From 959c7ee48894159bbfcf24389a54caede5df13f3 Mon Sep 17 00:00:00 2001
From: Liam Fitzgerald <liam.fitzgerald@tlon.io>
Date: Mon, 18 Jan 2021 16:30:05 +1000
Subject: [PATCH] LinkWindow, VirtualScroller: virtualise correctly

---
 .../src/views/apps/links/LinkResource.tsx     | 32 ++++++--------
 .../src/views/apps/links/LinkWindow.tsx       | 30 ++++++++++++-
 .../views/apps/links/components/LinkItem.tsx  | 20 +++++++--
 .../src/views/components/VirtualScroller.tsx  | 43 ++++++++-----------
 4 files changed, 77 insertions(+), 48 deletions(-)

diff --git a/pkg/interface/src/views/apps/links/LinkResource.tsx b/pkg/interface/src/views/apps/links/LinkResource.tsx
index e7deda0853..f8a06a2a7d 100644
--- a/pkg/interface/src/views/apps/links/LinkResource.tsx
+++ b/pkg/interface/src/views/apps/links/LinkResource.tsx
@@ -60,30 +60,26 @@ export function LinkResource(props: LinkResourceProps) {
   }
 
   return (
-    <Col alignItems="center" height="100%" width="100%" overflowY="auto">
+    <Col alignItems="center" height="100%" width="100%" overflowY="hidden">
       <Switch>
         <Route
           exact
           path={relativePath("")}
           render={(props) => {
             return (
-              <Col width="100%" p={4} alignItems="center" maxWidth="768px">
-                <Col width="100%" flexShrink='0'>
-                  <LinkSubmit s3={s3} name={name} ship={ship.slice(1)} api={api} />
-                </Col>
-                <LinkWindow
-                  association={resource}
-                  contacts={contacts}
-                  resource={resourcePath}
-                  graph={graph}
-                  unreads={unreads}
-                  baseUrl={resourceUrl}
-                  group={group}
-                  path={resource["group-path"]}
-                  api={api}
-                  mb={3}
-                />
-              </Col>
+              <LinkWindow
+                s3={s3}
+                association={resource}
+                contacts={contacts}
+                resource={resourcePath}
+                graph={graph}
+                unreads={unreads}
+                baseUrl={resourceUrl}
+                group={group}
+                path={resource["group-path"]}
+                api={api}
+                mb={3}
+              />
             );
           }}
         />
diff --git a/pkg/interface/src/views/apps/links/LinkWindow.tsx b/pkg/interface/src/views/apps/links/LinkWindow.tsx
index dd7113a69b..62a1a15d8c 100644
--- a/pkg/interface/src/views/apps/links/LinkWindow.tsx
+++ b/pkg/interface/src/views/apps/links/LinkWindow.tsx
@@ -1,4 +1,6 @@
-import React, { useRef, useCallback, useEffect } from "react";
+import React, { useRef, useCallback, useEffect, useMemo } from "react";
+import { Col } from "@tlon/indigo-react";
+import bigInt from 'big-integer';
 import {
   Association,
   Graph,
@@ -7,10 +9,12 @@ import {
   LocalUpdateRemoteContentPolicy,
   Group,
   Rolodex,
+  S3State,
 } from "~/types";
 import GlobalApi from "~/logic/api/global";
 import VirtualScroller from "~/views/components/VirtualScroller";
 import { LinkItem } from "./components/LinkItem";
+import LinkSubmit from "./components/LinkSubmit";
 
 interface LinkWindowProps {
   association: Association;
@@ -24,6 +28,7 @@ interface LinkWindowProps {
   group: Group;
   path: string;
   api: GlobalApi;
+  s3: S3State;
 }
 export function LinkWindow(props: LinkWindowProps) {
   const { graph, api, association } = props;
@@ -42,12 +47,24 @@ export function LinkWindow(props: LinkWindowProps) {
     list.calculateVisibleItems();
   }, [graph.size]);
 
+  const first = graph.peekLargest()?.[0];
+
+  const [,,ship, name] = association['app-path'].split('/');
+
+  const style = useMemo(() => 
+    ({ 
+      height: "100%", 
+      width: "100%",
+      display: 'flex', 
+      flexDirection: 'column', 
+      alignItems: 'center' 
+    }), []);
 
