From 0c304a2abc6e65023a8169e9bb7a71e449a6c8c4 Mon Sep 17 00:00:00 2001
From: Chris Walsh <christopher@drumshift.com>
Date: Thu, 12 Aug 2021 16:01:51 -0700
Subject: [PATCH] Add dashboard previous-period comparison metrics

---
 components/metrics/MetricCard.js         | 29 ++++++++++++++--
 components/metrics/MetricCard.module.css | 20 +++++++++++
 components/metrics/MetricsBar.js         | 42 ++++++++++++++++++++----
 pages/api/website/[id]/stats.js          | 10 +++++-
 4 files changed, 91 insertions(+), 10 deletions(-)

diff --git a/components/metrics/MetricCard.js b/components/metrics/MetricCard.js
index 6209509c..d0394b97 100644
--- a/components/metrics/MetricCard.js
+++ b/components/metrics/MetricCard.js
@@ -3,13 +3,38 @@ import { useSpring, animated } from 'react-spring';
 import { formatNumber } from '../../lib/format';
 import styles from './MetricCard.module.css';
 
-const MetricCard = ({ value = 0, label, format = formatNumber }) => {
+const MetricCard = ({
+  value = 0,
+  change = 0,
+  label,
+  reverseColors = false,
+  format = formatNumber,
+}) => {
   const props = useSpring({ x: Number(value) || 0, from: { x: 0 } });
+  const changeProps = useSpring({ x: Number(change) || 0, from: { x: 0 } });
 
   return (
     <div className={styles.card}>
       <animated.div className={styles.value}>{props.x.interpolate(x => format(x))}</animated.div>
-      <div className={styles.label}>{label}</div>
+      <div className={styles.label}>
+        {label}
+        {~~change === 0 && <span className={styles.change}>{format(0)}</span>}
+        {~~change !== 0 && (
+          <animated.span
+            className={`${styles.change} ${
+              change >= 0
+                ? !reverseColors
+                  ? styles.positive
+                  : styles.negative
+                : !reverseColors
+                ? styles.negative
+                : styles.positive
+            }`}
+          >
+            {changeProps.x.interpolate(x => `${change >= 0 ? '+' : ''}${format(x)}`)}
+          </animated.span>
+        )}
+      </div>
     </div>
   );
 };
diff --git a/components/metrics/MetricCard.module.css b/components/metrics/MetricCard.module.css
index 50b92ac8..76a69609 100644
--- a/components/metrics/MetricCard.module.css
+++ b/components/metrics/MetricCard.module.css
@@ -16,4 +16,24 @@
 .label {
   font-size: var(--font-size-normal);
   white-space: nowrap;
+  display: flex;
+  align-items: center;
+  gap: 5px;
+}
+
+.change {
+  font-size: 12px;
+  padding: 0 5px;
+  border-radius: 5px;
+  margin-left: 4px;
+  border: 1px solid var(--gray200);
+  color: var(--gray500);
+}
+
+.change.positive {
+  color: var(--green500);
+}
+
+.change.negative {
+  color: var(--red500);
 }
diff --git a/components/metrics/MetricsBar.js b/components/metrics/MetricsBar.js
index 945cd5e2..435870a1 100644
--- a/components/metrics/MetricsBar.js
+++ b/components/metrics/MetricsBar.js
@@ -34,14 +34,22 @@ export default function MetricsBar({ websiteId, className }) {
     [url, modified],
   );
 
-  const formatFunc = format ? formatLongNumber : formatNumber;
+  const formatFunc = format
+    ? n => (n >= 0 ? formatLongNumber(n) : `-${formatLongNumber(Math.abs(n))}`)
+    : formatNumber;
 
   function handleSetFormat() {
     setFormat(state => !state);
   }
 
   const { pageviews, uniques, bounces, totaltime } = data || {};
-  const num = Math.min(uniques, bounces);
+  const num = Math.min(data && uniques.value, data && bounces.value);
+  const diffs = data && {
+    pageviews: pageviews.value - pageviews.change,
+    uniques: uniques.value - uniques.change,
+    bounces: bounces.value - bounces.change,
+    totaltime: totaltime.value - totaltime.change,
+  };
 
   return (
     <div className={classNames(styles.bar, className)} onClick={handleSetFormat}>
@@ -51,18 +59,27 @@ export default function MetricsBar({ websiteId, className }) {
         <>
           <MetricCard
             label={<FormattedMessage id="metrics.views" defaultMessage="Views" />}
-            value={pageviews}
+            value={pageviews.value}
+            change={pageviews.change}
             format={formatFunc}
           />
           <MetricCard
             label={<FormattedMessage id="metrics.visitors" defaultMessage="Visitors" />}
-            value={uniques}
+            value={uniques.value}
+            change={uniques.change}
             format={formatFunc}
           />
           <MetricCard
             label={<FormattedMessage id="metrics.bounce-rate" defaultMessage="Bounce rate" />}
-            value={uniques ? (num / uniques) * 100 : 0}
+            value={uniques.value ? (num / uniques.value) * 100 : 0}
+            change={
+              uniques.value && uniques.change
+                ? (num / uniques.value) * 100 -
+                    (Math.min(diffs.uniques, diffs.bounces) / diffs.uniques) * 100 || 0
+                : 0
+            }
             format={n => Number(n).toFixed(0) + '%'}
+            reverseColors
           />
           <MetricCard
             label={
@@ -71,8 +88,19 @@ export default function MetricsBar({ websiteId, className }) {
                 defaultMessage="Average visit time"
               />
             }
-            value={totaltime && pageviews ? totaltime / (pageviews - bounces) : 0}
-            format={n => formatShortTime(n, ['m', 's'], ' ')}
+            value={
+              totaltime.value && pageviews.value
+                ? totaltime.value / (pageviews.value - bounces.value)
+                : 0
+            }
+            change={
+              totaltime.value && pageviews.value
+                ? (diffs.totaltime / (diffs.pageviews - diffs.bounces) -
+                    totaltime.value / (pageviews.value - bounces.value)) *
+                    -1 || 0
+                : 0
+            }
+            format={n => `${n < 0 ? '-' : ''}${formatShortTime(Math.abs(~~n), ['m', 's'], ' ')}`}
           />
         </>
       )}
diff --git a/pages/api/website/[id]/stats.js b/pages/api/website/[id]/stats.js
index 8b80a363..80dd22ec 100644
--- a/pages/api/website/[id]/stats.js
+++ b/pages/api/website/[id]/stats.js
@@ -14,10 +14,18 @@ export default async (req, res) => {
     const startDate = new Date(+start_at);
     const endDate = new Date(+end_at);
 
+    const distance = end_at - start_at;
+    const prevStartDate = new Date(+start_at - distance);
+    const prevEndDate = new Date(+end_at - distance);
+
     const metrics = await getWebsiteStats(websiteId, startDate, endDate, { url });
+    const prevPeriod = await getWebsiteStats(websiteId, prevStartDate, prevEndDate, { url });
 
     const stats = Object.keys(metrics[0]).reduce((obj, key) => {
-      obj[key] = Number(metrics[0][key]) || 0;
+      obj[key] = {
+        value: Number(metrics[0][key]) || 0,
+        change: Number(metrics[0][key] - prevPeriod[0][key]) || 0,
+      };
       return obj;
     }, {});