/**
 * LandveX Finance — API Layer
 * Sprint 3: UI-refaktorering
 * 
 * Centraliserad fetch-wrapper med auth, timeout, retry och felhantering.
 */

const API_BASE = '';
const TENANT = 'landvex';
const DEFAULT_TIMEOUT = 10000;
const MAX_RETRIES = 1;

// ── Helpers ──
function getToken() {
  // Försök hämta JWT från cookie eller localStorage
  const match = document.cookie.match(/wavult_token=([^;]+)/);
  if (match) return decodeURIComponent(match[1]);
  try {
    return localStorage.getItem('wavult:token');
  } catch { return null; }
}

function buildHeaders() {
  const h = {
    'x-internal-source': 'ouroboros-system',
    'x-tenant-id': TENANT,
  };
  const tok = getToken();
  if (tok) h['Authorization'] = `Bearer ${tok}`;
  return h;
}

// ── Core fetch ──
export async function api(path, method = 'GET', body = null, opts = {}) {
  const url = path.startsWith('http') ? path : `${API_BASE}${path}`;
  const timeout = opts.timeout || DEFAULT_TIMEOUT;
  const retries = opts.retries ?? MAX_RETRIES;

  const headers = { ...buildHeaders() };
  if (body && method !== 'GET') {
    headers['Content-Type'] = 'application/json';
  }

  let lastError;
  for (let attempt = 0; attempt <= retries; attempt++) {
    const ctrl = new AbortController();
    const t = setTimeout(() => ctrl.abort(), timeout);

    try {
      const options = {
        method,
        headers,
        signal: ctrl.signal,
      };
      if (body && method !== 'GET') {
        options.body = JSON.stringify(body);
      }

      const r = await fetch(url, options);
      clearTimeout(t);

      if (!r.ok) {
        const err = new Error(`HTTP ${r.status}: ${r.statusText}`);
        err.status = r.status;
        err.code = `HTTP_${r.status}`;
        throw err;
      }

      // Tomt svar (204)
      if (r.status === 204) return null;

      const contentType = r.headers.get('content-type') || '';
      if (contentType.includes('application/json')) {
        return await r.json();
      }
      return await r.text();

    } catch (e) {
      clearTimeout(t);
      lastError = e;

      // Retry vid nätverksfel eller 5xx
      const shouldRetry = attempt < retries && (
        e.name === 'AbortError' ||
        e.name === 'TypeError' ||
        (e.status >= 500 && e.status < 600)
      );

      if (!shouldRetry) break;

      // Exponential backoff
      await new Promise(r => setTimeout(r, 1000 * (attempt + 1)));
    }
  }

  throw lastError;
}

// ── Convenience methods ──
export const get = (path, opts) => api(path, 'GET', null, opts);
export const post = (path, body, opts) => api(path, 'POST', body, opts);
export const put = (path, body, opts) => api(path, 'PUT', body, opts);
export const del = (path, opts) => api(path, 'DELETE', null, opts);

// ── Typed API wrappers ──
export async function getJournal(params = {}) {
  const qs = new URLSearchParams(params).toString();
  return get(`/api/ledger/journal?${qs}`);
}

export async function getTrialBalance(fiscalYear, period) {
  const qs = new URLSearchParams({ fiscal_year: fiscalYear, period }).toString();
  return get(`/api/ledger/trial-balance?${qs}`);
}

export async function getAccounts() {
  return get('/api/ledger/accounts');
}

export async function getPeriods(fiscalYear) {
  return get(`/api/ledger/periods?fiscal_year=${fiscalYear}`);
}

export async function getInvoices(fiscalYear) {
  return get(`/api/ledger/invoices?fiscal_year=${fiscalYear}`);
}

export async function createJournalEntry(entry) {
  return post('/api/ledger/journal', entry);
}

export async function postJournalEntry(id) {
  return post(`/api/ledger/journal/${id}/post`, {});
}

export async function createInvoice(invoice) {
  return post('/api/ledger/invoices', invoice);
}

export async function getTasks() {
  return get('/api/ledger/tasks');
}

export async function uploadReceipt(entryId, file) {
  const formData = new FormData();
  formData.append('file', file);

  const url = `/api/ledger/journal/${entryId}/upload`;
  const headers = buildHeaders();
  delete headers['Content-Type']; // Låt browser sätta boundary

  const r = await fetch(url, {
    method: 'POST',
    headers,
    body: formData,
  });

  if (!r.ok) throw new Error(`Upload failed: ${r.status}`);
  return r.json();
}

export async function getReceipts(entryId) {
  return get(`/api/ledger/journal/${entryId}/receipts`);
}

export async function exportSIE4(fiscalYear) {
  return get(`/api/ledger/export/sie4?fiscal_year=${fiscalYear}`);
}

// ── Health ──
export async function getHealth() {
  return get('/health');
}

export async function getFinanceHealth() {
  return get('/health/finance');
}

export default { api, get, post, put, del, getJournal, getTrialBalance, getAccounts, getPeriods, getInvoices, createJournalEntry, postJournalEntry, createInvoice, getTasks, uploadReceipt, getReceipts, exportSIE4, getHealth, getFinanceHealth };