FlatPricing.sol

We would recommend adding require(_oneTokenInWei > 0) in the constructor, you should not be able to declare this variable to 0 because it will break the calculatePrice function.

DayToken.sol

https://github.com/BlockchainLabsNZ/chronologic/blob/dev/contracts/DayToken.sol#L259
function updateBalanceOf(uint256 _id) internal returns (bool success) {

This function should always return a bool, it only returns true, and never false.

Day Token

https://github.com/BlockchainLabsNZ/chronologic/blob/dev/contracts/DayToken.sol#L566

balances[this] = safeSub(balances[this], minBalanceToSell + sellingPriceInDayOf[msg.sender]);
balances[msg.sender] = safeAdd(balances[msg.sender], minBalanceToSell + sellingPriceInDayOf[msg.sender]);

We recommend using safe math for adding minBalanceToSell and sellingPriceInDayOf together.

The latest version of Solidity supported by Truffle.js is 0.4.13, the contracts are all using 0.4.11

The logic in the comment above does not match with the code, the minBalanceToSend is not added to _offerInDay

This line of code does match the comment from above, which means one of these is wrong.

In this current state you be able to withdraw more than you sold for.

ERC20.sol and ERC20Basic.sol

The names of the parameters deviate from the standard naming conventions in ERC20 Token Standard. We would recommend following them exactly.

ERC20 Token Standard

Example:

ERC20Basic.sol
function balanceOf(address who) constant returns (uint);

ERC20 Token Standard
function balanceOf(address _owner) constant returns (uint balance);

DayToken.sol

There is a pattern used throughout this file for identifying if an ID is a contributor. The modifier onlyContributor uses it, and several other functions use it too. In the interest of not repeating yourself, a function should be created like

function isContributor(uint id) returns (bool isContributor) {
    return (id <= latestContributerId && id != 0);
}

StandardToken.sol

https://github.com/BlockchainLabsNZ/chronologic/blob/dev/contracts/StandardToken.sol#L68
require(!((_value != 0) && (allowed[msg.sender][_spender] != 0)));

The above line could be simplified to

require((_value == 0) || (allowed[msg.sender][_spender] == 0));

Which is much easier to read.

https://github.com/OpenZeppelin/zeppelin-solidity/blob/master/contracts/token/StandardToken.sol#L50

DayToken.sol

https://github.com/BlockchainLabsNZ/chronologic/blob/dev/contracts/DayToken.sol#L411
contributors[toId].totalTransferredDay = contributors[toId].totalTransferredDay + int(_value);

_value is an uint, it will always be a positive number, there is no reason to cast it to an int

DayToken.sol

https://github.com/BlockchainLabsNZ/chronologic/blob/dev/contracts/DayToken.sol#L234
function getTotalMinted(address _adr) public constant returns (int256) {

This function returns the number of DAY tokens minted, using the type int which means that it expects there could be a negative amount. Is this correct?

UpgradeableToken.sol

* Somebody has upgraded some of his tokens.

Should probably say

* Somebody has upgraded some of their tokens.

DayToken.sol

/** Funtion to allow seller to get back his deposited amount of day tokens...

to

/** Function to allow seller to get back their deposited amount of day tokens...

etc

Add Constant modifier to SafeMath functions as they don't modify storage

DayToken.sol

This variable was created a few lines above, use this instead of repeating yourself.

We would recommend using a code linter and picking a consistent style guide.

This would make the code look cleaner, and more professional.

StandardToken.sol

https://github.com/BlockchainLabsNZ/chronologic/blob/dev/contracts/StandardToken.sol#L47

balances[_to] = safeAdd(balances[_to],_value);
balances[_from] = safeSub(balances[_from],_value);

These two lines should be swapped to prevent code re-entrancy attacks

DayToken.sol

sellMintingAddress isn't transferring the actual amount specified by the user, instead it's transferring minBalanceToSell

DayToken.sol

https://github.com/BlockchainLabsNZ/chronologic/blob/dev/contracts/DayToken.sol#L414

balances[_to] = safeAdd(balances[_to], _value);
balances[_from] = safeSub(balances[_from], _value);
allowed[_from][msg.sender] = safeSub(_allowance, _value);

Subtractions should be made before addition to prevent a re-entrancy attack. We recommend re-ordering these lines.

DayToken.sol

https://github.com/BlockchainLabsNZ/chronologic/blob/dev/contracts/DayToken.sol#L217
function getMintingPowerByAddress is repeating code from function getMintingPowerById

Change the contents of the getMintingPowerByAddress function to:

return getMintingPowerById(idOf[_adr]);

Examples:

We would recommend using a static variable for these numbers so you can tell what they are meant to be, and change them easily if needed.

The SOLD status is never used, this should be removed, or used.

DayToken.sol

https://github.com/BlockchainLabsNZ/chronologic/blob/dev/contracts/DayToken.sol#L380
balances[_to] = safeAdd(balances[msg.sender], _value);

When you make a transfer, the receivers balance will be equal to the senders balance plus the value sent, instead of the receivers balance plus the value sent.

The correct code would be:

balances[_to] = safeAdd(balances[_to], _value);

This error could inadvertently burn or clone all tokens in existence. If you make a transfer to the owner/team multisig address from an address with a small number of tokens, the entire supply other than the small number of tokens will be lost completely.

You could also clone tokens by transferring from a high balance address, to a low balance address.

DayToken.sol

https://github.com/BlockchainLabsNZ/chronologic/blob/dev/contracts/DayToken.sol#L74

e.g

uint256 public bounty;
    /* Minimum Balance in Day tokens required to sell a minting address */
    uint256 minBalanceToSell;
    /* Team address lock down period from issued time, in seconds */
    uint256 teamLockPeriodInSec;  //Initialize and set function
    /* Duration in secs that we consider as a day. (For test deployment purposes,
       if we want to decrease length of a day. default: 84600)*/
    uint256 public DayInSecs;
    address crowdsaleAddress;

Some variables do not state public or private, it's best to be explicit.

DayToken.sol

balances[this] = safeAdd(balances[this], minBalanceToSell);
balances[msg.sender] = safeSub(balances[msg.sender], minBalanceToSell);