using System;
using System.Collections.Generic;
using System.IO;
using System.Threading.Tasks;
using Azure.Storage.Blobs;
using Azure.Storage.Blobs.Models;
using Azure.Storage.Sas;
using Bit.Core.Enums;
using Bit.Core.Models.Data;
using Bit.Core.Models.Table;
using Bit.Core.Settings;

namespace Bit.Core.Services
{
    public class AzureAttachmentStorageService : IAttachmentStorageService
    {
        public FileUploadType FileUploadType => FileUploadType.Azure;
        public const string EventGridEnabledContainerName = "attachments-v2";
        private const string _defaultContainerName = "attachments";
        private readonly static string[] _attachmentContainerName = { "attachments", "attachments-v2" };
        private static readonly TimeSpan blobLinkLiveTime = TimeSpan.FromMinutes(1);
        private readonly BlobServiceClient _blobServiceClient;
        private readonly Dictionary<string, BlobContainerClient> _attachmentContainers = new Dictionary<string, BlobContainerClient>();
        private string BlobName(Guid cipherId, CipherAttachment.MetaData attachmentData, Guid? organizationId = null, bool temp = false) =>
            string.Concat(
                temp ? "temp/" : "",
                $"{cipherId}/",
                organizationId != null ? $"{organizationId.Value}/" : "",
                attachmentData.AttachmentId
            );

        public static (string cipherId, string organizationId, string attachmentId) IdentifiersFromBlobName(string blobName)
        {
            var parts = blobName.Split('/');
            switch (parts.Length)
            {
                case 4:
                    return (parts[1], parts[2], parts[3]);
                case 3:
                    if (parts[0] == "temp")
                    {
                        return (parts[1], null, parts[2]);
                    }
                    else
                    {
                        return (parts[0], parts[1], parts[2]);
                    }
                case 2:
                    return (parts[0], null, parts[1]);
                default:
                    throw new Exception("Cannot determine cipher information from blob name");
            }
        }

        public AzureAttachmentStorageService(
            GlobalSettings globalSettings)
        {
            _blobServiceClient = new BlobServiceClient(globalSettings.Attachment.ConnectionString);
        }

        public async Task<string> GetAttachmentDownloadUrlAsync(Cipher cipher, CipherAttachment.MetaData attachmentData)
        {
            await InitAsync(attachmentData.ContainerName);
            var blobClient = _attachmentContainers[attachmentData.ContainerName].GetBlobClient(BlobName(cipher.Id, attachmentData));
            var sasUri = blobClient.GenerateSasUri(BlobSasPermissions.Read, DateTime.UtcNow.Add(blobLinkLiveTime));
            return sasUri.ToString();
        }

        public async Task<string> GetAttachmentUploadUrlAsync(Cipher cipher, CipherAttachment.MetaData attachmentData)
        {
            await InitAsync(EventGridEnabledContainerName);
            var blobClient = _attachmentContainers[EventGridEnabledContainerName].GetBlobClient(BlobName(cipher.Id, attachmentData));
            attachmentData.ContainerName = EventGridEnabledContainerName;
            var sasUri = blobClient.GenerateSasUri(BlobSasPermissions.Create | BlobSasPermissions.Write, DateTime.UtcNow.Add(blobLinkLiveTime));
            return sasUri.ToString();
        }

        public async Task UploadNewAttachmentAsync(Stream stream, Cipher cipher, CipherAttachment.MetaData attachmentData)
        {
            attachmentData.ContainerName = _defaultContainerName;
            await InitAsync(_defaultContainerName);
            var blobClient = _attachmentContainers[_defaultContainerName].GetBlobClient(BlobName(cipher.Id, attachmentData));

            var metadata = new Dictionary<string, string>();
            metadata.Add("cipherId", cipher.Id.ToString());
            if (cipher.UserId.HasValue)
            {
                metadata.Add("userId", cipher.UserId.Value.ToString());
            }
            else
            {
                metadata.Add("organizationId", cipher.OrganizationId.Value.ToString());
            }

            var headers = new BlobHttpHeaders
            {
                ContentDisposition = $"attachment; filename=\"{attachmentData.AttachmentId}\""
            };
            await blobClient.UploadAsync(stream, new BlobUploadOptions { Metadata = metadata, HttpHeaders = headers });
        }

        public async Task UploadShareAttachmentAsync(Stream stream, Guid cipherId, Guid organizationId, CipherAttachment.MetaData attachmentData)
        {
            attachmentData.ContainerName = _defaultContainerName;
            await InitAsync(_defaultContainerName);
            var blobClient = _attachmentContainers[_defaultContainerName].GetBlobClient(
                BlobName(cipherId, attachmentData, organizationId, temp: true));

            var metadata = new Dictionary<string, string>();
            metadata.Add("cipherId", cipherId.ToString());
            metadata.Add("organizationId", organizationId.ToString());

            var headers = new BlobHttpHeaders
            {
                ContentDisposition = $"attachment; filename=\"{attachmentData.AttachmentId}\""
            };
            await blobClient.UploadAsync(stream, new BlobUploadOptions { Metadata = metadata, HttpHeaders = headers });
        }

