LinkDrop contract

LinkDrop contract allows any user to create a link that their friends can use to claim NFT tokens even if they don't have an account yet.

The way it works (remember this is an example, do not use the same account names):

Preliminar considerations:

• NFT contract is already created under account nft_hodler.

Deploy and initialize:

• Deploy the linkdrop smart contract with name linkdrop.
• Initialize the contract calling linkdrop.init("nft_hodler").
• Transfer onwership of the NFT to linkdrop.

Sender, that has NEAR:

• Creates a new key pair (pk1, privkey1).
• Calls linkdrop.send(pk1).
• Sends a link to any supported wallet app with privkey1 as part of URL.

Receiver, that doesn't have NEAR account:

• Receives link to the wallet with privkey1.
• Wallet creates new key pair for this user (or they generate it via HSM) (pk2, privkey2).
• Enters the new_account_id receiver want for their new account.
• Wallet creates a transaction to linkdrop.create_account_and_claim(new_account_id, pk2) and singns it using (pk1, privkey1).
• Contract creates new account with new_account_id name and pk2 as full access key and transfers NFT ownership to new_account_id.

If Receiver already has account (or Sender wants to get back the money):

• Sign tx with (pk1, privkey1) to call linkdrop.claim(account_id), which transfers the NFT ownership to account_id.