using Amazon.Runtime;
using Amazon.S3;
using Houston.Settings;
using Microsoft.Extensions.Options;

namespace Houston.Extensions;

public static class DocumentsExtensions
{
    extension(IServiceCollection services)
    {
        public IServiceCollection AddDocumentsClient()
        {
            return services.AddKeyedScoped<IAmazonS3>("Documents", (services, _) =>
            {
                var settings = services.GetRequiredService<IOptions<DocumentsSettings>>();
                var client = new AmazonS3Client(
                    new BasicAWSCredentials(settings.Value.S3.Key, settings.Value.S3.Secret),
                    new AmazonS3Config { ServiceURL = settings.Value.S3.Endpoint });

                // The SDK percent-encodes the separators in x-amz-copy-source ("bucket%2Fkey%2Fdoc.pdf").
                // AWS decodes that again, our S3 splits bucket and key on the first literal slash and ends up
                // without a key ("Invalid copy source object key"), so the separators are restored here. The
                // event runs before the signer, hence the corrected value is the one that gets signed.
                client.BeforeRequestEvent += (_, args) =>
                {
                    if (args is WebServiceRequestEventArgs { Headers: { } headers }
                        && headers.TryGetValue("x-amz-copy-source", out var copySource)
                        && copySource.Contains("%2F", StringComparison.Ordinal))
                    {
                        headers["x-amz-copy-source"] = copySource.Replace("%2F", "/", StringComparison.Ordinal);
                    }
                };

                return client;
            });
        }
    }