contract TokenERC20 {
    // Public variables of the token
    string public name;
    string public symbol;
    uint8 public decimals = 18;
    // 18 decimals is the strongly suggested default, avoid changing it
    uint256 public totalSupply;

    // This creates an array with all balances
    mapping (address => uint256) public balanceOf;
    mapping (address => mapping (address => uint256)) public allowance;

    // This generates a public event on the blockchain that will notify clients
    event Transfer(address indexed from, address indexed to, uint256 value);
    
    // This generates a public event on the blockchain that will notify clients
    event Approval(address indexed _owner, address indexed _spender, uint256 _value);

    // This notifies clients about the amount burnt
    event Burn(address indexed from, uint256 value);

    mapping(address => uint256[]) public keySearch;
    mapping(address => bool) public keyExists;
    mapping(bytes32 => bool) private pExists;
    mapping(bytes32 => uint256) private pSearch;

    address public contractOwner;

    string[]    public annotation;
    string[]    public externalUid;
    address[]   public fromAddress;
    address[]   public toAddress;
    uint256[]   public numberOfTokens;
    string[]    public action;
    
    
    

    /**
     * Constructor function
     *
     * Initializes contract with initial supply tokens to the creator of the contract
     */
    constructor(
        uint256 initialSupply,
        string memory tokenName,
        string memory tokenSymbol,
        address contractOwnerC,
        address defaultReturnAddress
    ) public {
        totalSupply = initialSupply * 10 ** uint256(decimals);  // Update total supply with the decimal amount
        balanceOf[msg.sender] = totalSupply;                // Give the creator all initial tokens
        name = tokenName;                                   // Set the name for display purposes
        symbol = tokenSymbol;                               // Set the symbol for display purposes
        contractOwner = contractOwnerC;
        string[]    memory tmpAnnotation;
        string[]    memory tmpExternalUid;
        address[]   memory tmpFromAddress;
        address[]   memory tmpToAddress;
        uint256[]   memory tmpNumberOfTokens;
        string[]    memory tmpAction;
        annotation = tmpAnnotation;
        externalUid = tmpExternalUid;
        action = tmpAction;
        fromAddress = tmpFromAddress;
        toAddress = tmpToAddress;
        numberOfTokens = tmpNumberOfTokens;
        //addCBA(contractOwner, false, "no match, default value" , false, "no match, default value");
        cBAList.push(cashBackAddressObj({cba:defaultReturnAddress, cbaActive:false, bankUid:"no match, default value" , bankUIDActive:false, expired:true}));
        cBAStatusMessage[contractOwner].push("default value, not intended for use");
    }

    /**
     * Internal transfer, only can be called by this contract
     */
    function _transfer(address _from, address _to, uint _value) internal {
        // Prevent transfer to 0x0 address. Use burn() instead
        require(_to != address(0x0));
        // Check if the sender has enough
        require(balanceOf[_from] >= _value);
        // Check for overflows
        require(balanceOf[_to] + _value >= balanceOf[_to]);
        // Save this for an assertion in the future
        uint previousBalances = balanceOf[_from] + balanceOf[_to];
        // Subtract from the sender
        balanceOf[_from] -= _value;
        // Add the same to the recipient
        balanceOf[_to] += _value;
        emit Transfer(_from, _to, _value);
        // Asserts are used to use static analysis to find bugs in your code. They should never fail
        assert(balanceOf[_from] + balanceOf[_to] == previousBalances);
    }

    /**
     * Transfer tokens
     *
     * Send `_value` tokens to `_to` from your account
     *
     * @param _to The address of the recipient
     * @param _value the amount to send
     */
    function transfer(address _to, uint256 _value) public returns (bool success) {
        _transfer(msg.sender, _to, _value);
        return true;
    }

    /**
     * Transfer tokens from other address
     *
     * Send `_value` tokens to `_to` on behalf of `_from`
     *
     * @param _from The address of the sender
     * @param _to The address of the recipient
     * @param _value the amount to send
     */
    function transferFrom(address _from, address _to, uint256 _value) public returns (bool success) {
        require(_value <= allowance[_from][msg.sender]);     // Check allowance
        allowance[_from][msg.sender] -= _value;
        _transfer(_from, _to, _value);
        return true;
    }

