using System.Security.Cryptography;
using System.Text;

namespace JobTrackerApi.Services;

public static class AvatarStorage
{
    private const string FilePrefix = "file:";

    public static async Task<string> StoreAsync(string dataRoot, string userId, byte[] bytes, string contentType, CancellationToken cancellationToken)
    {
        var userKey = Convert.ToHexString(SHA256.HashData(Encoding.UTF8.GetBytes(userId))).ToLowerInvariant();
        var folder = Path.Combine(dataRoot, "Avatars", userKey);
        Directory.CreateDirectory(folder);
        var extension = contentType switch { "image/png" => ".png", "image/webp" => ".webp", _ => ".jpg" };
        var path = Path.Combine(folder, "avatar" + extension);
        foreach (var old in Directory.EnumerateFiles(folder, "avatar.*")) if (!string.Equals(old, path, StringComparison.OrdinalIgnoreCase)) File.Delete(old);
        await File.WriteAllBytesAsync(path, bytes, cancellationToken);
        return FilePrefix + path;
    }

    public static string? Resolve(string? value)
    {
        if (string.IsNullOrWhiteSpace(value) || !value.StartsWith(FilePrefix, StringComparison.Ordinal)) return value;
        var path = value[FilePrefix.Length..];
        if (!File.Exists(path)) return null;
        var contentType = Path.GetExtension(path).ToLowerInvariant() switch { ".png" => "image/png", ".webp" => "image/webp", _ => "image/jpeg" };
        return $"data:{contentType};base64,{Convert.ToBase64String(File.ReadAllBytes(path))}";
    }

    public static void Delete(string? value)
    {
        if (value?.StartsWith(FilePrefix, StringComparison.Ordinal) != true) return;
        var path = value[FilePrefix.Length..];
        if (File.Exists(path)) File.Delete(path);
    }
}