Update edit history frontend

app/src/frontend/pages/changes.css

@@ -0,0 +1,7 @@
+.edit-history-link {
+    margin-top: 4em;
+}
+
+.edit-history-latest-link {
+    float: right;
+}

app/src/frontend/pages/changes.tsx

@@ -1,31 +1,88 @@
+import { parse } from 'query-string';
 import React, { useEffect, useState } from 'react';
+import { Link, RouteComponentProps } from 'react-router-dom';
+
+import './changes.css';
 
 import { apiGet } from '../apiHelpers';
 import { BuildingEditSummary } from '../building/edit-history/building-edit-summary';
+import ErrorBox from '../components/error-box';
 import InfoBox from '../components/info-box';
 import { EditHistoryEntry } from '../models/edit-history-entry';
 
-const ChangesPage = () => {
-    const [history, setHistory] = useState<EditHistoryEntry[]>(undefined);
+interface PagingInfo {
+    id_for_older_query: string;
+    id_for_newer_query: string;
+}
+
+const recordsPerPage = 20;
+
+const ChangesPage = (props: RouteComponentProps) => {
+    const { after_id, before_id } = parse(props.location.search);
+
+    const [history, setHistory] = useState<EditHistoryEntry[]>();
+    const [paging, setPaging] = useState<PagingInfo>();
+    const [error, setError] = useState();
 
     useEffect(() => {
         const fetchData = async () => {
-            const {history} = await apiGet(`/api/history`);
+            setHistory(null);
+            setPaging(null);
+
+            let url = `/api/history?count=${recordsPerPage}`;
+            if(after_id) {
+                url = `${url}&after_id=${after_id}`;
+            }
+            
+            if (before_id) {
+                url = `${url}&before_id=${before_id}`;
+            }
+            try {
+                const {history, paging, error} = await apiGet(url);
+
+                if(error) {
+                    setError(error);
+                } else {
+                    setHistory(history);
+                    setPaging(paging);
+                }
+            } catch (err) {
+                setError('Connection problem. Please try again later...');
+            }
 
-            setHistory(history);
         };
 
         fetchData();
-    }, []);
+    }, [props.location.search]);
     
     return (
         <article>
             <section className="main-col">
                 <h1>Global edit history</h1>
 
+                {
+                    paging?.id_for_newer_query &&
+                        <Link className='edit-history-link' to={`?after_id=${paging.id_for_newer_query}`}>Show more recent changes</Link>
+                }
+                {
+                    (after_id || before_id) &&
+                        <Link className='edit-history-latest-link' to='?'>Show latest changes</Link>
+                }
                 <ul className="edit-history-list">
-                    {(history == undefined || history.length == 0) ?
-                        <InfoBox msg="No changes in the last week"></InfoBox> :
+                    {
+                        error &&
+                            <ErrorBox msg={error}></ErrorBox>
+                    }
+                    {
+                        error == undefined && history == undefined &&
+                            <InfoBox msg="Loading history..."></InfoBox>
+                    }
+                    {
+                        (history?.length === 0) &&
+                            <InfoBox msg="No changes so far"></InfoBox>
+                    }
+                    {   
+                        (history != undefined && history.length > 0) &&
                         history.map(entry => (
                             <li key={`${entry.revision_id}`} className="edit-history-list-element">
                                 <BuildingEditSummary
@@ -37,6 +94,10 @@ const ChangesPage = () => {
                         ))
                     }
                 </ul>
+                {
+                    paging?.id_for_older_query &&
+                        <Link to={`?before_id=${paging.id_for_older_query}`}>Show older changes</Link>
+                }
             </section>
         </article>
     );

app/src/frontend/styles/layout.css

@@ -49,6 +49,11 @@ article .color-block {
     padding-left: 1em;
     padding-right: 1em;
 }
+@media(min-width: 768px) {
+    .main-col {
+        min-width: 48em;
+    }
+}
 hr {
     display: block;
     height: 1px;