using System;

namespace AutoIngest.Engine
{
    /// <summary>
    /// Human-readable byte formatting — one source of truth used by the import pipeline, the
    /// retention sweep, and the settings UI. Switch expression: single exit, no magic numbers
    /// inline at call sites, scales from bytes to gigabytes.
    /// </summary>
    public static class FileSize
    {
        const long KB = 1024;
        const long MB = 1024 * 1024;
        const long GB = 1024 * 1024 * 1024;

        public static string Format(long bytes) => bytes switch
        {
            < KB => $"{bytes} B",
            < MB => $"{bytes / (double)KB:F1} KB",
            < GB => $"{bytes / (double)MB:F1} MB",
            _    => $"{bytes / (double)GB:F2} GB"
        };
    }
}