package progress

import (
	"fmt"
	"time"
)

// humanSize formats a byte count by abbreviating it: divide by
// 1024 while the value is at least one unit and a larger unit remains, then bump
// to the next unit when the quotient is >=922 (so 0.9Mi shows instead of 922Ki).
// The unit ladder is capped at Gi, so a terabyte prints
// as "1024.0GiB". When human is false it prints the raw integer with a B suffix.
func humanSize(n int64, human bool) string {
	if !human {
		return fmt.Sprintf("%dB", n)
	}
	const unit = 1024
	if n < unit {
		return fmt.Sprintf("%dB", n)
	}
	// "KMG" caps the ladder at Gi (the units {"","Ki","Mi","Gi"}).
	const suffixes = "KMG"
	div, exp := int64(unit), 0
	for v := n / unit; v >= unit && exp+1 < len(suffixes); v /= unit {
		div *= unit
		exp++
	}
	// Bump to the next unit when the quotient is >=922 and a unit remains, so
	// 922*1024 bytes reads as 0.9MiB rather than 922KiB.
	if q := n / div; q >= 922 && exp+1 < len(suffixes) {
		div *= unit
		exp++
	}
	val := float64(n) / float64(div)
	suffix := suffixes[exp]
	// One decimal for small mantissas and for anything that overflowed the
	// capped Gi unit (1024.0GiB and up); a bare integer otherwise (e.g. 20MiB).
	if val < 10 || exp == len(suffixes)-1 && val >= unit {
		return fmt.Sprintf("%.1f%ciB", val, suffix)
	}
	return fmt.Sprintf("%.0f%ciB", val, suffix)
}

// secfmt renders a duration as "1h2m3s", appending each unit only when it is
// nonzero (but still showing seconds when the whole input is 0):
// 3600s->"1h", 120s->"2m", 3720s->"1h2m". A non-positive or absurd
// duration renders as "--".
func secfmt(d time.Duration) string {
	s := int64(d.Seconds())
	if s < 0 || d > 99*time.Hour {
		return "--"
	}
	h, m, sec := s/3600, (s%3600)/60, s%60
	var str string
	if h > 0 {
		str += fmt.Sprintf("%dh", h)
	}
	if m > 0 {
		str += fmt.Sprintf("%dm", m)
	}
	if sec > 0 || s == 0 {
		str += fmt.Sprintf("%ds", sec)
	}
	return str
}

// percent returns completed/total as a 0-100 integer, or 0 when total is unknown.
func percent(completed, total int64) int {
	if total <= 0 {
		return 0
	}
	return int(completed * 100 / total)
}