/**
 * @module api
 * Data Layer: Fetches metric data from the backend API.
 * Provides functions to retrieve and handle metrics related to exit analysis.
 */

const API_BASE_URL = '/metrics';

/**
 * Fetches exit metrics from the API.
 *
 * @async
 * @function fetchMetrics
 * @param {Object} [params={}] - Optional query parameters.
 * @param {('pinned'|'unpinned')} [params.filter] - Filters runs by pinned/unpinned status.
 * @param {string} [params.setup_fingerprint] - Restricts metrics to runs with identical setup_fingerprint.
 * @returns {Promise<Array<{run_id: string, setup_fingerprint: string, warn_rate: number, unknown_rate: number, delta_t_stats: Object, timestamp: string}>>}
 * Returns an array of metrics objects.
 */
export async function fetchMetrics(params = {}) {
  const url = new URL(API_BASE_URL, window.location.origin);

  if (params.filter) {
    url.searchParams.append('filter', params.filter);
  }
  if (params.setup_fingerprint) {
    url.searchParams.append('setup_fingerprint', params.setup_fingerprint);
  }

  try {
    const response = await fetch(url.toString(), {
      method: 'GET',
      headers: {
        'Accept': 'application/json'
      }
    });

    if (!response.ok) {
      console.error(`Fetch error: HTTP ${response.status}`);
      return [];
    }

    const data = await response.json();

    if (!Array.isArray(data)) {
      console.error('Unexpected API response format (expected an array).');
      return [];
    }

    return data.map(item => ({
      run_id: item.run_id ?? '',
      setup_fingerprint: item.setup_fingerprint ?? '',
      warn_rate: Number(item.warn_rate ?? 0),
      unknown_rate: Number(item.unknown_rate ?? 0),
      delta_t_stats: item.delta_t_stats ?? {},
      timestamp: item.timestamp ?? ''
    }));
  } catch (err) {
    console.error('Error fetching metrics:', err);
    return [];
  }
}