Add simple pagination to user feeds.

This is simply based on sequence numbers and the `gt`/`lt` arguments of
`createUserStream`.

src/index.js

@@ -264,11 +264,20 @@ router
   })
   .get("/author/:feed", async (ctx) => {
     const { feed } = ctx.params;
+
+    const gt = Number(ctx.request.query['gt'] || -1);
+    const lt = Number(ctx.request.query['lt'] || -1);
+
+    if (lt > 0 && gt > 0 && gt >= lt)
+      throw new Error("Given search range is empty");
+
     const author = async (feedId) => {
       const description = await about.description(feedId);
       const name = await about.name(feedId);
       const image = await about.image(feedId);
-      const messages = await post.fromPublicFeed(feedId);
+      const messages = await post.fromPublicFeed(feedId, gt, lt);
+      const firstPost = await post.firstBy(feedId);
+      const lastPost = await post.latestBy(feedId);
       const relationship = await friend.getRelationship(feedId);
 
       const avatarUrl = `/image/256/${encodeURIComponent(image)}`;
@@ -276,6 +285,8 @@ router
       return authorView({
         feedId,
         messages,
+        firstPost,
+        lastPost,
         name,
         description,
         avatarUrl,
@@ -342,17 +353,27 @@ router
   .get("/profile/", async (ctx) => {
     const myFeedId = await meta.myFeedId();
 
+    const gt = Number(ctx.request.query['gt'] || -1);
+    const lt = Number(ctx.request.query['lt'] || -1);
+
+    if (lt > 0 && gt > 0 && gt >= lt)
+      throw new Error("Given search range is empty");
+
     const description = await about.description(myFeedId);
     const name = await about.name(myFeedId);
     const image = await about.image(myFeedId);
 
-    const messages = await post.fromPublicFeed(myFeedId);
+    const messages = await post.fromPublicFeed(myFeedId, gt, lt);
+    const firstPost = await post.firstBy(myFeedId);
+    const lastPost = await post.latestBy(myFeedId);
 
     const avatarUrl = `/image/256/${encodeURIComponent(image)}`;
 
     ctx.body = await authorView({
       feedId: myFeedId,
       messages,
+      firstPost,
+      lastPost,
       name,
       description,
       avatarUrl,

src/models.js

@@ -627,14 +627,45 @@ module.exports = ({ cooler, isPublic }) => {
       })
     );
 
+  const getLimitPost = async (feedId, reverse) => {
+    const ssb = await cooler.open();
+    const source = ssb.createUserStream({ id: feedId, reverse: reverse });
+    const messages = await new Promise((resolve, reject) => {
+      pull(
+        source,
+        pull.filter((msg) => isDecrypted(msg) === false && isPost(msg)),
+        pull.take(1),
+        pull.collect((err, collectedMessages) => {
+          if (err) {
+            reject(err);
+          } else {
+            resolve(transform(ssb, collectedMessages, feedId));
+          }
+        })
+      );
+    });
+    return messages.length ? messages[0] : undefined;
+  };
+
   const post = {
-    fromPublicFeed: async (feedId, customOptions = {}) => {
+    firstBy: async (feedId) => {
+      return getLimitPost(feedId, false);
+    },
+    latestBy: async (feedId) => {
+      return getLimitPost(feedId, true);
+    },
+    fromPublicFeed: async (feedId, gt = -1, lt = -1, customOptions = {}) => {
       const ssb = await cooler.open();
 
       const myFeedId = ssb.id;
 
-      const options = configure({ id: feedId }, customOptions);
-
+      let defaultOptions = { id: feedId };
+      if (lt >= 0)
+        defaultOptions.lt = lt;
+      if (gt >= 0)
+        defaultOptions.gt = gt;
+      defaultOptions.reverse = !(gt >= 0 && lt < 0);
+      const options = configure(defaultOptions, customOptions);
       const { blocking } = await models.friend.getRelationship(feedId);
 
       // Avoid streaming any messages from this feed. If we used the social
@@ -661,7 +692,10 @@ module.exports = ({ cooler, isPublic }) => {
         );
       });
 
-      return messages;
+      if (!defaultOptions.reverse)
+        return messages.reverse();
+      else
+        return messages;
     },
     mentionsMe: async (customOptions = {}) => {
       const ssb = await cooler.open();

src/views/i18n.js

@@ -62,6 +62,13 @@ const i18n = {
     follow: "Follow",
     block: "Block",
     unblock: "Unblock",
+    newerPosts: "Newer posts",
+    olderPosts: "Older posts",
+    feedRangeEmpty: "The given range is empty for this feed. Try viewing the ",
+    seeFullFeed: "full feed",
+    feedEmpty: "The local client has never seen posts from this account.",
+    beginningOfFeed: "This is the beginning of the feed",
+    noNewerPosts: "No newer posts have been reveived yet.",
     relationshipFollowing: "You are following",
     relationshipYou: "This is you",
     relationshipBlocking: "You are blocking",

src/views/index.js

@@ -512,6 +512,8 @@ exports.authorView = ({
   description,
   feedId,
   messages,
+  firstPost,
+  lastPost,
   name,
   relationship,
 }) => {
@@ -600,10 +602,56 @@ exports.authorView = ({
     )
   );
 
+  const linkUrl = relationship.me ? '/profile/' : `/author/${encodeURIComponent(feedId)}/`;
+
+  let items = messages.map((msg) => post({ msg }));
+  if (items.length === 0) {
+    if (lastPost === undefined) {
+      items.push(
+        section(
+          div(
+            span(i18n.feedEmpty)
+          )
+        )
+      );
+    } else {
+      items.push(
+        section(
+          div(
+            span(i18n.feedRangeEmpty),
+            a({ href: `${linkUrl}` }, i18n.seeFullFeed)
+          )
+        )
+      );
+    }
+  } else {
+    const highestSeqNum = messages[0].value.sequence;
+    const lowestSeqNum = messages[messages.length-1].value.sequence;
+    let newerPostsLink;
+    if (lastPost !== undefined && highestSeqNum < lastPost.value.sequence)
+      newerPostsLink = a({ href: `${linkUrl}?gt=${highestSeqNum}` }, i18n.newerPosts);
+    else
+      newerPostsLink = span(i18n.newerPosts, { title: i18n.noNewerPosts });
+    let olderPostsLink;
+    if (lowestSeqNum > firstPost.value.sequence)
+      olderPostsLink = a({ href: `${linkUrl}?lt=${lowestSeqNum}` }, i18n.olderPosts);
+    else
+      olderPostsLink = span(i18n.olderPosts, { title: i18n.beginningOfFeed });
+    const pagination = section(
+      { class: "message" },
+      footer(
+        div(newerPostsLink, olderPostsLink),
+        br()
+      )
+    );
+    items.unshift(pagination);
+    items.push(pagination);
+  }
+
   return template(
     i18n.profile,
     prefix,
-    messages.map((msg) => post({ msg }))
+    items
   );
 };