patterm/internal/app/sidebar.go

package app

import (
	"fmt"
	"os"
	"strings"
	"time"
)

const (
	sidebarCols = 28
	statusRows  = 1
)

// fitName returns name truncated to fit budget visible cells, with a
// trailing "…" when it overflows. Operates on RAW (unstyled) input;
// the caller wraps the result in SGR. Returns "" when budget <= 0.
func fitName(name string, budget int) string {
	if budget <= 0 {
		return ""
	}
	runes := []rune(name)
	if len(runes) <= budget {
		return name
	}
	if budget == 1 {
		return "…"
	}
	return string(runes[:budget-1]) + "…"
}

// marqueeWindow returns the window of name starting at offset, exactly
// budget cells wide. Pre: caller has decided the name overflows budget
// and offset is in [0, len([]rune(name))-budget]. Operates on RAW
// (unstyled) input.
func marqueeWindow(name string, budget, offset int) string {
	if budget <= 0 {
		return ""
	}
	runes := []rune(name)
	if len(runes) <= budget {
		return name
	}
	if offset < 0 {
		offset = 0
	}
	end := offset + budget
	if end > len(runes) {
		end = len(runes)
		offset = end - budget
		if offset < 0 {
			offset = 0
		}
	}
	return string(runes[offset:end])
}

// clampVisible truncates s so that its visible (non-SGR) length is at
// most width cells, preserving any active style by appending a reset.
// Used as a defensive net by write() so a row whose decoration was
// mis-sized still cannot spill past the sidebar band into the PTY area.
func clampVisible(s string, width int) string {
	if width <= 0 {
		return ""
	}
	if visibleLen(s) <= width {
		return s
	}
	var b strings.Builder
	b.Grow(len(s))
	visible := 0
	inEsc := false
	for _, r := range s {
		if inEsc {
			b.WriteRune(r)
			if r == 'm' || r == 'H' {
				inEsc = false
			}
			continue
		}
		if r == 0x1b {
			inEsc = true
			b.WriteRune(r)
			continue
		}
		if visible >= width {
			break
		}
		b.WriteRune(r)
		visible++
	}
	b.WriteString(styleReset)
	return b.String()
}

// chooseSidebarSuffix decides whether to keep or drop the trailing
// timer indicator from a sidebar row's suffix. When the row's name
// would have to ellipsise with the timer present, but the budget
// freed by dropping the timer still leaves at least 6 cells for the
// name, the timer is dropped. The name is the only identifier the
// user has for that row; the timer is recoverable from the status
// line and palette.
func chooseSidebarSuffix(nameRuneLen, width int, prefix, suffix, timer string) (string, int) {
	prefixCost := visibleLen(prefix)
	budget := width - prefixCost - visibleLen(suffix)
	if nameRuneLen <= budget || timer == "" {
		return suffix, budget
	}
	slim := strings.TrimSuffix(suffix, timer)
	if slim == suffix {
		return suffix, budget
	}
	slimBudget := width - prefixCost - visibleLen(slim)
	if slimBudget >= 6 {
		return slim, slimBudget
	}
	return suffix, budget
}

// rowNameSlot returns the unstyled name cell for a sidebar row.
// Unfocused (or focused-and-fitting) rows get fitName with a trailing
// "…" on overflow. The focused row, when its name overflows the
// budget, gets the current marquee window — exactly budget cells
// wide so the surrounding row geometry stays put while it animates.
func (st *uiState) rowNameSlot(id, rawName string, budget int, focused bool) string {
	if budget <= 0 {
		return ""
	}
	runes := []rune(rawName)
	if !focused || len(runes) <= budget {
		return fitName(rawName, budget)
	}
	off, _, _ := st.marquee.step(id, len(runes), budget, time.Now())
	return marqueeWindow(rawName, budget, off)
}

