using System.Runtime.CompilerServices;
using Amazon.S3;
using Amazon.S3.Model;
using Amazon.S3.Transfer;
using Microsoft.Extensions.Logging;
using MimeMapping;
using Musify.Application.Contracts;
using Musify.Application.Shared;
using Musify.Infrastructure.Configuration;

namespace Musify.Infrastructure.Services;

public sealed class StorageService(
    IAmazonS3 amazonS3,
    ILogger<StorageService> logger,
    InfrastructureStorageConfiguration storageClientConfiguration)
    : IStorageService
{
    public async Task<Stream?> GetFileAsync(string bucket, string key, CancellationToken cancellationToken)
    {
        try
        {
            var response = await amazonS3.GetObjectAsync(
                new GetObjectRequest { BucketName = bucket, Key = key }, cancellationToken);
            logger.LogDebug("Retrieved file from S3 {Bucket}/{Key}", bucket, key);
            return response.ResponseStream;
        }
        catch (AmazonS3Exception exception) when (exception.ErrorCode == "NoSuchKey")
        {
            logger.LogDebug("File not found in S3 {Bucket}/{Key}", bucket, key);
            return null;
        }
    }

    public async Task<string> GetUploadUrlAsync(
        string bucket,
        string key,
        string contentType,
        TimeSpan expirationTime,
        bool preventOverwrite = true,
        CancellationToken cancellationToken = default)
    {
        var request = new GetPreSignedUrlRequest
        {
            BucketName = bucket,
            Key = key,
            Expires = DateTime.UtcNow + expirationTime,
            Protocol = storageClientConfiguration.UseHttp ? Protocol.HTTP : Protocol.HTTPS,
            Verb = HttpVerb.PUT,
            ContentType = contentType
        };

        if (preventOverwrite)
            request.Headers["If-None-Match"] = "*";

        logger.LogDebug("Generating pre-signed upload URL for {Bucket}/{Key}", bucket, key);
        return await amazonS3.GetPreSignedURLAsync(request);
    }

    public async Task<ObjectMetaData?> HeadObjectAsync(string bucket, string key, CancellationToken cancellationToken)
    {
        try
        {
            var response = await amazonS3.GetObjectMetadataAsync(bucket, key, cancellationToken);
            return new ObjectMetaData(response.Headers.ContentType, response.ContentLength);
        }
        catch (AmazonS3Exception exception) when (exception.StatusCode == System.Net.HttpStatusCode.NotFound)
        {
            return null;
        }
    }

    public async Task RemoveFileAsync(string bucket, string key, CancellationToken cancellationToken)
    {
        logger.LogDebug("Removing file from S3 {Bucket}/{Key}", bucket, key);
        await amazonS3.DeleteObjectAsync(new DeleteObjectRequest { BucketName = bucket, Key = key }, cancellationToken);
    }

    public async Task<IReadOnlyList<string>> TransferFilesAsync(
        string sourceDirectory, string bucket, string route, CancellationToken cancellationToken)
    {
        using var transferUtility = new TransferUtility(amazonS3);

        var uploadedKeys = new List<string>();

        foreach (var filePath in Directory.GetFiles(sourceDirectory, "*"))
        {
            var key = StorageKey.Combine(route, Path.GetFileName(filePath));

            await transferUtility.UploadAsync(
                new TransferUtilityUploadRequest
                {
                    FilePath = filePath,
                    BucketName = bucket,
                    Key = key,
                    ContentType = MimeUtility.GetMimeMapping(filePath)
                },
                cancellationToken);

            uploadedKeys.Add(key);
            logger.LogDebug("Transferred file to S3 {Bucket}/{Key}", bucket, key);
        }

        logger.LogInformation("Transferred {Count} files to {Bucket}/{Route}", uploadedKeys.Count, bucket, route);

        return uploadedKeys;
    }

    public async Task UploadFileAsync(string filePath, string bucket, string key, CancellationToken cancellationToken)
    {
        await using var fileStream = File.OpenRead(filePath);
        await UploadFileAsync(fileStream, MimeUtility.GetMimeMapping(filePath), bucket, key, cancellationToken);
    }

    public async Task UploadFileAsync(Stream sourceStream, string contentType, string bucket, string key, CancellationToken cancellationToken)
    {
        await amazonS3.PutObjectAsync(
            new PutObjectRequest { BucketName = bucket, ContentType = contentType, InputStream = sourceStream, Key = key },
            cancellationToken);
        logger.LogDebug("Uploaded file to S3 {Bucket}/{Key}", bucket, key);
    }

    public async Task CopyFileAsync(
        string sourceBucket, string sourceKey, string destinationBucket, string destinationKey, CancellationToken cancellationToken)
    {
        await amazonS3.CopyObjectAsync(
            new CopyObjectRequest
            {
                SourceBucket = sourceBucket,
                SourceKey = sourceKey,
                DestinationBucket = destinationBucket,
                DestinationKey = destinationKey
            },
            cancellationToken);

        logger.LogDebug("Copied file from {SourceBucket}/{SourceKey} to {DestinationBucket}/{DestinationKey}",
            sourceBucket, sourceKey, destinationBucket, destinationKey);
    }

    public async IAsyncEnumerable<StorageObject> ListObjectsAsync(
        string bucket, string prefix, [EnumeratorCancellation] CancellationToken cancellationToken)
    {
        var listRequest = new ListObjectsV2Request
        {
            BucketName = bucket,
            Prefix = prefix.EndsWith('/') ? prefix : $"{prefix}/"
        };

        ListObjectsV2Response listResponse;
        do
        {
            listResponse = await amazonS3.ListObjectsV2Async(listRequest, cancellationToken);
            foreach (var s3Object in listResponse.S3Objects ?? [])
                yield return new StorageObject(s3Object.Key, (s3Object.LastModified ?? DateTime.UtcNow).ToUniversalTime());

            listRequest.ContinuationToken = listResponse.NextContinuationToken;
        }
        while (listResponse.IsTruncated == true);
    }
}