rtnetmon/internal/monitor/ui.go

package monitor

import (
	"context"
	"fmt"
	"sort"
	"strings"
	"time"

	tcell "github.com/gdamore/tcell/v2"
)

// Frame counter for the timestamp spinner (ticks once per second)
var (
	timestampSpinFrame      = 0
	lastTimestampSpinUpdate = time.Now()
)

// Put writes text to the screen at the specified position with style
func Put(scr tcell.Screen, x, y int, txt string, st tcell.Style) {
	for i, r := range txt {
		scr.SetContent(x+i, y, r, nil, st)
	}
}

// HLine creates a horizontal line of the specified width
func HLine(w int) string { return strings.Repeat("=", w) }

// DrawRainbowText draws text with rainbow colors
func DrawRainbowText(scr tcell.Screen, x, y int, text string, colors []tcell.Style) {
	for i, char := range text {
		// Cycle through the rainbow colors
		colorIndex := i % len(colors)
		style := colors[colorIndex]
		// Draw the character with the current rainbow color
		scr.SetContent(x+i, y, char, nil, style)
	}
}

// CreateMeter creates a visual meter using ASCII characters
func (m *Monitor) CreateMeter(value int) (string, tcell.Style) {
	if value > m.MaxMeterValue {
		value = m.MaxMeterValue
	}
	if value < 0 {
		value = 0
	}

	// Calculate the number of fill characters to show
	fillCount := value * m.MeterFillWidth / m.MaxMeterValue
	if fillCount > m.MeterFillWidth {
		fillCount = m.MeterFillWidth
	}

	// Build the meter string
	var b strings.Builder
	b.WriteRune(MeterStart)

	// Add fill characters
	for i := 0; i < fillCount; i++ {
		b.WriteRune(MeterFill)
	}

	// Add empty spaces
	for i := 0; i < m.MeterFillWidth-fillCount; i++ {
		b.WriteRune(MeterEmpty)
	}

	b.WriteRune(MeterEnd)

	// Get the appropriate style for this meter value
	// Using reverse=true because for packet loss, low values are good
	style := MeterColorForValue(value, m.MaxMeterValue, true)

	return b.String(), style
}

// DrawInterface draws the interface status on the screen
func (m *Monitor) DrawInterface(scr tcell.Screen, y, w int, st *InterfaceStatus) int {
	Put(scr, 0, y, HLine(w), CDefault)

	// header line
	healthy := st.IsHealthy(m.TCPTimeout)
	style := CBrightGreen
	if !healthy {
		style = CBrightRed
	}
	st.mu.RLock()
	header := fmt.Sprintf("%s: %s —   %s", st.Name, st.Label, st.IPInfo)
	spinChar := Spins[st.SpinFrame]
	spinnerFrame := st.SpinFrame
	meterValue := st.MeterValue
	st.mu.RUnlock()

	// Create the meter with appropriate style
	meter, meterStyle := m.CreateMeter(meterValue)

	// Get rainbow color for spinner (cycle through colors)
	spinnerStyle := CRainbow[spinnerFrame%len(CRainbow)]

	Put(scr, 0, y+1, "== ", CDefault)
	Put(scr, 3, y+1, string(spinChar)+" ", spinnerStyle) // Colorful spinner
	Put(scr, 5, y+1, meter+" ", meterStyle)              // Colored meter
	Put(scr, 5+m.MeterWidth+1, y+1, header, style)       // Move the header after the meter
	Put(scr, 0, y+2, HLine(w), CDefault)
	y += 4

	/* reachability */
	st.mu.RLock()
	total := len(st.Reachable)
	good := 0
	for _, ok := range st.Reachable {
		if ok {
			good++
		}
	}
	age := time.Since(st.LastPing).Round(time.Second)
	reachStyle := CBrightGreen
	if good != total {
		reachStyle = CBrightRed
	}

	// Get last drop time and age
	dropTimeStr := "never"
	dropAgeStr := "N/A"
	if !st.LastDrop.IsZero() {
		dropTimeStr = st.LastDrop.Format("15:04:05")
		dropAgeStr = time.Since(st.LastDrop).Round(time.Second).String()
	}

