64 lines
No EOL
2.1 KiB
C#
64 lines
No EOL
2.1 KiB
C#
using Iceshrimp.Backend.Core.Database;
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using Microsoft.AspNetCore.Http.Extensions;
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using Microsoft.AspNetCore.Mvc;
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using Microsoft.AspNetCore.Mvc.Filters;
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namespace Iceshrimp.Backend.Controllers.Attributes;
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public class LinkPaginationAttribute(int defaultLimit, int maxLimit) : ActionFilterAttribute
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{
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public int DefaultLimit => defaultLimit;
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public int MaxLimit => maxLimit;
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public override async Task OnActionExecutionAsync(ActionExecutingContext context, ActionExecutionDelegate next)
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{
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ArgumentNullException.ThrowIfNull(context, nameof(context));
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ArgumentNullException.ThrowIfNull(next, nameof(next));
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OnActionExecuting(context);
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if (context.Result != null) return;
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var result = await next();
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HandlePagination(context.ActionArguments, result);
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OnActionExecuted(result);
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}
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private void HandlePagination(IDictionary<string, object?> actionArguments, ActionExecutedContext context)
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{
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if (actionArguments.Count == 0) return;
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var query = actionArguments.Values.OfType<IPaginationQuery>().FirstOrDefault();
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if (query == null) return;
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if (context.Result is not OkObjectResult result) return;
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if (result.Value is not IEnumerable<IEntity> entities) return;
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var ids = entities.Select(p => p.Id).ToList();
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if (ids.Count == 0) return;
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if (query.MinId != null) ids.Reverse();
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List<string> links = [];
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var limit = Math.Min(query.Limit ?? defaultLimit, maxLimit);
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var request = context.HttpContext.Request;
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if (ids.Count >= limit)
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{
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var next = new QueryBuilder { { "limit", limit.ToString() }, { "max_id", ids.Last() } };
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links.Add($"<{GetUrl(request, next.ToQueryString())}>; rel=\"next\"");
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}
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var prev = new QueryBuilder { { "limit", limit.ToString() }, { "min_id", ids.First() } };
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links.Add($"<{GetUrl(request, prev.ToQueryString())}>; rel=\"prev\"");
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context.HttpContext.Response.Headers.Link = string.Join(", ", links);
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}
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private static string GetUrl(HttpRequest request, QueryString query)
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{
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return UriHelper.BuildAbsolute("https", request.Host, request.PathBase, request.Path, query);
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}
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}
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public interface IPaginationQuery
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{
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public string? MinId { get; }
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public int? Limit { get; }
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} |