replace pipe to less with bubbletea internal pager (#57)

cmd/pager.go

@@ -0,0 +1,120 @@
+package cmd
+
+// pager setup using bubbletea
+// file shamlelessly copied from:
+// https://github.com/charmbracelet/bubbletea/tree/main/examples/pager
+
+import (
+	"fmt"
+	"os"
+	"strings"
+
+	"github.com/charmbracelet/bubbles/viewport"
+	tea "github.com/charmbracelet/bubbletea"
+	"github.com/charmbracelet/lipgloss"
+)
+
+var (
+	titleStyle = func() lipgloss.Style {
+		b := lipgloss.RoundedBorder()
+		b.Right = "├"
+		return lipgloss.NewStyle().BorderStyle(b).Padding(0, 1)
+	}()
+
+	infoStyle = func() lipgloss.Style {
+		b := lipgloss.RoundedBorder()
+		b.Left = "┤"
+		return titleStyle.BorderStyle(b)
+	}()
+)
+
+type model struct {
+	content  string
+	title    string
+	ready    bool
+	viewport viewport.Model
+}
+
+func (m model) Init() tea.Cmd {
+	return nil
+}
+
+func (m model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
+	var (
+		cmd  tea.Cmd
+		cmds []tea.Cmd
+	)
+
+	switch msg := msg.(type) {
+	case tea.KeyMsg:
+		if k := msg.String(); k == "ctrl+c" || k == "q" || k == "esc" {
+			return m, tea.Quit
+		}
+
+	case tea.WindowSizeMsg:
+		headerHeight := lipgloss.Height(m.headerView())
+		footerHeight := lipgloss.Height(m.footerView())
+		verticalMarginHeight := headerHeight + footerHeight
+
+		if !m.ready {
+			// Since this program is using the full size of the viewport we
+			// need to wait until we've received the window dimensions before
+			// we can initialize the viewport. The initial dimensions come in
+			// quickly, though asynchronously, which is why we wait for them
+			// here.
+			m.viewport = viewport.New(msg.Width, msg.Height-verticalMarginHeight)
+			m.viewport.YPosition = headerHeight
+			m.viewport.SetContent(m.content)
+			m.ready = true
+		} else {
+			m.viewport.Width = msg.Width
+			m.viewport.Height = msg.Height - verticalMarginHeight
+		}
+	}
+
+	// Handle keyboard and mouse events in the viewport
+	m.viewport, cmd = m.viewport.Update(msg)
+	cmds = append(cmds, cmd)
+
+	return m, tea.Batch(cmds...)
+}
+
+func (m model) View() string {
+	if !m.ready {
+		return "\n  Initializing..."
+	}
+	return fmt.Sprintf("%s\n%s\n%s", m.headerView(), m.viewport.View(), m.footerView())
+}
+
+func (m model) headerView() string {
+	// title := titleStyle.Render("RPN Help Overview")
+	title := titleStyle.Render(m.title)
+	line := strings.Repeat("─", max(0, m.viewport.Width-lipgloss.Width(title)))
+	return lipgloss.JoinHorizontal(lipgloss.Center, title, line)
+}
+
+func (m model) footerView() string {
+	info := infoStyle.Render(fmt.Sprintf("%3.f%%", m.viewport.ScrollPercent()*100))
+	line := strings.Repeat("─", max(0, m.viewport.Width-lipgloss.Width(info)))
+	return lipgloss.JoinHorizontal(lipgloss.Center, line, info)
+}
+
+func max(a, b int) int {
+	if a > b {
+		return a
+	}
+	return b
+}
+
+func Pager(title, message string) {
+	p := tea.NewProgram(
+		model{content: message, title: title},
+		tea.WithAltScreen(),       // use the full size of the terminal in its "alternate screen buffer"
+		tea.WithMouseCellMotion(), // turn on mouse support so we can track the mouse wheel
+	)
+
+	if _, err := p.Run(); err != nil {
+		fmt.Println("could not run pager:", err)
+		os.Exit(1)
+	}
+}

cmd/root.go

@@ -17,12 +17,9 @@ along with this program. If not, see <http://www.gnu.org/licenses/>.
 package cmd
 
 import (
-	"bytes"
 	"errors"
 	"fmt"
-	"log"
 	"os"
-	"os/exec"
 	"strings"
 
 	"github.com/spf13/cobra"
@@ -30,24 +27,6 @@ import (
 	"github.com/tlinden/tablizer/lib"
 )
 
-func man() {
-	man := exec.Command("less", "-")
-
-	var buffer bytes.Buffer
-
-	buffer.Write([]byte(manpage))
-
-	man.Stdout = os.Stdout
-	man.Stdin = &buffer
-	man.Stderr = os.Stderr
-
-	err := man.Run()
-
-	if err != nil {
-		log.Fatal(err)
-	}
-}
-
 func completion(cmd *cobra.Command, mode string) error {
 	switch mode {
 	case "bash":
@@ -94,7 +73,7 @@ func Execute() {
 			}
 
 			if ShowManual {
-				man()
+				Pager("tablizer manual page", manpage)
 
 				return
 			}