Luna/Luna.Configuration/Services/Providers/ProviderOptionsProvider.cs

using System.Text.RegularExpressions;
using Tomlyn;

namespace Luna.Configuration.Services.Providers;

internal sealed class ProviderOptionsProvider(string? searchPath = null)
{
    private readonly EmbeddedResourceLoader embeddedResourceLoader = new();

    public IEnumerable<(string Name, ProviderOptions Options)> GetProviderOptions()
    {
        return string.IsNullOrWhiteSpace(searchPath)
            ? GetProviderOptionsFromEmbeddedResources()
            : GetProviderOptionsFromFiles();
    }

    private IEnumerable<(string Name, ProviderOptions Options)> GetProviderOptionsFromFiles()
    {
        ArgumentException.ThrowIfNullOrEmpty(searchPath);

        var files = Directory.Exists(searchPath)
            ? Directory.EnumerateFiles(searchPath, "Provider.*.toml")
            : [];
        
        foreach (var file in files)
        {
            var name = Path.GetFileName(file).ToProviderName();
            using var reader = File.OpenText(file);
            var providerOptions = TomlSerializer.Deserialize<ProviderOptions>(reader);

            yield return (name, providerOptions
                ?? throw new FormatException($"Invalid provider config file: {file}"));
        }
    }

    private IEnumerable<(string Name, ProviderOptions Options)> GetProviderOptionsFromEmbeddedResources()
    {
        var resources = embeddedResourceLoader.ListResources("Provider.*.toml");
        foreach (var resource in resources)
        {
            var name = resource.ToProviderName();
            var content = embeddedResourceLoader.LoadAsync(resource).GetAwaiter().GetResult();
            var providerOptions = TomlSerializer.Deserialize<ProviderOptions>(content);

            yield return (name, providerOptions
                ?? throw new FormatException($"Invalid provider config embedded resource: {resource}"));
        }
    }
}

internal static partial class ProviderStringExtensions
{
    [GeneratedRegex(@"Provider\.(.+)\.toml", RegexOptions.IgnoreCase | RegexOptions.Compiled)]
    private static partial Regex ProviderNameRegex { get; }

    extension(string str)
    {
        public string ToProviderName() => ProviderNameRegex.Match(str) is { Success: true } match
            ? match.Groups[1].Value
            : throw new FormatException($"Invalid provider config file name: {str}");
    }
}