Pair

[
  {
    "anonymous": false,
    "inputs": [
      {
        "indexed": true,
        "internalType": "address",
        "name": "owner",
        "type": "address"
      },
      {
        "indexed": true,
        "internalType": "address",
        "name": "spender",
        "type": "address"
      },
      {
        "indexed": false,
        "internalType": "uint256",
        "name": "amount",
        "type": "uint256"
      }
    ],
    "name": "Approval",
    "type": "event"
  },
  {
    "anonymous": false,
    "inputs": [
      {
        "indexed": true,
        "internalType": "address",
        "name": "sender",
        "type": "address"
      },
      {
        "indexed": false,
        "internalType": "uint256",
        "name": "amount0",
        "type": "uint256"
      },
      {
        "indexed": false,
        "internalType": "uint256",
        "name": "amount1",
        "type": "uint256"
      },
      {
        "indexed": true,
        "internalType": "address",
        "name": "to",
        "type": "address"
      }
    ],
    "name": "Burn",
    "type": "event"
  },
  {
    "anonymous": false,
    "inputs": [
      {
        "indexed": true,
        "internalType": "address",
        "name": "sender",
        "type": "address"
      },
      {
        "indexed": true,
        "internalType": "address",
        "name": "recipient",
        "type": "address"
      },
      {
        "indexed": false,
        "internalType": "uint256",
        "name": "amount0",
        "type": "uint256"
      },
      {
        "indexed": false,
        "internalType": "uint256",
        "name": "amount1",
        "type": "uint256"
      }
    ],
    "name": "Claim",
    "type": "event"
  },
  {
    "anonymous": false,
    "inputs": [
      {
        "indexed": true,
        "internalType": "address",
        "name": "sender",
        "type": "address"
      },
      {
        "indexed": false,
        "internalType": "uint256",
        "name": "amount0",
        "type": "uint256"
      },
      {
        "indexed": false,
        "internalType": "uint256",
        "name": "amount1",
        "type": "uint256"
      }
    ],
    "name": "Fees",
    "type": "event"
  },
  {
    "anonymous": false,
    "inputs": [
      {
        "indexed": false,
        "internalType": "uint8",
        "name": "version",
        "type": "uint8"
      }
    ],
    "name": "Initialized",
    "type": "event"
  },
  {
    "anonymous": false,
    "inputs": [
      {
        "indexed": true,
        "internalType": "address",
        "name": "sender",
        "type": "address"
      },
      {
        "indexed": false,
        "internalType": "uint256",
        "name": "amount0",
        "type": "uint256"
      },
      {
        "indexed": false,
        "internalType": "uint256",
        "name": "amount1",
        "type": "uint256"
      }
    ],
    "name": "Mint",
    "type": "event"
  },
  {
    "anonymous": false,
    "inputs": [
      {
        "indexed": true,
        "internalType": "address",
        "name": "sender",
        "type": "address"
      },
      {
        "indexed": false,
        "internalType": "uint256",
        "name": "amount0In",
        "type": "uint256"
      },
      {
        "indexed": false,
        "internalType": "uint256",
        "name": "amount1In",
        "type": "uint256"
      },
      {
        "indexed": false,
        "internalType": "uint256",
        "name": "amount0Out",
        "type": "uint256"
      },
      {
        "indexed": false,
        "internalType": "uint256",
        "name": "amount1Out",
        "type": "uint256"
      },
      {
        "indexed": true,
        "internalType": "address",
        "name": "to",
        "type": "address"
      }
    ],
    "name": "Swap",
    "type": "event"
  },
  {
    "anonymous": false,
    "inputs": [
      {
        "indexed": false,
        "internalType": "uint256",
        "name": "reserve0",
        "type": "uint256"
      },
      {
        "indexed": false,
        "internalType": "uint256",
        "name": "reserve1",
        "type": "uint256"
      }
    ],
    "name": "Sync",
    "type": "event"
  },
  {
    "anonymous": false,
    "inputs": [
      {
        "indexed": true,
        "internalType": "address",
        "name": "from",
        "type": "address"
      },
      {
        "indexed": true,
        "internalType": "address",
        "name": "to",
        "type": "address"
      },
      {
        "indexed": false,
        "internalType": "uint256",
        "name": "amount",
        "type": "uint256"
      }
    ],
    "name": "Transfer",
    "type": "event"
  },
  {
    "anonymous": false,
    "inputs": [
      {
        "indexed": false,
        "internalType": "uint256",
        "name": "volume0",
        "type": "uint256"
      },
      {
        "indexed": false,
        "internalType": "uint256",
        "name": "volume1",
        "type": "uint256"
      }
    ],
    "name": "VolumeUpdated",
    "type": "event"
  },
  {
    "inputs": [
      {
        "internalType": "address",
        "name": "",
        "type": "address"
      },
      {
        "internalType": "address",
        "name": "",
        "type": "address"
      }
    ],
    "name": "allowance",
    "outputs": [
      {
        "internalType": "uint256",
        "name": "",
        "type": "uint256"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "address",
        "name": "spender",
        "type": "address"
      },
      {
        "internalType": "uint256",
        "name": "amount",
        "type": "uint256"
      }
    ],
    "name": "approve",
    "outputs": [
      {
        "internalType": "bool",
        "name": "",
        "type": "bool"
      }
    ],
    "stateMutability": "nonpayable",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "address",
        "name": "",
        "type": "address"
      }
    ],
    "name": "balanceOf",
    "outputs": [
      {
        "internalType": "uint256",
        "name": "",
        "type": "uint256"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [],
    "name": "blockTimestampLast",
    "outputs": [
      {
        "internalType": "uint256",
        "name": "",
        "type": "uint256"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "address",
        "name": "to",
        "type": "address"
      }
    ],
    "name": "burn",
    "outputs": [
      {
        "internalType": "uint256",
        "name": "amount0",
        "type": "uint256"
      },
      {
        "internalType": "uint256",
        "name": "amount1",
        "type": "uint256"
      }
    ],
    "stateMutability": "nonpayable",
    "type": "function"
  },
  {
    "inputs": [],
    "name": "claimFees",
    "outputs": [
      {
        "internalType": "uint256",
        "name": "claimed0",