// formatShortDuration renders a duration as a short, sidebar-friendly
// suffix: ms under 1s, "12s" under 60s, "3m" otherwise.
func formatShortDuration(d time.Duration) string {
	if d <= 0 {
		return "0s"
	}
	if d < time.Second {
		return fmt.Sprintf("%dms", int(d/time.Millisecond))
	}
	if d < time.Minute {
		return fmt.Sprintf("%ds", int(d/time.Second))
	}
	if d < time.Hour {
		return fmt.Sprintf("%dm", int(d/time.Minute))
	}
	return fmt.Sprintf("%dh", int(d/time.Hour))
}

// drawSidebar paints the right-rail session tree + scratchpad list.
// SPEC §4: the rail is the active session's child hierarchy on top and
// the scratchpad list (with preview) on the bottom.
//
// Implementation note: the PTY child's winsize is constrained to the
// computed main viewport, so the sidebar region is outside the child's
// cursor range. We can redraw freely without fighting the child for cells.
func (st *uiState) drawSidebar() {
	var entry time.Time
	if st.metrics != nil {
		entry = time.Now()
	}
	st.mu.Lock()
	palOpen := st.palette != nil
	focus := st.focusedID
	focusPad := st.focusedPad
	activeAgent := st.activeAgentID
	st.mu.Unlock()
	if palOpen {
		return
	}

	layout := st.layoutSnapshot()
	if !layout.sidebarVisible || layout.hostRows < 4 {
		return
	}
	left := int(layout.sidebarLeft)
	width := int(layout.sidebarWidth) - 1
	maxRow := int(layout.statusRow) - statusRows

	var b strings.Builder
	for r := 1; r <= maxRow; r++ {
		fmt.Fprintf(&b, "\x1b[%d;%dH%s│%s", r, left-1, styleBorder, styleReset)
	}

	row := 1
	// write paints one styled line into the sidebar column band and pads
	// it out to `width` cells. Content may carry inline SGR escapes —
	// visibleLen ignores them when computing padding.
	write := func(content string) {
		if row > maxRow {
			return
		}
		if visibleLen(content) > width {
			content = clampVisible(content, width)
		}
		pad := width - visibleLen(content)
		if pad < 0 {
			pad = 0
		}
		fmt.Fprintf(&b, "\x1b[%d;%dH%s%s%s\x1b[K",
			row, left, content, strings.Repeat(" ", pad), styleReset)
		row++
	}
	writeHeader := func(text string) {
		write(" " + styleActive + text + styleReset)
		write(" " + styleBorder + strings.Repeat("─", width-2) + styleReset)
	}
	// timerIndicator returns a short " ⏱ 12s" or " ⏸ paused" suffix
	// when c has a pending or paused timer attached (owns or watches).
	// Empty string when no timer is in play.
	timerIndicator := func(c *Child) string {
		if st.timers == nil {
			return ""
		}
		info := st.timers.activeForChild(c.ID)
		if info == nil {
			return ""
		}
		if info.Status == timerStatusPaused {
			return " " + styleDim + "⏸" + styleReset
		}
		remaining := ""
		if info.FiresAtUnixMS > 0 {
			d := time.Until(time.UnixMilli(info.FiresAtUnixMS))
			if d < 0 {
				d = 0
			}
			remaining = formatShortDuration(d)
		}
		return " " + styleDim + "⏱" + styleReset + " " + styleHint + remaining + styleReset
	}
	statusGlyph := func(c *Child, focused bool) string {
		if c.Status() != StatusRunning {
			return styleDim + "○" + styleReset
		}
		// Idle-detection states paint over the plain running glyph so
		// the rail communicates "running but waiting on you" vs "running
		// and busy" at a glance. Focused entries always use the accent
		// colour so the user's selection stays visible.
		style := styleHint
		if focused {
			style = styleAccent
		}
		switch c.IdleState() {
		case StateError:
			return styleError + "✕" + styleReset
		case StatePermission:
			return styleAccent + "?" + styleReset
		case StateThinking:
			return style + "◐" + styleReset
		case StateIdle:
			return style + "○" + styleReset
		case StateWorking:
			return style + "●" + styleReset
		default:
			return style + "●" + styleReset
		}
	}

