using PostFundManagement.Application.Services.Shared;
using PostFundManagement.Domain.Errors;

namespace PostFundManagement.Application.Abstractions;

public abstract class S3ServiceBase(IAmazonS3 amazonS3)
{
    protected readonly IAmazonS3 Client = amazonS3;

    protected abstract string BucketName { get; }
    protected abstract string CdnBaseUrl { get; }

    public virtual async ValueTask<Result<string>> UploadFileAsync(string fileName, Stream fileStream, string contentType, CancellationToken cancellationToken = default) =>
        await Result.Try((Func<ValueTask<Result<string>>>)(async () =>
        {
            if (string.IsNullOrWhiteSpace(BucketName))
                return Result.Fail<string>(Domain.Errors.ValidationError.Create("Bucket name is not configured."));

            if (string.IsNullOrWhiteSpace(CdnBaseUrl))
                return Result.Fail<string>(Domain.Errors.ValidationError.Create("CDN base URL is not configured."));

            await using var stream = new MemoryStream();

            await fileStream.CopyToAsync(stream, cancellationToken);
            await fileStream.DisposeAsync();

            stream.Seek(0, SeekOrigin.Begin);

            var fileHash = HashService.StreamToSha256Hash(stream);

            if (string.IsNullOrWhiteSpace(fileHash))
                return Result.Fail<string>(CreateError.Create("Failed to compute file hash."));

            var fileKey = $"{fileHash.ToLower(CultureInfo.InvariantCulture)}{Path.GetExtension(fileName)}";

            var putRequest = new PutObjectRequest
            {
                BucketName = BucketName,
                Key = fileKey,
                InputStream = stream,
                ContentType = contentType,
                UseChunkEncoding = false,
            };

            stream.Seek(0, SeekOrigin.Begin);

            var response = await Client.PutObjectAsync(putRequest, cancellationToken);

            return response.HttpStatusCode != HttpStatusCode.OK
                ? Result.Fail<string>(CreateError.Create($"Failed to upload {fileName} to S3."))
                : Result.Ok($"{CdnBaseUrl}/{fileKey}");
        }));

    public virtual async ValueTask<Result> DeleteFileAsync(string fileKey, CancellationToken cancellationToken = default) =>
        await Result.Try((Func<ValueTask<Result>>)(async () =>
        {
            if (string.IsNullOrWhiteSpace(BucketName))
                return Result.Fail(NotFoundError.Create("Bucket name is not configured."));

            var response = await Client.DeleteObjectAsync(new DeleteObjectRequest
            {
                BucketName = BucketName,
                Key = fileKey
            }, cancellationToken);

            return Result.FailIf(response.HttpStatusCode == HttpStatusCode.NoContent, 
                UpdateError.Create($"Failed to delete {fileKey} from S3."));
        }));
}