refactor: use Link HTTP header for pagination

src/lib/api.js

@@ -2,6 +2,31 @@ const errors = {
     AUTHENTICATION_FAILED: "AUTHENTICATION_FAILED",
 };
 
+/**
+ * Parses a HTTP Link header
+ * @param {string} header - the HTTP Link header string
+ */
+function _parseLinkHeader(header) {
+    // remove whitespace and split
+    let links = header.replace(/\ /g, "").split(",");
+
+    return links.map(l => {
+        let parts = l.split(";");
+
+        // assuming 0th is URL, removing <>
+        let url = new URL(parts[0].slice(1, -1));
+
+        // get rel inbetween double-quotes
+        let rel = parts[1].match(/"(.*?)"/g)[0].slice(1, -1);
+
+        return {
+            url, rel
+        }
+    })
+}
+
+_parseLinkHeader(`<https://wetdry.world/api/v1/timelines/home?max_id=114857293229157171>; rel="next", <https://wetdry.world/api/v1/timelines/home?min_id=114857736990577458>; rel="prev"`)
+
 /**
  * GET /api/v1/instance
  * @param {string} host - The domain of the target server.
@@ -258,9 +283,43 @@ export async function getTimeline(host, token, timeline, max_id, local_only, rem
     const data = await fetch(url, {
         method: 'GET',
         headers: { "Authorization": token ? `Bearer ${token}` : null }
-    }).then(res => res.json());
+    })
 
-    return data;
+    let links = _parseLinkHeader(data.headers.get("Link"));
+
+    return {
+        data: await data.json(),
+        prev: links.find(f=>f.rel=="prev"),
+        next: links.find(f=>f.rel=="next")
+    };
+}
+
+/**
+ * GET /api/v1/favourites
+ * @param {string} host - The domain of the target server.
+ * @param {string} token - The application token.
+ * @param {string} max_id - If provided, only shows posts after this ID.
+ */
+export async function getFavourites(host, token, max_id) {
+    let url = `https://${host}/api/v1/favourites`;
+
+    let params = new URLSearchParams();
+    if (max_id) params.append("max_id", max_id);
+    const params_string = params.toString();
+    if (params_string) url += '?' + params_string;
+    
+    const data = await fetch(url, {
+        method: 'GET',
+        headers: { "Authorization": token ? `Bearer ${token}` : null }
+    })
+
+    let links = _parseLinkHeader(data.headers.get("Link"));
+
+    return {
+        data: await data.json(),
+        prev: links.find(f=>f.rel=="prev"),
+        next: links.find(f=>f.rel=="next")
+    };
 }
 
 /**
@@ -560,25 +619,3 @@ export async function getUserPinnedPosts(host, token, user_id) {
 
     return data;
 }
-
-/**
- * GET /api/v1/favourites
- * @param {string} host - The domain of the target server.
- * @param {string} token - The application token.
- * @param {string} max_id - If provided, only shows posts after this ID.
- */
-export async function getFavourites(host, token, timeline, max_id) {
-    let url = `https://${host}/api/v1/favourites`;
-
-    let params = new URLSearchParams();
-    if (max_id) params.append("max_id", max_id);
-    const params_string = params.toString();
-    if (params_string) url += '?' + params_string;
-    
-    const data = await fetch(url, {
-        method: 'GET',
-        headers: { "Authorization": token ? `Bearer ${token}` : null }
-    }).then(res => res.json());
-
-    return data;
-}

src/lib/timeline.js

@@ -10,14 +10,14 @@ export const timeline = writable([]);
 const lang = Lang();
 
 let loading = false;
+let last_post = false;
 
 export async function getTimeline(timelineType = "home", clean, localOnly = false, remoteOnly = false) {
     if (loading) return; // no spamming!!
     loading = true;
 
-    let last_post = false;
-    if (!clean && get(timeline).length > 0)
-        last_post = get(timeline)[get(timeline).length - 1].id;
+    // if (!clean && get(timeline).length > 0)
+    //     last_post = get(timeline)[get(timeline).length - 1].id;
 
     let timeline_data;
     switch(timelineType) {
@@ -25,7 +25,7 @@ export async function getTimeline(timelineType = "home", clean, localOnly = fals
             timeline_data = await api.getFavourites(
                 get(server).host,
                 get(app).token,
-                last_post,
+                last_post
             )
             break;
             
@@ -47,10 +47,15 @@ export async function getTimeline(timelineType = "home", clean, localOnly = fals
         return;
     }
 
-    if (clean) timeline.set([]);
+    if (clean) {
+        timeline.set([]);
+        last_post = false;
+    } else {
+        last_post = timeline_data.next.url.searchParams.get("max_id")
+    } 
 
-    for (let i in timeline_data) {
-        const post_data = timeline_data[i];
+    for (let i in timeline_data.data) {
+        const post_data = timeline_data.data[i];
         const post = await parsePost(post_data, 1);
         if (!post) {
             if (post === null || post === undefined) {