	// Processes section — top-level command/terminal processes,
	// session-wide (does not change when the user switches agent tabs).
	writeHeader("Processes")
	procs := processList(st.sess.Children())
	if len(procs) == 0 {
		write("   " + styleDim + "(none)" + styleReset)
	}
	for _, c := range procs {
		if row > maxRow {
			break
		}
		focused := c.ID == focus
		glyph := statusGlyph(c, focused)
		marker := ""
		if c.AutoRestart() {
			marker = " " + styleDim + "⟳" + styleReset
		}
		timer := timerIndicator(c)
		var prefix, openStyle string
		if focused {
			prefix = " " + styleAccent + "▎" + styleReset + " " + glyph + " "
			openStyle = styleBold
		} else {
			prefix = "   " + glyph + " "
			openStyle = styleHint
		}
		raw := c.DisplayName()
		suffix, budget := chooseSidebarSuffix(len([]rune(raw)), width, prefix, marker+timer, timer)
		nameCell := st.rowNameSlot(c.ID, raw, budget, focused)
		write(prefix + openStyle + nameCell + styleReset + suffix)
	}

	// Agent Tree section — formerly "Session tree". Shows the active
	// agent tab's root plus its sub-agents. The active agent is pinned
	// by activeAgentID, so the tree keeps showing the right tab even
	// when focus moves into the Processes section above.
	if row+2 <= maxRow {
		write("")
	}
	writeHeader("Agent Tree")
	agents := visibleAgentTree(st.sess.Children(), activeAgent)
	if len(agents) == 0 {
		write("   " + styleDim + "(empty)" + styleReset)
	}
	for _, c := range agents {
		if row > maxRow {
			break
		}
		indent := ""
		if c.ParentID != "" {
			indent = "  "
		}
		focused := c.ID == focus
		glyph := statusGlyph(c, focused)
		timer := timerIndicator(c)
		var prefix, openStyle string
		if focused {
			prefix = " " + styleAccent + "▎" + styleReset + " " + indent + glyph + " "
			openStyle = styleBold
		} else {
			prefix = "   " + indent + glyph + " "
			openStyle = styleHint
		}
		raw := c.DisplayName()
		suffix, budget := chooseSidebarSuffix(len([]rune(raw)), width, prefix, timer, timer)
		nameCell := st.rowNameSlot(c.ID, raw, budget, focused)
		write(prefix + openStyle + nameCell + styleReset + suffix)
	}

	// Scratchpads list — names only. The preview pane used to live
	// here and clobbered the main viewport when content overflowed the
	// rail. Focus moves to a pad via Ctrl+W/S; the content renders in
	// the main viewport via repaintFocusedPad. SPEC §4.
	if row+2 <= maxRow {
		write("")
		writeHeader("Scratchpads")
		entries := st.padsList()
		if entries != nil {
			if len(entries) == 0 {
				write("   " + styleDim + "(none)" + styleReset)
			} else {
				for _, e := range entries {
					if row > maxRow {
						break
					}
					focused := e.Name == focusPad
					var prefix, openStyle string
					if focused {
						prefix = " " + styleAccent + "▎" + styleReset + " "
						openStyle = styleBold
					} else {
						prefix = "   "
						openStyle = styleHint
					}
					budget := width - visibleLen(prefix)
					nameCell := st.rowNameSlot("pad:"+e.Name, e.Name, budget, focused)
					write(prefix + openStyle + nameCell + styleReset)
				}
			}
		}
	}

	// Blank-fill any rows the rail content didn't cover so stale
	// content from a previous redraw doesn't linger.
	for row <= maxRow {
		write("")
	}

	frame := b.String()
	st.chromeCacheMu.Lock()
	if frame == st.sidebarCache {
		st.chromeCacheMu.Unlock()
		if st.metrics != nil {
			st.metrics.recordSidebar(time.Since(entry), true)
		}
		return
	}
	st.sidebarCache = frame
	st.chromeCacheMu.Unlock()
	if st.metrics != nil {
		defer func() { st.metrics.recordSidebar(time.Since(entry), false) }()
	}

	st.outMu.Lock()
	// Save cursor; emit the sidebar; restore.
	fmt.Fprintf(os.Stdout, "\x1b7%s\x1b8", frame)
	st.outMu.Unlock()
}