feat: add ability to follow and unfollow a user on their profile page

convex/follows.ts

@@ -0,0 +1,116 @@
+import { v } from 'convex/values';
+import { mutation, query } from './_generated/server';
+import { userQuery } from './users';
+
+export const addFollow = mutation({
+  args: { followingId: v.id('users') },
+  handler: async (ctx, args) => {
+    const clerkUser = await ctx.auth.getUserIdentity();
+
+    if (clerkUser === null) {
+      return;
+    }
+
+    const user = await userQuery(ctx, clerkUser.subject);
+
+    if (user === null) {
+      return;
+    }
+
+    const existingFollow = await ctx.db
+      .query('follows')
+      .withIndex('by_following_follower_id', q =>
+        q.eq('following', args.followingId).eq('follower', user._id)
+      )
+      .unique();
+
+    if (existingFollow !== null) {
+      return;
+    }
+
+    await ctx.db.insert('follows', {
+      following: args.followingId,
+      follower: user._id,
+    });
+  },
+});
+
+export const removeFollow = mutation({
+  args: { followingId: v.id('users') },
+  handler: async (ctx, args) => {
+    const clerkUser = await ctx.auth.getUserIdentity();
+
+    if (clerkUser === null) {
+      return;
+    }
+
+    const user = await userQuery(ctx, clerkUser.subject);
+
+    if (user === null) {
+      return;
+    }
+
+    const existingFollow = await ctx.db
+      .query('follows')
+      .withIndex('by_following_follower_id', q =>
+        q.eq('following', args.followingId).eq('follower', user._id)
+      )
+      .unique();
+
+    if (existingFollow === null) {
+      return;
+    }
+
+    await ctx.db.delete(existingFollow._id);
+  },
+});
+
+export const getUserFollowerCount = query({
+  args: { userId: v.id('users') },
+  handler: async (ctx, args) => {
+    const followers = await ctx.db
+      .query('follows')
+      .withIndex('by_following', q => q.eq('following', args.userId))
+      .collect();
+
+    return followers.length;
+  },
+});
+
+export const getUserFollowingCount = query({
+  args: { userId: v.id('users') },
+  handler: async (ctx, args) => {
+    const followings = await ctx.db
+      .query('follows')
+      .withIndex('by_follower', q => q.eq('follower', args.userId))
+      .collect();
+
+    return followings.length;
+  },
+});
+
+export const getFollowing = query({
+  args: { followingId: v.id('users') },
+  handler: async (ctx, args) => {
+    const currentClerkUser = await ctx.auth.getUserIdentity();
+
+    if (currentClerkUser == null) {
+      return false;
+    }
+
+    const user = await userQuery(ctx, currentClerkUser.subject);
+
+    if (user == null) {
+      return false;
+    }
+
+    const following = await ctx.db
+      .query('follows')
+      .withIndex('by_following_follower_id', q =>
+        q.eq('following', args.followingId).eq('follower', user._id)
+      )
+      .unique();
+
+    return following !== null;
+  },
+});