        "type": "uint256"
      },
      {
        "internalType": "uint256",
        "name": "claimed1",
        "type": "uint256"
      }
    ],
    "stateMutability": "nonpayable",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "address",
        "name": "",
        "type": "address"
      }
    ],
    "name": "claimable0",
    "outputs": [
      {
        "internalType": "uint256",
        "name": "",
        "type": "uint256"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "address",
        "name": "",
        "type": "address"
      }
    ],
    "name": "claimable1",
    "outputs": [
      {
        "internalType": "uint256",
        "name": "",
        "type": "uint256"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "address",
        "name": "tokenIn",
        "type": "address"
      },
      {
        "internalType": "uint256",
        "name": "amountIn",
        "type": "uint256"
      }
    ],
    "name": "current",
    "outputs": [
      {
        "internalType": "uint256",
        "name": "amountOut",
        "type": "uint256"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [],
    "name": "currentCumulativePrices",
    "outputs": [
      {
        "internalType": "uint256",
        "name": "reserve0Cumulative",
        "type": "uint256"
      },
      {
        "internalType": "uint256",
        "name": "reserve1Cumulative",
        "type": "uint256"
      },
      {
        "internalType": "uint256",
        "name": "blockTimestamp",
        "type": "uint256"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [],
    "name": "decimals",
    "outputs": [
      {
        "internalType": "uint8",
        "name": "",
        "type": "uint8"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [],
    "name": "factory",
    "outputs": [
      {
        "internalType": "address",
        "name": "",
        "type": "address"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [],
    "name": "fees",
    "outputs": [
      {
        "internalType": "address",
        "name": "",
        "type": "address"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "uint256",
        "name": "amountIn",
        "type": "uint256"
      },
      {
        "internalType": "address",
        "name": "tokenIn",
        "type": "address"
      }
    ],
    "name": "getAmountOut",
    "outputs": [
      {
        "internalType": "uint256",
        "name": "",
        "type": "uint256"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [],
    "name": "getReserves",
    "outputs": [
      {
        "internalType": "uint256",
        "name": "_reserve0",
        "type": "uint256"
      },
      {
        "internalType": "uint256",
        "name": "_reserve1",
        "type": "uint256"
      },
      {
        "internalType": "uint256",
        "name": "_blockTimestampLast",
        "type": "uint256"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [],
    "name": "hook",
    "outputs": [
      {
        "internalType": "address",
        "name": "",
        "type": "address"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [],
    "name": "index0",
    "outputs": [
      {
        "internalType": "uint256",
        "name": "",
        "type": "uint256"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [],
    "name": "index1",
    "outputs": [
      {
        "internalType": "uint256",
        "name": "",
        "type": "uint256"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [],
    "name": "initialize",
    "outputs": [],
    "stateMutability": "nonpayable",
    "type": "function"
  },
  {
    "inputs": [],
    "name": "lastObservation",
    "outputs": [
      {
        "components": [
          {
            "internalType": "uint256",
            "name": "timestamp",
            "type": "uint256"
          },
          {
            "internalType": "uint256",
            "name": "reserve0Cumulative",
            "type": "uint256"
          },
          {
            "internalType": "uint256",
            "name": "reserve1Cumulative",
            "type": "uint256"
          }
        ],
        "internalType": "struct Pair.Observation",
        "name": "",
        "type": "tuple"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [],
    "name": "metadata",
    "outputs": [
      {
        "internalType": "uint256",
        "name": "dec0",
        "type": "uint256"
      },
      {
        "internalType": "uint256",
        "name": "dec1",
        "type": "uint256"
      },
      {
        "internalType": "uint256",
        "name": "r0",
        "type": "uint256"
      },
      {
        "internalType": "uint256",
        "name": "r1",
        "type": "uint256"
      },
      {
        "internalType": "bool",
        "name": "st",
        "type": "bool"
      },
      {
        "internalType": "address",
        "name": "t0",
        "type": "address"
      },
      {
        "internalType": "address",
        "name": "t1",
        "type": "address"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "address",
        "name": "to",
        "type": "address"
      }
    ],
    "name": "mint",
    "outputs": [
      {
        "internalType": "uint256",
        "name": "liquidity",
        "type": "uint256"
      }
    ],
    "stateMutability": "nonpayable",
    "type": "function"
  },
  {
    "inputs": [],
    "name": "name",
    "outputs": [
      {
        "internalType": "string",
        "name": "",
        "type": "string"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "address",
        "name": "",
        "type": "address"
      }
    ],
    "name": "nonces",
    "outputs": [
      {
        "internalType": "uint256",
        "name": "",
        "type": "uint256"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [],
    "name": "observationLength",
    "outputs": [
      {
        "internalType": "uint256",
        "name": "",
        "type": "uint256"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "uint256",
        "name": "",
        "type": "uint256"
      }
    ],
    "name": "observations",
    "outputs": [
      {
        "internalType": "uint256",
        "name": "timestamp",
        "type": "uint256"
      },
      {
        "internalType": "uint256",
        "name": "reserve0Cumulative",
        "type": "uint256"
      },
      {
        "internalType": "uint256",
        "name": "reserve1Cumulative",
        "type": "uint256"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "address",
        "name": "owner",
        "type": "address"
      },
      {
        "internalType": "address",
        "name": "spender",
        "type": "address"
      },
      {
        "internalType": "uint256",
        "name": "value",
        "type": "uint256"
      },
      {
        "internalType": "uint256",
        "name": "deadline",
