From 915adb722a23ca9e9410120996559383eb6037c5 Mon Sep 17 00:00:00 2001
From: Aaron William Po <apo2@uwo.ca>
Date: Sun, 9 Apr 2023 18:41:58 -0400
Subject: [PATCH] Implement react-intersection-observer to facilitate infinite
 scroll

Uses react-intersection-observer to load more comments when the last of the previously loaded comments is in the viewport.
---
 components/BeerById/BeerCommentForm.tsx       | 13 +--
 .../BeerById/BeerPostCommentsSection.tsx      | 71 +++++++++++----
 components/BeerById/BeerPostLikeButton.tsx    |  6 +-
 components/BeerById/CommentCardBody.tsx       | 91 +++++++++----------
 .../BeerById/CommentLoadingCardBody.tsx       |  6 +-
 components/ui/Spinner.tsx                     |  4 +-
 contexts/userContext.ts                       |  4 +-
 hooks/useBeerPostComments.ts                  | 47 +++++-----
 package-lock.json                             | 15 +++
 package.json                                  |  1 +
 prisma/seed/create/createNewUsers.ts          |  2 +-
 prisma/seed/index.ts                          |  6 +-
 12 files changed, 157 insertions(+), 109 deletions(-)

diff --git a/components/BeerById/BeerCommentForm.tsx b/components/BeerById/BeerCommentForm.tsx
index 780ceb1..0de427f 100644
--- a/components/BeerById/BeerCommentForm.tsx
+++ b/components/BeerById/BeerCommentForm.tsx
@@ -8,7 +8,6 @@ import { Rating } from 'react-daisyui';
 import { useForm, SubmitHandler } from 'react-hook-form';
 import { z } from 'zod';
 
-
 import { useRouter } from 'next/router';
 import useBeerPostComments from '@/hooks/useBeerPostComments';
 import Button from '../ui/forms/Button';
@@ -18,10 +17,9 @@ import FormLabel from '../ui/forms/FormLabel';
 import FormSegment from '../ui/forms/FormSegment';
 import FormTextArea from '../ui/forms/FormTextArea';
 
-
 interface BeerCommentFormProps {
   beerPost: z.infer<typeof beerPostQueryResult>;
-  mutate: ReturnType<typeof useBeerPostComments>['mutate']
+  mutate: ReturnType<typeof useBeerPostComments>['mutate'];
 }
 
 const BeerCommentForm: FunctionComponent<BeerCommentFormProps> = ({
@@ -43,7 +41,6 @@ const BeerCommentForm: FunctionComponent<BeerCommentFormProps> = ({
     reset({ rating: 0, content: '' });
   }, [reset]);
 
-  const router = useRouter();
   const onSubmit: SubmitHandler<z.infer<typeof BeerCommentValidationSchema>> = async (
     data,
   ) => {
@@ -54,14 +51,8 @@ const BeerCommentForm: FunctionComponent<BeerCommentFormProps> = ({
       rating: data.rating,
       beerPostId: beerPost.id,
     });
+    await mutate();
     reset();
-
-    const submitTasks: Promise<unknown>[] = [
-      router.push(`/beers/${beerPost.id}`, undefined, { scroll: false }),
-      mutate(),
-    ];
-
-    await Promise.all(submitTasks);
   };
 
   const { errors } = formState;
diff --git a/components/BeerById/BeerPostCommentsSection.tsx b/components/BeerById/BeerPostCommentsSection.tsx
index a60559e..bfeb7c9 100644
--- a/components/BeerById/BeerPostCommentsSection.tsx
+++ b/components/BeerById/BeerPostCommentsSection.tsx
@@ -3,20 +3,35 @@ import UserContext from '@/contexts/userContext';
 
 import beerPostQueryResult from '@/services/BeerPost/schema/BeerPostQueryResult';
 
