Function buildCacheKey

src/utils/cache.ts:66–91

(
  endpoint: string,
  params: Record<string, string | number | string[] | undefined>
)

 * Example:         prices/AAPL_a1b2c3d4e5f6.json
 */
export function buildCacheKey(
  endpoint: string,
  params: Record<string, string | number | string[] | undefined>
): string {
  // Build a canonical string from sorted, non-empty params
  const sortedParams = Object.entries(params)
    .filter(([, v]) => v !== undefined && v !== null)
    .sort(([a], [b]) => a.localeCompare(b))
    .map(([k, v]) => `${k}=${Array.isArray(v) ? [...v].sort().join(',') : v}`)
    .join('&');

  const raw = `${endpoint}?${sortedParams}`;
  const hash = createHash('md5').update(raw).digest('hex').slice(0, 12);

  // Turn "/prices/" → "prices"
  const cleanEndpoint = endpoint
    .replace(/^\//, '')
    .replace(/\/$/, '')
    .replace(/\//g, '_');

  // Prefix with ticker when available for human-readable filenames (optional)
  const ticker = typeof params.ticker === 'string' ? params.ticker.toUpperCase() : null;
  const prefix = ticker ? `${ticker}_` : '';

  return `${cleanEndpoint}/${prefix}${hash}.json`;
}

/**
 * Validate that a parsed object has the shape of a CacheEntry.