uptop/internal/tui/panel.go

package tui

import (
	"strings"

	"github.com/charmbracelet/lipgloss"
)

type scrollbar struct {
	pos     int
	total   int
	visible int
}

func (m Model) titledPanelH(title, content, footer string, width, height, scrollOffset int, sb scrollbar, focused bool) string {
	if height <= 0 {
		return m.titledPanel(title, content, width, focused)
	}

	borderColor := m.theme.Border
	titleColor := m.theme.Muted
	if focused {
		borderColor = m.theme.Accent
		titleColor = m.theme.Accent
	}

	bc := lipgloss.NewStyle().Foreground(borderColor)
	tc := lipgloss.NewStyle().Foreground(titleColor).Bold(true)

	innerW := width - 2
	if innerW < 10 {
		innerW = 10
	}

	titleRendered := tc.Render(" " + title + " ")
	titleLen := len([]rune(title)) + 2
	fillLen := innerW - titleLen - 1
	if fillLen < 0 {
		fillLen = 0
	}

	top := bc.Render("╭─") + titleRendered + bc.Render(strings.Repeat("─", fillLen)+"╮")
	bottom := bc.Render("╰" + strings.Repeat("─", innerW) + "╯")

	contentStyle := lipgloss.NewStyle().Width(innerW).MaxWidth(innerW)
	inner := contentStyle.Render(content)
	contentLines := strings.Split(inner, "\n")

	var footerLines []string
	if footer != "" {
		footerRendered := contentStyle.Render(footer)
		footerLines = strings.Split(footerRendered, "\n")
	}

	bodyH := height - 2 - len(footerLines)
	if bodyH < 1 {
		bodyH = 1
	}

	if scrollOffset > len(contentLines)-bodyH {
		scrollOffset = len(contentLines) - bodyH
	}
	if scrollOffset < 0 {
		scrollOffset = 0
	}

	end := scrollOffset + bodyH
	if end > len(contentLines) {
		end = len(contentLines)
	}
	visible := contentLines[scrollOffset:end]

	if sb.total == 0 && len(contentLines) > bodyH {
		sb = scrollbar{pos: scrollOffset, total: len(contentLines), visible: bodyH}
	}
	sbVisible := sb.visible
	if sbVisible <= 0 {
		sbVisible = bodyH
	}
	showScrollbar := sb.total > 0 && sb.total > sbVisible
	var thumbStart, thumbEnd int
	if showScrollbar {
		thumbSize := bodyH * sbVisible / sb.total
		if thumbSize < 1 {
			thumbSize = 1
		}
		scrollRange := sb.total - sbVisible
		if scrollRange < 1 {
			scrollRange = 1
		}
		trackSpace := bodyH - thumbSize
		thumbStart = sb.pos * trackSpace / scrollRange
		if thumbStart < 0 {
			thumbStart = 0
		}
		thumbEnd = thumbStart + thumbSize
		if thumbEnd > bodyH {
			thumbEnd = bodyH
		}
	}

	scrollTrack := lipgloss.NewStyle().Foreground(m.theme.Border).Render("░")
	scrollThumb := lipgloss.NewStyle().Foreground(m.theme.Accent).Render("█")

	borderLine := func(line string, idx int) string {
		rightBorder := bc.Render("│")
		if showScrollbar && idx >= thumbStart && idx < thumbEnd {
			rightBorder = scrollThumb
		} else if showScrollbar {
			rightBorder = scrollTrack
		}
		return bc.Render("│") + line + strings.Repeat(" ", max(0, innerW-lipgloss.Width(line))) + rightBorder
	}
	emptyLine := func(idx int) string {
		return borderLine(strings.Repeat(" ", innerW), idx)
	}

	var lines []string
	lines = append(lines, top)
	for i, line := range visible {
		lines = append(lines, borderLine(line, i))
	}
	for i := len(visible); len(lines) < height-1-len(footerLines); i++ {
		lines = append(lines, emptyLine(i))
	}
	for _, line := range footerLines {
		lines = append(lines, borderLine(line, -1))
	}
	lines = append(lines, bottom)

	return strings.Join(lines, "\n")
}

func (m Model) titledPanel(title, content string, width int, focused bool) string {
	borderColor := m.theme.Border
	titleColor := m.theme.Muted
	if focused {
		borderColor = m.theme.Accent
		titleColor = m.theme.Accent
	}

	bc := lipgloss.NewStyle().Foreground(borderColor)
	tc := lipgloss.NewStyle().Foreground(titleColor).Bold(true)

	innerW := width - 2
	if innerW < 10 {
		innerW = 10
	}

	titleRendered := tc.Render(" " + title + " ")
	titleLen := len([]rune(title)) + 2
	fillLen := innerW - titleLen - 1
	if fillLen < 0 {
		fillLen = 0
	}

	top := bc.Render("╭─") + titleRendered + bc.Render(strings.Repeat("─", fillLen)+"╮")

	contentStyle := lipgloss.NewStyle().Width(innerW).MaxWidth(innerW)
	inner := contentStyle.Render(content)

	var lines []string
	lines = append(lines, top)
	for _, line := range strings.Split(inner, "\n") {
		lines = append(lines, bc.Render("│")+line+strings.Repeat(" ", max(0, innerW-lipgloss.Width(line)))+bc.Render("│"))
	}
	lines = append(lines, bc.Render("╰"+strings.Repeat("─", innerW)+"╯"))

	return strings.Join(lines, "\n")
}

func max(a, b int) int {
	if a > b {
		return a
	}
	return b
}

func placeOverlay(fg string, termW, termH int) string {
	return lipgloss.Place(termW, termH, lipgloss.Center, lipgloss.Center, fg)
}