using System.IO;
using System.Linq;
using System.Security.Cryptography;
using System.Text;
using System.Text.Json;
using API.Helpers;
using Microsoft.AspNetCore.Http;
using Microsoft.Net.Http.Headers;
namespace API.Extensions;
public static class HttpExtensions
{
public static void AddPaginationHeader(this HttpResponse response, int currentPage,
int itemsPerPage, int totalItems, int totalPages)
{
var paginationHeader = new PaginationHeader(currentPage, itemsPerPage, totalItems, totalPages);
var options = new JsonSerializerOptions()
{
PropertyNamingPolicy = JsonNamingPolicy.CamelCase
};
response.Headers.Add("Pagination", JsonSerializer.Serialize(paginationHeader, options));
response.Headers.Add("Access-Control-Expose-Headers", "Pagination");
}
///
/// Calculates SHA256 hash for a byte[] and sets as ETag. Ensures Cache-Control: private header is added.
///
///
/// If byte[] is null or empty, will only add cache-control
public static void AddCacheHeader(this HttpResponse response, byte[] content)
{
if (content is not {Length: > 0}) return;
response.Headers.Add(HeaderNames.ETag, string.Concat(SHA256.HashData(content).Select(x => x.ToString("X2"))));
response.Headers.CacheControl = $"private,max-age=100";
}
///
/// Calculates SHA256 hash for a cover image filename and sets as ETag. Ensures Cache-Control: private header is added.
///
///
///
/// Maximum amount of seconds to set for Cache-Control
public static void AddCacheHeader(this HttpResponse response, string filename, int maxAge = 10)
{
if (filename is not {Length: > 0}) return;
var hashContent = filename + File.GetLastWriteTimeUtc(filename);
response.Headers.Add("ETag", string.Concat(SHA256.HashData(Encoding.UTF8.GetBytes(hashContent)).Select(x => x.ToString("X2"))));
if (maxAge != 10)
{
response.Headers.CacheControl = $"max-age={maxAge}";
}
}
}