Marketplace Smart Contract Documentation

Here's the technical documentation for each function in the Marketplace smart contract:

totalListings()

This function is a view function that returns the total number of listings created in the marketplace. It retrieves the value of the listingsCounter variable, which represents the total number of listings, and returns it.

getFirstElement()

This function is a view function that returns the offers counter of the first listing in the marketplace. It retrieves the offersCounter value from the first listing (index 0) in the listings mapping and returns it.

totalOffers(uint256 _listingId)

This function is a view function that returns the total number of offers for a specific listing. It takes a parameter _listingId representing the ID of the listing and retrieves the offersCounter value from the corresponding listing in the listings mapping. It then returns the value.

createListing(string _title, string _description, uint256 _price)

This function allows a user to create a new listing in the marketplace. It takes three parameters: _title (string) representing the title of the listing, _description (string) representing the description of the listing, and _price (uint256) representing the price of the listing.

Inside the function, it first checks that the _price is greater than zero using a require statement. It then creates a new Listing struct with the provided parameters and other default values such as seller, sold, offersCounter, and offers.

The new listing is stored in the listings mapping with the listingsCounter as the key. The listingsCounter is incremented, and a listingCreated event is emitted with the ID of the new listing.

makeOffer(uint256 _amount, uint256 _listingId)

This function allows a user to make an offer on a specific listing. It takes two parameters: _amount (uint256) representing the offer amount, and _listingId (uint256) representing the ID of the listing.

The function first performs several require statements to validate the offer conditions, such as ensuring the offer amount is greater than zero, the listing ID exists, the user is not the seller of the listing, and the listing is not already sold.

If the offer conditions are met, a new Offer struct is created with the provided offer amount, the address of the buyer (the caller), and an initial status of OfferStatus.PENDING.

The new offer is stored in the offers mapping of the corresponding listing using the offersCounter as the key. If the offer amount matches the listing price, the offer is automatically accepted by calling the _acceptOffer function.

Finally, an offerReceived event is emitted with the listing ID and the ID of the new offer, and the offersCounter is incremented.

_acceptOffer(uint256 _listingId, uint256 _offerId)

This private function is called internally to accept an offer for a listing. It takes two parameters: _listingId (uint256) representing the ID of the listing, and _offerId (uint256) representing the ID of the offer.

The function updates the status of the offer to OfferStatus.ACCEPTED in the offers mapping of the corresponding listing. It also sets the sold status of the listing to true.

An offerAccepted event is emitted with the listing ID and the ID of the accepted offer. The function can also include the logic for transferring funds from the buyer to the seller.

acceptOffer(uint256 _listingId, uint256 _offerId)

This function allows the seller of a listing to accept a specific offer. It takes two parameters: _listingId (uint256) representing the ID of the listing, and _offerId (uint256) representing the ID of the offer.

The function first performs several require statements to validate the offer acceptance conditions, such as ensuring the offer ID exists, the caller is the seller of the listing, and the offer status is OfferStatus.PENDING.

If the conditions are met, the function updates the status of the offer to OfferStatus.ACCEPTED in the offers mapping of the corresponding listing. It also sets the sold status of the listing to true.

An offerAccepted event is emitted with the listing ID and the ID of the accepted offer. The function can also include the logic for transferring funds from the buyer to the seller.

declineOffer(uint256 _listingId, uint256 _offerId)

This function allows the seller of a listing to decline a specific offer. It takes two parameters: _listingId (uint256) representing the ID of the listing, and _offerId (uint256) representing the ID of the offer.

The function first performs several require statements to validate the offer decline conditions, such as ensuring the offer ID exists, the caller is the seller of the listing, and the offer status is OfferStatus.PENDING.

If the conditions are met, the function updates the status of the offer to OfferStatus.DECLINED in the offers mapping of the corresponding listing. It also sets the sold status of the listing to false.

An offerDeclined event is emitted with the listing ID and the ID of the declined offer. The function can also include the logic for refunding the offer sender.

getListing(uint256 _listingId)

This function is a view function that returns the details of a specific listing. It takes one parameter: _listingId (uint256) representing the ID of the listing.

The function retrieves the corresponding Listing struct from the listings mapping using the _listingId and returns the individual fields such as title, description, price, seller, sold, and offersCounter.

getListingOffer(uint256 _listingId, uint256 _offerId)

This function is a view function that returns the details of a specific offer for a listing. It takes two parameters: _listingId (uint256) representing the ID of the listing, and _offerId (uint256) representing the ID of the offer.

The function retrieves the corresponding Offer struct from the offers mapping of the specified listing using the _listingId and _offerId, and returns the individual fields such as amount, buyer, and status.