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214 lines
4.1 KiB
214 lines
4.1 KiB
package main
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import (
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"fmt"
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"io/ioutil"
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"os"
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"path"
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"github.com/MichaelMure/go-term-markdown"
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"github.com/awesome-gocui/gocui"
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"github.com/mattn/go-isatty"
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"github.com/pkg/errors"
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)
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const padding = 4
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func main() {
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if len(os.Args) >= 2 && (os.Args[1] == "version" || os.Args[1] == "--version") {
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printVersion()
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return
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}
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var content []byte
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switch len(os.Args) {
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case 1:
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if isatty.IsTerminal(os.Stdin.Fd()) {
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exitError(fmt.Errorf("usage: %s <file.md>", os.Args[0]))
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}
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data, err := ioutil.ReadAll(os.Stdin)
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if err != nil {
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exitError(errors.Wrap(err, "error while reading STDIN"))
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}
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content = data
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case 2:
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data, err := ioutil.ReadFile(os.Args[1])
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if err != nil {
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exitError(errors.Wrap(err, "error while reading file"))
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}
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err = os.Chdir(path.Dir(os.Args[1]))
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if err != nil {
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exitError(err)
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}
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content = data
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default:
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exitError(fmt.Errorf("only one file is supported"))
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}
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g, err := gocui.NewGui(gocui.OutputNormal, false)
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if err != nil {
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exitError(errors.Wrap(err, "error starting the interactive UI"))
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}
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defer g.Close()
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ui, err := newUi(g)
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if err != nil {
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exitError(err)
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}
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ui.setContent(content)
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if err := g.MainLoop(); err != nil && err != gocui.ErrQuit {
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exitError(err)
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}
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}
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func exitError(err error) {
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_, _ = fmt.Fprintln(os.Stderr, err)
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os.Exit(1)
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}
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const renderView = "render"
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type ui struct {
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keybindings []keybinding
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raw string
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// current width of the view
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width int
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XOffset int
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YOffset int
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// number of lines in the rendered markdown
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lines int
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}
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func newUi(g *gocui.Gui) (*ui, error) {
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result := &ui{
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width: -1,
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}
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g.SetManagerFunc(result.layout)
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result.keybindings = []keybinding{
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{"", gocui.KeyCtrlC, gocui.ModNone, result.quit},
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{renderView, 'q', gocui.ModNone, result.quit},
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{renderView, 'k', gocui.ModNone, result.up},
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{renderView, gocui.KeyCtrlP, gocui.ModNone, result.up},
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{renderView, gocui.KeyArrowUp, gocui.ModNone, result.up},
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{renderView, 'j', gocui.ModNone, result.down},
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{renderView, gocui.KeyCtrlN, gocui.ModNone, result.down},
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{renderView, gocui.KeyArrowDown, gocui.ModNone, result.down},
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{renderView, gocui.KeyPgup, gocui.ModNone, result.pageUp},
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{renderView, gocui.KeyPgdn, gocui.ModNone, result.pageDown},
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{renderView, gocui.KeySpace, gocui.ModNone, result.pageDown},
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}
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for _, kb := range result.keybindings {
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err := kb.Register(g)
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if err != nil {
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return nil, err
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}
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}
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return result, nil
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}
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func (ui *ui) setContent(content []byte) {
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ui.raw = string(content)
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ui.width = -1
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}
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func (ui *ui) layout(g *gocui.Gui) error {
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maxX, maxY := g.Size()
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v, err := g.SetView(renderView, ui.XOffset, -ui.YOffset, maxX, maxY, 0)
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if err != nil {
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if !gocui.IsUnknownView(err) {
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return err
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}
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v.Frame = false
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v.Wrap = false
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}
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if len(ui.raw) > 0 && ui.width != maxX {
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ui.width = maxX
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v.Clear()
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_, _ = v.Write(ui.render(g))
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}
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_, err = g.SetCurrentView(renderView)
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if err != nil {
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return err
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}
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return nil
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}
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func (ui *ui) render(g *gocui.Gui) []byte {
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maxX, _ := g.Size()
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opts := []markdown.Options{
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// needed when going through gocui
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markdown.WithImageDithering(markdown.DitheringWithBlocks),
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}
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rendered := markdown.Render(ui.raw, maxX-1-padding, padding, opts...)
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ui.lines = 0
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for _, b := range rendered {
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if b == '\n' {
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ui.lines++
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}
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}
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return rendered
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}
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func (ui *ui) quit(g *gocui.Gui, v *gocui.View) error {
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return gocui.ErrQuit
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}
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func (ui *ui) up(g *gocui.Gui, v *gocui.View) error {
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ui.YOffset -= 1
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ui.YOffset = max(ui.YOffset, 0)
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return nil
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}
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func (ui *ui) down(g *gocui.Gui, v *gocui.View) error {
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_, maxY := g.Size()
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ui.YOffset += 1
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ui.YOffset = min(ui.YOffset, ui.lines-maxY+1)
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ui.YOffset = max(ui.YOffset, 0)
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return nil
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}
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func (ui *ui) pageUp(g *gocui.Gui, v *gocui.View) error {
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_, maxY := g.Size()
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ui.YOffset -= maxY / 2
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ui.YOffset = max(ui.YOffset, 0)
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return nil
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}
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func (ui *ui) pageDown(g *gocui.Gui, v *gocui.View) error {
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_, maxY := g.Size()
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ui.YOffset += maxY / 2
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ui.YOffset = min(ui.YOffset, ui.lines-maxY+1)
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ui.YOffset = max(ui.YOffset, 0)
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return nil
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}
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func min(a, b int) int {
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if a < b {
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return a
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}
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return b
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}
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func max(a, b int) int {
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if a > b {
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return a
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}
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return b
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}
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