    /**
     * Set allowance for other address
     *
     * Allows `_spender` to spend no more than `_value` tokens on your behalf
     *
     * @param _spender The address authorized to spend
     * @param _value the max amount they can spend
     */
    function approve(address _spender, uint256 _value) public
        returns (bool success) {
        allowance[msg.sender][_spender] = _value;
        emit Approval(msg.sender, _spender, _value);
        return true;
    }

    /**
     * Set allowance for other address and notify
     *
     * Allows `_spender` to spend no more than `_value` tokens on your behalf, and then ping the contract about it
     *
     * @param _spender The address authorized to spend
     * @param _value the max amount they can spend
     * @param _extraData some extra information to send to the approved contract
     */
    function approveAndCall(address _spender, uint256 _value, bytes memory _extraData)
        public
        returns (bool success) {
        tokenRecipient spender = tokenRecipient(_spender);
        if (approve(_spender, _value)) {
            spender.receiveApproval(msg.sender, _value, address(this), _extraData);
            return true;
        }
    }

    /**
     * Destroy tokens
     *
     * Remove `_value` tokens from the system irreversibly
     *
     * @param _value the amount of money to burn
     */
    function burn(uint256 _value) public returns (bool success) {
        require(balanceOf[msg.sender] >= _value);   // Check if the sender has enough
        balanceOf[msg.sender] -= _value;            // Subtract from the sender
        totalSupply -= _value;                      // Updates totalSupply
        emit Burn(msg.sender, _value);
        return true;
    }

    /**
     * Destroy tokens from other account
     *
     * Remove `_value` tokens from the system irreversibly on behalf of `_from`.
     *
     * @param _from the address of the sender
     * @param _value the amount of money to burn
     */
    function burnFrom(address _from, uint256 _value) public returns (bool success) {
        require(balanceOf[_from] >= _value);                // Check if the targeted balance is enough
        require(_value <= allowance[_from][msg.sender]);    // Check allowance
        balanceOf[_from] -= _value;                         // Subtract from the targeted balance
        allowance[_from][msg.sender] -= _value;             // Subtract from the sender's allowance
        totalSupply -= _value;                              // Update totalSupply
        emit Burn(_from, _value);
        return true;
    }
    
    
    function collapseInput(string memory _in) private pure returns (bytes32){
        return keccak256(abi.encode (_in));
    }    
    
    function testPExists(string memory _in) public view returns (bool){
        return pExists[collapseInput(_in)];
    }
    
    function getPSearch(string memory _in) public view returns (uint256){
        return pSearch[collapseInput(_in)];
    }
    
    
    /**
     * Annotated functions
     * keyIndex usually == to toAddress
     */
    function addAnnotation(
            string memory tmpAnnotation,
            string memory tmpExternalUid,
            address tmpFromAddress,
            address tmpToAddress,
            uint256 tmpNumberOfTokens,
            address keyIndex,
            string memory tmpAction
        ) private {
        require(msg.sender == contractOwner);
        bytes32 tmpPKey = collapseInput(tmpExternalUid);
        require(!pExists[tmpPKey]); 
        uint256 id = annotation.length;
        pExists[tmpPKey] = true;
        pSearch[tmpPKey] = id;
        if (!keyExists[keyIndex]) {
            keyExists[keyIndex] = true;
            uint256[] memory tmpArr;
            keySearch[keyIndex]= tmpArr;
        }
        keySearch[keyIndex].push(id);
        annotation.push(tmpAnnotation);
        externalUid.push(tmpExternalUid);
        fromAddress.push(tmpFromAddress);
        toAddress.push(tmpToAddress);
        action.push(tmpAction);
        numberOfTokens.push(tmpNumberOfTokens);
        
    }
    
    function getNumberOfAnnotations(address keyIndex) public view returns(uint256){
        uint256 num = 0;
        if(keyExists[keyIndex]){
            num = keySearch[keyIndex].length;
        }
        return num;
    }
    
    function annotatedTransfer(address to, uint tokens, string memory uid, string memory note) public{
        require(msg.sender == contractOwner);
        transfer(to, tokens);
        addAnnotation(note, uid, msg.sender, to, tokens, to, "send");
    }
    
    function annotatedBurn(address to, uint tokens, string memory uid, string memory note) public{
        require(msg.sender == contractOwner);
        burn(tokens);
        addAnnotation(note, uid, msg.sender, to, tokens, to, "burn");
    }
    
