feat(export): X-coordinate helpers (date, # days reach, daily field)

frontend/src/lib/dataExport.js

@@ -56,6 +56,70 @@ export function listExportableParams(dailyTemplate, statuses) {
   return params;
 }
 
+// Numeric value of a daily field on one status (mirrors the metrics plot's helper).
+export function numericFieldVal(status, field) {
+  if (!field) return null;
+  const raw = field.builtin ? status?.[field.key] : status?.custom_fields?.[field.fieldId];
+  const n = parseFloat(raw);
+  return Number.isNaN(n) ? null : n;
+}
+
+// Ordered row members for the chosen X coordinate.
+// xField: '__date__' | '__days__' | <daily fieldId>
+export function listSampleMembers(statuses, xField, dailyTemplate) {
+  const list = statuses ?? [];
+  if (xField === '__date__') {
+    const keys = new Set();
+    for (const s of list) if (s?.date) keys.add(dateKey(s.date));
+    return [...keys].sort().map((k) => ({ id: k, label: k, sampleValue: k }));
+  }
+  if (xField === '__days__') {
+    const counts = new Map();
+    for (const s of list) {
+      if (s?.animal_id == null || !s?.date) continue;
+      counts.set(s.animal_id, (counts.get(s.animal_id) ?? 0) + 1);
+    }
+    const max = counts.size ? Math.max(...counts.values()) : 0;
+    return Array.from({ length: max }, (_, i) => ({ id: String(i + 1), label: String(i + 1), sampleValue: i + 1 }));
+  }
+  const field = (dailyTemplate ?? []).find((f) => f.fieldId === xField);
+  const vals = new Set();
+  for (const s of list) {
+    const v = numericFieldVal(s, field);
+    if (v !== null) vals.add(v);
+  }
+  return [...vals].sort((a, b) => a - b).map((v) => ({ id: String(v), label: String(v), sampleValue: v }));
+}
+
+// animalId -> Map(sampleValue -> status). First status per (subject, sampleValue) wins,
+// scanning each subject's statuses in ascending date order.
+export function buildSampleIndex(statuses, xField, dailyTemplate) {
+  const bySubject = new Map();
+  for (const s of statuses ?? []) {
+    if (s?.animal_id == null || !s?.date) continue;
+    if (!bySubject.has(s.animal_id)) bySubject.set(s.animal_id, []);
+    bySubject.get(s.animal_id).push(s);
+  }
+  const field = xField !== '__date__' && xField !== '__days__'
+    ? (dailyTemplate ?? []).find((f) => f.fieldId === xField)
+    : null;
+
+  const index = new Map();
+  for (const [animalId, subjStatuses] of bySubject) {
+    const ordered = [...subjStatuses].sort((a, b) => dateKey(a.date).localeCompare(dateKey(b.date)));
+    const m = new Map();
+    ordered.forEach((s, i) => {
+      let key;
+      if (xField === '__date__') key = dateKey(s.date);
+      else if (xField === '__days__') key = i + 1;
+      else { const v = numericFieldVal(s, field); if (v === null) return; key = v; }
+      if (!m.has(key)) m.set(key, s);
+    });
+    index.set(animalId, m);
+  }
+  return index;
+}
+
 export const EXPORT_DIMENSIONS = [
   { dim: 'date', label: 'Date' },
   { dim: 'subject', label: 'Subject' },

frontend/tests/dataExport.test.js

@@ -335,3 +335,55 @@ describe('listParameterMembers / listDimensionMembers', () => {
     expect(listDimensionMembers('parameter', ctx)[0].id).toBe('__total__');
   });
 });
+
+import { numericFieldVal, listSampleMembers, buildSampleIndex } from '../src/lib/dataExport';
+
+const sDaily = [{ fieldId: 'c-w', key: 'w', label: 'Weight', builtin: false, active: true }];
+const sStatuses = [
+  { animal_id: 'a1', date: '2026-07-01T00:00:00Z', custom_fields: { 'c-w': '250' } },
+  { animal_id: 'a1', date: '2026-07-03T00:00:00Z', custom_fields: { 'c-w': '260' } },
+  { animal_id: 'a2', date: '2026-07-01T00:00:00Z', custom_fields: { 'c-w': '250' } },
+];
+
+describe('numericFieldVal', () => {
+  it('reads builtin via key and custom via fieldId, parsed to number', () => {
+    expect(numericFieldVal({ weight: '250' }, { builtin: true, key: 'weight' })).toBe(250);
+    expect(numericFieldVal({ custom_fields: { 'c-w': '12.5' } }, { builtin: false, fieldId: 'c-w' })).toBe(12.5);
+  });
+  it('returns null for non-numeric, missing, or no field', () => {
+    expect(numericFieldVal({ custom_fields: { 'c-w': 'abc' } }, { builtin: false, fieldId: 'c-w' })).toBeNull();
+    expect(numericFieldVal({}, { builtin: true, key: 'weight' })).toBeNull();
+    expect(numericFieldVal({ weight: 1 }, null)).toBeNull();
+  });
+});
+
+describe('listSampleMembers', () => {
+  it('date: distinct dates sorted', () => {
+    expect(listSampleMembers(sStatuses, '__date__', sDaily).map((m) => m.sampleValue)).toEqual(['2026-07-01', '2026-07-03']);
+  });
+  it('# days reach: 1..max records per subject', () => {
+    expect(listSampleMembers(sStatuses, '__days__', sDaily).map((m) => m.sampleValue)).toEqual([1, 2]);
+  });
+  it('daily field: distinct numeric values sorted ascending', () => {
+    expect(listSampleMembers(sStatuses, 'c-w', sDaily).map((m) => m.sampleValue)).toEqual([250, 260]);
+  });
+});
+
+describe('buildSampleIndex', () => {
+  it('date coord maps animalId -> dateKey -> status', () => {
+    const idx = buildSampleIndex(sStatuses, '__date__', sDaily);
+    expect(idx.get('a1').get('2026-07-03').date).toContain('2026-07-03');
+  });
+  it('# days reach assigns per-subject ordinals in date order', () => {
+    const idx = buildSampleIndex(sStatuses, '__days__', sDaily);
+    expect(idx.get('a1').get(1).date).toContain('2026-07-01');
+    expect(idx.get('a1').get(2).date).toContain('2026-07-03');
+    expect(idx.get('a2').get(1).date).toContain('2026-07-01');
+    expect(idx.get('a2').has(2)).toBe(false);
+  });
+  it('daily field maps numeric value to first status by date', () => {
+    const idx = buildSampleIndex(sStatuses, 'c-w', sDaily);
+    expect(idx.get('a1').get(250).date).toContain('2026-07-01');
+    expect(idx.get('a1').get(260).date).toContain('2026-07-03');
+  });
+});