package bot

import (
	"fmt"
	"strings"
)

const miToKM = 1.60934

// formatDist formats a KM value in the user's preferred unit.
func formatDist(km float64, unit string) string {
	if unit == "miles" {
		return fmt.Sprintf("%.1f mi", km/miToKM)
	}
	return fmt.Sprintf("%.1f km", km)
}

// distanceComparison returns a fun contextual comparison string.
func distanceComparison(km float64) string {
	switch {
	case km >= 384400:
		return "You've cycled **to the Moon!** 🌕"
	case km >= 40075:
		return fmt.Sprintf("That's **%.1f laps around the Earth!** 🌏", km/40075)
	case km >= 1892:
		return fmt.Sprintf("That's like riding **London → Rome** (%.0f%%)! 🗺️", km/1892*100)
	case km >= 500:
		return fmt.Sprintf("That's like riding **Amsterdam → Paris** and back (%.0f%%)! 🇫🇷", km/830*100)
	default:
		return "Keep pedalling — the KMs are adding up! 💪"
	}
}

// progressBar renders a simple ASCII progress bar.
func progressBar(current, max float64, width int) string {
	if max <= 0 {
		return ""
	}
	pct := current / max
	if pct > 1 {
		pct = 1
	}
	filled := int(pct * float64(width))
	bar := ""
	for i := 0; i < width; i++ {
		if i < filled {
			bar += "█"
		} else {
			bar += "░"
		}
	}
	return fmt.Sprintf("[%s] %.0f%%", bar, pct*100)
}

// fmtKM formats a KM value with comma separators (e.g. 5243.3 → "5,243.3").
// decimals controls how many decimal places to show.
func fmtKM(km float64, decimals int) string {
	s := fmt.Sprintf(fmt.Sprintf("%%.%df", decimals), km)
	parts := strings.SplitN(s, ".", 2)
	intPart := parts[0]

	n := len(intPart)
	var out []byte
	for i := 0; i < n; i++ {
		if i > 0 && (n-i)%3 == 0 {
			out = append(out, ',')
		}
		out = append(out, intPart[i])
	}
	if len(parts) > 1 {
		return string(out) + "." + parts[1]
	}
	return string(out)
}

func plural(n int) string {
	if n == 1 {
		return ""
	}
	return "s"
}