// Dual-mode data source: static (bootstrap tag) vs server (fetch /api/*).
window.BacktestDataSource = {
  isStatic() {
    return !!document.getElementById('run-data');
  },

  async loadBootstrap() {
    if (this.isStatic()) {
      const runData = JSON.parse(document.getElementById('run-data').textContent);
      // Static mode: version is frozen at report-generation time and lives
      // inside the embedded payload. Fall back to defaults for old reports.
      return {
        config: null,
        runs: [],
        currentRun: runData,
        version: runData.version || { semver: '0.4.1', build: 0, commit: 'dev', deployed_at: null },
      };
    }
    const [config, runs, version] = await Promise.all([
      fetch('/api/config').then((r) => {
        if (!r.ok) throw new Error(`GET /api/config failed: ${r.status}`);
        return r.json();
      }),
      fetch('/api/runs').then((r) => {
        if (!r.ok) throw new Error(`GET /api/runs failed: ${r.status}`);
        return r.json();
      }),
      // Version is non-critical — never fail the whole bootstrap on a /api/version blip.
      fetch('/api/version')
        .then((r) => (r.ok ? r.json() : null))
        .catch(() => null),
    ]);
    return { config, runs, currentRun: null, version };
  },

  async runBacktest(request) {
    const r = await fetch('/api/run', {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify(request),
    });
    if (r.status === 429) throw new Error('A backtest is already running');
    if (!r.ok) throw new Error(`Run failed: ${r.status} ${await r.text()}`);
    return r.json();
  },

  async getRun(id) {
    const r = await fetch(`/api/runs/${id}`);
    if (!r.ok) throw new Error(`Load run failed: ${r.status}`);
    return r.json();
  },

  async loadRuns() {
    const r = await fetch('/api/runs');
    if (!r.ok) throw new Error(`GET /api/runs failed: ${r.status}`);
    return r.json();
  },

  async loadBars({ symbol, timeframe, start, end, indicators = [], params = {} }) {
    const qs = new URLSearchParams({
      symbol,
      timeframe,
      start,
      end,
    });
    if (indicators.length) qs.set('indicators', indicators.join(','));
    for (const [k, v] of Object.entries(params)) {
      if (v !== undefined && v !== null && v !== '') qs.set(k, String(v));
    }
    const r = await fetch(`/api/bars?${qs.toString()}`);
    if (!r.ok) {
      const body = await r.text();
      throw new Error(`GET /api/bars failed: ${r.status} ${body}`);
    }
    return r.json();
  },
};