// SPDX-License-Identifier: MIT
pragma solidity 0.8.30;

/// @notice DEMONSTRATION TOKENS ON ROBINHOOD CHAIN. Neither token has monetary value or claims on real assets.
contract DemoUSD {
    string public constant name = "Veridion Demo USD";
    string public constant symbol = "dUSD";
    uint8 public constant decimals = 6;
    uint256 public totalSupply;
    mapping(address => uint256) public balanceOf;
    mapping(address => mapping(address => uint256)) public allowance;
    mapping(address => uint256) public nextClaimAt;
    event Transfer(address indexed from, address indexed to, uint256 value);
    event Approval(address indexed owner, address indexed spender, uint256 value);
    function faucet() external {
        require(block.timestamp >= nextClaimAt[msg.sender], "FAUCET_COOLDOWN");
        nextClaimAt[msg.sender] = block.timestamp + 1 days;
        uint256 amount = 10_000 * 1e6;
        totalSupply += amount;
        balanceOf[msg.sender] += amount;
        emit Transfer(address(0), msg.sender, amount);
    }
    function approve(address spender, uint256 amount) external returns (bool) {
        allowance[msg.sender][spender] = amount;
        emit Approval(msg.sender, spender, amount);
        return true;
    }
    function transfer(address to, uint256 amount) external returns (bool) {
        _transfer(msg.sender, to, amount); return true;
    }
    function transferFrom(address from, address to, uint256 amount) external returns (bool) {
        uint256 permitted = allowance[from][msg.sender];
        require(permitted >= amount, "INSUFFICIENT_ALLOWANCE");
        allowance[from][msg.sender] = permitted - amount;
        emit Approval(from, msg.sender, permitted - amount);
        _transfer(from, to, amount); return true;
    }
    function _transfer(address from, address to, uint256 amount) internal {
        require(to != address(0), "ZERO_ADDRESS");
        require(balanceOf[from] >= amount, "INSUFFICIENT_BALANCE");
        balanceOf[from] -= amount; balanceOf[to] += amount;
        emit Transfer(from, to, amount);
    }
}

/// @notice Fixed 1:1 test-token vault. No yield, admin, upgrade, or external strategy.
/// @dev Demonstrates allowance, custody, share minting and redemption; not a real RWA offering.
contract VeridionDemoVault {
    string public constant name = "Veridion Demo Vault Share";
    string public constant symbol = "vDEMO";
    uint8 public constant decimals = 6;
    DemoUSD public asset;
    uint256 public totalSupply;
    mapping(address => uint256) public balanceOf;
    mapping(address => mapping(address => uint256)) public allowance;
    event Transfer(address indexed from, address indexed to, uint256 value);
    event Approval(address indexed owner, address indexed spender, uint256 value);
    event Deposit(address indexed account, uint256 assets, uint256 shares);
    event Redeem(address indexed account, uint256 assets, uint256 shares);
    constructor() {
        require(block.chainid == 4663, "ROBINHOOD_MAINNET_ONLY");
        asset = new DemoUSD();
    }
    function totalAssets() external view returns (uint256) { return asset.balanceOf(address(this)); }
    function deposit(uint256 amount) external {
        require(amount > 0, "ZERO_AMOUNT");
        require(asset.transferFrom(msg.sender, address(this), amount), "TRANSFER_FAILED");
        totalSupply += amount; balanceOf[msg.sender] += amount;
        emit Transfer(address(0), msg.sender, amount);
        emit Deposit(msg.sender, amount, amount);
    }
    function redeem(uint256 shares) external {
        require(shares > 0, "ZERO_AMOUNT");
        require(balanceOf[msg.sender] >= shares, "INSUFFICIENT_SHARES");
        balanceOf[msg.sender] -= shares; totalSupply -= shares;
        emit Transfer(msg.sender, address(0), shares);
        require(asset.transfer(msg.sender, shares), "TRANSFER_FAILED");
        emit Redeem(msg.sender, shares, shares);
    }
    function approve(address spender, uint256 amount) external returns (bool) {
        allowance[msg.sender][spender] = amount;
        emit Approval(msg.sender, spender, amount); return true;
    }
    function transfer(address to, uint256 amount) external returns (bool) {
        _transfer(msg.sender, to, amount); return true;
    }
    function transferFrom(address from, address to, uint256 amount) external returns (bool) {
        uint256 permitted = allowance[from][msg.sender];
        require(permitted >= amount, "INSUFFICIENT_ALLOWANCE");
        allowance[from][msg.sender] = permitted - amount;
        emit Approval(from, msg.sender, permitted - amount);
        _transfer(from, to, amount); return true;
    }
    function _transfer(address from, address to, uint256 amount) internal {
        require(to != address(0), "ZERO_ADDRESS");
        require(balanceOf[from] >= amount, "INSUFFICIENT_SHARES");
        balanceOf[from] -= amount; balanceOf[to] += amount;
        emit Transfer(from, to, amount);
    }
}