package main

import "syscall"

type StorageMetrics struct {
	Mountpoint   string  `json:"mountpoint"`
	TotalBytes   uint64  `json:"totalBytes"`
	UsedBytes    uint64  `json:"usedBytes"`
	FreeBytes    uint64  `json:"freeBytes"`
	UsagePercent float64 `json:"usagePercent"`
}

func readStorageMetrics(path string) (StorageMetrics, error) {
	var stat syscall.Statfs_t
	if err := syscall.Statfs(path, &stat); err != nil {
		return StorageMetrics{}, err
	}
	total := stat.Blocks * uint64(stat.Bsize)
	free := stat.Bavail * uint64(stat.Bsize)
	used := total - free
	var percent float64
	if total > 0 {
		percent = float64(used) / float64(total) * 100
	}
	return StorageMetrics{
		Mountpoint: path, TotalBytes: total, UsedBytes: used,
		FreeBytes: free, UsagePercent: percent,
	}, nil
}