#include "usagefmt.hpp"

namespace {

constexpr qreal kKib = 1024.0;
constexpr qreal kMib = kKib * 1024.0;
constexpr qreal kGib = kMib * 1024.0;

bool finitePositive(qreal v) {
	return std::isfinite(v) && v >= 0.0;
}

} // namespace

namespace ZShell::services::usagefmt {

FormatResult UsageFmt::formatKib(qreal kib) const {
	if (!finitePositive(kib)) {
		return {0.0, 0.0, "KiB"};
	}

	if (kib >= kGib) {
		return {kib / kGib, 0.0, "GiB"};
	}
	if (kib >= kMib) {
		return {kib / kMib, 0.0, "MiB"};
	}
	if (kib >= kKib) {
		return {kib / kKib, 0.0, "KiB"};
	}

	return {kib, 0.0, "KiB"};
}

FormatResult UsageFmt::formatKib(qreal kib, qreal total) const {
	if (!finitePositive(kib) || !finitePositive(total)) {
		return {0.0, 0.0, "KiB"};
	}
	if (total >= kGib) {
		return {kib / kGib, total / kGib, "TiB"};
	}
	if (total >= kMib) {
		return {kib / kMib, total / kMib, "GiB"};
	}
	if (total >= kKib) {
		return {kib / kKib, total / kKib, "MiB"};
	}
	return {kib, total, "KiB"};
}

FormatResult UsageFmt::formatBytes(qreal bytes) const {
	static constexpr std::array<const char*, 5> units = {
		"B", "KB", "MB", "GB", "TB"};

	qreal value = finitePositive(bytes) ? bytes : 0.0;
	const qreal k = 1024.0;
	std::size_t i = 0;

	while (value >= k && i < units.size() - 1) {
		value /= k;
		i++;
	}

	return {value, 0.0, units[i]};
}

} // namespace ZShell::services::usagefmt