public sale for checkerchain

Sales.rs

#![no_std]

elrond_wasm::imports!();

const EGLD_DECIMALS_VALUE: u64 = 100000000;

#[elrond_wasm::contract]
pub trait CHECKERSale {
    /// Necessary configuration when deploying:
    /// `max_amount` - max amount of EGLD that can be used to buy $MUNCHKIN.  
    /// `min_amount` - min amount of EGLD that can be used to buy $MUNCHKIN.  
    /// `initial_price` - price for $MUNCHKIN token in EGLD (how much $MUNCHKIN for 1 EGLD)
    /// `token_id` - $MUNCHKIN token ID.
    #[init]
    fn init(
        &self,
        max_amount: BigUint,
        min_amount: BigUint,
        initial_price: BigUint,
        checker_token_id: TokenIdentifier,
    ) -> SCResult<()> {
        require!(&max_amount > BigUint::from(0), "Max amount cannot be set to zero!");
        require!(&min_amount > BigUint::from(0), "Min amount cannot be set to zero!");
        require!(&initial_price > BigUint::from(0), "Initial price cannot be set to zero!");

        require!(
            checker_token_id.is_egld() || checker_token_id.is_valid_esdt_identifier(),
            "Invalid token provided"
        );
        let caller: Address = self.blockchain().get_caller();
        self.set_owner(&caller);

        self.price().set(&initial_price);

        self.max_amount().set(&max_amount);

        self.min_amount().set(&min_amount);

        self.sale_token_id().set(&checker_token_id);

        Ok(())
    }

    // endpoints

    /// User sends some tokens to the contract in order to exchange it for $Munchkin
    /// Optional `_data` argument is ignored.
    #[payable("EGLD")]
    #[endpoint]
    fn buy(
        &self,
        #[payment_amount] payment_amount: BigUint,
    ) -> SCResult<()> {
        require!(
            payment_amount <= self.max_amount().get(),
            "The payment is too high"
        );
        require!(
            payment_amount >= self.min_amount().get(),
            "The payment is too low"
        );

        let balance = self.blockchain().get_sc_balance(&self.sale_token_id().get(), 0);
        require!(
            balance > 0,
            "No more token to sale."
        );
        let current_price = self.price().get();
        let one_egld = BigUint::from(EGLD_DECIMALS_VALUE);
        let result_edst_token_amount = ( &current_price * &payment_amount ) / one_egld;
        require!(
            balance > result_edst_token_amount,
            "Not enough tokens for sale."
        );

        //send the ESDT token amount to the user
        let caller = self.blockchain().get_caller();
        let token_id = self.sale_token_id().get();
        self.send()
        .direct(&caller, &token_id, 0, &result_edst_token_amount, b"Munchkin sale successful :).");

        Ok(())
    }

    /// Optional `_data` argument is ignored.
    #[payable("*")]
    #[endpoint]
    fn deposit(
        &self,
        #[payment_amount] _payment_amount: BigUint,
    ) -> SCResult<()> {

        Ok(())
    }

    // storage

    #[storage_set("owner")]
    fn set_owner(&self, address: &Address);

    #[view]
    #[storage_get("owner")]
    fn get_owner(&self) -> Address;


    #[view(getSaleToken)]
    #[storage_mapper("saleTokenId")]
    fn sale_token_id(&self) -> SingleValueMapper<TokenIdentifier>;

    #[view(getMaxAmount)]
    #[storage_mapper("maxAmount")]
    fn max_amount(&self) -> SingleValueMapper<BigUint>;

    #[view(getMinAmount)]
    #[storage_mapper("minAmount")]
    fn min_amount(&self) -> SingleValueMapper<BigUint>;

    #[view(getIncreaseAmount)]
    #[storage_mapper("increaseAmount")]
    fn increase_amount(&self) -> SingleValueMapper<BigUint>;

    #[view(getPrice)]
    #[storage_mapper("price")]
    fn price(&self) -> SingleValueMapper<BigUint>;

}