-import { FC, useContext } from 'react';
+import { FC, MutableRefObject, useContext, useRef } from 'react';
 import { z } from 'zod';
 import useBeerPostComments from '@/hooks/useBeerPostComments';
 import { useRouter } from 'next/router';
+import { useInView } from 'react-intersection-observer';
 import BeerCommentForm from './BeerCommentForm';
 
 import CommentCardBody from './CommentCardBody';
 import NoCommentsCard from './NoCommentsCard';
 import CommentLoadingCardBody from './CommentLoadingCardBody';
+import Spinner from '../ui/Spinner';
 
 interface BeerPostCommentsSectionProps {
   beerPost: z.infer<typeof beerPostQueryResult>;
 }
 
+const LoadingComponent: FC<{ length: number }> = ({ length }) => {
+  return (
+    <>
+      {Array.from({ length }).map((_, i) => (
+        <CommentLoadingCardBody key={i} />
+      ))}
+      <div className="p-1">
+        <Spinner size="sm" />
+      </div>
+    </>
+  );
+};
+
 const BeerPostCommentsSection: FC<BeerPostCommentsSectionProps> = ({ beerPost }) => {
   const { user } = useContext(UserContext);
   const router = useRouter();
@@ -24,13 +39,22 @@ const BeerPostCommentsSection: FC<BeerPostCommentsSectionProps> = ({ beerPost })
   const pageNum = parseInt(router.query.comments_page as string, 10) || 1;
   const PAGE_SIZE = 6;
 
-  const { comments, isLoading, mutate, setSize, size, isLoadingMore } =
+  const { comments, isLoading, mutate, setSize, size, isLoadingMore, isAtEnd } =
     useBeerPostComments({
       id,
       pageNum,
       pageSize: PAGE_SIZE,
     });
 
+  const { ref } = useInView({
+    delay: 3000,
+    onChange: (visible) => {
+      if (!visible || isAtEnd) return;
+      setSize(size + 1);
+    },
+  });
+
+  const sectionRef: MutableRefObject<HTMLDivElement | null> = useRef(null);
   return (
     <div className="w-full space-y-3 md:w-[60%]">
       <div className="card h-96 bg-base-300">
@@ -46,19 +70,36 @@ const BeerPostCommentsSection: FC<BeerPostCommentsSectionProps> = ({ beerPost })
       </div>
 
       {comments && !!comments.length && !isLoading && (
-        <div className="card bg-base-300 pb-6">
-          {comments.map((comment) => (
-            <CommentCardBody key={comment.id} comment={comment} mutate={mutate} />
-          ))}
+        <div className="card bg-base-300 pb-6" ref={sectionRef}>
+          {comments.map((comment, index) => {
+            const isLastComment = index === comments.length - 1;
 
-          {isLoadingMore &&
-            Array.from({ length: PAGE_SIZE }).map((_, i) => (
-              <CommentLoadingCardBody key={i} />
-            ))}
+            return (
+              <div ref={isLastComment ? ref : undefined} key={comment.id}>
+                <CommentCardBody comment={comment} mutate={mutate} />
+              </div>
+            );
+          })}
 
-          <button type="button" onClick={() => setSize(size + 1)}>
-            load more
-          </button>
+          {!!isLoadingMore && (
+            <div>
+              <LoadingComponent length={Math.floor(PAGE_SIZE / 2)} />
+            </div>
+          )}
+
+          {isAtEnd && (
+            <div className="flex h-10 items-center justify-center text-center">
+              <button
+                className="btn-ghost btn-sm btn"
+                type="button"
+                onClick={() => {
+                  sectionRef.current!.scrollIntoView({ behavior: 'smooth' });
+                }}
+              >
+                Scroll to top of comments
+              </button>
+            </div>
+          )}
         </div>
       )}
 
@@ -66,9 +107,7 @@ const BeerPostCommentsSection: FC<BeerPostCommentsSectionProps> = ({ beerPost })
 
