//go:build linux

package monitor

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

// percentFull is the top of the 0..100 percentage scale.
const percentFull = 100.0

// Meter fill thresholds, expressed as percent-good (100 = best, 0 = worst).
const (
	meterExcellent = 90
	meterGood      = 75
	meterFair      = 60
	meterMediocre  = 40
	meterPoor      = 20
)

// TCP latency thresholds, in milliseconds.
const (
	latencyGood     = 50
	latencyModerate = 100
	latencyHigh     = 200
)

// lossWarnPercent is the packet-loss level above which the display warns.
const lossWarnPercent = 5

func styleBrightGreen() tcell.Style {
	return tcell.StyleDefault.Foreground(tcell.ColorGreen).Bold(true)
}

func styleGreen() tcell.Style {
	return tcell.StyleDefault.Foreground(tcell.ColorGreen)
}

func styleDimGreen() tcell.Style {
	return tcell.StyleDefault.Foreground(tcell.ColorGreen).Dim(true)
}

func styleYellow() tcell.Style {
	return tcell.StyleDefault.Foreground(tcell.ColorYellow)
}

func styleOrange() tcell.Style {
	return tcell.StyleDefault.Foreground(tcell.ColorOrange)
}

func styleRed() tcell.Style {
	return tcell.StyleDefault.Foreground(tcell.ColorRed)
}

func styleBrightRed() tcell.Style {
	return tcell.StyleDefault.Foreground(tcell.ColorRed).Bold(true)
}

// rainbow returns the color cycle used for spinners and the clock.
func rainbow() []tcell.Style {
	return []tcell.Style{
		tcell.StyleDefault.Foreground(tcell.ColorRed),
		tcell.StyleDefault.Foreground(tcell.ColorOrange),
		tcell.StyleDefault.Foreground(tcell.ColorYellow),
		tcell.StyleDefault.Foreground(tcell.ColorGreen),
		tcell.StyleDefault.Foreground(tcell.ColorBlue),
		tcell.StyleDefault.Foreground(tcell.ColorPurple),
	}
}

// MeterColorForValue returns the color style for a meter value. When reverse
// is true, low values are good (green) and high values bad (red); otherwise
// high values are good.
func MeterColorForValue(value, maxValue int, reverse bool) tcell.Style {
	percentage := float64(value) / float64(maxValue) * percentFull
	if reverse {
		percentage = percentFull - percentage
	}

	switch {
	case percentage >= meterExcellent:
		return styleBrightGreen()
	case percentage >= meterGood:
		return styleGreen()
	case percentage >= meterFair:
		return styleDimGreen()
	case percentage >= meterMediocre:
		return styleYellow()
	case percentage >= meterPoor:
		return styleOrange()
	default:
		return styleRed()
	}
}

// StyleLatency returns the style for a TCP latency in milliseconds.
func StyleLatency(ms float64) tcell.Style {
	switch {
	case ms < latencyGood:
		return styleBrightGreen()
	case ms < latencyModerate:
		return styleGreen()
	case ms < latencyHigh:
		return styleYellow()
	default:
		return styleRed()
	}
}

// StyleLoss returns the style for a packet-loss percentage.
func StyleLoss(p float64) tcell.Style {
	switch {
	case p == 0:
		return styleBrightGreen()
	case p < lossWarnPercent:
		return styleYellow()
	default:
		return styleBrightRed()
	}
}