init

lib/strength/stats.ts

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+import type { StrengthExercise, StrengthWorkout } from "@/lib/models/strength";
+
+export function exerciseVolumeKg(exercise: StrengthExercise): number {
+  return exercise.sets.reduce((sum, set) => sum + (set.weightKg ?? 0) * (set.reps ?? 0), 0);
+}
+
+export function exerciseTopWeightKg(exercise: StrengthExercise): number | undefined {
+  const weights = exercise.sets
+    .map((set) => set.weightKg)
+    .filter((weight): weight is number => weight !== undefined);
+  return weights.length > 0 ? Math.max(...weights) : undefined;
+}
+
+export function workoutVolumeKg(workout: StrengthWorkout): number {
+  return workout.exercises.reduce((sum, exercise) => sum + exerciseVolumeKg(exercise), 0);
+}
+
+export type ExerciseHistoryPoint = {
+  date: Date;
+  volumeKg: number;
+  topWeightKg?: number;
+};
+
+/**
+ * History of a single exercise across past workouts (oldest first, including
+ * the workout it was found in), used to chart progression.
+ */
+export function getExerciseHistory(
+  exerciseName: string,
+  workouts: StrengthWorkout[],
+  limit: number
+): ExerciseHistoryPoint[] {
+  const points: ExerciseHistoryPoint[] = [];
+  for (const workout of workouts) {
+    const exercise = workout.exercises.find((e) => e.name === exerciseName);
+    if (!exercise) continue;
+    points.push({
+      date: workout.date,
+      volumeKg: exerciseVolumeKg(exercise),
+      topWeightKg: exerciseTopWeightKg(exercise),
+    });
+  }
+
+  points.sort((a, b) => a.date.getTime() - b.date.getTime());
+  return points.slice(-limit);
+}