       {isLoading && (
         <div className="card bg-base-300 pb-6">
-          {Array.from({ length: PAGE_SIZE }).map((_, i) => (
-            <CommentLoadingCardBody key={i} />
-          ))}
+          <LoadingComponent length={PAGE_SIZE} />
         </div>
       )}
     </div>
diff --git a/components/BeerById/BeerPostLikeButton.tsx b/components/BeerById/BeerPostLikeButton.tsx
index 68e4285..bc54a92 100644
--- a/components/BeerById/BeerPostLikeButton.tsx
+++ b/components/BeerById/BeerPostLikeButton.tsx
@@ -3,7 +3,6 @@ import sendLikeRequest from '@/requests/sendLikeRequest';
 import { FC, useEffect, useState } from 'react';
 import { FaThumbsUp, FaRegThumbsUp } from 'react-icons/fa';
 
-
 import useGetLikeCount from '@/hooks/useGetLikeCount';
 
 const BeerPostLikeButton: FC<{
@@ -32,8 +31,9 @@ const BeerPostLikeButton: FC<{
   return (
     <button
       type="button"
-      className={`btn gap-2 rounded-2xl ${!isLiked ? 'btn-ghost outline' : 'btn-primary'
-        }`}
+      className={`btn gap-2 rounded-2xl ${
+        !isLiked ? 'btn-ghost outline' : 'btn-primary'
+      }`}
       onClick={() => {
         handleLike();
       }}
diff --git a/components/BeerById/CommentCardBody.tsx b/components/BeerById/CommentCardBody.tsx
index 21a7a3b..613fb0f 100644
--- a/components/BeerById/CommentCardBody.tsx
+++ b/components/BeerById/CommentCardBody.tsx
@@ -8,11 +8,13 @@ import { FC, useContext } from 'react';
 import { Rating } from 'react-daisyui';
 
 import { FaEllipsisH } from 'react-icons/fa';
+import { useInView } from 'react-intersection-observer';
 import { z } from 'zod';
 
 interface CommentCardProps {
   comment: z.infer<typeof BeerCommentQueryResult>;
   mutate: ReturnType<typeof useBeerPostComments>['mutate'];
+  ref?: ReturnType<typeof useInView>['ref'];
 }
 
 const CommentCardDropdown: FC<CommentCardProps> = ({ comment, mutate }) => {
@@ -42,16 +44,10 @@ const CommentCardDropdown: FC<CommentCardProps> = ({ comment, mutate }) => {
         className="dropdown-content menu rounded-box w-52 bg-base-100 p-2 shadow"
       >
         <li>
-
-
           {isCommentOwner ? (
-
             <button onClick={handleDelete}>Delete</button>
-
           ) : (
-
             <button>Report</button>
-
           )}
         </li>
       </ul>
@@ -59,52 +55,51 @@ const CommentCardDropdown: FC<CommentCardProps> = ({ comment, mutate }) => {
   );
 };
 
-const CommentCardBody: FC<CommentCardProps>
-  = ({ comment, mutate }) => {
-    const { user } = useContext(UserContext);
+const CommentCardBody: FC<CommentCardProps> = ({ comment, mutate, ref }) => {
+  const { user } = useContext(UserContext);
 
-    const timeDistance = useTimeDistance(new Date(comment.createdAt));
+  const timeDistance = useTimeDistance(new Date(comment.createdAt));
 
