import { requestWalletNonce, verifyWalletSignature } from "./api";

export type WalletKind = "tokenPocket" | "metaMask" | "imToken";

const bnbChainIdHex = "0x38";

export type EthereumProvider = {
  isMetaMask?: boolean;
  isTokenPocket?: boolean;
  isImToken?: boolean;
  providers?: EthereumProvider[];
  request: <T = unknown>(args: {
    method: string;
    params?: unknown[];
  }) => Promise<T>;
};

export function getInjectedEthereum(): EthereumProvider | null {
  if (typeof window === "undefined") return null;
  const maybeWindow = window as typeof window & { ethereum?: EthereumProvider };
  return maybeWindow.ethereum ?? null;
}

export function getInjectedWallet(kind?: WalletKind): EthereumProvider | null {
  const ethereum = getInjectedEthereum();
  if (!ethereum || !kind) return ethereum;
  const providers = ethereum.providers?.length
    ? ethereum.providers
    : [ethereum];
  const match = providers.find((provider) => {
    if (kind === "metaMask") return provider.isMetaMask;
    if (kind === "tokenPocket") return provider.isTokenPocket;
    if (kind === "imToken") return provider.isImToken;
    return false;
  });
  return match ?? null;
}

async function ensureBnbChain(ethereum: EthereumProvider): Promise<void> {
  try {
    await ethereum.request({
      method: "wallet_switchEthereumChain",
      params: [{ chainId: bnbChainIdHex }],
    });
  } catch (error) {
    const code = (error as { code?: number | string }).code;
    if (code !== 4902 && code !== "4902") throw error;
    await ethereum.request({
      method: "wallet_addEthereumChain",
      params: [
        {
          blockExplorerUrls: ["https://bscscan.com"],
          chainId: bnbChainIdHex,
          chainName: "BNB Smart Chain",
          nativeCurrency: { decimals: 18, name: "BNB", symbol: "BNB" },
          rpcUrls: ["https://bsc-dataseed.binance.org"],
        },
      ],
    });
  }
}

export async function signInWithInjectedWallet(kind?: WalletKind): Promise<{
  token: string;
  wallet: string;
}> {
  const ethereum = getInjectedWallet(kind);
  if (!ethereum) throw new Error("No injected wallet found");

  await ensureBnbChain(ethereum);

  const accounts = await ethereum.request<string[]>({
    method: "eth_requestAccounts",
  });
  const address = accounts[0];
  if (!address) throw new Error("No wallet account returned");

  const nonce = await requestWalletNonce(address);
  const signature = await ethereum.request<string>({
    method: "personal_sign",
    params: [nonce.message, address],
  });
  return verifyWalletSignature({
    address,
    message: nonce.message,
    signature,
  });
}