        "type": "uint256"
      },
      {
        "internalType": "uint8",
        "name": "v",
        "type": "uint8"
      },
      {
        "internalType": "bytes32",
        "name": "r",
        "type": "bytes32"
      },
      {
        "internalType": "bytes32",
        "name": "s",
        "type": "bytes32"
      }
    ],
    "name": "permit",
    "outputs": [],
    "stateMutability": "nonpayable",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "address",
        "name": "tokenIn",
        "type": "address"
      },
      {
        "internalType": "uint256",
        "name": "amountIn",
        "type": "uint256"
      },
      {
        "internalType": "uint256",
        "name": "points",
        "type": "uint256"
      }
    ],
    "name": "prices",
    "outputs": [
      {
        "internalType": "uint256[]",
        "name": "",
        "type": "uint256[]"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "address",
        "name": "tokenIn",
        "type": "address"
      },
      {
        "internalType": "uint256",
        "name": "amountIn",
        "type": "uint256"
      },
      {
        "internalType": "uint256",
        "name": "granularity",
        "type": "uint256"
      }
    ],
    "name": "quote",
    "outputs": [
      {
        "internalType": "uint256",
        "name": "amountOut",
        "type": "uint256"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [],
    "name": "reserve0",
    "outputs": [
      {
        "internalType": "uint256",
        "name": "",
        "type": "uint256"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [],
    "name": "reserve0CumulativeLast",
    "outputs": [
      {
        "internalType": "uint256",
        "name": "",
        "type": "uint256"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [],
    "name": "reserve1",
    "outputs": [
      {
        "internalType": "uint256",
        "name": "",
        "type": "uint256"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [],
    "name": "reserve1CumulativeLast",
    "outputs": [
      {
        "internalType": "uint256",
        "name": "",
        "type": "uint256"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "address",
        "name": "tokenIn",
        "type": "address"
      },
      {
        "internalType": "uint256",
        "name": "amountIn",
        "type": "uint256"
      },
      {
        "internalType": "uint256",
        "name": "points",
        "type": "uint256"
      },
      {
        "internalType": "uint256",
        "name": "window",
        "type": "uint256"
      }
    ],
    "name": "sample",
    "outputs": [
      {
        "internalType": "uint256[]",
        "name": "",
        "type": "uint256[]"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "address",
        "name": "_hook",
        "type": "address"
      }
    ],
    "name": "setHook",
    "outputs": [],
    "stateMutability": "nonpayable",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "address",
        "name": "to",
        "type": "address"
      }
    ],
    "name": "skim",
    "outputs": [],
    "stateMutability": "nonpayable",
    "type": "function"
  },
  {
    "inputs": [],
    "name": "stable",
    "outputs": [
      {
        "internalType": "bool",
        "name": "",
        "type": "bool"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "address",
        "name": "",
        "type": "address"
      }
    ],
    "name": "supplyIndex0",
    "outputs": [
      {
        "internalType": "uint256",
        "name": "",
        "type": "uint256"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "address",
        "name": "",
        "type": "address"
      }
    ],
    "name": "supplyIndex1",
    "outputs": [
      {
        "internalType": "uint256",
        "name": "",
        "type": "uint256"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "uint256",
        "name": "amount0Out",
        "type": "uint256"
      },
      {
        "internalType": "uint256",
        "name": "amount1Out",
        "type": "uint256"
      },
      {
        "internalType": "address",
        "name": "to",
        "type": "address"
      },
      {
        "internalType": "bytes",
        "name": "data",
        "type": "bytes"
      }
    ],
    "name": "swap",
    "outputs": [],
    "stateMutability": "nonpayable",
    "type": "function"
  },
  {
    "inputs": [],
    "name": "symbol",
    "outputs": [
      {
        "internalType": "string",
        "name": "",
        "type": "string"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [],
    "name": "sync",
    "outputs": [],
    "stateMutability": "nonpayable",
    "type": "function"
  },
  {
    "inputs": [],
    "name": "token0",
    "outputs": [
      {
        "internalType": "address",
        "name": "",
        "type": "address"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [],
    "name": "token1",
    "outputs": [
      {
        "internalType": "address",
        "name": "",
        "type": "address"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [],
    "name": "tokens",
    "outputs": [
      {
        "internalType": "address",
        "name": "",
        "type": "address"
      },
      {
        "internalType": "address",
        "name": "",
        "type": "address"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [],
    "name": "totalSupply",
    "outputs": [
      {
        "internalType": "uint256",
        "name": "",
        "type": "uint256"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "address",
        "name": "dst",
        "type": "address"
      },
      {
        "internalType": "uint256",
        "name": "amount",
        "type": "uint256"
      }
    ],
    "name": "transfer",
    "outputs": [
      {
        "internalType": "bool",
        "name": "",
        "type": "bool"
      }
    ],
    "stateMutability": "nonpayable",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "address",
        "name": "src",
        "type": "address"
      },
      {
        "internalType": "address",
        "name": "dst",
        "type": "address"
      },
      {
        "internalType": "uint256",
        "name": "amount",
        "type": "uint256"
      }
    ],
    "name": "transferFrom",
    "outputs": [
      {
        "internalType": "bool",
        "name": "",
        "type": "bool"
      }
    ],
    "stateMutability": "nonpayable",
    "type": "function"
  },
  {
    "inputs": [],
    "name": "volume0",
    "outputs": [
      {
        "internalType": "uint256",
        "name": "",
        "type": "uint256"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [],
    "name": "volume1",
    "outputs": [
      {
        "internalType": "uint256",
        "name": "",
        "type": "uint256"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  }
]

