using Microsoft.AspNetCore.Mvc.Infrastructure;
using Microsoft.Extensions.DependencyInjection;
using System;
using System.Threading.Tasks;

namespace Microsoft.AspNetCore.Mvc
{
    /// <summary>
    /// Represents an <see cref="ActionResult"/> that when executed
    /// will write a file from a blob to the response.
    /// </summary>
    public class BlobStorageResult : FileResult
    {
        public BlobStorageResult(string blobUrl, string contentType) : base(contentType)
        {
            if (string.IsNullOrWhiteSpace(BlobUrl = blobUrl))
            {
                throw new ArgumentException($"'{nameof(blobUrl)}' cannot be null or whitespace.", nameof(blobUrl));
            }
        }

        /// <summary>Gets the URL for the block blob to be returned.</summary>
        public string BlobUrl { get; }

        /// <summary>Gets or sets the <c>Content-Type</c> header if the value is already known.</summary>
        public long? ContentLength { get; set; }

        /// <summary>
        /// Gets or sets whether blob properties should be retrieved before downloading.
        /// Useful when the file size is not known in advance
        /// </summary>
        public bool GetPropertiesBeforeDownload { get; set; }

        /// <inheritdoc/>
        public override Task ExecuteResultAsync(ActionContext context)
        {
            if (context == null) throw new ArgumentNullException(nameof(context));

            var executor = context.HttpContext.RequestServices.GetRequiredService<IActionResultExecutor<BlobStorageResult>>();
            return executor.ExecuteAsync(context, this);
        }
    }
}