pragma solidity ^0.4.24;

import "./IST20.sol";
import "openzeppelin-solidity/contracts/ownership/Ownable.sol";

/**
 * @title Interface for all security tokens
 */
contract ISecurityToken is IST20, Ownable {

    uint8 public constant PERMISSIONMANAGER_KEY = 1;
    uint8 public constant TRANSFERMANAGER_KEY = 2;
    uint8 public constant STO_KEY = 3;
    uint8 public constant CHECKPOINT_KEY = 4;
    uint256 public granularity;

    // Value of current checkpoint
    uint256 public currentCheckpointId;

    // Total number of non-zero token holders
    uint256 public investorCount;

    // List of token holders
    address[] public investors;

    // Permissions this to a Permission module, which has a key of 1
    // If no Permission return false - note that IModule withPerm will allow ST owner all permissions anyway
    // this allows individual modules to override this logic if needed (to not allow ST owner all permissions)
    function checkPermission(address _delegate, address _module, bytes32 _perm) public view returns(bool);

    /**
     * @notice returns module list for a module type
     * @param _moduleType is which type of module we are trying to remove
     * @param _moduleIndex is the index of the module within the chosen type
     */
    function getModule(uint8 _moduleType, uint _moduleIndex) public view returns (bytes32, address);

    /**
     * @notice returns module list for a module name - will return first match
     * @param _moduleType is which type of module we are trying to remove
     * @param _name is the name of the module within the chosen type
     */
    function getModuleByName(uint8 _moduleType, bytes32 _name) public view returns (bytes32, address);

    /**
     * @notice Queries totalSupply as of a defined checkpoint
     * @param _checkpointId Checkpoint ID to query as of
     */
    function totalSupplyAt(uint256 _checkpointId) public view returns(uint256);

    /**
     * @notice Queries balances as of a defined checkpoint
     * @param _investor Investor to query balance for
     * @param _checkpointId Checkpoint ID to query as of
     */
    function balanceOfAt(address _investor, uint256 _checkpointId) public view returns(uint256);

    /**
     * @notice Creates a checkpoint that can be used to query historical balances / totalSuppy
     */
    function createCheckpoint() public returns(uint256);

    /**
     * @notice gets length of investors array
     * NB - this length may differ from investorCount if list has not been pruned of zero balance investors
     * @return length
     */
    function getInvestorsLength() public view returns(uint256);

}