-    return (
-      <div className="card-body animate-in fade-in-10">
-        <div className="flex flex-col justify-between sm:flex-row">
-          <div>
-            <h3 className="font-semibold sm:text-2xl">
-              <Link href={`/users/${comment.postedBy.id}`} className="link-hover link">
-                {comment.postedBy.username}
-              </Link>
-            </h3>
-            <h4 className="italic">
-              posted{' '}
-              <time
-                className="tooltip tooltip-bottom"
-                data-tip={format(new Date(comment.createdAt), 'MM/dd/yyyy')}
-              >
-                {timeDistance}
-              </time>{' '}
-              ago
-            </h4>
-          </div>
-
-          {user && <CommentCardDropdown comment={comment} mutate={mutate} />}
+  return (
+    <div className="card-body animate-in fade-in-10" ref={ref}>
+      <div className="flex flex-col justify-between sm:flex-row">
+        <div>
+          <h3 className="font-semibold sm:text-2xl">
+            <Link href={`/users/${comment.postedBy.id}`} className="link-hover link">
+              {comment.postedBy.username}
+            </Link>
+          </h3>
+          <h4 className="italic">
+            posted{' '}
+            <time
+              className="tooltip tooltip-bottom"
+              data-tip={format(new Date(comment.createdAt), 'MM/dd/yyyy')}
+            >
+              {timeDistance}
+            </time>{' '}
+            ago
+          </h4>
         </div>
 
-        <div className="space-y-1">
-          <Rating value={comment.rating}>
-            {Array.from({ length: 5 }).map((val, index) => (
-              <Rating.Item
-                name="rating-1"
-                className="mask mask-star cursor-default"
-                disabled
-                aria-disabled
-                key={index}
-              />
-            ))}
-          </Rating>
-          <p>{comment.content}</p>
-        </div>
+        {user && <CommentCardDropdown comment={comment} mutate={mutate} />}
       </div>
-    );
-  };
+
+      <div className="space-y-1">
+        <Rating value={comment.rating}>
+          {Array.from({ length: 5 }).map((val, index) => (
+            <Rating.Item
+              name="rating-1"
+              className="mask mask-star cursor-default"
+              disabled
+              aria-disabled
+              key={index}
+            />
+          ))}
+        </Rating>
+        <p>{comment.content}</p>
+      </div>
+    </div>
+  );
+};
 
 export default CommentCardBody;
diff --git a/components/BeerById/CommentLoadingCardBody.tsx b/components/BeerById/CommentLoadingCardBody.tsx
index 2d0e292..b662594 100644
--- a/components/BeerById/CommentLoadingCardBody.tsx
+++ b/components/BeerById/CommentLoadingCardBody.tsx
@@ -1,12 +1,14 @@
 const CommentLoadingCardBody = () => {
   return (
-    <div className="animate card-body h-64 fade-in-10">
+    <div className="animate card-body h-52 fade-in-10">
       <div className="flex animate-pulse space-x-4 slide-in-from-top">
         <div className="flex-1 space-y-4 py-1">
           <div className="h-4 w-3/4 rounded bg-base-100" />
           <div className="space-y-2">
             <div className="h-4 rounded bg-base-100" />
-            <div className="h-4 w-5/6 rounded bg-base-100" />
+            <div className="h-4 w-11/12 rounded bg-base-100" />
+            <div className="h-4 w-10/12 rounded bg-base-100" />
+            <div className="h-4 w-11/12 rounded bg-base-100" />
           </div>
         </div>
       </div>
diff --git a/components/ui/Spinner.tsx b/components/ui/Spinner.tsx
index 5baaec3..df69177 100644
--- a/components/ui/Spinner.tsx
+++ b/components/ui/Spinner.tsx
@@ -6,8 +6,8 @@ interface SpinnerProps {
 
 const Spinner: FC<SpinnerProps> = ({ size = 'md' }) => {
   const spinnerWidths: Record<NonNullable<SpinnerProps['size']>, `w-[${number}px]`> = {
-    xs: 'w-[10px]',
-    sm: 'w-[20px]',
+    xs: 'w-[45px]',
+    sm: 'w-[60px]',
     md: 'w-[100px]',
     lg: 'w-[150px]',
     xl: 'w-[200px]',
diff --git a/contexts/userContext.ts b/contexts/userContext.ts
index cc6a1f6..7345769 100644
--- a/contexts/userContext.ts
+++ b/contexts/userContext.ts
@@ -1,4 +1,4 @@
-import  useUser  from '@/hooks/useUser';
+import useUser from '@/hooks/useUser';
 import GetUserSchema from '@/services/User/schema/GetUserSchema';
 import { createContext } from 'react';
 import { z } from 'zod';
@@ -7,7 +7,7 @@ const UserContext = createContext<{
   user?: z.infer<typeof GetUserSchema>;
   error?: unknown;
   isLoading: boolean;
-  mutate?: ReturnType<typeof useUser>['mutate']
+  mutate?: ReturnType<typeof useUser>['mutate'];
 }>({ isLoading: true });
 