// SPDX-License-Identifier: AGPL-3.0-only
pragma solidity 0.8.19;

import "@openzeppelin/contracts-upgradeable/proxy/utils/Initializable.sol";
import "./libraries/Math.sol";
import "./interfaces/IERC20.sol";
import "./interfaces/IPairCallee.sol";
import "./interfaces/IPairFactory.sol";
import "./interfaces/IRugController.sol";
import "./interfaces/IHook.sol";
import "./PairFees.sol";

contract Pair is Initializable {

    string public name;
    string public symbol;
    uint8 public constant decimals = 18;

    /// @notice Used to denote stable or volatile pair, not immutable since construction happens in the initialize method for CREATE2 deterministic addresses
    bool public stable;

    uint256 public totalSupply;

    mapping(address => mapping (address => uint)) public allowance;
    mapping(address => uint) public balanceOf;

    bytes32 internal DOMAIN_SEPARATOR;
    /// @dev keccak256("Permit(address owner,address spender,uint256 value,uint256 nonce,uint256 deadline)");
    bytes32 internal constant PERMIT_TYPEHASH = 0x6e71edae12b1b97f4d1f60370fef10105fa2faae0126114a169c64845d6126c9;
    mapping(address => uint) public nonces;

    uint256 internal constant MINIMUM_LIQUIDITY = 10**3;

    address public token0;
    address public token1;
    address public fees;
    address public factory;
    address public hook;

    // Structure to capture time period obervations every 30 minutes, used for local oracles
    struct Observation {
        uint timestamp;
        uint reserve0Cumulative;
        uint reserve1Cumulative;
    }

    // Capture oracle reading every 30 minutes
    uint constant periodSize = 1800;

    Observation[] public observations;

    uint internal decimals0;
    uint internal decimals1;

    uint public reserve0;
    uint public reserve1;
    uint public blockTimestampLast;

    uint public reserve0CumulativeLast;
    uint public reserve1CumulativeLast;

    // Cumulative volume trackers (input amounts)
    uint256 public volume0;
    uint256 public volume1;

    // index0 and index1 are used to accumulate fees, this is split out from normal trades to keep the swap "clean"
    // this further allows LP holders to easily claim fees for tokens they have/staked
    uint public index0;
    uint public index1;

    // position assigned to each LP to track their current index0 & index1 vs the global position
    mapping(address => uint) public supplyIndex0;
    mapping(address => uint) public supplyIndex1;

    // tracks the amount of unclaimed, but claimable tokens off of fees for token0 and token1
    mapping(address => uint) public claimable0;
    mapping(address => uint) public claimable1;

    /// @dev simple re-entrancy check
    bool internal _locked;

    event Fees(address indexed sender, uint amount0, uint amount1);
    event Mint(address indexed sender, uint amount0, uint amount1);
    event Burn(address indexed sender, uint amount0, uint amount1, address indexed to);
    event Swap(
        address indexed sender,
        uint amount0In,
        uint amount1In,
        uint amount0Out,
        uint amount1Out,
        address indexed to
    );
    event Sync(uint reserve0, uint reserve1);
    event Claim(address indexed sender, address indexed recipient, uint amount0, uint amount1);
    event VolumeUpdated(uint256 volume0, uint256 volume1);

    event Transfer(address indexed from, address indexed to, uint amount);
    event Approval(address indexed owner, address indexed spender, uint amount);

    modifier lock() {
        require(!_locked, "No re-entrancy");
        _locked = true;
        _;
        _locked = false;
    }

    function initialize() public initializer {
        factory = msg.sender;
        (address _token0, address _token1, bool _stable) = IPairFactory(msg.sender).getInitializable();
        (token0, token1, stable) = (_token0, _token1, _stable);
        PairFees pairFees = new PairFees();
        pairFees.initialize(_token0, _token1);
        fees = address(pairFees);

        if (_stable) {
            name = string(abi.encodePacked("StableV1 AMM - ", IERC20(_token0).symbol(), "/", IERC20(_token1).symbol()));
            symbol = string(abi.encodePacked("sAMM-", IERC20(_token0).symbol(), "/", IERC20(_token1).symbol()));
        } else {
            name = string(abi.encodePacked("VolatileV1 AMM - ", IERC20(_token0).symbol(), "/", IERC20(_token1).symbol()));
            symbol = string(abi.encodePacked("vAMM-", IERC20(_token0).symbol(), "/", IERC20(_token1).symbol()));
        }

