Initial commit

internal/pager/pager.go

@@ -0,0 +1,143 @@
+/*
+ * LURE - Linux User REpository
+ * Copyright (C) 2023 Elara Musayelyan
+ *
+ * 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 pager
+
+import (
+	"fmt"
+	"strings"
+
+	"github.com/charmbracelet/bubbles/viewport"
+	tea "github.com/charmbracelet/bubbletea"
+	"github.com/charmbracelet/lipgloss"
+	"github.com/muesli/reflow/wordwrap"
+)
+
+var (
+	titleStyle lipgloss.Style
+	infoStyle  lipgloss.Style
+)
+
+func init() {
+	b1 := lipgloss.RoundedBorder()
+	b1.Right = "\u251C"
+	titleStyle = lipgloss.NewStyle().BorderStyle(b1).Padding(0, 1)
+
+	b2 := lipgloss.RoundedBorder()
+	b2.Left = "\u2524"
+	infoStyle = titleStyle.Copy().BorderStyle(b2)
+}
+
+type Pager struct {
+	model pagerModel
+}
+
+func New(name, content string) *Pager {
+	return &Pager{
+		model: pagerModel{
+			name:    name,
+			content: content,
+		},
+	}
+}
+
+func (p *Pager) Run() error {
+	prog := tea.NewProgram(
+		p.model,
+		tea.WithMouseCellMotion(),
+		tea.WithAltScreen(),
+	)
+
+	_, err := prog.Run()
+	return err
+}
+
+type pagerModel struct {
+	name     string
+	content  string
+	ready    bool
+	viewport viewport.Model
+}
+
+func (pm pagerModel) Init() tea.Cmd {
+	return nil
+}
+
+func (pm pagerModel) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
+	var (
+		cmd  tea.Cmd
+		cmds []tea.Cmd
+	)
+
+	switch msg := msg.(type) {
+	case tea.KeyMsg:
+		k := msg.String()
+		if k == "ctrl+c" || k == "q" || k == "esc" {
+			return pm, tea.Quit
+		}
+	case tea.WindowSizeMsg:
+		headerHeight := lipgloss.Height(pm.headerView())
+		footerHeight := lipgloss.Height(pm.footerView())
+		verticalMarginHeight := headerHeight + footerHeight
+
+		if !pm.ready {
+			pm.viewport = viewport.New(msg.Width, msg.Height-verticalMarginHeight)
+			pm.viewport.HighPerformanceRendering = true
+			pm.viewport.YPosition = headerHeight + 1
+			pm.viewport.SetContent(wordwrap.String(pm.content, msg.Width))
+			pm.ready = true
+		} else {
+			pm.viewport.Width = msg.Width
+			pm.viewport.Height = msg.Height - verticalMarginHeight
+		}
+
+		cmds = append(cmds, viewport.Sync(pm.viewport))
+	}
+
+	// Handle keyboard and mouse events in the viewport
+	pm.viewport, cmd = pm.viewport.Update(msg)
+	cmds = append(cmds, cmd)
+
+	return pm, tea.Batch(cmds...)
+}
+
+func (pm pagerModel) View() string {
+	if !pm.ready {
+		return "\n  Initializing..."
+	}
+	return fmt.Sprintf("%s\n%s\n%s", pm.headerView(), pm.viewport.View(), pm.footerView())
+}
+
+func (pm pagerModel) headerView() string {
+	title := titleStyle.Render(pm.name)
+	line := strings.Repeat("─", max(0, pm.viewport.Width-lipgloss.Width(title)))
+	return lipgloss.JoinHorizontal(lipgloss.Center, title, line)
+}
+
+func (pm pagerModel) footerView() string {
+	info := infoStyle.Render(fmt.Sprintf("%3.f%%", pm.viewport.ScrollPercent()*100))
+	line := strings.Repeat("─", max(0, pm.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
+}