// SPDX-License-Identifier: MIT
pragma solidity 0.8.7;

// ----------------------------------------------------------------------------
// ERC Token Standard #20 Interface
//
// ----------------------------------------------------------------------------
abstract contract ERC20Interface {
    function totalSupply() public virtual view returns (uint);
    function balanceOf(address tokenOwner) public virtual view returns (uint balance);
    function allowance(address tokenOwner, address spender) public virtual view returns (uint remaining);
    function transfer(address to, uint tokens) public virtual returns (bool success);
    function approve(address spender, uint tokens) public virtual returns (bool success);
    function transferFrom(address from, address to, uint tokens) public virtual returns (bool success);

    event Transfer(address indexed from, address indexed to, uint tokens);
    event Approval(address indexed tokenOwner, address indexed spender, uint tokens);
}

// ----------------------------------------------------------------------------
// Safe Math Library
// ----------------------------------------------------------------------------
contract SafeMath {
    function safeAdd(uint a, uint b) public pure returns (uint c) {
        c = a + b;
        require(c >= a);
    }
    function safeSub(uint a, uint b) public pure returns (uint c) {
        require(b <= a); c = a - b; 
    } 
    function safeMul(uint a, uint b) public pure returns (uint c) { 
        c = a * b; require(a == 0 || c / a == b); 
    } 
    function safeDiv(uint a, uint b) public pure returns (uint c) { 
        require(b > 0);
        c = a / b;
    }
}

contract SantalumCoin is ERC20Interface, SafeMath {
    string public name;
    string public symbol;
    uint8 public decimals; // 18 decimals is the strongly suggested default, avoid changing it
    uint256 public tokenBirth;
    uint256 public price;

    uint256 public _totalSupply;

    mapping(address => uint) balances;
    mapping(address => mapping(address => uint)) allowed;

    /**
     * Constrctor function
     *
     * Initializes contract with initial supply tokens to the creator of the contract
     */
    constructor() {
        name = "Santalum";
        symbol = "SST";
        decimals = 18;
        _totalSupply = 840000000 * (10**decimals);
        tokenBirth = block.timestamp;
        price = 100000000000000000;

        balances[msg.sender] = _totalSupply;
        emit Transfer(address(0), msg.sender, _totalSupply);
    }

    function totalSupply() public override view returns (uint) {
        return _totalSupply;
    }

    function balanceOf(address tokenOwner) public override view returns (uint balance) {
        return balances[tokenOwner];
    }

    function allowance(address tokenOwner, address spender) public override view returns (uint remaining) {
        return allowed[tokenOwner][spender];
    }

    function approve(address spender, uint tokens) public override returns (bool success) {
        allowed[msg.sender][spender] = tokens;
        emit Approval(msg.sender, spender, tokens);
        return true;
    }

    function transfer(address to, uint tokens) public override returns (bool success) {
        require(tokens <= balances[msg.sender]);
        balances[msg.sender] = safeSub(balances[msg.sender], tokens);
        balances[to] = safeAdd(balances[to], tokens);
        emit Transfer(msg.sender, to, tokens);
        return true;
    }

    function transferFrom(address from, address to, uint tokens) public override returns (bool success) {
        require(tokens <= balances[from]);
        require(tokens <= allowed[from][msg.sender]);
        balances[from] = safeSub(balances[from], tokens);
        allowed[from][msg.sender] = safeSub(allowed[from][msg.sender], tokens);
        balances[to] = safeAdd(balances[to], tokens);
        emit Transfer(from, to, tokens);
        return true;
    }

    function getPrice() public view returns (uint256 c) {
        uint a = 1;
        uint b = getAge();
        c = a + (b * 1644) / 1000000;
    }

    function getAge() public view returns (uint256 d) {
        uint256 a = block.timestamp;
        uint256 b = a - tokenBirth;
        uint256 c = b - b % 86400;
        if(c == 0) {
            d = 1;
        } else {
            d = c / 86400;
        }
    }
}