wtf/modules/textfile/widget.go

package textfile

import (
	"bytes"
	"fmt"
	"io/ioutil"
	"log"
	"os"
	"path/filepath"
	"time"

	"github.com/alecthomas/chroma/formatters"
	"github.com/alecthomas/chroma/lexers"
	"github.com/alecthomas/chroma/styles"
	"github.com/gdamore/tcell"
	"github.com/radovskyb/watcher"
	"github.com/rivo/tview"
	"github.com/wtfutil/wtf/wtf"
)

const HelpText = `
  Keyboard commands for Textfile:

    /: Show/hide this help window
    h: Previous text file
    l: Next text file
    o: Open the text file in the operating system

    arrow left:  Previous text file
    arrow right: Next text file
`

type Widget struct {
	wtf.HelpfulWidget
	wtf.MultiSourceWidget
	wtf.TextWidget

	app      *tview.Application
	settings *Settings
}

func NewWidget(app *tview.Application, pages *tview.Pages, settings *Settings) *Widget {
	widget := Widget{
		HelpfulWidget:     wtf.NewHelpfulWidget(app, pages, HelpText),
		MultiSourceWidget: wtf.NewMultiSourceWidget(settings.common.Name, "filePath", "filePaths"),
		TextWidget:        wtf.NewTextWidget(app, settings.common, true),

		app:      app,
		settings: settings,
	}

	// Don't use a timer for this widget, watch for filesystem changes instead
	widget.settings.common.RefreshInterval = 0

	widget.HelpfulWidget.SetView(widget.View)
	widget.LoadSources()
	widget.SetDisplayFunction(widget.display)
	widget.View.SetWrap(true)
	widget.View.SetWordWrap(true)
	widget.View.SetInputCapture(widget.keyboardIntercept)

	go widget.watchForFileChanges()

	return &widget
}

/* -------------------- Exported Functions -------------------- */

// Refresh is only called once on start-up. Its job is to display the
// text files that first time. After that, the watcher takes over
func (widget *Widget) Refresh() {
	widget.app.QueueUpdateDraw(func() {
		widget.display()
	})
}

/* -------------------- Unexported Functions -------------------- */

func (widget *Widget) display() {
	title := fmt.Sprintf("[green]%s[white]", widget.CurrentSource())
	title = widget.ContextualTitle(title)

	_, _, width, _ := widget.View.GetRect()
	text := widget.settings.common.SigilStr(len(widget.Sources), widget.Idx, width) + "\n"

	if widget.settings.format {
		text = text + widget.formattedText()
	} else {
		text = text + widget.plainText()
	}

	widget.View.SetTitle(title) // <- Writes to TextView's title
	widget.View.SetText(text)   // <- Writes to TextView's text
}

func (widget *Widget) fileName() string {
	return filepath.Base(widget.CurrentSource())
}

func (widget *Widget) formattedText() string {
	filePath, _ := wtf.ExpandHomeDir(widget.CurrentSource())

	file, err := os.Open(filePath)
	if err != nil {
		return err.Error()
	}

	lexer := lexers.Match(filePath)
	if lexer == nil {
		lexer = lexers.Fallback
	}

	style := styles.Get(widget.settings.formatStyle)
	if style == nil {
		style = styles.Fallback
	}
	formatter := formatters.Get("terminal256")
	if formatter == nil {
		formatter = formatters.Fallback
	}

	contents, _ := ioutil.ReadAll(file)
	iterator, _ := lexer.Tokenise(nil, string(contents))

	var buf bytes.Buffer
	formatter.Format(&buf, style, iterator)

	return tview.TranslateANSI(buf.String())
}

func (widget *Widget) plainText() string {
	filePath, _ := wtf.ExpandHomeDir(widget.CurrentSource())

	fmt.Println(filePath)

	text, err := ioutil.ReadFile(filePath)
	if err != nil {
		return err.Error()
	}
	return string(text)
}

func (widget *Widget) keyboardIntercept(event *tcell.EventKey) *tcell.EventKey {
	switch string(event.Rune()) {
	case "/":
		widget.ShowHelp()
		return nil
	case "h":
		widget.Prev()
		return nil
	case "l":
		widget.Next()
		return nil
	case "o":
		wtf.OpenFile(widget.CurrentSource())
		return nil
	}

	switch event.Key() {
	case tcell.KeyLeft:
		widget.Prev()
		return nil
	case tcell.KeyRight:
		widget.Next()
		return nil
	default:
		return event
	}

	return event
}

func (widget *Widget) watchForFileChanges() {
	watch := watcher.New()
	watch.FilterOps(watcher.Write)

	go func() {
		for {
			select {
			case <-watch.Event:
				widget.display()
			case err := <-watch.Error:
				log.Fatalln(err)
			case <-watch.Closed:
				return
			}
		}
	}()

	// Watch each textfile for changes
	for _, source := range widget.Sources {
		fullPath, err := wtf.ExpandHomeDir(source)
		if err == nil {
			if err := watch.Add(fullPath); err != nil {
				log.Fatalln(err)
			}
		}
	}

	// Start the watching process - it'll check for changes every 100ms.
	if err := watch.Start(time.Millisecond * 100); err != nil {
		log.Fatalln(err)
	}
}