using Amazon.Runtime;
using Amazon.S3;
using Amazon.S3.Model;

namespace TheCr3w.Shared.Storage;

public class R2StorageOptions
{
    public string Endpoint { get; set; } = "https://bf705752e38169fedb83efd5b747390e.r2.cloudflarestorage.com";
    public string BucketName { get; set; } = "thecr3w-app";
    public string Region { get; set; } = "auto";
    public string AccessKeyId { get; set; } = string.Empty;
    public string SecretAccessKey { get; set; } = string.Empty;
}

public interface IR2StorageService
{
    string GeneratePreSignedDownloadUrl(string objectKey, TimeSpan? duration = null);
    string GeneratePreSignedUploadUrl(string objectKey, string contentType, TimeSpan? duration = null);
    Task<bool> ObjectExistsAsync(string objectKey, CancellationToken cancellationToken = default);
}

public class R2StorageService : IR2StorageService
{
    private readonly R2StorageOptions _options;
    private readonly IAmazonS3 _s3Client;

    public R2StorageService(R2StorageOptions options)
    {
        _options = options ?? throw new ArgumentNullException(nameof(options));

        var credentials = new BasicAWSCredentials(_options.AccessKeyId, _options.SecretAccessKey);
        var config = new AmazonS3Config
        {
            ServiceURL = _options.Endpoint,
            AuthenticationRegion = _options.Region,
            ForcePathStyle = true
        };

        _s3Client = new AmazonS3Client(credentials, config);
    }

    /// <summary>
    /// Generuje krótko żyjący (domyślnie 15 minut) podpisany adres URL (Pre-signed S3 GET)
    /// pozwalający na bezpośrednie pobranie artefaktu z Cloudflare R2 bez obciążania serwera.
    /// </summary>
    public string GeneratePreSignedDownloadUrl(string objectKey, TimeSpan? duration = null)
    {
        var expires = DateTime.UtcNow.Add(duration ?? TimeSpan.FromMinutes(15));
        var request = new GetPreSignedUrlRequest
        {
            BucketName = _options.BucketName,
            Key = objectKey,
            Verb = HttpVerb.GET,
            Expires = expires
        };

        return _s3Client.GetPreSignedURL(request);
    }

    /// <summary>
    /// Generuje krótko żyjący (domyślnie 30 minut) podpisany adres URL (Pre-signed S3 PUT)
    /// pozwalający na bezpieczny upload pliku do Cloudflare R2.
    /// </summary>
    public string GeneratePreSignedUploadUrl(string objectKey, string contentType, TimeSpan? duration = null)
    {
        var expires = DateTime.UtcNow.Add(duration ?? TimeSpan.FromMinutes(30));
        var request = new GetPreSignedUrlRequest
        {
            BucketName = _options.BucketName,
            Key = objectKey,
            Verb = HttpVerb.PUT,
            Expires = expires,
            ContentType = contentType
        };

        return _s3Client.GetPreSignedURL(request);
    }

    public async Task<bool> ObjectExistsAsync(string objectKey, CancellationToken cancellationToken = default)
    {
        try
        {
            var response = await _s3Client.GetObjectMetadataAsync(new GetObjectMetadataRequest
            {
                BucketName = _options.BucketName,
                Key = objectKey
            }, cancellationToken);

            return response.HttpStatusCode == System.Net.HttpStatusCode.OK;
        }
        catch (AmazonS3Exception ex) when (ex.StatusCode == System.Net.HttpStatusCode.NotFound)
        {
            return false;
        }
    }
}