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

import {ERC20} from "@openzeppelin/contracts/token/ERC20/ERC20.sol";

/// @title FixedSupplyCoin
/// @notice A plain ERC-20 whose entire supply is created once at deployment.
/// @dev There is no owner, administrator, tax, blacklist, pause, or post-deployment mint function.
contract FixedSupplyCoin is ERC20 {
    error EmptyName();
    error EmptySymbol();
    error InvalidInitialHolder();
    error InvalidSupply();

    uint256 public immutable INITIAL_SUPPLY;

    constructor(
        string memory name_,
        string memory symbol_,
        uint256 wholeTokenSupply_,
        address initialHolder_
    ) ERC20(name_, symbol_) {
        if (bytes(name_).length == 0) revert EmptyName();
        if (bytes(symbol_).length == 0) revert EmptySymbol();
        if (initialHolder_ == address(0)) revert InvalidInitialHolder();
        if (wholeTokenSupply_ == 0 || wholeTokenSupply_ > 100_000_000_000) {
            revert InvalidSupply();
        }

        uint256 supply = wholeTokenSupply_ * 10 ** decimals();
        INITIAL_SUPPLY = supply;
        _mint(initialHolder_, supply);
    }
}