        public async Task StartShareAttachmentAsync(Guid cipherId, Guid organizationId, CipherAttachment.MetaData data)
        {
            await InitAsync(data.ContainerName);
            var source = _attachmentContainers[data.ContainerName].GetBlobClient(
                    BlobName(cipherId, data, organizationId, temp: true));
            if (!await source.ExistsAsync())
            {
                return;
            }

            await InitAsync(_defaultContainerName);
            var dest = _attachmentContainers[_defaultContainerName].GetBlobClient(BlobName(cipherId, data));
            if (!await dest.ExistsAsync())
            {
                return;
            }

            var original = _attachmentContainers[_defaultContainerName].GetBlobClient(
                BlobName(cipherId, data, temp: true));
            await original.DeleteIfExistsAsync();
            await original.StartCopyFromUriAsync(dest.Uri);

            await dest.DeleteIfExistsAsync();
            await dest.StartCopyFromUriAsync(source.Uri);
        }

        public async Task RollbackShareAttachmentAsync(Guid cipherId, Guid organizationId, CipherAttachment.MetaData attachmentData, string originalContainer)
        {
            await InitAsync(attachmentData.ContainerName);
            var source = _attachmentContainers[attachmentData.ContainerName].GetBlobClient(
                BlobName(cipherId, attachmentData, organizationId, temp: true));
            await source.DeleteIfExistsAsync();

            await InitAsync(originalContainer);
            var original = _attachmentContainers[originalContainer].GetBlobClient(
                BlobName(cipherId, attachmentData, temp: true));
            if (!await original.ExistsAsync())
            {
                return;
            }

            var dest = _attachmentContainers[originalContainer].GetBlobClient(
                BlobName(cipherId, attachmentData));
            await dest.DeleteIfExistsAsync();
            await dest.StartCopyFromUriAsync(original.Uri);
            await original.DeleteIfExistsAsync();
        }

        public async Task DeleteAttachmentAsync(Guid cipherId, CipherAttachment.MetaData attachmentData)
        {
            await InitAsync(attachmentData.ContainerName);
            var blobClient = _attachmentContainers[attachmentData.ContainerName].GetBlobClient(
                BlobName(cipherId, attachmentData));
            await blobClient.DeleteIfExistsAsync();
        }

        public async Task CleanupAsync(Guid cipherId) => await DeleteAttachmentsForPathAsync($"temp/{cipherId}");

        public async Task DeleteAttachmentsForCipherAsync(Guid cipherId) =>
            await DeleteAttachmentsForPathAsync(cipherId.ToString());

        public async Task DeleteAttachmentsForOrganizationAsync(Guid organizationId)
        {
            await InitAsync(_defaultContainerName);
        }

        public async Task DeleteAttachmentsForUserAsync(Guid userId)
        {
            await InitAsync(_defaultContainerName);
        }

        public async Task<(bool, long?)> ValidateFileAsync(Cipher cipher, CipherAttachment.MetaData attachmentData, long leeway)
        {
            await InitAsync(attachmentData.ContainerName);

            var blobClient = _attachmentContainers[attachmentData.ContainerName].GetBlobClient(BlobName(cipher.Id, attachmentData));

            try
            {
                var blobProperties = await blobClient.GetPropertiesAsync();

                var metadata = blobProperties.Value.Metadata;
                metadata["cipherId"] = cipher.Id.ToString();
                if (cipher.UserId.HasValue)
                {
                    metadata["userId"] = cipher.UserId.Value.ToString();
                }
                else
                {
                    metadata["organizationId"] = cipher.OrganizationId.Value.ToString();
                }
                await blobClient.SetMetadataAsync(metadata);

                var headers = new BlobHttpHeaders
                {
                    ContentDisposition = $"attachment; filename=\"{attachmentData.AttachmentId}\""
                };
                await blobClient.SetHttpHeadersAsync(headers);

                var length = blobProperties.Value.ContentLength;
                if (length < attachmentData.Size - leeway || length > attachmentData.Size + leeway)
                {
                    return (false, length);
                }

                return (true, length);
            }
            catch (Exception ex)
            {
                return (false, null);
            }
        }

        private async Task DeleteAttachmentsForPathAsync(string path)
        {
            foreach (var container in _attachmentContainerName)
            {
                await InitAsync(container);
                var blobContainerClient = _attachmentContainers[container];

                var blobItems = blobContainerClient.GetBlobsAsync(BlobTraits.None, BlobStates.None, prefix: path);
                await foreach (var blobItem in blobItems)
                {
                    BlobClient blobClient = blobContainerClient.GetBlobClient(blobItem.Name);
                    await blobClient.DeleteIfExistsAsync();
                }
            }
        }

        private async Task InitAsync(string containerName)
        {
            if (!_attachmentContainers.ContainsKey(containerName) || _attachmentContainers[containerName] == null)
            {
                _attachmentContainers[containerName] = _blobServiceClient.GetBlobContainerClient(containerName);
                if (containerName == "attachments")
                {
                    await _attachmentContainers[containerName].CreateIfNotExistsAsync(PublicAccessType.Blob, null, null);
                }
                else
                {
                    await _attachmentContainers[containerName].CreateIfNotExistsAsync(PublicAccessType.None, null, null);
                }
            }
        }
    }
}