/**
 * TradeMate API Client
 * Communicates with TradeMate backend from the browser extension.
 * All functions are async, return parsed JSON or throw on error.
 * Errors from 402/403 carry structured data for upgrade prompts.
 */

const STORAGE_KEYS = {
  API_URL: 'trademate_api_url',
  TOKEN: 'trademate_token',
};

export class ApiError extends Error {
  constructor(message, status, data = {}) {
    super(message);
    this.name = 'ApiError';
    this.status = status;
    this.data = data;       // parsed response body (may contain credits_remaining)
    this.isCreditError = status === 402;
  }
}

async function getConfig() {
  const { apiUrl, token } = await chrome.storage.local.get([STORAGE_KEYS.API_URL, STORAGE_KEYS.TOKEN]);
  if (!apiUrl) throw new ApiError('请先设置 API 地址', 0);
  if (!token) throw new ApiError('请先设置 API Token', 0);
  return { apiUrl: apiUrl.replace(/\/+$/, ''), token };
}

async function request(path, options = {}) {
  const { apiUrl, token } = await getConfig();
  const url = `${apiUrl}${path}`;

  const res = await fetch(url, {
    method: options.method || 'POST',
    headers: {
      'Content-Type': 'application/json',
      'Authorization': `Bearer ${token}`,
      ...options.headers,
    },
    body: options.body ? JSON.stringify(options.body) : undefined,
  });

  if (!res.ok) {
    let detail = `HTTP ${res.status}`;
    let body = {};
    try {
      body = await res.json();
      detail = body.detail || detail;
    } catch {}
    throw new ApiError(detail, res.status, body);
  }

  return res.json();
}

/** Login: get JWT token from username + password */
export async function login(username, password, apiUrl) {
  const url = `${apiUrl.replace(/\/+$/, '')}/api/v1/auth/login`;
  const res = await fetch(url, {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({ username, password }),
  });
  if (!res.ok) {
    let detail = '登录失败';
    try { const e = await res.json(); detail = e.detail || detail; } catch {}
    throw new ApiError(detail, res.status);
  }
  const data = await res.json();
  return data.access_token;
}

/** Get current credit balance */
export async function getBalance() {
  const data = await request('/api/v1/credits/balance', { method: 'GET' });
  return {
    balance: data.balance ?? 0,
    totalPurchased: data.total_purchased ?? 0,
    totalUsed: data.total_used ?? 0,
    subscription: data.subscription ?? null,
    freeTrialUsed: data.free_trial_used ?? false,
    dailyFreeTranslateCharsLeft: data.daily_free_translate_chars_left ?? 0,
    rates: data.rates ?? {},
  };
}

/** Get available subscription plans */
export async function getSubscriptionPlans() {
  return request('/api/v1/credits/subscription-plans', { method: 'GET' });
}

/** Get available credit packages */
export async function getCreditPackages() {
  return request('/api/v1/credits/packages', { method: 'GET' });
}

/** Translate text */
export async function translate(text, targetLang = 'zh', sourceLang = 'auto') {
  return request('/api/v1/translate', {
    body: { text, target_lang: targetLang, source_lang: sourceLang, context: 'trade' },
  });
}

/** Generate reply suggestions */
export async function generateReply(inquiry, tone = 'professional', count = 3) {
  return request('/api/v1/translate/reply', {
    body: { inquiry, tone, count },
  });
}

/** Search for potential customers */
export async function searchLeads(productDescription, targetMarket = 'US') {
  return request('/api/v1/discovery/search', {
    body: { product_description: productDescription, target_market: targetMarket },
  });
}

/** Generate marketing copy */
export async function generateMarketing(productName, description, style = 'professional', count = 3) {
  return request('/api/v1/marketing/generate', {
    body: {
      product_name: productName,
      description,
      style,
      count,
      target: 'US importers',
      language: 'en',
    },
  });
}

/** Generate keywords */
export async function generateKeywords(productName, description, count = 10) {
  return request('/api/v1/marketing/keywords', {
    body: { product_name: productName, description, count, language: 'en' },
  });
}