feat: add utility functions with unit tests (#63)

feat: add utility functions with unit tests

src/utils/__tests__/formatCurrency.test.ts

@@ -0,0 +1,33 @@
+import { describe, it, expect } from 'vitest';
+import { formatCurrency } from '../formatCurrency';
+
+describe('formatCurrency', () => {
+  it('formats 0 cents as $0.00', () => {
+    expect(formatCurrency(0)).toBe('$0.00');
+  });
+
+  it('formats 199 cents as $1.99', () => {
+    expect(formatCurrency(199)).toBe('$1.99');
+  });
+
+  it('formats 10000 cents as $100.00', () => {
+    expect(formatCurrency(10000)).toBe('$100.00');
+  });
+
+  it('handles negative values', () => {
+    expect(formatCurrency(-500)).toBe('-$5.00');
+  });
+
+  it('handles large numbers', () => {
+    expect(formatCurrency(99999999)).toBe('$999,999.99');
+  });
+
+  it('supports custom locale', () => {
+    expect(formatCurrency(1999, 'de-DE', 'EUR')).toContain('19,99');
+  });
+
+  it('supports custom currency', () => {
+    const result = formatCurrency(1000, 'en-US', 'EUR');
+    expect(result).toContain('10.00');
+  });
+});

src/utils/__tests__/formatDate.test.ts

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+import { describe, it, expect, beforeEach, afterEach, vi } from 'vitest';
+import { formatDate } from '../formatDate';
+
+describe('formatDate', () => {
+  describe('short style', () => {
+    it('formats an ISO date string', () => {
+      const result = formatDate('2024-03-15', 'short');
+      expect(result).toMatch(/Mar 15, 2024/);
+    });
+
+    it('formats a Date object', () => {
+      const result = formatDate(new Date('2024-03-15'), 'short');
+      expect(result).toMatch(/Mar 15, 2024/);
+    });
+  });
+
+  describe('long style', () => {
+    it('formats with weekday and full month name', () => {
+      const result = formatDate('2024-03-15', 'long');
+      expect(result).toMatch(/Friday/);
+      expect(result).toMatch(/March/);
+    });
+  });
+
+  describe('relative style', () => {
+    beforeEach(() => {
+      vi.useFakeTimers();
+    });
+
+    afterEach(() => {
+      vi.useRealTimers();
+    });
+
+    it('returns "just now" for very recent dates', () => {
+      const now = new Date('2024-01-01T12:00:00Z');
+      vi.setSystemTime(now);
+      const result = formatDate(new Date('2024-01-01T11:59:59Z'), 'relative');
+      expect(result).toBe('just now');
+    });
+
+    it('returns minutes ago', () => {
+      const now = new Date('2024-01-01T12:00:00Z');
+      vi.setSystemTime(now);
+      const result = formatDate(new Date('2024-01-01T11:45:00Z'), 'relative');
+      expect(result).toBe('15m ago');
+    });
+
+    it('returns hours ago', () => {
+      const now = new Date('2024-01-01T12:00:00Z');
+      vi.setSystemTime(now);
+      const result = formatDate(new Date('2024-01-01T09:00:00Z'), 'relative');
+      expect(result).toBe('3h ago');
+    });
+
+    it('returns days ago', () => {
+      const now = new Date('2024-01-05T12:00:00Z');
+      vi.setSystemTime(now);
+      const result = formatDate(new Date('2024-01-01T12:00:00Z'), 'relative');
+      expect(result).toBe('4d ago');
+    });
+  });
+});

src/utils/__tests__/storeSlugs.test.ts

@@ -0,0 +1,46 @@
+import { describe, it, expect } from 'vitest';
+import { getStore, getStoreName, STORE_SLUGS } from '../storeSlugs';
+
+describe('storeSlugs', () => {
+  describe('STORE_SLUGS constant', () => {
+    it('contains meijer, kroger, and target', () => {
+      expect(STORE_SLUGS).toHaveProperty('meijer');
+      expect(STORE_SLUGS).toHaveProperty('kroger');
+      expect(STORE_SLUGS).toHaveProperty('target');
+    });
+  });
+
+  describe('getStore', () => {
+    it('returns store data for known slug', () => {
+      const store = getStore('meijer');
+      expect(store).toEqual({
+        name: 'Meijer',
+        color: '#e31837',
+        icon: '/icons/stores/meijer.svg',
+      });
+    });
+
+    it('returns null for unknown slug', () => {
+      expect(getStore('unknown-store')).toBeNull();
+    });
+
+    it('is case insensitive', () => {
+      expect(getStore('KROGER')).toBeTruthy();
+      expect(getStore('Target')).toBeTruthy();
+    });
+  });
+
+  describe('getStoreName', () => {
+    it('returns store name for known slug', () => {
+      expect(getStoreName('kroger')).toBe('Kroger');
+    });
+
+    it('returns raw slug for unknown store', () => {
+      expect(getStoreName('unknown-store')).toBe('unknown-store');
+    });
+
+    it('is case insensitive', () => {
+      expect(getStoreName('TARGET')).toBe('Target');
+    });
+  });
+});

src/utils/formatCurrency.ts

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+export function formatCurrency(
+  cents: number,
+  locale = 'en-US',
+  currency = 'USD'
+): string {
+  return new Intl.NumberFormat(locale, {
+    style: 'currency',
+    currency,
+  }).format(cents / 100);
+}

src/utils/formatDate.ts

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+export function formatDate(
+  date: string | Date,
+  style: 'short' | 'long' | 'relative' = 'short'
+): string {
+  const d = typeof date === 'string' ? new Date(date) : date;
+
+  if (style === 'short') {
+    return d.toLocaleDateString('en-US', {
+      month: 'short',
+      day: 'numeric',
+      year: 'numeric',
+    });
+  }
+
+  if (style === 'long') {
+    return d.toLocaleDateString('en-US', {
+      weekday: 'long',
+      month: 'long',
+      day: 'numeric',
+      year: 'numeric',
+    });
+  }
+
+  // relative
+  const diff = Date.now() - d.getTime();
+  const seconds = Math.floor(diff / 1000);
+  if (seconds < 60) return 'just now';
+  const minutes = Math.floor(seconds / 60);
+  if (minutes < 60) return `${minutes}m ago`;
+  const hours = Math.floor(minutes / 60);
+  if (hours < 24) return `${hours}h ago`;
+  const days = Math.floor(hours / 24);
+  return `${days}d ago`;
+}

src/utils/storeSlugs.ts

@@ -0,0 +1,13 @@
+export const STORE_SLUGS: Record<string, { name: string; color: string; icon: string }> = {
+  meijer: { name: 'Meijer', color: '#e31837', icon: '/icons/stores/meijer.svg' },
+  kroger: { name: 'Kroger', color: '#0033a0', icon: '/icons/stores/kroger.svg' },
+  target: { name: 'Target', color: '#cc0000', icon: '/icons/stores/target.svg' },
+};
+
+export function getStore(slug: string) {
+  return STORE_SLUGS[slug.toLowerCase()] ?? null;
+}
+
+export function getStoreName(slug: string): string {
+  return getStore(slug)?.name ?? slug;
+}