/**
 * Aperture — Backend API Wrapper
 * All communication with the FastAPI backend goes through this module.
 */

const BASE = '';  // same-origin; empty string = relative to current host

/**
 * Fetch wrapper with JSON handling and error propagation.
 * @param {string} path  - Relative path, e.g. "/api/eo-products"
 * @param {object} opts  - fetch() options (optional)
 * @returns {Promise<any>}
 */
async function apiFetch(path, opts = {}) {
  const headers = { 'Content-Type': 'application/json', ...(opts.headers || {}) };
  const session = JSON.parse(sessionStorage.getItem('aperture_session') || 'null');
  if (session) {
    headers['Authorization'] = `Bearer ${session.email}:${session.token}`;
  }
  const res = await fetch(BASE + path, { ...opts, headers });
  if (!res.ok) {
    let detail = res.statusText;
    try {
      const body = await res.json();
      if (Array.isArray(body.detail)) {
        detail = body.detail.map(e => e.msg || JSON.stringify(e)).join('; ');
      } else {
        detail = body.detail || JSON.stringify(body);
      }
    } catch (_) { /* ignore parse errors */ }
    throw new Error(`API ${res.status}: ${detail}`);
  }
  // 204 No Content — nothing to parse
  if (res.status === 204) return null;
  return res.json();
}

/* ── EO Products ─────────────────────────────────────────── */

/**
 * List all available EO products.
 * @returns {Promise<Array<{id, name, category, question, estimated_minutes}>>}
 */
export async function listProducts() {
  return apiFetch('/api/eo-products');
}

/* ── Jobs ────────────────────────────────────────────────── */

/**
 * Submit a new analysis job.
 * @param {{aoi, time_range, product_ids, email}} payload
 * @returns {Promise<{id, status}>}
 */
export async function submitJob(payload) {
  return apiFetch('/api/jobs', {
    method: 'POST',
    body: JSON.stringify(payload),
  });
}

/**
 * Get current status and results for a job.
 * @param {string} jobId
 * @returns {Promise<{id, status, progress, results, created_at, updated_at, error}>}
 */
export async function getJob(jobId) {
  return apiFetch(`/api/jobs/${jobId}`);
}

/* ── Downloads ───────────────────────────────────────────── */

/**
 * Return auth headers for the current session (for raw fetch calls).
 */
export function authHeaders() {
  const session = JSON.parse(sessionStorage.getItem('aperture_session') || 'null');
  if (!session) return {};
  return { 'Authorization': `Bearer ${session.email}:${session.token}` };
}

/**
 * Fetch a file with auth and trigger a browser download.
 *
 * The anchor must be attached to the DOM for .click() to work
 * reliably in Safari/Firefox, and the object URL must outlive the
 * click event long enough for the browser to start the download.
 *
 * @param {string} url - File endpoint URL
 * @param {string} filename - Suggested download filename
 */
export async function authDownload(url, filename) {
  const res = await fetch(url, { headers: authHeaders() });
  if (!res.ok) {
    let detail = res.statusText;
    try {
      const body = await res.json();
      detail = body.detail || detail;
    } catch (_) { /* ignore */ }
    throw new Error(`Download failed (${res.status}): ${detail}`);
  }
  const blob = await res.blob();
  const objectUrl = URL.createObjectURL(blob);
  const a = document.createElement('a');
  a.href = objectUrl;
  a.download = filename;
  a.style.display = 'none';
  document.body.appendChild(a);
  a.click();
  // Defer cleanup so the browser has time to start the download.
  setTimeout(() => {
    document.body.removeChild(a);
    URL.revokeObjectURL(objectUrl);
  }, 1500);
}

/**
 * Returns the URL for the PDF report download.
 * @param {string} jobId
 * @returns {string}
 */
export function reportUrl(jobId) {
  return `${BASE}/api/jobs/${jobId}/report`;
}

/**
 * Returns the URL for the data package download.
 * @param {string} jobId
 * @returns {string}
 */
export function packageUrl(jobId) {
  return `${BASE}/api/jobs/${jobId}/package`;
}

/**
 * Returns the URL for an EO product map PNG.
 * @param {string} jobId
 * @param {string} productId
 * @returns {string}
 */
export function mapUrl(jobId, productId) {
  return `${BASE}/api/jobs/${jobId}/maps/${productId}`;
}

/**
 * Returns the URL for EO product spatial data JSON.
 * @param {string} jobId
 * @param {string} productId
 * @returns {string}
 */
export function spatialUrl(jobId, productId) {
  return `${BASE}/api/jobs/${jobId}/spatial/${productId}`;
}

/**
 * Fetch composite overview score + compound signals for the dashboard.
 * @param {string} jobId
 * @returns {Promise<{overview, compound_signals}>}
 */
export async function getJobOverview(jobId) {
  return apiFetch(`/api/jobs/${jobId}/overview`);
}

/* ── AOI Advisor ───────────────────────────────────────── */

/**
 * Get Claude-powered region insight for an AOI.
 * @param {Array<number>} bbox - [minLon, minLat, maxLon, maxLat]
 * @returns {Promise<{context, recommended_start, recommended_end, product_priorities, reasoning} | null>}
 */
export async function getAoiAdvice(bbox) {
  try {
    const result = await apiFetch('/api/aoi-advice', {
      method: 'POST',
      body: JSON.stringify({ bbox }),
    });
    // Treat all-null as failure
    if (!result || !result.context) return null;
    return result;
  } catch {
    return null;
  }
}

/* ── Auth ───────────────────────────────────────────────── */

export async function requestMagicLink(email) {
  return apiFetch('/api/auth/request', {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({ email }),
  });
}

export async function verifyToken(email, token) {
  return apiFetch('/api/auth/verify', {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({ email, token }),
  });
}

export async function listJobs() {
  return apiFetch('/api/jobs');
}