        decimals0 = 10**IERC20(_token0).decimals();
        decimals1 = 10**IERC20(_token1).decimals();

        observations.push(Observation(block.timestamp, 0, 0));
    }

    /// @notice Register the hook contract for this pair. Only the factory may set it.
    function setHook(address _hook) external {
        require(msg.sender == factory, "!factory");
        hook = _hook;
    }

    function observationLength() external view returns (uint) {
        return observations.length;
    }

    function lastObservation() public view returns (Observation memory) {
        return observations[observations.length-1];
    }

    function metadata() external view returns (uint dec0, uint dec1, uint r0, uint r1, bool st, address t0, address t1) {
        return (decimals0, decimals1, reserve0, reserve1, stable, token0, token1);
    }

    function tokens() external view returns (address, address) {
        return (token0, token1);
    }

    /// @dev claim accumulated but unclaimed fees (viewable via claimable0 and claimable1)
    function claimFees() external returns (uint claimed0, uint claimed1) {
        _updateFor(msg.sender);

        claimed0 = claimable0[msg.sender];
        claimed1 = claimable1[msg.sender];

        if (claimed0 > 0 || claimed1 > 0) {
            claimable0[msg.sender] = 0;
            claimable1[msg.sender] = 0;

            PairFees(fees).claimFeesFor(msg.sender, claimed0, claimed1);

            emit Claim(msg.sender, msg.sender, claimed0, claimed1);
        }
    }

    /// @dev Accrue fees on token0
    function _update0(uint amount) internal {
        _safeTransfer(token0, fees, amount); // transfer the fees out to PairFees
        uint256 _ratio = amount * 1e18 / totalSupply; // 1e18 adjustment is removed during claim
        if (_ratio > 0) {
            index0 += _ratio;
        }
        emit Fees(msg.sender, amount, 0);
    }

    /// @dev Accrue fees on token1
    function _update1(uint amount) internal {
        _safeTransfer(token1, fees, amount);
        uint256 _ratio = amount * 1e18 / totalSupply;
        if (_ratio > 0) {
            index1 += _ratio;
        }
        emit Fees(msg.sender, 0, amount);
    }

    /**
     * @notice This function must be called on any balance changes, otherwise can be used to infinitely claim fees
     * Fees are segregated from core funds, so fees can never put liquidity at risk
     */
    function _updateFor(address recipient) internal {
        uint _supplied = balanceOf[recipient]; // get LP balance of `recipient`
        if (_supplied > 0) {
            uint _supplyIndex0 = supplyIndex0[recipient]; // get last adjusted index0 for recipient
            uint _supplyIndex1 = supplyIndex1[recipient];
            uint _index0 = index0; // get global index0 for accumulated fees
            uint _index1 = index1;
            supplyIndex0[recipient] = _index0; // update user current position to global position
            supplyIndex1[recipient] = _index1;
            uint _delta0 = _index0 - _supplyIndex0; // see if there is any difference that need to be accrued
            uint _delta1 = _index1 - _supplyIndex1;
            if (_delta0 > 0) {
                uint _share = _supplied * _delta0 / 1e18; // add accrued difference for each supplied token
                claimable0[recipient] += _share;
            }
            if (_delta1 > 0) {
                uint _share = _supplied * _delta1 / 1e18;
                claimable1[recipient] += _share;
            }
        } else {
            supplyIndex0[recipient] = index0; // new users are set to the default global state
            supplyIndex1[recipient] = index1;
        }
    }

    function getReserves() public view returns (uint _reserve0, uint _reserve1, uint _blockTimestampLast) {
        _reserve0 = reserve0;
        _reserve1 = reserve1;
        _blockTimestampLast = blockTimestampLast;
    }

    /// @dev update reserves and, on the first call per block, price accumulators
    function _update(uint balance0, uint balance1, uint _reserve0, uint _reserve1) internal {
        uint blockTimestamp = block.timestamp;
        uint timeElapsed = blockTimestamp - blockTimestampLast; // overflow is desired
        if (timeElapsed > 0 && _reserve0 != 0 && _reserve1 != 0) {
            reserve0CumulativeLast += _reserve0 * timeElapsed;
            reserve1CumulativeLast += _reserve1 * timeElapsed;
        }

        Observation memory _point = lastObservation();
        timeElapsed = blockTimestamp - _point.timestamp; // compare the last observation with current timestamp, if greater than 30 minutes, record a new event
        if (timeElapsed > periodSize) {
            observations.push(Observation(blockTimestamp, reserve0CumulativeLast, reserve1CumulativeLast));
        }
        reserve0 = balance0;
        reserve1 = balance1;
        blockTimestampLast = blockTimestamp;
        emit Sync(reserve0, reserve1);
    }

    /// @dev produces the cumulative price using counterfactuals to save gas and avoid a call to sync.
    function currentCumulativePrices() public view returns (uint reserve0Cumulative, uint reserve1Cumulative, uint blockTimestamp) {
        blockTimestamp = block.timestamp;
        reserve0Cumulative = reserve0CumulativeLast;
        reserve1Cumulative = reserve1CumulativeLast;

