import type { PopoConfig, PopoToken } from "./types.js";
import { resolvePopoCredentials } from "./accounts.js";

// Token cache
let cachedToken: PopoToken | null = null;
let cachedAppKey: string | null = null;

/**
 * Get a valid access token, refreshing if necessary.
 */
export async function getAccessToken(cfg: PopoConfig): Promise<string> {
  const creds = resolvePopoCredentials(cfg);
  if (!creds) {
    throw new Error("POPO credentials not configured (appKey, appSecret required)");
  }

  const now = Date.now();

  // Check if we have a valid cached token
  if (
    cachedToken &&
    cachedAppKey === creds.appKey &&
    cachedToken.accessExpiredAt > now + 60000 // 1 minute buffer
  ) {
    return cachedToken.accessToken;
  }

  // Check if we can use refresh token
  if (
    cachedToken &&
    cachedAppKey === creds.appKey &&
    cachedToken.refreshExpiredAt > now + 60000
  ) {
    try {
      cachedToken = await refreshAccessToken(cfg, cachedToken.refreshToken);
      return cachedToken.accessToken;
    } catch {
      // Fall through to get a new token
    }
  }

  // Get a new token
  cachedToken = await fetchNewToken(cfg);
  cachedAppKey = creds.appKey;
  return cachedToken.accessToken;
}

/**
 * Fetch a new token using appKey and appSecret.
 */
async function fetchNewToken(cfg: PopoConfig): Promise<PopoToken> {
  const creds = resolvePopoCredentials(cfg);
  if (!creds) {
    throw new Error("POPO credentials not configured");
  }

  const response = await fetch(`${creds.server}/auth/token`, {
    method: "POST",
    headers: {
      "Content-Type": "application/json",
    },
    body: JSON.stringify({
      appKey: creds.appKey,
      appSecret: creds.appSecret,
    }),
  });

  if (!response.ok) {
    throw new Error(`POPO token request failed: ${response.status} ${response.statusText}`);
  }

  const data = (await response.json()) as {
    code?: number;
    message?: string;
    result?: {
      accessToken: string;
      accessExpiredAt: number;
      refreshToken: string;
      refreshExpiredAt: number;
    };
  };

  if (data.code !== 200 || !data.result) {
    throw new Error(`POPO token request failed: ${data.message || "unknown error"}`);
  }

  return {
    accessToken: data.result.accessToken,
    accessExpiredAt: data.result.accessExpiredAt,
    refreshToken: data.result.refreshToken,
    refreshExpiredAt: data.result.refreshExpiredAt,
  };
}

/**
 * Refresh an access token using a refresh token.
 */
export async function refreshAccessToken(
  cfg: PopoConfig,
  refreshToken: string
): Promise<PopoToken> {
  const creds = resolvePopoCredentials(cfg);
  if (!creds) {
    throw new Error("POPO credentials not configured");
  }

  const response = await fetch(`${creds.server}/auth/refresh`, {
    method: "POST",
    headers: {
      "Content-Type": "application/json",
    },
    body: JSON.stringify({
      appKey: creds.appKey,
      refreshToken,
    }),
  });

  if (!response.ok) {
    throw new Error(`POPO token refresh failed: ${response.status} ${response.statusText}`);
  }

  const data = (await response.json()) as {
    code?: number;
    message?: string;
    result?: {
      accessToken: string;
      accessExpiredAt: number;
      refreshToken: string;
      refreshExpiredAt: number;
    };
  };

  if (data.code !== 200 || !data.result) {
    throw new Error(`POPO token refresh failed: ${data.message || "unknown error"}`);
  }

  return {
    accessToken: data.result.accessToken,
    accessExpiredAt: data.result.accessExpiredAt,
    refreshToken: data.result.refreshToken,
    refreshExpiredAt: data.result.refreshExpiredAt,
  };
}

/**
 * Clear the token cache.
 */
export function clearTokenCache() {
  cachedToken = null;
  cachedAppKey = null;
}