 export default UserContext;
diff --git a/hooks/useBeerPostComments.ts b/hooks/useBeerPostComments.ts
index 690eef6..3a75e56 100644
--- a/hooks/useBeerPostComments.ts
+++ b/hooks/useBeerPostComments.ts
@@ -21,36 +21,39 @@ interface UseBeerPostCommentsProps {
  *   the data.
  */
 const useBeerPostComments = ({ id, pageSize }: UseBeerPostCommentsProps) => {
+  const fetcher = async (url: string) => {
+    const response = await fetch(url);
+    const json = await response.json();
+    const count = response.headers.get('X-Total-Count');
+    const parsed = APIResponseValidationSchema.safeParse(json);
+
+    if (!parsed.success) {
+      throw new Error(parsed.error.message);
+    }
+    const parsedPayload = z.array(BeerCommentQueryResult).safeParse(parsed.data.payload);
+
+    if (!parsedPayload.success) {
+      throw new Error(parsedPayload.error.message);
+    }
+
+    const pageCount = Math.ceil(parseInt(count as string, 10) / pageSize);
+    return { comments: parsedPayload.data, pageCount };
+  };
+
   const { data, error, isLoading, mutate, size, setSize } = useSWRInfinite(
     (index) => `/api/beers/${id}/comments?page_num=${index + 1}&page_size=${pageSize}`,
-    async (url) => {
-      const response = await fetch(url);
-      const json = await response.json();
-      const count = response.headers.get('X-Total-Count');
-      const parsed = APIResponseValidationSchema.safeParse(json);
-
-      if (!parsed.success) {
-        throw new Error(parsed.error.message);
-      }
-      const parsedPayload = z
-
-        .array(BeerCommentQueryResult)
-        .safeParse(parsed.data.payload);
-
-      if (!parsedPayload.success) {
-        throw new Error(parsedPayload.error.message);
-      }
-
-      const pageCount = Math.ceil(parseInt(count as string, 10) / pageSize);
-      return { comments: parsedPayload.data, pageCount };
-    },
+    fetcher,
+    { parallel: true },
   );
 
   const comments = data?.flatMap((d) => d.comments) ?? [];
+  const pageCount = data?.[0].pageCount ?? 0;
 
   const isLoadingMore =
     isLoading || (size > 0 && data && typeof data[size - 1] === 'undefined');
 
+  const isAtEnd = !(size < data?.[0].pageCount!);
+
   return {
     comments,
     isLoading,
@@ -59,6 +62,8 @@ const useBeerPostComments = ({ id, pageSize }: UseBeerPostCommentsProps) => {
     size,
     setSize,
     isLoadingMore,
+    isAtEnd,
+    pageCount,
   };
 };
 
