package webapp

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

// Template helpers. Kept in their own file so templates.go stays
// focused on parsing/wiring.

// fmtBytes renders a byte count as a human-readable string. The
// unit is picked automatically (B / KiB / MiB / GiB / TiB).
func fmtBytes(n uint64) string {
	const k = 1024
	if n < k {
		return fmt.Sprintf("%d B", n)
	}
	div, exp := uint64(k), 1
	for n2 := n / k; n2 >= k; n2 /= k {
		div *= k
		exp++
	}
	suffix := []string{"KiB", "MiB", "GiB", "TiB", "PiB"}[exp-1]
	return fmt.Sprintf("%.2f %s", float64(n)/float64(div), suffix)
}

// fmtPercent renders a 0..100 number as "N.NN%".
func fmtPercent(p float64) string {
	return fmt.Sprintf("%.2f%%", p)
}

// fmtDuration renders a duration as "1d 2h 3m 4s". The format is
// stable across short and long uptimes.
func fmtDuration(d time.Duration) string {
	if d < 0 {
		d = 0
	}
	days := int(d / (24 * time.Hour))
	d -= time.Duration(days) * 24 * time.Hour
	hours := int(d / time.Hour)
	d -= time.Duration(hours) * time.Hour
	minutes := int(d / time.Minute)
	d -= time.Duration(minutes) * time.Minute
	seconds := int(d / time.Second)
	switch {
	case days > 0:
		return fmt.Sprintf("%dd %dh %dm %ds", days, hours, minutes, seconds)
	case hours > 0:
		return fmt.Sprintf("%dh %dm %ds", hours, minutes, seconds)
	case minutes > 0:
		return fmt.Sprintf("%dm %ds", minutes, seconds)
	default:
		return fmt.Sprintf("%ds", seconds)
	}
}

// fmtTime renders a timestamp as "2006-01-02 15:04:05 UTC".
func fmtTime(t time.Time) string {
	if t.IsZero() {
		return "—"
	}
	return t.UTC().Format("2006-01-02 15:04:05 UTC")
}

// fmtBool renders a bool as "yes" / "no".
func fmtBool(b bool) string {
	if b {
		return "yes"
	}
	return "no"
}

// sanitizeName strips characters that could break out of an HTML
// attribute when interpolated by a template. Template auto-escapes
// by default, but a paranoid layer here keeps audit targets safe
// when they are rendered into other contexts.
func sanitizeName(s string) string {
	s = strings.ReplaceAll(s, "\x00", "")
	if len(s) > 128 {
		s = s[:128]
	}
	return s
}