implement rpc calculate_dao_maximum_withdraw in sdk

packages/ckb-sdk-core/src/index.ts

@@ -1,7 +1,7 @@
 /// <reference types="../types/global" />
 
 import RPC from '@nervosnetwork/ckb-sdk-rpc'
-import { ParameterRequiredException } from '@nervosnetwork/ckb-sdk-utils/lib/exceptions'
+import { ParameterRequiredException, HexStringWithout0xException } from '@nervosnetwork/ckb-sdk-utils/lib/exceptions'
 import * as utils from '@nervosnetwork/ckb-sdk-utils'
 
 import generateRawTransaction from './generateRawTransaction'
@@ -420,6 +420,35 @@ class CKB {
     }
   }
 
+  public calculateDaoMaximumWithdraw = async (
+      outPoint: CKBComponents.OutPoint,
+      withdrawBlockHash: string
+  ): Promise<string> => {
+    const depositTx = await this.rpc.getTransaction(outPoint.txHash)
+    if (depositTx.txStatus.status !== 'committed') throw new Error('Transaction is not committed yet')
+    const depositCell = depositTx.transaction.outputs[+outPoint.index]
+    const depositBlockHash = depositTx.txStatus.blockHash
+    const depositHeader = await this.rpc.getHeader(depositBlockHash)
+    const depositAr = this.#extracDaoData(depositHeader.dao).ar
+    const withDrawHeader = await this.rpc.getHeader(withdrawBlockHash)
+    const withdrawAr = this.#extracDaoData(withDrawHeader.dao).ar
+    return utils.calculateMaximumWithdraw(depositCell, depositAr, withdrawAr);
+  }
+
+  #extracDaoData = (dao: CKBComponents.DAO) => {
+    if (!dao.startsWith('0x')) {
+      throw new HexStringWithout0xException(dao)
+    }
+    const value = dao.replace('0x', '');
+    const toBigEndian = utils.toBigEndian;
+    return {
+      c: toBigEndian(`0x${value.slice(0, 8)}`),
+      ar: toBigEndian(`0x${value.slice(16, 32)}`),
+      s: toBigEndian(`0x${value.slice(32, 48)}`),
+      u: toBigEndian(`0x${value.slice(48, 64)}`)
+    }
+  }
+
   #secp256k1DepsShouldBeReady = () => {
     if (!this.config.secp256k1Dep) {
       throw new ParameterRequiredException('Secp256k1 dep')

packages/ckb-sdk-utils/src/convertors/index.ts

@@ -1,4 +1,4 @@
-import { assertToBeHexStringOrBigint } from '../validators'
+import { assertToBeHexStringOrBigint, assertToBeHexString } from '../validators'
 import { HexStringWithout0xException } from '../exceptions'
 
 /**
@@ -61,6 +61,19 @@ export const hexToBytes = (rawhex: string | number | bigint) => {
   return new Uint8Array(bytes)
 }
 
+/**
+ * Converts a hex string in little endian into big endian
+ *
+ * @memberof convertors
+ * @param {string} le16 The hex string to convert
+ * @returns {string} Returns a big endian
+ */
+ export const toBigEndian = (leHex: string) => {
+  assertToBeHexString(leHex)
+  const bytes = hexToBytes(leHex);
+  return `0x${bytes.reduceRight((pre, cur) => pre + cur.toString(16), '')}`
+}
+
 export const bytesToHex = (bytes: Uint8Array): string =>
   `0x${[...bytes].map(b => b.toString(16).padStart(2, '0')).join('')}`
 
@@ -70,4 +83,5 @@ export default {
   toUint64Le,
   hexToBytes,
   bytesToHex,
+  toBigEndian
 }

packages/ckb-sdk-utils/src/index.ts

@@ -4,7 +4,7 @@ import { hexToBytes } from './convertors'
 import { pubkeyToAddress, AddressOptions } from './address'
 import { ParameterRequiredException } from './exceptions'
 import crypto from './crypto'
-import { serializeScript } from './serialization/script'
+import { serializeOutput, serializeScript } from './serialization';
 import { serializeRawTransaction, serializeTransaction, serializeWitnessArgs } from './serialization/transaction'
 import { PERSONAL } from './const'
 
@@ -44,3 +44,29 @@ export const privateKeyToPublicKey = (privateKey: string) => {
 
 export const privateKeyToAddress = (privateKey: string, options: AddressOptions) =>
   pubkeyToAddress(privateKeyToPublicKey(privateKey), options)
+
+export const calculateMaximumWithdraw = (
+  depositCell: CKBComponents.CellOutput,
+  depositAr: string,
+  withdrawAr: string
+) => {
+    const depositCellSerialized = serializeOutput(depositCell).slice(2).length / 2;
+    console.log(depositCellSerialized);
+    const occupiedCapacity = JSBI.asUintN(
+      64,
+      JSBI.multiply(JSBI.BigInt(100000000), JSBI.BigInt(depositCellSerialized))
+    );
+    return JSBI.add(
+      JSBI.divide(
+        JSBI.multiply(
+          JSBI.subtract(
+            JSBI.asUintN(64, JSBI.BigInt(depositCell.capacity)),
+            occupiedCapacity
+          ),
+          JSBI.asUintN(64, JSBI.BigInt(withdrawAr))
+        ),
+        JSBI.asUintN(64, JSBI.BigInt(depositAr))
+      ),
+      occupiedCapacity
+    ).toString()
+}