diff --git a/package-lock.json b/package-lock.json
index 4137c48..c29ccf7 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -35,6 +35,7 @@
         "react-email": "^1.9.0",
         "react-hook-form": "^7.43.9",
         "react-icons": "^4.8.0",
+        "react-intersection-observer": "^9.4.3",
         "sparkpost": "^2.1.4",
         "swr": "^2.1.2",
         "zod": "^3.21.4"
@@ -8341,6 +8342,14 @@
         "react": "*"
       }
     },
+    "node_modules/react-intersection-observer": {
+      "version": "9.4.3",
+      "resolved": "https://registry.npmjs.org/react-intersection-observer/-/react-intersection-observer-9.4.3.tgz",
+      "integrity": "sha512-WNRqMQvKpupr6MzecAQI0Pj0+JQong307knLP4g/nBex7kYfIaZsPpXaIhKHR+oV8z+goUbH9e10j6lGRnTzlQ==",
+      "peerDependencies": {
+        "react": "^15.0.0 || ^16.0.0 || ^17.0.0 || ^18.0.0"
+      }
+    },
     "node_modules/react-is": {
       "version": "16.13.1",
       "resolved": "https://registry.npmjs.org/react-is/-/react-is-16.13.1.tgz",
@@ -15901,6 +15910,12 @@
       "integrity": "sha512-N6+kOLcihDiAnj5Czu637waJqSnwlMNROzVZMhfX68V/9bu9qHaMIJC4UdozWoOk57gahFCNHwVvWzm0MTzRjg==",
       "requires": {}
     },
+    "react-intersection-observer": {
+      "version": "9.4.3",
+      "resolved": "https://registry.npmjs.org/react-intersection-observer/-/react-intersection-observer-9.4.3.tgz",
+      "integrity": "sha512-WNRqMQvKpupr6MzecAQI0Pj0+JQong307knLP4g/nBex7kYfIaZsPpXaIhKHR+oV8z+goUbH9e10j6lGRnTzlQ==",
+      "requires": {}
+    },
     "react-is": {
       "version": "16.13.1",
       "resolved": "https://registry.npmjs.org/react-is/-/react-is-16.13.1.tgz",
diff --git a/package.json b/package.json
index 5efb564..61d2955 100644
--- a/package.json
+++ b/package.json
@@ -38,6 +38,7 @@
     "react-email": "^1.9.0",
     "react-hook-form": "^7.43.9",
     "react-icons": "^4.8.0",
+    "react-intersection-observer": "^9.4.3",
     "sparkpost": "^2.1.4",
     "swr": "^2.1.2",
     "zod": "^3.21.4"
diff --git a/prisma/seed/create/createNewUsers.ts b/prisma/seed/create/createNewUsers.ts
index 9af1101..c34bf4e 100644
--- a/prisma/seed/create/createNewUsers.ts
+++ b/prisma/seed/create/createNewUsers.ts
@@ -18,7 +18,7 @@ const createNewUsers = async ({ numberOfUsers }: CreateNewUsersArgs) => {
 
   // eslint-disable-next-line no-plusplus
   for (let i = 0; i < numberOfUsers; i++) {
-    const randomValue = crypto.randomBytes(4).toString('hex');
+    const randomValue = crypto.randomBytes(8).toString('hex');
     const firstName = faker.name.firstName();
     const lastName = faker.name.lastName();
     const username = `${firstName[0]}.${lastName}.${randomValue}`;
diff --git a/prisma/seed/index.ts b/prisma/seed/index.ts
index d6b52a1..6d4ae14 100644
--- a/prisma/seed/index.ts
+++ b/prisma/seed/index.ts
@@ -29,7 +29,7 @@ import createNewUsers from './create/createNewUsers';
       createNewBeerTypes({ joinData: { users } }),
     ]);
     const beerPosts = await createNewBeerPosts({
-      numberOfPosts: 48,
+      numberOfPosts: 200,
       joinData: { breweryPosts, beerTypes, users },
     });
 
@@ -41,11 +41,11 @@ import createNewUsers from './create/createNewUsers';
       breweryImages,
     ] = await Promise.all([
       createNewBeerPostComments({
-        numberOfComments: 1000,
+        numberOfComments: 45000,
         joinData: { beerPosts, users },
       }),
       createNewBreweryPostComments({
-        numberOfComments: 1000,
+        numberOfComments: 45000,
         joinData: { breweryPosts, users },
       }),
       createNewBeerPostLikes({