hopefully not a horribly foolish refactoring

Femto.Modules.Blog/Application/Queries/GetPosts/Dto/GetPostsQueryResult.cs

@@ -0,0 +1,3 @@
+namespace Femto.Modules.Blog.Application.Queries.GetPosts.Dto;
+
+public record GetPostsQueryResult(IList<PostDto> Posts, Guid? Next);

Femto.Modules.Blog/Application/Queries/GetPosts/Dto/PostAuthorDto.cs

@@ -0,0 +1,3 @@
+namespace Femto.Modules.Blog.Application.Queries.GetPosts.Dto;
+
+public record PostAuthorDto(Guid AuthorId, string Username);

Femto.Modules.Blog/Application/Queries/GetPosts/Dto/PostDto.cs

@@ -0,0 +1,3 @@
+namespace Femto.Modules.Blog.Application.Queries.GetPosts.Dto;
+
+public record PostDto(Guid PostId, string Text, IList<PostMediaDto> Media, DateTimeOffset CreatedAt, PostAuthorDto Author);

Femto.Modules.Blog/Application/Queries/GetPosts/Dto/PostMediaDto.cs

@@ -0,0 +1,3 @@
+namespace Femto.Modules.Blog.Application.Queries.GetPosts.Dto;
+
+public record PostMediaDto(Uri Url, int? Width, int? Height);

Femto.Modules.Blog/Application/Queries/GetPosts/GetPostsQuery.cs

@@ -0,0 +1,25 @@
+using Femto.Common.Domain;
+using Femto.Modules.Blog.Application.Queries.GetPosts.Dto;
+
+namespace Femto.Modules.Blog.Application.Queries.GetPosts;
+
+public class GetPostsQuery : IQuery<GetPostsQueryResult>
+{
+    public Guid? From { get; init; }
+    public int Amount { get; init; } = 20;
+    public Guid? AuthorId { get; init; }
+    public string? Author { get; set; }
+    
+    /// <summary>
+    /// Default is to load in reverse chronological order
+    /// TODO this is not exposed on the client as it probably wouldn't work that well
+    /// </summary>
+    public GetPostsDirection Direction { get; init; } = GetPostsDirection.Backward;
+
+}
+
+public enum GetPostsDirection
+{
+    Forward,
+    Backward
+}

Femto.Modules.Blog/Application/Queries/GetPosts/GetPostsQueryHandler.cs

@@ -0,0 +1,109 @@
+using Dapper;
+using Femto.Common.Infrastructure.DbConnection;
+using Femto.Modules.Blog.Application.Queries.GetPosts.Dto;
+using MediatR;
+
+namespace Femto.Modules.Blog.Application.Queries.GetPosts;
+
+public class GetPostsQueryHandler(IDbConnectionFactory connectionFactory)
+    : IRequestHandler<GetPostsQuery, GetPostsQueryResult>
+{
+    public async Task<GetPostsQueryResult> Handle(
+        GetPostsQuery query,
+        CancellationToken cancellationToken
+    )
+    {
+        using var conn = connectionFactory.GetConnection();
+
+        var orderBy = query.Direction is GetPostsDirection.Backward ? "desc" : "asc";
+        var pageFilter = query.Direction is GetPostsDirection.Backward ? "<=" : ">=";
+
+        // lang=sql
+        var sql = $$"""
+            with page as (
+                select blog.post.*, blog.author.username as Username, blog.author.id as AuthorId
+                from blog.post
+                inner join blog.author on blog.author.id = blog.post.author_id
+                where (@username is null or blog.author.username = @username)
+                and (@authorGuid is null or blog.author.id = @authorGuid)
+                and (@cursor is null or blog.post.id {{pageFilter}} @cursor)
+                order by blog.post.id {{orderBy}}
+                limit @amount
+            )
+            select
+                page.id as PostId,
+                page.content as Content,
+                blog.post_media.url as MediaUrl,
+                blog.post_media.width as MediaWidth,
+                blog.post_media.height as MediaHeight,
+                page.posted_on as PostedOn,
+                page.Username,
+                page.AuthorId
+                from page
+            left join blog.post_media on blog.post_media.post_id = page.id
+            order by page.id {{orderBy}}
+            """;
+
+        var result = await conn.QueryAsync<QueryResult>(
+            sql,
+            new
+            {
+                username = query.Author,
+                authorGuid = query.AuthorId,
+                cursor = query.From,
+                // load an extra one to take for the curst
+                amount = query.Amount + 1,
+            }
+        );
+
+        var rows = result.ToList();
+
+        var posts = rows.GroupBy(row => row.PostId)
+            .Select(group =>
+            {
+                var postId = group.Key;
+                var post = group.First();
+                var media = group
+                    .Select(row =>
+                    {
+                        if (row.MediaUrl is not null)
+                        {
+                            return new PostMediaDto(
+                                new Uri(row.MediaUrl),
+                                row.MediaHeight,
+                                row.MediaHeight
+                            );
+                        }
+                        else
+                            return null;
+                    })
+                    .OfType<PostMediaDto>()
+                    .ToList();
+                return new PostDto(
+                    postId,
+                    post.Content,
+                    media,
+                    post.PostedOn,
+                    new PostAuthorDto(post.AuthorId, post.Username)
+                );
+            })
+            .ToList();
+
+        var next = rows.Count >= query.Amount ? rows.LastOrDefault()?.PostId : null;
+
+        return new GetPostsQueryResult(posts, next);
+    }
+
+    internal class QueryResult
+    {
+        public Guid PostId { get; set; }
+        public string Content { get; set; }
+        public string? MediaUrl { get; set; }
+        public string? MediaType { get; set; }
+        public int? MediaWidth { get; set; }
+        public int? MediaHeight { get; set; }
+        public DateTimeOffset PostedOn { get; set; }
+        public Guid AuthorId { get; set; }
+        public string Username { get; set; }
+    }
+}