pragma solidity ^0.4.15;

contract ERC20Token
{
    uint256 totSupply;
    
    string sym;
    string nam;

    uint8 public decimals = 0;
    
    mapping (address => uint256) balances;
    
    mapping (address => mapping (address => uint256)) allowed;

    event Transfer(
        address indexed from,
        address indexed to,
        uint256 value);

    event Approval(
        address indexed owner,
        address indexed spender,
        uint256 value);

    function symbol() public constant returns (string)
    {
        return sym;
    }

    function name() public constant returns (string)
    {
        return nam;
    }
   
    function totalSupply() public constant returns (uint256)
    {
        return totSupply;
    }

    function balanceOf(address holderAddress) public constant returns (uint256 balance)
    {
        return balances[holderAddress];
    }
 
    function allowance(address ownerAddress, address spenderAddress) public constant returns (uint256 remaining)
    {
        return allowed[ownerAddress][spenderAddress];
    }

    function transfer(address toAddress, uint256 amount) public returns (bool success)
    {
        return xfer(msg.sender, toAddress, amount);
    }

    function transferFrom(address fromAddress, address toAddress, uint256 amount) public returns (bool success)
    {
        require(amount <= allowed[fromAddress][msg.sender]);
        allowed[fromAddress][msg.sender] -= amount;
        xfer(fromAddress, toAddress, amount);
        return true;
    }

    function xfer(address fromAddress, address toAddress, uint amount) internal returns (bool success)
    {
        require(amount <= balances[fromAddress]);
        balances[fromAddress] -= amount;
        balances[toAddress] += amount;
        Transfer(fromAddress, toAddress, amount);
        return true;
    }

    function approve(address spender, uint256 value) returns (bool) 
    {
        require((value == 0) || (allowed[msg.sender][spender] == 0));

        allowed[msg.sender][spender] = value;
        Approval(msg.sender, spender, value);
        return true;
    }

    function increaseApproval (address spender, uint addedValue) returns (bool success)
    {
        allowed[msg.sender][spender] = allowed[msg.sender][spender] + addedValue;
        Approval(msg.sender, spender, allowed[msg.sender][spender]);
        return true;
    }

    function decreaseApproval (address spender, uint subtractedValue) returns (bool success)
    {
        uint oldValue = allowed[msg.sender][spender];

        if (subtractedValue > oldValue) {
            allowed[msg.sender][spender] = 0;
        } else {
            allowed[msg.sender][spender] = oldValue - subtractedValue;
        }
        Approval(msg.sender, spender, allowed[msg.sender][spender]);
        return true;
    }
}

contract PlanetBlockchainToken is ERC20Token
{
    address public owner = msg.sender;
    address public newOwner;

    function PlanetBlockchainToken()
    {
        sym = 'PBT';
        nam = 'Planet BlockChain Token';
        decimals = 18;

    }

    function issue(address toAddress, uint amount, string externalId, string reason) public returns (bool)
    {
        require(owner == msg.sender);
        totSupply += amount;
        balances[toAddress] += amount;
        Issue(toAddress, amount, externalId, reason);
        Transfer(0x0, toAddress, amount);
        return true;
    }
    
    function redeem(uint amount) public returns (bool)
    {
        require(balances[msg.sender] >= amount);
        totSupply -= amount;
        balances[msg.sender] -= amount;
        Redeem(msg.sender, amount);
        Transfer(msg.sender, 0x0, amount);
        return true;
    }

    modifier onlyOwner {
        require(msg.sender == owner);
        _;
    }

    function transferOwnership(address _newOwner) public onlyOwner {
        newOwner = _newOwner;
    }

    function acceptOwnership() public {
        require(msg.sender == newOwner);
        OwnershipTransferred(owner, newOwner);
        owner = newOwner;
        newOwner = 0x0;
    }
    
    event Issue(address indexed toAddress, uint256 amount, string externalId, string reason);

    event Redeem(address indexed fromAddress, uint256 amount);

    event OwnershipTransferred(address indexed _from, address indexed _to);
}