        // if time has elapsed since the last update on the pair, mock the accumulated price values
        (uint _reserve0, uint _reserve1, uint _blockTimestampLast) = getReserves();
        if (_blockTimestampLast != blockTimestamp) {
            // subtraction overflow is desired
            uint timeElapsed = blockTimestamp - _blockTimestampLast;
            reserve0Cumulative += _reserve0 * timeElapsed;
            reserve1Cumulative += _reserve1 * timeElapsed;
        }
    }

    /// @dev gives the current twap price measured from amountIn * tokenIn gives amountOut
    function current(address tokenIn, uint amountIn) external view returns (uint amountOut) {
        Observation memory _observation = lastObservation();
        (uint reserve0Cumulative, uint reserve1Cumulative,) = currentCumulativePrices();
        if (block.timestamp == _observation.timestamp) {
            _observation = observations[observations.length-2];
        }

        uint timeElapsed = block.timestamp - _observation.timestamp;
        uint _reserve0 = (reserve0Cumulative - _observation.reserve0Cumulative) / timeElapsed;
        uint _reserve1 = (reserve1Cumulative - _observation.reserve1Cumulative) / timeElapsed;
        amountOut = _getAmountOut(amountIn, tokenIn, _reserve0, _reserve1);
    }

    /// @dev as per `current`, however allows user configured granularity, up to the full window size
    function quote(address tokenIn, uint amountIn, uint granularity) external view returns (uint amountOut) {
        uint [] memory _prices = sample(tokenIn, amountIn, granularity, 1);
        uint priceAverageCumulative;
        for (uint i = 0; i < _prices.length; i++) {
            priceAverageCumulative += _prices[i];
        }
        return priceAverageCumulative / granularity;
    }

    /// @dev returns a memory set of twap prices
    function prices(address tokenIn, uint amountIn, uint points) external view returns (uint[] memory) {
        return sample(tokenIn, amountIn, points, 1);
    }

    function sample(address tokenIn, uint amountIn, uint points, uint window) public view returns (uint[] memory) {
        uint[] memory _prices = new uint[](points);

        uint length = observations.length-1;
        uint i = length - (points * window);
        uint nextIndex = 0;
        uint index = 0;

        for (; i < length; i+=window) {
            nextIndex = i + window;
            uint timeElapsed = observations[nextIndex].timestamp - observations[i].timestamp;
            uint _reserve0 = (observations[nextIndex].reserve0Cumulative - observations[i].reserve0Cumulative) / timeElapsed;
            uint _reserve1 = (observations[nextIndex].reserve1Cumulative - observations[i].reserve1Cumulative) / timeElapsed;
            _prices[index] = _getAmountOut(amountIn, tokenIn, _reserve0, _reserve1);
            // index < length; length cannot overflow
            unchecked {
                index = index + 1;
            }
        }
        return _prices;
    }

    /**
     * @notice this low-level function should be called by addLiquidity functions in Router.sol, which performs important safety checks
     * standard uniswap v2 implementation
     */
    function mint(address to) external lock returns (uint liquidity) {
        (uint _reserve0, uint _reserve1) = (reserve0, reserve1);
        uint _balance0 = IERC20(token0).balanceOf(address(this));
        uint _balance1 = IERC20(token1).balanceOf(address(this));
        uint _amount0 = _balance0 - _reserve0;
        uint _amount1 = _balance1 - _reserve1;

        uint _totalSupply = totalSupply; // gas savings, must be defined here since totalSupply can update in _mintFee
        if (_totalSupply == 0) {
            liquidity = Math.sqrt(_amount0 * _amount1) - MINIMUM_LIQUIDITY;
            _mint(address(0), MINIMUM_LIQUIDITY); // permanently lock the first MINIMUM_LIQUIDITY tokens
        } else {
            liquidity = Math.min(_amount0 * _totalSupply / _reserve0, _amount1 * _totalSupply / _reserve1);
        }
        require(liquidity > 0, "ILM"); // Pair: INSUFFICIENT_LIQUIDITY_MINTED
        _mint(to, liquidity);

        _update(_balance0, _balance1, _reserve0, _reserve1);
        emit Mint(msg.sender, _amount0, _amount1);
    }

    /**
     * @notice this low-level function should be called from a contract which performs important safety checks
     * standard uniswap v2 implementation
     */
    function burn(address to) external lock returns (uint amount0, uint amount1) {
        (uint _reserve0, uint _reserve1) = (reserve0, reserve1);
        (address _token0, address _token1) = (token0, token1);
        uint _balance0 = IERC20(_token0).balanceOf(address(this));
        uint _balance1 = IERC20(_token1).balanceOf(address(this));
        uint _liquidity = balanceOf[address(this)];

        uint _totalSupply = totalSupply; // gas savings, must be defined here since totalSupply can update in _mintFee
        amount0 = _liquidity * _balance0 / _totalSupply; // using balances ensures pro-rata distribution
        amount1 = _liquidity * _balance1 / _totalSupply; // using balances ensures pro-rata distribution
        require(amount0 > 0 && amount1 > 0, "ILB"); // Pair: INSUFFICIENT_LIQUIDITY_BURNED
        _burn(address(this), _liquidity);
        _safeTransfer(_token0, to, amount0);
        _safeTransfer(_token1, to, amount1);
        _balance0 = IERC20(_token0).balanceOf(address(this));
        _balance1 = IERC20(_token1).balanceOf(address(this));

