package cobol

import (
	"fmt"
	"time"
)

func FormatDuration(d time.Duration) string {
	result := ""

	// check if it's more than a year
	years := int(d.Hours()) / (24 * 365)
	if years > 0 {
		result += fmt.Sprintf("%dy", years)
		return result
	}

	// check if it's more than a day
	days := int(d.Hours()) / 24
	if days > 0 {
		result += fmt.Sprintf("%dd", days)
		return result
	}

	// check if it's more than an hour
	hours := int(d.Hours()) % 24
	if hours > 0 {
		result += fmt.Sprintf("%dh", hours)
		return result
	}

	// check if it's more than a minute
	minutes := int(d.Minutes()) % 60
	if minutes > 0 {
		result += fmt.Sprintf("%dm", minutes)
		return result
	}

	// check if it's more than a second
	seconds := int(d.Seconds()) % 60
	if seconds > 0 {
		result += fmt.Sprintf("%ds", seconds)
		return result
	}

	// report in milliseconds
	ms := int(d.Milliseconds())
	if ms > 100 {
		// todo: print .3s, etc ?
	}
	if ms > 0 {
		result += fmt.Sprintf("%dms", ms)
		return result
	}

	// report in milliseconds
	mc := int(d.Microseconds())
	if mc > 0 {
		result += fmt.Sprintf("%dmc", mc)
		return result
	}

	ns := int(d.Nanoseconds())
	result += fmt.Sprintf("%dns", ns)
	return result
}