import BN from "bn.js";
import { Cell } from "../../boc/cell";
import TonHttpProvider from "../../providers/httpProvider";
import Address from "../../utils/address";
import { bytesToBase64, bytesToHex, sha256_sync } from "../../utils/utils";
import { parseAddress } from "../token/nft/utils";

export const DNS_CATEGORY_NEXT_RESOLVER = "dns_next_resolver"; // Smart Contract address
export const DNS_CATEGORY_WALLET = "wallet"; // Smart Contract address
export const DNS_CATEGORY_SITE = "site"; // ADNL address

/**
 * @param category  {string | undefined}
 * @return  {BN}
 */
export const categoryToBN = (category: string | undefined) => {
  if (!category) return new BN(0); // all categories
  const categoryBytes = new TextEncoder().encode(category);
  const categoryHash = new Uint8Array(sha256_sync(categoryBytes));
  return new BN(bytesToHex(categoryHash), 16);
};

/**
 * @param smartContractAddress   {Address}
 * @return {Cell}
 */
export const createSmartContractAddressRecord = (
  smartContractAddress: Address
) => {
  const cell = new Cell();
  cell.bits.writeUint(0x9fd3, 16); // https://github.com/ton-blockchain/ton/blob/7e3df93ca2ab336716a230fceb1726d81bac0a06/crypto/block/block.tlb#L827
  cell.bits.writeAddress(smartContractAddress);
  cell.bits.writeUint(0, 8); // flags
  return cell;
};

/**
 * @param adnlAddress   {BN}
 * @return {Cell}
 */
export const createAdnlAddressRecord = (adnlAddress: BN) => {
  const cell = new Cell();
  cell.bits.writeUint(0xad01, 16); // https://github.com/ton-blockchain/ton/blob/7e3df93ca2ab336716a230fceb1726d81bac0a06/crypto/block/block.tlb#L821
  cell.bits.writeUint(adnlAddress, 256);
  cell.bits.writeUint(0, 8); // flags
  return cell;
};

/**
 * @param smartContractAddress   {Address}
 * @return {Cell}
 */
export const createNextResolverRecord = (smartContractAddress: Address) => {
  const cell = new Cell();
  cell.bits.writeUint(0xba93, 16); // https://github.com/ton-blockchain/ton/blob/7e3df93ca2ab336716a230fceb1726d81bac0a06/crypto/block/block.tlb#L819
  cell.bits.writeAddress(smartContractAddress);
  return cell;
};

/**
 * @private
 * @param cell  {Cell}
 * @param prefix0 {number}
 * @param prefix1 {number}
 * @return {Address|null}
 */
const parseSmartContractAddressImpl = (
  cell: Cell,
  prefix0: number,
  prefix1: number
) => {
  if (cell.bits.array[0] !== prefix0 || cell.bits.array[1] !== prefix1)
    throw new Error("Invalid dns record value prefix");
  cell.bits.array = cell.bits.array.slice(2); // skip prefix - first 16 bits
  return parseAddress(cell);
};

/**
 * @param cell  {Cell}
 * @return {Address|null}
 */
export const parseSmartContractAddressRecord = (cell: Cell) => {
  return parseSmartContractAddressImpl(cell, 0x9f, 0xd3);
};

/**
 * @param cell  {Cell}
 * @return {Address|null}
 */
export const parseNextResolverRecord = (cell: Cell) => {
  return parseSmartContractAddressImpl(cell, 0xba, 0x93);
};

/**
 * @private
 * @param provider  {TonHttpProvider}
 * @param dnsAddress   {string} address of dns smart contract
 * @param rawDomainBytes {Uint8Array}
 * @param category  {string | undefined} category of requested DNS record
 * @param oneStep {boolean | undefined} non-recursive
 * @returns {Promise<Cell | Address | BN | null>}
 */
const dnsResolveImpl = async (
  provider: TonHttpProvider,
  dnsAddress: string,
  rawDomainBytes: Uint8Array,
  category: string | undefined,
  oneStep: boolean | undefined
): Promise<Cell | Address | BN | null> => {
  const len = rawDomainBytes.length * 8;