	// Simplified reachability line without drop info
	Put(scr, 0, y, fmt.Sprintf("Reachable: %d/%d (at %s, age %s)",
		good, total, st.LastPing.Format("15:04:05"), age), reachStyle)
	y++

	if good == total {
		Put(scr, 0, y, "Unreachable: none", CDefault)
	} else {
		var down []string
		for h, ok := range st.Reachable {
			if !ok {
				down = append(down, h)
			}
		}
		// Sort for consistent display
		sort.Strings(down)
		// Add drop info to the end of the unreachable line
		Put(scr, 0, y, fmt.Sprintf("Unreachable: %s (last drop at %s, age %s)",
			strings.Join(down, ", "), dropTimeStr, dropAgeStr), CBrightRed)
	}
	y += 2

	/* packet loss */
	Put(scr, 0, y, "Packet Loss:", CDefault)
	y++

	// Get all hosts and sort them for consistent display order
	var lossHosts []string
	for host := range st.Loss {
		lossHosts = append(lossHosts, host)
	}
	sort.Strings(lossHosts)

	// Find the maximum length of host names for alignment
	maxHostLen := 0
	for _, host := range lossHosts {
		if len(host) > maxHostLen {
			maxHostLen = len(host)
		}
	}

	// Add 1 for the colon
	maxHostLen += 1

	for _, host := range lossHosts {
		p := st.Loss[host] * 100
		// Use the maxHostLen for consistent alignment
		Put(scr, 0, y, fmt.Sprintf("%-*s %5.0f%%", maxHostLen, host+":", p), StyleLoss(p))
		y++
	}
	dAge := "N/A"
	if !st.LastDrop.IsZero() {
		dAge = time.Since(st.LastDrop).Round(time.Second).String()
	}
	Put(scr, 0, y, fmt.Sprintf("Dropped: %d (last at %s, age %s)",
		st.DroppedCount, st.LastDrop.Format("15:04:05"), dAge), CDefault)
	y += 2

	/* TCP table */
	Put(scr, 0, y, "TCP Connect Stats:", CDefault)
	y++
	// header row
	headerRow := fmt.Sprintf("%-*s %*s %*s %*s %*s %*s %*s %*s",
		m.HostWidth, "Host", m.NumWidth, "last", m.NumWidth, "min", m.NumWidth, "avg",
		m.NumWidth, "max", m.StdWidth, "stddev", m.NWidth, "n", m.LostWidth, "lost")
	Put(scr, 0, y, headerRow, CDefault)
	y++

	m.mu.RLock()
	tcpHosts := append([]string{}, m.tcpHosts...)
	m.mu.RUnlock()

	for _, hp := range tcpHosts {
		hist := st.TCP[hp]
		if len(hist) == 0 {
			continue
		}
		last := hist[len(hist)-1]
		mi, ma, av, sd := MinMaxAvgStd(hist)

		// Get host name without port for lost packets lookup
		hostName := strings.Split(hp, ":")[0]
		lost := st.LostPackets[hostName]

		// Add lost column
		row := fmt.Sprintf("%-*s %*s %*s %*s %*s %*s %*d %*d",
			m.HostWidth, hp,
			m.NumWidth, fmt.Sprintf("%.0fms", last),
			m.NumWidth, fmt.Sprintf("%.0fms", mi),
			m.NumWidth, fmt.Sprintf("%.0fms", av),
			m.NumWidth, fmt.Sprintf("%.0fms", ma),
			m.StdWidth, fmt.Sprintf("%.0fms", sd),
			m.NWidth, len(hist),
			m.LostWidth, lost,
		)
		Put(scr, 0, y, row, CDefault)
		// colourise individual numbers
		Put(scr, m.HostWidth+1, y, fmt.Sprintf("%*s", m.NumWidth, fmt.Sprintf("%.0fms", last)), StyleLatency(last))
		Put(scr, m.HostWidth+1+m.NumWidth+1, y, fmt.Sprintf("%*s", m.NumWidth, fmt.Sprintf("%.0fms", mi)), StyleLatency(mi))
		Put(scr, m.HostWidth+1+m.NumWidth*2+2, y, fmt.Sprintf("%*s", m.NumWidth, fmt.Sprintf("%.0fms", av)), StyleLatency(av))
		Put(scr, m.HostWidth+1+m.NumWidth*3+3, y, fmt.Sprintf("%*s", m.NumWidth, fmt.Sprintf("%.0fms", ma)), StyleLatency(ma))
		Put(scr, m.HostWidth+1+m.NumWidth*4+4, y, fmt.Sprintf("%*s", m.StdWidth, fmt.Sprintf("%.0fms", sd)), CDefault)
		// Colorize the lost packets column
		lostStyle := CDefault
		if lost > 0 {
			lostStyle = CRed
		}
		Put(scr, m.HostWidth+1+m.NumWidth*4+4+m.StdWidth+1+m.NWidth+1, y, fmt.Sprintf("%*d", m.LostWidth, lost), lostStyle)
		y++
	}
	y++

