package systemmetrics

import (
	"errors"
	"math"

	"tera-clone/services/tera-api/internal/domain"
)

// Free blocks include the filesystem reservation; available blocks do not.
// The meter reports physical usage, while available bytes reflect writable space.
func storageMetrics(path string, blocks, free, available, blockSize uint64) (*domain.StorageMetrics, error) {
	if blocks == 0 || blockSize == 0 || free > blocks || available > free || blocks > math.MaxUint64/blockSize {
		return nil, errors.New("invalid storage metrics")
	}
	return &domain.StorageMetrics{
		Path: path, TotalBytes: blocks * blockSize, UsedBytes: (blocks - free) * blockSize,
		AvailableBytes: available * blockSize, ReservedBytes: (free - available) * blockSize,
		UsagePercent: math.Round(float64(blocks-free)/float64(blocks)*1000) / 10,
	}, nil
}