  const domainCell = new Cell();
  domainCell.bits.writeBytes(rawDomainBytes);

  const categoryBN = await categoryToBN(category);
  const result = await provider.call2(dnsAddress, "dnsresolve", [
    ["tvm.Slice", bytesToBase64(await domainCell.toBoc(false))],
    ["num", categoryBN.toString()],
  ]);
  if (result.length !== 2) {
    throw new Error("Invalid dnsresolve response");
  }
  const resultLen = result[0].toNumber();

  let cell = result[1];
  if (cell instanceof Array && cell.length === 0) {
    cell = null;
  }

  if (cell && !cell.bits) {
    // not a Cell
    throw new Error("Invalid dnsresolve response");
  }

  if (resultLen === 0) {
    return null; // domain cannot be resolved
  }

  if (resultLen % 8 !== 0) {
    throw new Error("domain split not at a component boundary");
  }
  // if (rawDomainBytes[resultLen] !== 0) {
  //     throw new Error('domain split not at a component boundary');
  // }
  if (resultLen > len) {
    throw new Error("invalid response " + resultLen + "/" + len);
  } else if (resultLen === len) {
    if (category === DNS_CATEGORY_NEXT_RESOLVER) {
      return cell ? parseNextResolverRecord(cell) : null;
    } else if (category === DNS_CATEGORY_WALLET) {
      return cell ? parseSmartContractAddressRecord(cell) : null;
    } else if (category === DNS_CATEGORY_SITE) {
      return cell ? cell : null; // todo: convert to BN;
    } else {
      return cell;
    }
  } else {
    if (!cell) {
      return null; // domain cannot be resolved
    } else {
      const nextAddress = parseNextResolverRecord(cell);
      if (oneStep) {
        if (category === DNS_CATEGORY_NEXT_RESOLVER) {
          return nextAddress;
        } else {
          return null;
        }
      } else {
        if (!nextAddress) {
          return null;
        }
        return await dnsResolveImpl(
          provider,
          nextAddress.toString(),
          rawDomainBytes.slice(resultLen / 8),
          category,
          false
        );
      }
    }
  }
};

/**
 * Verify and convert domain
 * @param domain    {string}
 * @return {Uint8Array}
 */
const domainToBytes = (domain: string) => {
  if (!domain || !domain.length) {
    throw new Error("empty domain");
  }
  if (domain === ".") {
    return new Uint8Array([0]);
  }

  domain = domain.toLowerCase();

  for (let i = 0; i < domain.length; i++) {
    if (domain.charCodeAt(i) <= 32) {
      throw new Error("bytes in range 0..32 are not allowed in domain names");
    }
  }

  for (let i = 0; i < domain.length; i++) {
    const s = domain.substring(i, i + 1);
    for (let c = 127; c <= 159; c++) {
      // another control codes range
      if (s === String.fromCharCode(c)) {
        throw new Error(
          "bytes in range 127..159 are not allowed in domain names"
        );
      }
    }
  }

  const arr = domain.split(".");

  arr.forEach((part) => {
    if (!part.length) {
      throw new Error("domain name cannot have an empty component");
    }
  });

  let rawDomain = arr.reverse().join("\0") + "\0";
  if (rawDomain.length < 126) {
    rawDomain = "\0" + rawDomain;
  }

  return new TextEncoder().encode(rawDomain);
};

/**
 * @param provider  {TonHttpProvider}
 * @param rootDnsAddress {string} address of root DNS smart contract
 * @param domain    {string} e.g "sub.alice.ton"
 * @param category  {string | undefined} category of requested DNS record
 * @param oneStep {boolean | undefined} non-recursive
 * @returns {Promise<Cell | Address | BN | null>}
 */
export const dnsResolve = async (
  provider: TonHttpProvider,
  rootDnsAddress: string,
  domain: string,
  category: string | undefined,
  oneStep: boolean | undefined
) => {
  const rawDomainBytes = domainToBytes(domain);

  return dnsResolveImpl(
    provider,
    rootDnsAddress,
    rawDomainBytes,
    category,
    oneStep
  );
};