FixedSupplyToken

[
  {
    "inputs": [
      {
        "internalType": "string",
        "name": "name_",
        "type": "string"
      },
      {
        "internalType": "string",
        "name": "symbol_",
        "type": "string"
      },
      {
        "internalType": "string",
        "name": "contractURI_",
        "type": "string"
      },
      {
        "internalType": "uint256",
        "name": "totalSupply_",
        "type": "uint256"
      },
      {
        "internalType": "address",
        "name": "initialHolder_",
        "type": "address"
      }
    ],
    "stateMutability": "nonpayable",
    "type": "constructor"
  },
  {
    "inputs": [],
    "name": "InsufficientAllowance",
    "type": "error"
  },
  {
    "inputs": [],
    "name": "InsufficientBalance",
    "type": "error"
  },
  {
    "inputs": [],
    "name": "ZeroAddress",
    "type": "error"
  },
  {
    "anonymous": false,
    "inputs": [
      {
        "indexed": true,
        "internalType": "address",
        "name": "owner",
        "type": "address"
      },
      {
        "indexed": true,
        "internalType": "address",
        "name": "spender",
        "type": "address"
      },
      {
        "indexed": false,
        "internalType": "uint256",
        "name": "value",
        "type": "uint256"
      }
    ],
    "name": "Approval",
    "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": "value",
        "type": "uint256"
      }
    ],
    "name": "Transfer",
    "type": "event"
  },
  {
    "inputs": [
      {
        "internalType": "address",
        "name": "owner",
        "type": "address"
      },
      {
        "internalType": "address",
        "name": "spender",
        "type": "address"
      }
    ],
    "name": "allowance",
    "outputs": [
      {
        "internalType": "uint256",
        "name": "",
        "type": "uint256"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "address",
        "name": "spender",
        "type": "address"
      },
      {
        "internalType": "uint256",
        "name": "value",
        "type": "uint256"
      }
    ],
    "name": "approve",
    "outputs": [
      {
        "internalType": "bool",
        "name": "",
        "type": "bool"
      }
    ],
    "stateMutability": "nonpayable",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "address",
        "name": "account",
        "type": "address"
      }
    ],
    "name": "balanceOf",
    "outputs": [
      {
        "internalType": "uint256",
        "name": "",
        "type": "uint256"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [],
    "name": "contractURI",
    "outputs": [
      {
        "internalType": "string",
        "name": "",
        "type": "string"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [],
    "name": "decimals",
    "outputs": [
      {
        "internalType": "uint8",
        "name": "",
        "type": "uint8"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [],
    "name": "name",
    "outputs": [
      {
        "internalType": "string",
        "name": "",
        "type": "string"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [],
    "name": "symbol",
    "outputs": [
      {
        "internalType": "string",
        "name": "",
        "type": "string"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [],
    "name": "tokenURI",
    "outputs": [
      {
        "internalType": "string",
        "name": "",
        "type": "string"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [],
    "name": "totalSupply",
    "outputs": [
      {
        "internalType": "uint256",
        "name": "",
        "type": "uint256"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "address",
        "name": "to",
        "type": "address"
      },
      {
        "internalType": "uint256",
        "name": "value",
        "type": "uint256"
      }
    ],
    "name": "transfer",
    "outputs": [
      {
        "internalType": "bool",
        "name": "",
        "type": "bool"
      }
    ],
    "stateMutability": "nonpayable",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "address",
        "name": "from",
        "type": "address"
      },
      {
        "internalType": "address",
        "name": "to",
        "type": "address"
      },
      {
        "internalType": "uint256",
        "name": "value",
        "type": "uint256"
      }
    ],
    "name": "transferFrom",
    "outputs": [
      {
        "internalType": "bool",
        "name": "",
        "type": "bool"
      }
    ],
    "stateMutability": "nonpayable",
    "type": "function"
  }
]

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.24;

import {IERC20} from "./interfaces/IERC20.sol";

contract FixedSupplyToken is IERC20 {
    string public name;
    string public symbol;
    string public contractURI;
    uint8 public constant decimals = 18;

    uint256 public immutable override totalSupply;

    mapping(address account => uint256) public override balanceOf;
    mapping(address owner => mapping(address spender => uint256)) public override allowance;

    error ZeroAddress();
    error InsufficientBalance();
    error InsufficientAllowance();

    constructor(
        string memory name_,
        string memory symbol_,
        string memory contractURI_,
        uint256 totalSupply_,
        address initialHolder_
    ) {
        if (initialHolder_ == address(0)) revert ZeroAddress();

        name = name_;
        symbol = symbol_;
        contractURI = contractURI_;
        totalSupply = totalSupply_;
        balanceOf[initialHolder_] = totalSupply_;

        emit Transfer(address(0), initialHolder_, totalSupply_);
    }

    function tokenURI() external view returns (string memory) {
        return contractURI;
    }

    function transfer(address to, uint256 value) external override returns (bool) {
        _transfer(msg.sender, to, value);
        return true;
    }

    function approve(address spender, uint256 value) external override returns (bool) {
        if (spender == address(0)) revert ZeroAddress();

        allowance[msg.sender][spender] = value;
        emit Approval(msg.sender, spender, value);
        return true;
    }

    function transferFrom(address from, address to, uint256 value) external override returns (bool) {
        uint256 currentAllowance = allowance[from][msg.sender];
        if (currentAllowance < value) revert InsufficientAllowance();

        unchecked {
            allowance[from][msg.sender] = currentAllowance - value;
        }
        emit Approval(from, msg.sender, allowance[from][msg.sender]);

        _transfer(from, to, value);
        return true;
    }

    function _transfer(address from, address to, uint256 value) private {
        if (to == address(0)) revert ZeroAddress();

        uint256 fromBalance = balanceOf[from];
        if (fromBalance < value) revert InsufficientBalance();

        unchecked {
            balanceOf[from] = fromBalance - value;
            balanceOf[to] += value;
        }

        emit Transfer(from, to, value);
    }
}