Add one rep max calculator for best graphs

I tried out a bunch of formulas as well as
having them as options, and I ended up liking
the Brzycki formula the most.
https://en.wikipedia.org/wiki/One-repetition_maximum#Brzycki
All of them produced similar trends (for me) and the one using
exponents wouldn't work with the SQLite version on android
(can't use POWER function). Also having all the options looked
kind of cluttered. If people ask for it I'll add the other ones
later.

ViewBest.tsx

@@ -11,7 +11,7 @@ import {FileSystem} from 'react-native-file-access';
 import {IconButton} from 'react-native-paper';
 import Share from 'react-native-share';
 import {captureScreen} from 'react-native-view-shot';
-import {getVolumes, getWeightsBy} from './best.service';
+import {getOneRepMax, getVolumes, getWeightsBy} from './best.service';
 import {BestPageParams} from './BestPage';
 import Chart from './Chart';
 import {PADDING} from './constants';
@@ -59,12 +59,18 @@ export default function ViewBest() {
   );
 
   useEffect(() => {
-    if (metric === Metrics.Weight)
-      getWeightsBy(params.best.name, period).then(setWeights);
-    else if (metric === Metrics.Volume)
-      getVolumes(params.best.name, period).then(setVolumes);
     console.log(`${ViewBest.name}.useEffect`, {metric});
     console.log(`${ViewBest.name}.useEffect`, {period});
+    switch (metric) {
+      case Metrics.Weight:
+        getWeightsBy(params.best.name, period).then(setWeights);
+        break;
+      case Metrics.Volume:
+        getVolumes(params.best.name, period).then(setVolumes);
+        break;
+      default:
+        getOneRepMax({name: params.best.name, period}).then(setWeights);
+    }
   }, [params.best.name, metric, period]);
 
   return (
@@ -76,6 +82,7 @@ export default function ViewBest() {
         onValueChange={value => setMetric(value)}>
         <Picker.Item value={Metrics.Volume} label={Metrics.Volume} />
         <Picker.Item value={Metrics.Weight} label={Metrics.Weight} />
+        <Picker.Item value={Metrics.OneRepMax} label={Metrics.OneRepMax} />
       </Picker>
       <Picker
         style={{color: dark ? 'white' : 'black'}}
@@ -86,7 +93,7 @@ export default function ViewBest() {
         <Picker.Item value={Periods.Monthly} label={Periods.Monthly} />
         <Picker.Item value={Periods.Yearly} label={Periods.Yearly} />
       </Picker>
-      {metric === Metrics.Volume && (
+      {metric === Metrics.Volume ? (
         <Chart
           yData={volumes.map(v => v.value)}
           yFormat={(value: number) =>
@@ -97,8 +104,7 @@ export default function ViewBest() {
           xData={weights}
           xFormat={(_value, index) => formatMonth(weights[index].created!)}
         />
-      )}
-      {metric === Metrics.Weight && (
+      ) : (
         <Chart
           yData={weights.map(set => set.weight)}
           yFormat={value => `${value}${weights[0].unit}`}

best.service.ts

@@ -4,6 +4,31 @@ import Set from './set';
 import {defaultSet} from './set.service';
 import Volume from './volume';
 
+export const getOneRepMax = async ({
+  name,
+  period,
+}: {
+  name: string;
+  period: Periods;
+}) => {
+  // Brzycki formula https://en.wikipedia.org/wiki/One-repetition_maximum#Brzycki
+  const select = `
+    SELECT max(weight / (1.0278 - 0.0278 * reps)) AS weight, 
+    STRFTIME('%Y-%m-%d', created) as created, unit
+    FROM sets
+    WHERE name = ? AND NOT hidden
+    AND DATE(created) >= DATE('now', 'weekday 0', ?)
+    GROUP BY name, STRFTIME(?, created)
+  `;
+  let difference = '-7 days';
+  if (period === Periods.Monthly) difference = '-1 months';
+  else if (period === Periods.Yearly) difference = '-1 years';
+  let group = '%Y-%m-%d';
+  if (period === Periods.Yearly) group = '%Y-%m';
+  const [result] = await db.executeSql(select, [name, difference, group]);
+  return result.rows.raw();
+};
+
 export const getBestSet = async (name: string): Promise<Set> => {
   const bestWeight = `
     SELECT name, reps, unit, MAX(weight) AS weight 

metrics.ts

@@ -1,4 +1,5 @@
 export enum Metrics {
   Weight = 'Best weight per day',
   Volume = 'Volume per day',
+  OneRepMax = 'One rep max',
 }