how to create bridging-based rebalancing scripts

// monitor-balances.jsconst { ethers } = require('ethers');const axios = require('axios');class BalanceMonitor {
  constructor(config) {
    this.chains = config.chains;
    this.thresholds = config.thresholds;
  }

  async checkBalances() {
    const imbalances = [];
    
    for (const chain of this.chains) {
      const provider = new ethers.JsonRpcProvider(chain.rpc);
      
      for (const token of chain.tokens) {
        const balance = await this.getTokenBalance(
          provider, 
          token.address, 
          token.poolAddress        );
        
        const target = token.targetBalance;
        const diff = balance.sub(target);
        
        if (diff.abs().gt(token.threshold)) {
          imbalances.push({
            chain: chain.name,
            token: token.symbol,
            current: balance.toString(),
            target: target.toString(),
            difference: diff.toString(),
            needsRebalancing: diff.gt(0) ? 'excess' : 'deficit'
          });
        }
      }
    }
    
    return imbalances;
  }

  async getTokenBalance(provider, tokenAddress, poolAddress) {
    const abi = ['function balanceOf(address) view returns (uint256)'];
    const tokenContract = new ethers.Contract(tokenAddress, abi, provider);
    return await tokenContract.balanceOf(poolAddress);
  }}

// rebalancer.jsclass CrossChainRebalancer {
  constructor(bridgeConfig) {
    this.bridge = bridgeConfig;
  }

  async rebalance(imbalance) {
    const { source, destination, amount } = imbalance;
    
    // 1. Check if rebalancing is cost-effective
    const costEffective = await this.isCostEffective(source, destination, amount);
    if (!costEffective) return false;

    // 2. Execute cross-chain transfer via bridge
    const txHash = await this.executeBridgeTransfer(
      source.chainId,
      destination.chainId,
      amount,
      source.token    );

    // 3. Update destination liquidity pool
    await this.updateLiquidityPool(destination, amount);

    return txHash;
  }

  async executeBridgeTransfer(sourceChainId, destChainId, amount, token) {
    // Example using LayerZero or other bridge protocols
    const bridgeParams = {
      sourceChain: sourceChainId,
      destChain: destChainId,
      amount: amount.toString(),
      token: token.address,
      receiver: this.bridge.receiverAddress,
      adapterParams: ethers.solidityPacked(
        ['uint16', 'uint256'],
        [1, 200000] // version, gas limit
      )
    };

    // Bridge-specific implementation
    return await this.sendToBridge(bridgeParams);
  }}

// complete-rebalancer.jsconst { ethers } = require('ethers');require('dotenv').config();class BridgingRebalancer {
  constructor() {
    this.config = {
      chains: {
        ethereum: {
          rpc: process.env.ETH_RPC,
          chainId: 1,
          bridge: '0x...',
          tokens: {
            USDC: { address: '0xA0b869...', min: '10000', max: '100000' }
          }
        },
        arbitrum: {
          rpc: process.env.ARB_RPC,
          chainId: 42161,
          bridge: '0x...',
          tokens: {
            USDC: { address: '0xFF970A...', min: '5000', max: '50000' }
          }
        }
      },
      thresholds: {
        minRebalanceAmount: ethers.parseUnits('1000', 6), // $1000
        maxSlippage: 0.005, // 0.5%
        cooldownPeriod: 3600 // 1 hour
      }
    };
    
    this.lastRebalance = {};
  }

  async run() {
    try {
      // 1. Check balances across all chains
      const imbalances = await this.analyzeBalances();
      
      // 2. Find optimal rebalancing paths
      const rebalancePlan = await this.planRebalancing(imbalances);
      
      // 3. Execute if profitable and safe
      for (const action of rebalancePlan) {
        if (await this.shouldExecute(action)) {
          await this.executeRebalance(action);
        }
      }
    } catch (error) {
      console.error('Rebalancing failed:', error);
      await this.alertAdmin(error);
    }
  }

  async analyzeBalances() {
    const imbalances = [];
    
    for (const [chainName, chain] of Object.entries(this.config.chains)) {
      const provider = new ethers.JsonRpcProvider(chain.rpc);
      
      for (const [tokenSymbol, tokenConfig] of Object.entries(chain.tokens)) {
        const balance = await this.getPoolBalance(provider, tokenConfig.address);
        const normalized = ethers.formatUnits(balance, 6);
        
        if (normalized > tokenConfig.max) {
          imbalances.push({
            chain: chainName,
            token: tokenSymbol,
            type: 'excess',
            amount: normalized - tokenConfig.max,
            current: normalized          });
        } else if (normalized < tokenConfig.min) {
          imbalances.push({
            chain: chainName,
            token: tokenSymbol,
            type: 'deficit',
            amount: tokenConfig.min - normalized,
            current: normalized          });
        }
      }
    }
    
    return imbalances;
  }

  async planRebalancing(imbalances) {
    const excess = imbalances.filter(i => i.type === 'excess');
    const deficit = imbalances.filter(i => i.type === 'deficit');
    const actions = [];
    
