type QueryType = "balance" | "account";

export const defaultToken =
  "wSHV2S4qX9jFsLjQo8r1BsMLH2ZRKsZx6EJd1sbozGPieEC4Jf";

export async function getBalanceFromGraphQL(params: {
  publicKey: string;
  tokenId?: string;
  mina: string[];
}): Promise<bigint> {
  const { publicKey, mina } = params;
  const tokenId = params.tokenId ?? defaultToken;
  if (mina.length === 0) throw new Error("no mina endpoints provided");
  const account = await fetchAccountInternal({
    publicKey,
    tokenId,
    mina,
    queryType: "balance",
  });
  //console.log("getBalanceFromGraphQL account:", account);
  const balance = (account as any)?.account?.balance?.total;
  return balance ? BigInt(balance) : 0n;
}

export async function getAccountFromGraphQL(params: {
  publicKey: string;
  tokenId?: string;
  mina: string[];
}) {
  const { publicKey, mina } = params;
  const tokenId = params.tokenId ?? defaultToken;
  if (mina.length === 0) throw new Error("no mina endpoints provided");
  const account = await fetchAccountInternal({
    publicKey,
    tokenId,
    mina,
    queryType: "account",
  });
  return (account as any)?.account;
}

async function fetchAccountInternal(params: {
  publicKey: string;
  tokenId: string;
  mina: string[];
  timeout?: number;
  queryType: QueryType;
}) {
  const { publicKey, tokenId, mina, timeout, queryType } = params;
  const query =
    queryType === "balance"
      ? balanceQuery(publicKey, tokenId)
      : accountQuery(publicKey, tokenId);
  let [response, error] = await makeGraphqlRequest({
    query,
    mina,
    timeout,
  });
  if (error !== undefined) return { account: undefined, error };
  const account = (response as any)?.data?.account;
  if (!account) {
    return {
      account: undefined,
      error: {
        statusCode: 404,
        statusText: `fetchAccount: Account with public key ${publicKey} does not exist.`,
      },
    };
  }
  return {
    account,
    error: undefined,
  };
}

async function makeGraphqlRequest(params: {
  query: string;
  mina: string[];
  timeout?: number;
}) {
  const defaultTimeout = 5 * 60 * 1000; // 5 minutes
  const timeout = params.timeout ?? defaultTimeout;
  const { query, mina } = params;
  const graphqlEndpoint = mina[0];
  const fallbackEndpoints: string[] = mina.slice(1);
  if (graphqlEndpoint === "none")
    throw Error(
      "Should have made a graphql request, but don't know to which endpoint."
    );
  let timeouts: NodeJS.Timeout[] = [];
  const clearTimeouts = () => {
    timeouts.forEach((t) => clearTimeout(t));
    timeouts = [];
  };

  const makeRequest = async (url: string) => {
    const controller = new AbortController();
    const timer = setTimeout(() => controller.abort(), timeout);
    timeouts.push(timer);
    let body = JSON.stringify({
      operationName: null,
      query,
      variables: {},
    });
    try {
      let response = await fetch(url, {
        method: "POST",
        headers: { "Content-Type": "application/json" },
        body,
        signal: controller.signal,
      });
      return checkResponseStatus(response);
    } finally {
      clearTimeouts();
    }
  };
  // try to fetch from endpoints in pairs
  let timeoutErrors: { url1: string; url2: string; error: any }[] = [];
  let urls = [graphqlEndpoint, ...fallbackEndpoints];
  for (let i = 0; i < urls.length; i += 2) {
    let url1 = urls[i];
    let url2 = urls[i + 1];
    if (url2 === undefined) {
      try {
        return await makeRequest(url1);
      } catch (error) {
        return [undefined, inferError(error)] as [undefined, object];
      }
    }
    try {
      return await Promise.race([makeRequest(url1), makeRequest(url2)]);
    } catch (unknownError) {
      let error = inferError(unknownError);
      if (error.statusCode === 408) {
        // If the request timed out, try the next 2 endpoints
        timeoutErrors.push({ url1, url2, error });
      } else {
        // If the request failed for some other reason (e.g. o1js error), return the error
        return [undefined, error];
      }
    }
  }
  const statusText = timeoutErrors
    .map(
      ({ url1, url2, error }) =>
        `Request to ${url1} and ${url2} timed out. Error: ${error}`
    )
    .join("\n");
  return [undefined, { statusCode: 408, statusText }];
}

function inferError(error: unknown) {
  let errorMessage = JSON.stringify(error);
  if (error instanceof AbortSignal) {
    return { statusCode: 408, statusText: `Request Timeout: ${errorMessage}` };
  } else {
    return {
      statusCode: 500,
      statusText: `Unknown Error: ${errorMessage}`,
    };
  }
}

async function checkResponseStatus(
  response: Response
): Promise<[object, undefined] | [undefined, object]> {
  if (response.ok) {
    const jsonResponse = (await response.json()) as any;
    if (jsonResponse.errors && jsonResponse.errors.length > 0) {
      return [
        undefined,
        {
          statusCode: response.status,
          statusText: jsonResponse.errors
            .map((error: any) => error.message)
            .join("\n"),
        },
      ];
    } else if (jsonResponse.data === undefined) {
      return [
        undefined,
        {
          statusCode: response.status,
          statusText: `GraphQL response data is undefined`,
        },
      ];
    }
    return [jsonResponse, undefined];
  } else {
    return [
      undefined,
      {
        statusCode: response.status,
        statusText: response.statusText,
      },
    ];
  }
}

const balanceQuery = (publicKey: string, tokenId: string) => `{
  account(publicKey: "${publicKey}", token: "${tokenId}") {
    balance { total }
  }
}
`;

const accountQuery = (publicKey: string, tokenId: string) => `{
  account(publicKey: "${publicKey}", token: "${tokenId}") {
    publicKey
    token
    nonce
    balance { total }
    tokenSymbol
    receiptChainHash
    timing {
      initialMinimumBalance
      cliffTime
      cliffAmount
      vestingPeriod
      vestingIncrement
    }
    permissions {
      editState
      access
      send
      receive
      setDelegate
      setPermissions
      setVerificationKey {
        auth
        txnVersion
      }
      setZkappUri
      editActionState
      setTokenSymbol
      incrementNonce
      setVotingFor
      setTiming
    }
    delegateAccount { publicKey }
    votingFor
    zkappState
    verificationKey {
      verificationKey
      hash
    }
    actionState
    provedState
    zkappUri
  }
}
`;