const API_BASE = process.env.REACT_APP_API_URL !== undefined ? process.env.REACT_APP_API_URL : 'http://localhost:8001';

export async function fetchModels() {
  const resp = await fetch(`${API_BASE}/api/models`, { cache: 'no-store' });
  if (!resp.ok) throw new Error(`Failed to fetch models: ${resp.status}`);
  return resp.json();
}

export async function runComparisonStream(query, neonSelections, comparisonModelIds, sessionId, onGroupStart, onResponse, onDone, personaTarget = 'neon-only') {
  const resp = await fetch(`${API_BASE}/api/compare/stream`, {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({
      query,
      neon_selections: neonSelections,
      comparison_model_ids: comparisonModelIds,
      session_id: sessionId,
      persona_target: personaTarget,
    }),
  });
  if (!resp.ok) {
    const err = await resp.json().catch(() => ({ detail: resp.statusText }));
    throw new Error(err.detail || 'Comparison failed');
  }

  const reader = resp.body.getReader();
  const decoder = new TextDecoder();
  let buffer = '';

  while (true) {
    const { value, done } = await reader.read();
    if (done) break;
    buffer += decoder.decode(value, { stream: true });

    const parts = buffer.split('\n\n');
    buffer = parts.pop();

    for (const part of parts) {
      const lines = part.trim().split('\n');
      let eventType = 'message';
      let data = '';
      for (const line of lines) {
        if (line.startsWith('event: ')) eventType = line.slice(7).trim();
        else if (line.startsWith('data: ')) data = line.slice(6);
      }
      if (!data) continue;
      try {
        const parsed = JSON.parse(data);
        if (eventType === 'group_start') onGroupStart(parsed);
        else if (eventType === 'response') onResponse(parsed);
        else if (eventType === 'done') onDone();
      } catch (e) {
        console.warn('SSE parse error', e, data);
      }
    }
  }
}

export async function uploadCsvComparison(file, neonSelections, comparisonModelIds, personaTarget = 'neon-only') {
  const form = new FormData();
  form.append('file', file);
  form.append('neon_selections', JSON.stringify(neonSelections));
  form.append('comparison_model_ids', JSON.stringify(comparisonModelIds));
  form.append('persona_target', personaTarget);

  const resp = await fetch(`${API_BASE}/api/compare/csv`, {
    method: 'POST',
    body: form,
  });
  if (!resp.ok) {
    const err = await resp.json().catch(() => ({ detail: resp.statusText }));
    throw new Error(err.detail || 'CSV comparison failed');
  }
  return resp.blob();
}

export async function downloadHistory(sessionId) {
  const resp = await fetch(`${API_BASE}/api/history/${sessionId}/csv`);
  if (!resp.ok) throw new Error('No history available');
  return resp.blob();
}