    // Simple matching algorithm
    for (const e of excess) {
      for (const d of deficit) {
        if (e.token === d.token) {
          const amount = Math.min(e.amount, d.amount);
          if (amount > this.config.thresholds.minRebalanceAmount) {
            actions.push({
              source: e.chain,
              destination: d.chain,
              token: e.token,
              amount: amount,
              estimatedCost: await this.estimateCost(e.chain, d.chain, amount)
            });
          }
        }
      }
    }
    
    return actions.sort((a, b) => b.amount - a.amount);
  }

  async shouldExecute(action) {
    // 1. Check cooldown
    const key = `${action.source}-${action.destination}-${action.token}`;
    if (this.lastRebalance[key] && 
        Date.now() - this.lastRebalance[key] < this.config.thresholds.cooldownPeriod * 1000) {
      return false;
    }

    // 2. Check profitability (consider gas, bridge fees, slippage)
    const profitability = await this.calculateProfitability(action);
    
    // 3. Check destination capacity
    const hasCapacity = await this.checkDestinationCapacity(action);
    
    return profitability > 1.01 && hasCapacity; // At least 1% profit margin
  }

  async executeRebalance(action) {
    console.log(`Rebalancing ${action.amount} ${action.token} from ${action.source} to ${action.destination}`);
    
    // Implementation depends on your bridge protocol
    // Example for Stargate, LayerZero, etc.
    const tx = await this.bridgeTransfer(
      action.source,
      action.destination,
      action.amount,
      action.token    );
    
    // Update last rebalance time
    const key = `${action.source}-${action.destination}-${action.token}`;
    this.lastRebalance[key] = Date.now();
    
    return tx;
  }

  async bridgeTransfer(sourceChain, destChain, amount, token) {
    // Bridge-specific implementation
    // Common bridges: Stargate, Hop, Across, Synapse, LayerZero
    
    const bridgeAbi = [
      'function swap(uint16 dstChainId, uint256 amount, address to) payable returns (uint256)'
    ];
    
    const signer = new ethers.Wallet(process.env.PK, this.getProvider(sourceChain));
    const bridge = new ethers.Contract(this.config.chains[sourceChain].bridge, bridgeAbi, signer);
    
    const value = await this.estimateBridgeFee(sourceChain, destChain);
    
    const tx = await bridge.swap(
      this.config.chains[destChain].chainId,
      ethers.parseUnits(amount.toString(), 6),
      this.config.chains[destChain].receiver,
      { value: value }
    );
    
    await tx.wait();
    return tx.hash;
  }}

// test-rebalancer.jsconst { expect } = require('chai');describe('BridgingRebalancer', () => {
  let rebalancer;
  
  beforeEach(() => {
    rebalancer = new BridgingRebalancer();
  });
  
  it('should detect imbalances correctly', async () => {
    const imbalances = await rebalancer.analyzeBalances();
    expect(imbalances).to.be.an('array');
  });
  
  it('should create optimal rebalancing plan', async () => {
    const mockImbalances = [...];
    const plan = await rebalancer.planRebalancing(mockImbalances);
    expect(plan[0]).to.have.property('source');
    expect(plan[0]).to.have.property('destination');
  });});

// security.jsclass SecureRebalancer extends BridgingRebalancer {
  constructor() {
    super();
    this.security = {
      multiSig: process.env.MULTISIG_ADDRESS,
      maxDailyVolume: ethers.parseUnits('1000000', 6),
      dailyVolume: 0,
      whitelistedBridges: ['0x...', '0x...']
    };
  }

  async executeRebalance(action) {
    // 1. Validate bridge address
    if (!this.security.whitelistedBridges.includes(this.config.chains[action.source].bridge)) {
      throw new Error('Bridge not whitelisted');
    }
    
    // 2. Check daily limits
    const newVolume = this.security.dailyVolume + action.amount;
    if (newVolume > this.security.maxDailyVolume) {
      throw new Error('Daily volume limit exceeded');
    }
    
    // 3. Multi-sig approval for large amounts
    if (action.amount > ethers.parseUnits('10000', 6)) {
      await this.requestMultiSigApproval(action);
    }
    
    // 4. Execute with slippage protection
    const tx = await super.executeRebalance(action);
    
    // 5. Update volume tracking
    this.security.dailyVolume += action.amount;
    
    return tx;
  }}