/*

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    ███████ ███████ ██    ██ █████       ███████ ██ ████ ██ █████   ██████  ██ ██      ███████ 
         ██ ██   ██  ██  ██  ██          ██   ██ ██  ██  ██ ██      ██   ██ ██ ██      ██   ██ 
    ███████ ██   ██   ████   ███████     ██   ██ ██      ██ ███████ ██   ██ ██  ██████ ██   ██ 
                                                                                               
                                                                                            
*/

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

contract SaveAmerica {

    string private _name = "Save America";
    string private _symbol = "SAVE";
    uint8 private _decimals = 18;

    uint private _totalSupply = 100000000000 * 10 ** _decimals;

    address DEAD = 0x000000000000000000000000000000000000dEaD;
    address ZERO = 0x0000000000000000000000000000000000000000;

    mapping(address => uint) private _balances;
    mapping(address => mapping(address => uint)) private _allowances;
    
    event Transfer(address indexed from, address indexed to, uint value);
    event Approval(address indexed owner, address indexed spender, uint value);

    constructor(){
        _balances[msg.sender] = _totalSupply;
        emit Transfer(address(0), msg.sender, _totalSupply);
    }

    function transfer(address to, uint256 amount) public returns (bool) {
        address owner = msg.sender;
        _transfer(owner, to, amount);
        return true;
    }

    function transferFrom(
        address from,
        address to,
        uint256 amount
    ) public returns (bool) {
        address spender = msg.sender;
        _spendAllowance(from, spender, amount);
        _transfer(from, to, amount);
        return true;
    }

    function approve(address spender, uint256 amount) public returns (bool) {
        address owner = msg.sender;
        _approve(owner, spender, amount);
        return true;
    }

     function increaseAllowance(address spender, uint256 addedValue) public returns (bool) {
        address owner = msg.sender;
        _approve(owner, spender, allowance(owner, spender) + addedValue);
        return true;
    }

    function decreaseAllowance(address spender, uint256 subtractedValue) public returns (bool) {
        address owner = msg.sender;
        uint256 currentAllowance = allowance(owner, spender);
        require(currentAllowance >= subtractedValue, "ERC20: decreased allowance below zero");
        unchecked {
            _approve(owner, spender, currentAllowance - subtractedValue);
        }

        return true;
    }

    function _transfer(
        address from,
        address to,
        uint256 amount
    ) internal {
        require(from != address(0), "ERC20: transfer from the zero address");
        require(to != address(0), "ERC20: transfer to the zero address");

        uint256 fromBalance = _balances[from];
        require(fromBalance >= amount, "ERC20: transfer amount exceeds balance");
        
        _balances[from] = fromBalance - amount;
        
        _balances[to] += amount;

        emit Transfer(from, to, amount);
    }
    
    function _approve(
        address owner,
        address spender,
        uint256 amount
    ) internal {
        require(owner != address(0), "ERC20: approve from the zero address");
        require(spender != address(0), "ERC20: approve to the zero address");
        _allowances[owner][spender] = amount;
        emit Approval(owner, spender, amount);
    }

    function _spendAllowance(
        address owner,
        address spender,
        uint256 amount
    ) internal {
        uint256 currentAllowance = allowance(owner, spender);
        if (currentAllowance != type(uint256).max) {
            require(currentAllowance >= amount, "ERC20: insufficient allowance");
            unchecked {
                _approve(owner, spender, currentAllowance - amount);
            }
        }
    }

    function allowance(address owner, address spender) public view returns (uint256) {
        return _allowances[owner][spender];
    }

    function name() public view returns (string memory) {
        return _name;
    }

    function symbol() public view returns (string memory) {
        return _symbol;
    }

    function decimals() public view returns (uint8) {
        return _decimals;
    }

    function totalSupply() public view returns (uint256) {
        return _totalSupply;
    }

    function balanceOf(address account) public view returns (uint256) {
        return _balances[account];
    }

    function totalCirculationSupply() public view returns (uint256) {
        return _totalSupply - _balances[DEAD] - _balances[ZERO];
    }

}