   return (
     <VirtualScroller
       ref={(l) => (virtualList.current = l ?? undefined)}
       origin="top"
-      style={{ height: "100%", width: "100%" }}
+      style={style}
       onStartReached={() => {}}
       onScroll={() => {}}
       data={graph}
@@ -59,8 +76,17 @@ export function LinkWindow(props: LinkWindowProps) {
         const linkProps = {
           ...props,
           node,
+          measure,
           key: index.toString()
         };
+        if(index.eq(first ?? bigInt.zero)) {
+          return (
+            <Col mx="auto" mt="4" maxWidth="768px" width="100%" flexShrink='0'>
+              <LinkSubmit s3={props.s3} name={name} ship={ship.slice(1)} api={api} />
+              <LinkItem {...linkProps} />
+            </Col>
+          )
+        }
         return <LinkItem {...linkProps} />;
       }}
       loadRows={fetchLinks}
diff --git a/pkg/interface/src/views/apps/links/components/LinkItem.tsx b/pkg/interface/src/views/apps/links/components/LinkItem.tsx
index a8345ef0df..e34de6cfb0 100644
--- a/pkg/interface/src/views/apps/links/components/LinkItem.tsx
+++ b/pkg/interface/src/views/apps/links/components/LinkItem.tsx
@@ -1,4 +1,4 @@
-import React, { useState }  from 'react';
+import React, { useState, useEffect, useRef, useCallback }  from 'react';
 import { Link } from 'react-router-dom';
 import { Row, Col, Anchor, Box, Text, Icon, Action } from '@tlon/indigo-react';
 
@@ -19,6 +19,7 @@ interface LinkItemProps {
   path: string;
   contacts: Rolodex;
   unreads: Unreads;
+  measure: (el: any) => void;
 }
 
 export const LinkItem = (props: LinkItemProps) => {
@@ -29,9 +30,12 @@ export const LinkItem = (props: LinkItemProps) => {
     group,
     path,
     contacts,
+    measure,
     ...rest
   } = props;
 
+  const ref = useRef<HTMLDivElement | null>(null);
+
   const URLparser = new RegExp(
     /((?:([\w\d\.-]+)\:\/\/?){1}(?:(www)\.?){0,1}(((?:[\w\d-]+\.)*)([\w\d-]+\.[\w\d]+))){1}(?:\:(\d+)){0,1}((\/(?:(?:[^\/\s\?]+\/)*))(?:([^\?\/\s#]+?(?:.[^\?\s]+){0,1}){0,1}(?:\?([^\s#]+)){0,1})){0,1}(?:#([^#\s]+)){0,1}/
   );
@@ -70,9 +74,18 @@ export const LinkItem = (props: LinkItemProps) => {
   const markRead = () => {
     api.hark.markEachAsRead(props.association, '/', `/${index}`, 'link', 'link');
   }
+
+
+  const onMeasure = useCallback(() => {
+    ref.current && measure(ref.current);
+  }, [ref.current, measure])
+
+  useEffect(() => {
+    onMeasure();
+  }, [onMeasure]);
+
   return (
-    <Box width="100%" {...rest}>
-    
+    <Box mx="auto" maxWidth="768px" ref={ref} width="100%" {...rest}>
       <Box
         lineHeight="tall"
         display='flex'
@@ -90,6 +103,7 @@ export const LinkItem = (props: LinkItemProps) => {
           url={contents[1].url}
           text={contents[0].text}
           unfold={true}
+          onLoad={onMeasure}
           style={{ alignSelf: 'center' }}
           oembedProps={{
             p: 2,
diff --git a/pkg/interface/src/views/components/VirtualScroller.tsx b/pkg/interface/src/views/components/VirtualScroller.tsx
index e7a57ba54d..3dd67700dc 100644
--- a/pkg/interface/src/views/components/VirtualScroller.tsx
+++ b/pkg/interface/src/views/components/VirtualScroller.tsx
@@ -44,6 +44,8 @@ export default class VirtualScroller extends Component<VirtualScrollerProps, Vir
     timeout: ReturnType<typeof setTimeout>;
   } | undefined;
 
+  overscan = 150;
+
   OVERSCAN_SIZE = 100; // Minimum number of messages on either side before loadRows is called
 
   constructor(props: VirtualScrollerProps) {
@@ -53,7 +55,7 @@ export default class VirtualScroller extends Component<VirtualScrollerProps, Vir
       visibleItems: new BigIntOrderedMap(),
       endgap: props.origin === 'bottom' ? 0 : undefined,
       totalHeight: 0,
-      averageHeight: 64,
+      averageHeight: 130,
       scrollTop: props.origin === 'top' ? 0 : undefined
     };
 
@@ -61,8 +63,8 @@ export default class VirtualScroller extends Component<VirtualScrollerProps, Vir
     this.window = null;
     this.cache = new BigIntOrderedMap();
 