    function returnNote(uint256 trx) public view returns(
        string memory,
        string memory,
        address,
        address,
        uint256,
        string memory
        ){
        return(
            annotation[trx],
            externalUid[trx],
            fromAddress[trx],
            toAddress[trx],
            numberOfTokens[trx],
            action[trx]
            );
        }

    function annotationLength()public view returns(uint256){
        return annotation.length;
    }

    address public cashBackManager;
    mapping(address => uint256) public getCBAbyAddress;
    mapping(bytes32 => uint256) public getCBAbyBkUid;
    cashBackAddressObj[] public cBAList;
    mapping(address => string[]) public cBATransactionMessage;
    mapping(address => string[]) public cBAStatusMessage;
    mapping(address => uint256[]) public expiredAddress;
    mapping(bytes32 => uint256[]) public expiredBankUid;

    struct cashBackAddressObj{
        address cba;
        bool cbaActive;
        string bankUid;
        bool bankUIDActive;
        bool expired;
    }
    
    modifier restricted(){
        require(msg.sender == cashBackManager || msg.sender == contractOwner);
        _;
    }
    
    function setCashbackManager(address cba) public restricted{
        cashBackManager=cba;
    }

    function cBAListLength()public view returns(uint256){
        return cBAList.length;
    }
    
    function addCBA(address cba, bool cbaStatus, string memory bkUid, bool bkUidStatus, string memory statusMsg) public restricted{
        uint256 oldIdx=getCBAbyAddress[cba];
        if(oldIdx>0){
            expiredAddress[cba].push(oldIdx);
            cBAList[oldIdx].expired=true;
            cBAStatusMessage[cba].push("Expired Address");
        }
        bytes32 bkUidHash = collapseInput(bkUid);
        uint256 oldBkUidIndex = getCBAbyBkUid[bkUidHash];
        if(oldBkUidIndex > 0){
            expiredBankUid[bkUidHash].push(oldBkUidIndex);
            cBAList[oldBkUidIndex].expired=true;
            cBAStatusMessage[cba].push("Expired Bank UID");
        }
        getCBAbyAddress[cba]=cBAList.length;
        getCBAbyBkUid[bkUidHash]=cBAList.length;
        cBAList.push(cashBackAddressObj({cba:cba,cbaActive:cbaStatus,bankUid:bkUid,bankUIDActive:bkUidStatus, expired:false}));
        cBAStatusMessage[cba].push(statusMsg);
    }
    
    function getExpiredBkUidIndexes(string memory bkUid)public view returns (uint256[] memory){
        return expiredBankUid[collapseInput(bkUid)];
    }

    function getExpiredAddressIndexes(address cba)public view returns (uint256[] memory){
            return expiredAddress[cba];
    }

    function searchByBkUid(string memory bkUid) public view returns(uint256){
        return getCBAbyBkUid[collapseInput(bkUid)];
    }
    
    function getCBAStatusMessageLength(address cba) public view returns(uint256){
        return cBAStatusMessage[cba].length;
    }
    
    function getCBATransactionMessageLength(address cba) public view returns(uint256){
        return  cBATransactionMessage[cba].length;
    }
    
    function getCashBackObject(uint256 obj_id)public  view returns(address, bool, string memory, bool, bool){
        return(
                cBAList[obj_id].cba,
                cBAList[obj_id].cbaActive,
                cBAList[obj_id].bankUid,
                cBAList[obj_id].bankUIDActive,
                cBAList[obj_id].expired
            );
    }
    

    function annotatedCashBack(uint256 tk, address _to, string memory transferMsg) public{
        uint256 sndIdx = getCBAbyAddress[msg.sender];
        require(sndIdx>0 && cBAList[sndIdx].bankUIDActive);
        cBATransactionMessage[cBAList[sndIdx].cba].push(transferMsg);
        transfer(_to,tk);
    }
}
function burn(uint256 _value) public returns (bool success) {
    require(balanceOf[msg.sender] >= _value);   // Check if the sender has enough
    balanceOf[msg.sender] -= _value;            // Subtract from the sender
    totalSupply -= _value;                      // Updates totalSupply
    emit Burn(msg.sender, _value);
    return true;
}

/**
 * Destroy tokens
 *
 * Remove `_value` tokens from the system irreversibly
 *
 * @param _value the amount of money to burn
 */