	/* ICMP stats - combined into a single line with headers */
	// Calculate total lost packets
	lost := st.TotalICMPReq - st.TotalICMPRep
	if lost < 0 {
		lost = 0
	}

	// Create styles based on values
	lostStyle := CDefault
	if lost > 0 {
		lostStyle = CRed
	}

	// Define column widths and positions
	const valWidth = 9

	// Format the values with right alignment
	reqVal := fmt.Sprintf("%9d", st.TotalICMPReq)
	repVal := fmt.Sprintf("%9d", st.TotalICMPRep)
	lostVal := fmt.Sprintf("%9d", lost)

	// Header texts with the same width as values for right alignment
	reqHeader := fmt.Sprintf("%9s", "Requests")
	repHeader := fmt.Sprintf("%9s", "Replies")
	lostHeader := fmt.Sprintf("%9s", "Lost")

	// Draw the header line
	Put(scr, 0, y, "        ", CDefault)
	Put(scr, 8, y, reqHeader, CDefault)
	Put(scr, 8+valWidth+4, y, repHeader, CDefault)
	Put(scr, 8+2*(valWidth+4), y, lostHeader, CDefault)
	y++

	// Draw the values line
	Put(scr, 0, y, "ICMP:   ", CDefault)
	Put(scr, 8, y, reqVal, CDefault)
	Put(scr, 8+valWidth+4, y, repVal, CDefault)
	Put(scr, 8+2*(valWidth+4), y, lostVal, lostStyle)

	y += 2
	st.mu.RUnlock()
	return y
}

// uiLoop runs the UI event loop
func (m *Monitor) uiLoop(ctx context.Context) {
	m.logf("UI loop started")
	defer func() {
		m.logf("UI loop cleanup")
		m.screen.Clear()
		m.screen.ShowCursor(0, 0)
		m.screen.Fini()
		m.logf("Screen finalized")
	}()

	// Load PST location
	pstLoc, err := time.LoadLocation("America/Los_Angeles")
	if err != nil {
		m.logf("Error loading PST location: %v", err)
		pstLoc = time.UTC
	}

	// Function to draw the screen
	drawScreen := func() {
		w, _ := m.screen.Size()
		m.screen.Clear()

		// Draw the top horizontal line
		Put(m.screen, 0, 0, HLine(w), CDefault)

		// Get current time and format it
		now := time.Now()
		timeStr := now.Format(time.RFC1123Z)

		// Format time in PST
		pstTimeStr := now.In(pstLoc).Format(time.RFC1123Z)

		// Update the timestamp spinner once per second
		if time.Since(lastTimestampSpinUpdate) >= time.Second {
			timestampSpinFrame = (timestampSpinFrame + 1) % len(BrailleSpins)
			lastTimestampSpinUpdate = now
		}

		// Get braille spinner character
		brailleChar := BrailleSpins[timestampSpinFrame]

		// Draw the header with timestamp and spinner
		Put(m.screen, 0, 1, "== ", CDefault)
		Put(m.screen, 3, 1, string(brailleChar)+" ", CDefault)

		// Draw the timestamp with rainbow colors
		DrawRainbowText(m.screen, 5, 1, timeStr, CRainbow)

		// Add 5 space gap and PST time with rainbow colors
		DrawRainbowText(m.screen, 5+len(timeStr)+5, 1, pstTimeStr, CRainbow)

		// Draw the bottom horizontal line
		Put(m.screen, 0, 2, HLine(w), CDefault)

		// Draw the runtime
		Put(m.screen, 0, 3, "Runtime: "+time.Since(m.startTime).Round(time.Second).String(), CDefault)

		// Draw interfaces (one pane each; a single interface draws one pane)
		y := 5
		for _, st := range m.interfaces {
			y = m.DrawInterface(m.screen, y, w, st)
		}

		// Show the screen
		m.screen.Show()
	}

	// Initial draw
	drawScreen()

	// Even without a ticker, ensure we update at least every second
	// This is a backup in case there are no spinner updates
	backupTicker := time.NewTicker(time.Second)
	defer backupTicker.Stop()

	for {
		select {
		case <-ctx.Done():
			m.logf("Context cancelled, exiting UI loop")
			return
		case <-UIUpdateChan:
			// Update on spinner ticks (no rate limiting)
			drawScreen()
		case <-backupTicker.C:
			// Fallback to ensure we update at least once per second
			drawScreen()
		}
	}
}