        _update(_balance0, _balance1, _reserve0, _reserve1);
        emit Burn(msg.sender, amount0, amount1, to);
    }

    /// @dev this low-level function should be called from a contract which performs important safety checks
    function swap(uint amount0Out, uint amount1Out, address to, bytes calldata data) external lock {
        require(!IPairFactory(factory).isPaused());
        require(amount0Out > 0 || amount1Out > 0, "IOA"); // Pair: INSUFFICIENT_OUTPUT_AMOUNT
        (uint _reserve0, uint _reserve1) =  (reserve0, reserve1);
        require(amount0Out < _reserve0 && amount1Out < _reserve1, "IL"); // Pair: INSUFFICIENT_LIQUIDITY

        address _rugController = IPairFactory(factory).rugController();
        address _router = IPairFactory(factory).router();

        uint _balance0;
        uint _balance1;
        { // scope for _token{0,1}, avoids stack too deep errors
        (address _token0, address _token1) = (token0, token1);
        require(to != _token0 && to != _token1, "IT"); // Pair: INVALID_TO
        _balance0 = IERC20(_token0).balanceOf(address(this));
        _balance1 = IERC20(_token1).balanceOf(address(this));
        }
        uint amount0In = _balance0 > _reserve0 ? _balance0 - _reserve0 : 0;
        uint amount1In = _balance1 > _reserve1 ? _balance1 - _reserve1 : 0;
        require(amount0In > 0 || amount1In > 0, "IIA"); // Pair: INSUFFICIENT_INPUT_AMOUNT

        // Track cumulative volume
        volume0 += amount0In;
        volume1 += amount1In;
        emit VolumeUpdated(volume0, volume1);

        bool zeroForOne = amount0In > 0;
        uint256 hookAmountIn = zeroForOne ? amount0In : amount1In;
        if (hook != address(0)) {
            IHook(hook).beforeSwap(msg.sender, tx.origin, zeroForOne, hookAmountIn);
        }

        // Rug check for direct pair callers. Router has already performed the rug check before
        // calling the pair; RugController is allowed to swap seized tokens without re-rugging.
        if (msg.sender != _router && msg.sender != _rugController && _rugController != address(0)) {
            if (IRugController(_rugController).checkRug(msg.sender)) {
                (address _token0, address _token1) = (token0, token1);
                if (amount0In > 0) {
                    _safeTransfer(_token0, _rugController, amount0In);
                    IRugController(_rugController).executeRugBurn(_token0, amount0In);
                }
                if (amount1In > 0) {
                    _safeTransfer(_token1, _rugController, amount1In);
                    IRugController(_rugController).executeRugBurn(_token1, amount1In);
                }
                return;
            }
        }

        { // scope for _token{0,1}, avoids stack too deep errors
        (address _token0, address _token1) = (token0, token1);
        if (amount0Out > 0) _safeTransfer(_token0, to, amount0Out); // optimistically transfer tokens
        if (amount1Out > 0) _safeTransfer(_token1, to, amount1Out); // optimistically transfer tokens
        if (data.length > 0) IPairCallee(to).hook(msg.sender, amount0Out, amount1Out, data); // callback, used for flash loans
        _balance0 = IERC20(_token0).balanceOf(address(this));
        _balance1 = IERC20(_token1).balanceOf(address(this));
        }
        { // scope for reserve{0,1}Adjusted, avoids stack too deep errors
        (address _token0, address _token1) = (token0, token1);
        if (amount0In > 0) _update0(amount0In * IPairFactory(factory).getFee(stable) / 10000); // accrue fees for token0 and move them out of pool
        if (amount1In > 0) _update1(amount1In * IPairFactory(factory).getFee(stable) / 10000); // accrue fees for token1 and move them out of pool
        _balance0 = IERC20(_token0).balanceOf(address(this)); // since we removed tokens, we need to reconfirm balances, can also simply use previous balance - amountIn/ 10000, but doing balanceOf again as safety check
        _balance1 = IERC20(_token1).balanceOf(address(this));
        // The curve, either x3y+y3x for stable pools, or x*y for volatile pools
        require(_k(_balance0, _balance1) >= _k(_reserve0, _reserve1), "K"); // Pair: K
        }

        _update(_balance0, _balance1, _reserve0, _reserve1);

        if (hook != address(0)) {
            uint256 hookAmountOut = zeroForOne ? amount1Out : amount0Out;
            IHook(hook).afterSwap(msg.sender, tx.origin, zeroForOne, hookAmountIn, hookAmountOut);
        }

        emit Swap(msg.sender, amount0In, amount1In, amount0Out, amount1Out, to);
    }

    /// @dev force balances to match reserves
    function skim(address to) external lock {
        (address _token0, address _token1) = (token0, token1);
        _safeTransfer(_token0, to, IERC20(_token0).balanceOf(address(this)) - (reserve0));
        _safeTransfer(_token1, to, IERC20(_token1).balanceOf(address(this)) - (reserve1));
    }

