using Microsoft.EntityFrameworkCore;
using eprintServer.Data;
using eprintServer.Entities;
using eprintServer.Interfaces;
using Amazon.S3;
using Amazon.S3.Model;
using Amazon.S3.Transfer;

namespace eprintServer.Services
{
   public class FileStorageService : IFileStorageService
    {
        private readonly IAmazonS3 _s3Client;
        private readonly DataContext _context;
        private readonly IConfiguration _config;
        private readonly string _bucketName;

        public FileStorageService(IAmazonS3 s3Client, DataContext context, IConfiguration config)
        {
            _s3Client = s3Client;
            _context = context;
            _config = config;
            _bucketName = _config["S3Config:BucketName"];
        }

        public async Task<FileModel> SaveFileAsync(IFormFile file, string subDirectory)
        {
            var fileExtension = Path.GetExtension(file.FileName);
            var uniqueFileName = $"{Guid.NewGuid()}{fileExtension}";
            
            // Format the S3 Key (path inside the bucket)
            var s3Key = $"{subDirectory.TrimEnd('/')}/{uniqueFileName}";

            using (var stream = file.OpenReadStream())
            {
                var uploadRequest = new PutObjectRequest
                {
                    BucketName = _bucketName,
                    Key = s3Key,
                    InputStream = stream,
                    ContentType = file.ContentType,
                    CannedACL = S3CannedACL.PublicRead // Makes the file accessible via URL
                };

                await _s3Client.PutObjectAsync(uploadRequest);
            }

            // Construct the public URL
            // Format: https://{bucket}.fsn1.your-objectstorage.com/{key}
            var baseUrl = _config["S3Config:ServiceUrl"].Replace("https://", $"https://{_bucketName}.");
            var fileUrl = $"{baseUrl}/{s3Key}";

            var fileModel = new FileModel
            {
                Name = file.FileName,
                Url = fileUrl, // Now saving the full Cloud URL
                Type = file.ContentType,
                Size = file.Length
            };

            _context.FileModels.Add(fileModel);
            await _context.SaveChangesAsync();

            return fileModel;
        }

        public async Task DeleteFileAsync(long fileId)
        {
            var fileModel = await _context.FileModels.FindAsync(fileId);
            if (fileModel == null) return;

            // Extract the Key from the URL to delete from S3
            // URL looks like: https://bucket.host.com/folder/file.jpg
            // We need: folder/file.jpg
            var uri = new Uri(fileModel.Url);
            var s3Key = uri.AbsolutePath.TrimStart('/');

            await _s3Client.DeleteObjectAsync(_bucketName, s3Key);

            _context.FileModels.Remove(fileModel);
            await _context.SaveChangesAsync();
        }

        public async Task<List<FileModel>> SaveAllAsync(List<IFormFile> files, string subDirectory)
        {
            var savedFiles = new List<FileModel>();
            foreach (var file in files)
            {
                var savedFile = await SaveFileAsync(file, subDirectory);
                savedFiles.Add(savedFile);
            }
            return savedFiles;
        }


          public async Task<FileModel?> GetFileByIdAsync(long fileId)
        {
            return await _context.FileModels.FindAsync(fileId);
        }

        public async Task<List<FileModel>> GetFilesByIdsAsync(IEnumerable<long> fileIds)
        {
            return await _context.FileModels
                .Where(fm => fileIds.Contains(fm.Id))
                .ToListAsync();
        }
    }
}