a bit so we can find out if a signal killed fim or something else
		// An exit code of -1 means the program didn't exit in time or was terminated by a signal (per the docs)
		if exitError, ok := err.(*exec.ExitError); ok && exitError.ExitCode() != -1 {
			log.Fatalf("Error running fim : %s", err)
		}
	}

	// Stop fim slideshow advancing go routine
	close(stop_ticker)

	// Run config UI when slideshow stops
	app := tview.NewApplication()
	frame := tview.NewFrame(tview.NewBox().SetBackgroundColor(tcell.ColorBlack)).
		SetBorders(2, 2, 2, 2, 4, 4).
		AddText("PiFrame", true, tview.AlignCenter, tcell.ColorWhite).
		AddText("Configuration Utility", true, tview.AlignCenter, tcell.ColorRed)
	if err := app.SetRoot(frame, true).EnableMouse(true).Run(); err != nil {
		log.Fatalf("Error running UI : %s", err)
	}
}