add pager tui for 'api show' (#46)

pkg/cfg/config.go

@@ -35,7 +35,7 @@ import (
 )
 
 const (
-	Version string = `v0.0.19`
+	Version string = `v0.0.20`
 )
 
 var (

pkg/es/api.go

@@ -307,6 +307,7 @@ func ApiPathNames() []string {
 
 func ApiShow(conf *cfg.Config, showpath, verb string) error {
 	assets.LoadAssetOpenApi()
+	out := printer.Builder{}
 
 	op, err := matchOperation(showpath, verb)
 	if err != nil {
@@ -335,43 +336,46 @@ func ApiShow(conf *cfg.Config, showpath, verb string) error {
 		MarginBottom(1).
 		MarginLeft(2)
 
-	fmt.Println(bold.Render("ID: " + op.Op.ID))
-	fmt.Println(paragraph.Render(fmt.Sprintf("%s %s", op.Verb, showpath)))
+	out.WriteStringLine(bold.Render("ID: " + op.Op.ID))
+	out.WriteStringLine(paragraph.Render(fmt.Sprintf("%s %s", op.Verb, showpath)))
 
-	fmt.Println(bold.Render("Tags"))
-	fmt.Println(paragraph.Render(strings.Join(op.Op.Tags, ", ")))
+	out.WriteStringLine(bold.Render("Tags"))
+	out.WriteStringLine(paragraph.Render(strings.Join(op.Op.Tags, ", ")))
 
-	fmt.Println(bold.Render("Summary"))
-	fmt.Println(paragraph.Render(strings.TrimSpace(op.Op.Summary)))
+	out.WriteStringLine(bold.Render("Summary"))
+	out.WriteStringLine(paragraph.Render(strings.TrimSpace(op.Op.Summary)))
 
-	fmt.Println(bold.Render("Description"))
-	fmt.Println(string(description)) // already indented
+	out.WriteStringLine(bold.Render("Description"))
+	out.WriteStringLine(string(description)) // already indented
 
 	if len(params.Path) > 0 {
-		fmt.Println(bold.Render("Path Parameters"))
+		out.WriteStringLine(bold.Render("Path Parameters"))
 		for _, param := range params.Path {
-			fmt.Println(boldparagraph.Render(param.Param))
+			out.WriteStringLine(boldparagraph.Render(param.Param))
 			if param.Description != "" {
-				fmt.Println(indentparagraph.Render(param.Description))
+				//out.WriteStringLine(indentparagraph.Render(param.Description))
+				out.WriteStringLine(param.Description)
 			}
 		}
 	}
 
 	if len(params.Query) > 0 {
-		fmt.Println(bold.Render("Query Parameters"))
+		out.WriteStringLine(bold.Render("Query Parameters"))
 		for _, param := range params.Query {
-			fmt.Println(boldparagraph.Render(param.Param))
+			out.WriteStringLine(boldparagraph.Render(param.Param))
 			if param.Description != "" {
-				fmt.Println(indentparagraph.Render(param.Description))
+				out.WriteStringLine(indentparagraph.Render(param.Description))
 			}
 		}
 	}
 
 	if sample != "" {
-		fmt.Println(bold.Render("Example"))
-		fmt.Println(paragraph.Render(sample))
+		out.WriteStringLine(bold.Render("Example"))
+		out.WriteStringLine(paragraph.Render(sample))
 	}
 
+	printer.Pager(showpath, out.String())
+
 	return nil
 }
 

pkg/printer/builder.go

@@ -0,0 +1,28 @@
+/*
+Copyright © 2026 Thomas von Dein
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program. If not, see <http://www.gnu.org/licenses/>.
+*/
+package printer
+
+import "strings"
+
+// a wrapper around strings.Builder for convenience
+type Builder struct {
+	strings.Builder
+}
+
+func (builder *Builder) WriteStringLine(in string) {
+	builder.WriteString(in + "\n")
+}

pkg/printer/pager.go

@@ -0,0 +1,136 @@
+/*
+Copyright © 2026 Thomas von Dein
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program. If not, see <http://www.gnu.org/licenses/>.
+*/
+package printer
+
+// 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)
+	}
+}