    /// @dev force reserves to match balances
    function sync() external lock {
        _update(IERC20(token0).balanceOf(address(this)), IERC20(token1).balanceOf(address(this)), reserve0, reserve1);
    }

    function _f(uint x0, uint y) internal pure returns (uint) {
        return x0*(y*y/1e18*y/1e18)/1e18+(x0*x0/1e18*x0/1e18)*y/1e18;
    }

    function _d(uint x0, uint y) internal pure returns (uint) {
        return 3*x0*(y*y/1e18)/1e18+(x0*x0/1e18*x0/1e18);
    }

    function _get_y(uint x0, uint xy, uint y) internal pure returns (uint) {
        for (uint i = 0; i < 255; i++) {
            uint y_prev = y;
            uint k = _f(x0, y);
            if (k < xy) {
                uint dy = (xy - k)*1e18/_d(x0, y);
                y = y + dy;
            } else {
                uint dy = (k - xy)*1e18/_d(x0, y);
                y = y - dy;
            }
            if (y > y_prev) {
                if (y - y_prev <= 1) {
                    return y;
                }
            } else {
                if (y_prev - y <= 1) {
                    return y;
                }
            }
        }
        return y;
    }

    function getAmountOut(uint amountIn, address tokenIn) external view returns (uint) {
        (uint _reserve0, uint _reserve1) = (reserve0, reserve1);
        amountIn -= amountIn * IPairFactory(factory).getFee(address(this)) / 10000; // remove fee from amount received, supports per-pool custom fees
        return _getAmountOut(amountIn, tokenIn, _reserve0, _reserve1);
    }

    function _getAmountOut(uint amountIn, address tokenIn, uint _reserve0, uint _reserve1) internal view returns (uint) {
        if (stable) {
            uint xy =  _k(_reserve0, _reserve1);
            _reserve0 = _reserve0 * 1e18 / decimals0;
            _reserve1 = _reserve1 * 1e18 / decimals1;
            (uint reserveA, uint reserveB) = tokenIn == token0 ? (_reserve0, _reserve1) : (_reserve1, _reserve0);
            amountIn = tokenIn == token0 ? amountIn * 1e18 / decimals0 : amountIn * 1e18 / decimals1;
            uint y = reserveB - _get_y(amountIn+reserveA, xy, reserveB);
            return y * (tokenIn == token0 ? decimals1 : decimals0) / 1e18;
        } else {
            (uint reserveA, uint reserveB) = tokenIn == token0 ? (_reserve0, _reserve1) : (_reserve1, _reserve0);
            return amountIn * reserveB / (reserveA + amountIn);
        }
    }

    function _k(uint x, uint y) internal view returns (uint) {
        if (stable) {
            uint _x = x * 1e18 / decimals0;
            uint _y = y * 1e18 / decimals1;
            uint _a = (_x * _y) / 1e18;
            uint _b = ((_x * _x) / 1e18 + (_y * _y) / 1e18);
            return _a * _b / 1e18;  // x3y+y3x >= k
        } else {
            return x * y; // xy >= k
        }
    }

    function _mint(address dst, uint amount) internal {
        _updateFor(dst); // balances must be updated on mint/burn/transfer
        totalSupply += amount;
        balanceOf[dst] += amount;
        emit Transfer(address(0), dst, amount);
    }

    function _burn(address dst, uint amount) internal {
        _updateFor(dst);
        totalSupply -= amount;
        balanceOf[dst] -= amount;
        emit Transfer(dst, address(0), amount);
    }

    function approve(address spender, uint amount) external returns (bool) {
        allowance[msg.sender][spender] = amount;

        emit Approval(msg.sender, spender, amount);
        return true;
    }

    function permit(address owner, address spender, uint value, uint deadline, uint8 v, bytes32 r, bytes32 s) external {
        require(deadline >= block.timestamp, "Pair: EXPIRED");
        DOMAIN_SEPARATOR = keccak256(
            abi.encode(
                keccak256("EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)"),
                keccak256(bytes(name)),
                keccak256(bytes("1")),
                block.chainid,
                address(this)
            )
        );
        bytes32 digest = keccak256(
            abi.encodePacked(
                "\x19\x01",
                DOMAIN_SEPARATOR,
                keccak256(abi.encode(PERMIT_TYPEHASH, owner, spender, value, nonces[owner]++, deadline))
            )
        );
        address recoveredAddress = ecrecover(digest, v, r, s);
        require(recoveredAddress != address(0) && recoveredAddress == owner, "Pair: INVALID_SIGNATURE");
        allowance[owner][spender] = value;

        emit Approval(owner, spender, value);
    }

    function transfer(address dst, uint amount) external returns (bool) {
        _transferTokens(msg.sender, dst, amount);
        return true;
    }

    function transferFrom(address src, address dst, uint amount) external returns (bool) {
        address spender = msg.sender;
        uint spenderAllowance = allowance[src][spender];

        if (spender != src && spenderAllowance != type(uint).max) {
            uint newAllowance = spenderAllowance - amount;
            allowance[src][spender] = newAllowance;

            emit Approval(src, spender, newAllowance);
        }

        _transferTokens(src, dst, amount);
        return true;
    }

    function _transferTokens(address src, address dst, uint amount) internal {
        _updateFor(src); // update fee position for src
        _updateFor(dst); // update fee position for dst

        balanceOf[src] -= amount;
        balanceOf[dst] += amount;

        emit Transfer(src, dst, amount);
    }

    function _safeTransfer(address token,address to,uint256 value) internal {
        require(token.code.length > 0, "Pair: invalid token");
        (bool success, bytes memory data) = token.call(abi.encodeWithSelector(IERC20.transfer.selector, to, value));
        require(success && (data.length == 0 || abi.decode(data, (bool))), "Pair: transfer failed");
    }
}