-    this.recalculateTotalHeight = this.recalculateTotalHeight.bind(this);
-    this.calculateVisibleItems = this.calculateVisibleItems.bind(this);
+    this.recalculateTotalHeight = _.throttle(this.recalculateTotalHeight.bind(this), 200);
+    this.calculateVisibleItems = _.throttle(this.calculateVisibleItems.bind(this), 200);
     this.estimateIndexFromScrollTop = this.estimateIndexFromScrollTop.bind(this);
     this.invertedKeyHandler = this.invertedKeyHandler.bind(this);
     this.heightOf = this.heightOf.bind(this);
@@ -74,6 +76,8 @@ export default class VirtualScroller extends Component<VirtualScrollerProps, Vir
 
   componentDidMount() {
     this.calculateVisibleItems();
+
+    this.recalculateTotalHeight();
   }
 
   componentDidUpdate(prevProps: VirtualScrollerProps, prevState: VirtualScrollerState) {
@@ -107,7 +111,7 @@ export default class VirtualScroller extends Component<VirtualScrollerProps, Vir
     let { averageHeight } = this.state;
     let totalHeight = 0;
     this.props.data.forEach((datum, index) => {
-      totalHeight += this.heightOf(index);
+      totalHeight += Math.max(this.heightOf(index), 0);
     });
     averageHeight = Number((totalHeight / this.props.data.size).toFixed());
     totalHeight += (this.props.size - this.props.data.size) * averageHeight;
@@ -136,36 +140,23 @@ export default class VirtualScroller extends Component<VirtualScrollerProps, Vir
     let startgap = 0, heightShown = 0, endgap = 0;
     let startGapFilled = false;
     let visibleItems = new BigIntOrderedMap<any>();
-    let startBuffer = new BigIntOrderedMap<any>();
-    let endBuffer = new BigIntOrderedMap<any>();
     const { scrollTop, offsetHeight: windowHeight } = this.window;
-    const { averageHeight } = this.state;
+    const { averageHeight, totalHeight } = this.state;
     const { data, size: totalSize, onCalculateVisibleItems } = this.props;
 
-    const overscan = Math.max(windowHeight / 2, 200);
-
 
     [...data].forEach(([index, datum]) => {
       const height = this.heightOf(index);
-      if (startgap < (scrollTop - overscan) && !startGapFilled) {
-        startBuffer.set(index, datum);
+      if (startgap < (scrollTop - this.overscan) && !startGapFilled) {
         startgap += height;
-      } else if (heightShown < (windowHeight + overscan)) {
+      } else if (heightShown < (windowHeight + this.overscan)) {
         startGapFilled = true;
         visibleItems.set(index, datum);
         heightShown += height;
-      } else if (endBuffer.size < visibleItems.size) {
-        endBuffer.set(index, data.get(index));
-      } else {
-        endgap += height;
-      }
-    });
-
-
-    startBuffer.forEach((_datum, index) => {
-      startgap -= this.heightOf(index);
+      } 
     });
 
+    endgap = totalHeight - heightShown - startgap;
 
     const firstVisibleKey = visibleItems.peekSmallest()?.[0] ?? this.estimateIndexFromScrollTop(scrollTop)!;
     const smallest = data.peekSmallest();
@@ -184,7 +175,7 @@ export default class VirtualScroller extends Component<VirtualScrollerProps, Vir
     onCalculateVisibleItems ? onCalculateVisibleItems(visibleItems) : null;
     this.setState({
       startgap: Number(startgap.toFixed()),
-      visibleItems: new BigIntOrderedMap([...startBuffer, ...visibleItems, ...endBuffer]),
+      visibleItems,
       endgap: Number(endgap.toFixed()),
     });
   }
@@ -233,6 +224,8 @@ export default class VirtualScroller extends Component<VirtualScrollerProps, Vir
       }
     }
 
+    this.overscan = Math.max(element.offsetHeight * 3, 500);
+
     this.window = element;
     if (this.props.origin === 'bottom') {
        element.addEventListener('wheel', (event) => {
@@ -309,7 +302,7 @@ export default class VirtualScroller extends Component<VirtualScrollerProps, Vir
             height: element.offsetHeight,
             element
           });
-          _.debounce(this.recalculateTotalHeight, 500)();
+          this.recalculateTotalHeight();
         }
       };
       return renderer({ index, measure, scrollWindow: this.window });
@@ -317,7 +310,7 @@ export default class VirtualScroller extends Component<VirtualScrollerProps, Vir
 
     return (
       <Box overflowY='scroll' ref={this.setWindow.bind(this)} onScroll={this.onScroll.bind(this)} style={{ ...style, ...{ transform } }}>
-        <Box ref={this.scrollContainer} style={{ transform }}>
+        <Box ref={this.scrollContainer} style={{ transform, width: '100%' }}>
           <Box style={{ height: `${origin === 'top' ? startgap : endgap}px` }}></Box>
           {indexesToRender.map(render)}
           <Box style={{ height: `${origin === 'top' ? endgap : startgap}px` }}></Box>