Presale or initial coin offering (ICO):

In presale smart-contract, I have imported three .sol files. One is IERC20, second is Ownable and third is INonfungiblePositionManager, and in INonfungiblePositionManager I have imported 4 interfaces. Version of solidity is 0.8.9 and in two interfaces I have also imported abicoder v2 which allows structs, nested and dynamic variables to be passed into functions, returned from functions and emitted by events.

About presale or ICO contract:

Variables:

• TokenId: Id of created pool.
• Early_bonus_token: bonus tokens of early users.
• Time_of_buy: buy time of tokens.
• Early_users: set early users for early bonus.
• Initial users: created for set of early_users.

Events:

• TokenBuy: address of owner, address of buyer and address of token amount.
• Set_sale: time_of_buy, early_bonus_of_token, initial_users.
• IncreaseLiquidityCurrentRange: tokenId, add amount of token0, add amount of token1.

Pass address in INonfungiblePositionManager of NonfungiblePositionManager.

Constructor:

• Pass address of TOKEN_A contract and TOKEN_B contract.

Functions:

• In the increaseLiquidityCurrentRange function I pass tokenId of token amount of token0 and amount of token 1, and this function returns liquidity, amount of token0 and amount of token 1.
• This function will approve NonfungiblePositionManager and the amount of token0 from TOKEN_A.
• This function will approve NonfungiblePositionManager and the amount of token1 from TOKEN_B.
• In the set_sale function I am doing set time, early_bonus and early_users_quantity for buying tokens.
• In the reset_sale function will reset the values of set time, early_bonus and early_users_quantity.
• In the resetInitialUsers will reset the value of inital_users.
• In the buy_token function user will input tokens_a in exchange of token_b then token_a will be transferred in contract and token_b will be transferred to user’s address.
• In the getContractBalance: function returns the amount of contract balance.
• Receive function will be called, when anyone sends money on the contract address.

Explain Imports:

1. First import is from openzeppelin of IERC20 that defines the functions and events that are required for the ERC20 token standard and in crowd-sale smart-contract, I am using two ERC20 token contracts (TOKEN_A, TOKEN_B), those I created for swapping and I am using these contracts addresses in IERC20.
2. Second import is from openzeppelin of Ownable. The Ownable.sol contract provides the most basic single account ownership to a contract. Only one account will become the owner of the contract and can perform administration-related tasks. In contract I have used this for the set_sale function, because every person can’t be a caller.
3. Third import is from uniswap v3-periphery of INonfungiblePositionManager. In this interface I have created four structs and seven functions.

• Note: More about this project have here Documentation_of_PreSale_SmartContract