✨ Posting

DysonNetwork.Sphere/Post/PostService.cs

@@ -1,6 +1,157 @@
+using DysonNetwork.Sphere.Storage;
+using Microsoft.EntityFrameworkCore;
+using NodaTime;
+
 namespace DysonNetwork.Sphere.Post;
 
-public class PostService(AppDatabase db)
+public class PostService(AppDatabase db, FileService fs)
 {
-    
+    public async Task<Post> PostAsync(
+        Post post,
+        List<string>? attachments = null,
+        List<string>? tags = null,
+        List<string>? categories = null
+    )
+    {
+        if (attachments is not null)
+        {
+            post.Attachments = await db.Files.Where(e => attachments.Contains(e.Id)).ToListAsync();
+            // Re-order the list to match the id list places
+            post.Attachments = attachments
+                .Select(id => post.Attachments.First(a => a.Id == id))
+                .ToList();
+        }
+
+        if (tags is not null)
+        {
+            var existingTags = await db.PostTags.Where(e => tags.Contains(e.Slug)).ToListAsync();
+
+            // Determine missing slugs
+            var existingSlugs = existingTags.Select(t => t.Slug).ToHashSet();
+            var missingSlugs = tags.Where(slug => !existingSlugs.Contains(slug)).ToList();
+
+            var newTags = missingSlugs.Select(slug => new PostTag { Slug = slug }).ToList();
+            if (newTags.Count > 0)
+            {
+                await db.PostTags.AddRangeAsync(newTags);
+                await db.SaveChangesAsync();
+            }
+
+            post.Tags = existingTags.Concat(newTags).ToList();
+        }
+
+        if (categories is not null)
+        {
+            post.Categories = await db.PostCategories.Where(e => categories.Contains(e.Slug)).ToListAsync();
+            if (post.Categories.Count != categories.Distinct().Count())
+                throw new InvalidOperationException("Categories contains one or more categories that wasn't exists.");
+        }
+        
+        if (post.Empty)
+            throw new InvalidOperationException("Cannot create a post with barely no content.");
+
+        // TODO Notify the subscribers
+
+        db.Posts.Add(post);
+        await db.SaveChangesAsync();
+        await fs.MarkUsageRangeAsync(post.Attachments, 1);
+
+        return post;
+    }
+
+    public async Task<Post> UpdatePostAsync(
+        Post post,
+        List<string>? attachments = null,
+        List<string>? tags = null,
+        List<string>? categories = null
+    )
+    {
+        post.EditedAt = Instant.FromDateTimeUtc(DateTime.UtcNow);
+
+        if (attachments is not null)
+        {
+            var records = await db.Files.Where(e => attachments.Contains(e.Id)).ToListAsync();
+
+            var previous = post.Attachments.ToDictionary(f => f.Id);
+            var current = records.ToDictionary(f => f.Id);
+
+            // Detect added files
+            var added = current.Keys.Except(previous.Keys).Select(id => current[id]).ToList();
+            // Detect removed files
+            var removed = previous.Keys.Except(current.Keys).Select(id => previous[id]).ToList();
+
+            // Update attachments
+            post.Attachments = attachments.Select(id => current[id]).ToList();
+
+            // Call mark usage
+            await fs.MarkUsageRangeAsync(added, 1);
+            await fs.MarkUsageRangeAsync(removed, -1);
+        }
+        
+        if (tags is not null)
+        {
+            var existingTags = await db.PostTags.Where(e => tags.Contains(e.Slug)).ToListAsync();
+
+            // Determine missing slugs
+            var existingSlugs = existingTags.Select(t => t.Slug).ToHashSet();
+            var missingSlugs = tags.Where(slug => !existingSlugs.Contains(slug)).ToList();
+
+            var newTags = missingSlugs.Select(slug => new PostTag { Slug = slug }).ToList();
+            if (newTags.Count > 0)
+            {
+                await db.PostTags.AddRangeAsync(newTags);
+                await db.SaveChangesAsync();
+            }
+
+            post.Tags = existingTags.Concat(newTags).ToList();
+        }
+
+        if (categories is not null)
+        {
+            post.Categories = await db.PostCategories.Where(e => categories.Contains(e.Slug)).ToListAsync();
+            if (post.Categories.Count != categories.Distinct().Count())
+                throw new InvalidOperationException("Categories contains one or more categories that wasn't exists.");
+        } 
+        
+        if (post.Empty)
+            throw new InvalidOperationException("Cannot edit a post to barely no content.");
+        
+        db.Update(post);
+        await db.SaveChangesAsync();
+        
+        return post;
+    }
+
+    public async Task DeletePostAsync(Post post)
+    {
+        db.Posts.Remove(post);
+        await db.SaveChangesAsync();
+        await fs.MarkUsageRangeAsync(post.Attachments, -1);
+    }
+}
+
+public static class PostQueryExtensions
+{
+    public static IQueryable<Post> FilterWithVisibility(this IQueryable<Post> source, Account.Account? currentUser,
+        bool isListing = false)
+    {
+        var now = Instant.FromDateTimeUtc(DateTime.UtcNow);
+
+        source = isListing switch
+        {
+            true when currentUser is not null => source.Where(e =>
+                e.Visibility != PostVisibility.Unlisted || e.Publisher.AccountId == currentUser.Id),
+            true => source.Where(e => e.Visibility != PostVisibility.Unlisted),
+            _ => source
+        };
+
+        if (currentUser is null)
+            return source
+                .Where(e => e.PublishedAt != null && now >= e.PublishedAt)
+                .Where(e => e.Visibility == PostVisibility.Public);
+
+        return source
+            .Where(e => e.PublishedAt != null && now >= e.PublishedAt && e.Publisher.AccountId == currentUser.Id)
+            .Where(e => e.Visibility != PostVisibility.Private || e.Publisher.AccountId == currentUser.Id);
+    }
 }