ERC20 Crowdsale (Pause crowdsale for x time after y% of total token supply is bought)

Smart Contracts
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1

To get this out of the way - I am fairly new to Solidity... Can't understand every concept yet.

I have been trying to create a Crowdsale for an ERC20 token in order to practice using OpenZeppelin libraries / standards.
The goal of my project was:

  1. Create an ERC20 token
  2. Create a Crowdsale (which will hold all of the token supply, has a 1 to 1 ERC20 token to Wei ratio)
  3. Make the Crowdsale pause itself for X days/weeks/months after (say) 50% of the ERC20 tokens are bought.

From what I understood, those X days/weeks/months should be calculated by an estimation of time until Z blocks are mined, or something like that. I haven't delved deeper into this subject yet since I'm taking it step by step.

My current issue is - I don't know what the best practice is in order to pause the contract (from within itself, automatically) when the cap of 50% is reached. I don't really know if using CappedCrowdsale is necessary, because I plan on having the Crowdsale open again after X time has passed, and I don't know if that is possible once that cap is reached. Currently I have added the following override of _postValidatePurchase:

function _postValidatePurchase(address beneficiary, uint256 weiAmount) internal view {
        super._postValidatePurchase(beneficiary, weiAmount);
        if (weiRaised == cap) {
            pause;
        }
    }

But it doesn't seem to work and I don't really know how to make it work.

I've been working on this project using OpenZeppelin's Remix IDE.
My full .sol files are the following -

OgreToken.sol

// SPDX-License-Identifier: MIT
pragma solidity ^0.5.0;

import "@openzeppelin/contracts@2.5.1/token/ERC20/ERC20.sol";
import "@openzeppelin/contracts@2.5.1/token/ERC20/ERC20Mintable.sol";
import "@openzeppelin/contracts@2.5.1/token/ERC20/ERC20Detailed.sol";

contract OgreToken is ERC20, ERC20Detailed, ERC20Mintable {
    constructor() ERC20Detailed("OgreToken", "OT", 18) public {
    }
}

and

OgreCrowdsaleDeployer.sol

// SPDX-License-Identifier: MIT
pragma solidity ^0.5.0;

import "./OgreToken.sol";
import "@openzeppelin/contracts@2.5.1/crowdsale/Crowdsale.sol";
import "@openzeppelin/contracts@2.5.1/crowdsale/validation/CappedCrowdsale.sol";
import "@openzeppelin/contracts@2.5.1/crowdsale/validation/PausableCrowdsale.sol";

contract OgreCrowdsale is Crowdsale, PausableCrowdsale, CappedCrowdsale {
    constructor(
        uint256 _rate,
        address payable _wallet,
        OgreToken _token,
        uint256 _cap
    )
    PausableCrowdsale()
    CappedCrowdsale(_cap)
    Crowdsale(_rate, _wallet, _token)
    public
    {

    }

    function _postValidatePurchase(address beneficiary, uint256 weiAmount) internal view {
        super._postValidatePurchase(beneficiary, weiAmount);
        if (weiRaised == cap) {
            pause;
        }
    }
}

contract OgreCrowdsaleDeployer {
    address public token_address;
    address public crowdsale_address;

    constructor()
    public
    {
        // Create the token
        OgreToken ogreToken = new OgreToken();
        token_address = address(ogreToken);

        uint total_supply = 10 ** uint256(ogreToken.decimals());

        // Create the crowdsale and tell it about the token
        OgreCrowdsale ogreCrowdsale = new OgreCrowdsale(
            1, // _rate
            msg.sender, // _wallet
            ogreToken, // _token
            total_supply / 2 // _cap - half of total supply
        );
        crowdsale_address = address(ogreCrowdsale);

        ogreToken.mint(crowdsale_address, total_supply);

        ogreCrowdsale.addPauser(msg.sender);
        ogreCrowdsale.addPauser(crowdsale_address);
        ogreCrowdsale.renouncePauser();
    }
}

Thank you in advance for any type of help or suggestions! :slight_smile: