Animal Marketplace

I - AnimalToken

It is an ERC721 Token just with some additional functions.

Mint

function _mint(address to, uint tokenId) internal {
    require(to != address(0), "address 0x0");
    require(!_exists(tokenId), "token already exists");
    tokenOwner[tokenId] = to;
    ownedTokensCount[to].increment();
    emit Transfer(address(0), to, tokenId);
}

function mint(uint tokenId) public {
    _mint(msg.sender, tokenId);
}

MintNewToken (from two others)

function mintNewToken(uint tokenId1, uint tokenId2, uint new_tokenId) public {
    require(ownerOf(tokenId1) == ownerOf(tokenId2), "not owner of both tokens");
    _mint(msg.sender, new_tokenId);
}

Burn

function _burn(uint tokenId) internal {
    require(ownerOf(tokenId) == msg.sender, "not owner of token");
    clearApproval(tokenId);
    ownedTokensCount[msg.sender].decrement();
    tokenOwner[tokenId] = address(0);
    emit Transfer(msg.sender, address(0), tokenId);
}

function burn(uint tokenId) public {
    _burn(tokenId);
}

II - Marketplace

Deposit/Withdraw Animal Allow user to list his animal on the marketplace contract. Marketplace owns the contracts until animal is saled.

Sale Allow user to sale his animal.

Auction Allow user to put his animal on auction.

Breeding Allow user to breed two of his animals.

Fight Allow two user to agree on a fight and a reward.

III - No problem to compile and migrate