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Offer.md

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Module 0x1::Offer

use 0x1::Collection2;
use 0x1::Errors;
use 0x1::Signer;
use 0x1::Timestamp;

Resource Offer

A wrapper around value offered that can be claimed by the address stored in for when after lock time.

struct Offer<Offered> has key
Fields
offered: Offered
for: address
time_lock: u64

Constants

An offer of the specified type for the account does not match

const EOFFER_DNE_FOR_ACCOUNT: u64 = 101;

Offer is not unlocked yet.

const EOFFER_NOT_UNLOCKED: u64 = 102;

Function create

Publish a value of type Offered under the sender's account. The value can be claimed by either the for address or the transaction sender.

public fun create<Offered: store>(account: &signer, offered: Offered, for: address, lock_period: u64)
Implementation 
public fun create<Offered: store>(account: &signer, offered: Offered, for: address, lock_period: u64) {
    let time_lock = Timestamp::now_seconds() + lock_period;
    //TODO should support multi Offer?
    move_to(account, Offer<Offered> { offered, for, time_lock });
}
Specification 
include Timestamp::AbortsIfTimestampNotExists;
aborts_if Timestamp::now_seconds() + lock_period > max_u64();
aborts_if exists<Offer<Offered>>(Signer::address_of(account));

Function redeem

Claim the value of type Offered published at offer_address. Only succeeds if the sender is the intended recipient stored in for or the original publisher offer_address, and now >= time_lock Also fails if no such value exists.

public fun redeem<Offered: store>(account: &signer, offer_address: address): Offered
Implementation 
public fun redeem<Offered: store>(account: &signer, offer_address: address): Offered acquires Offer {
    let Offer<Offered> { offered, for, time_lock } = move_from<Offer<Offered>>(offer_address);
    let sender = Signer::address_of(account);
    let now = Timestamp::now_seconds();
    assert!(sender == for || sender == offer_address, Errors::invalid_argument(EOFFER_DNE_FOR_ACCOUNT));
    assert!(now >= time_lock, Errors::not_published(EOFFER_NOT_UNLOCKED));
    offered
}
Specification 
aborts_if !exists<Offer<Offered>>(offer_address);
aborts_if Signer::address_of(account) != global<Offer<Offered>>(offer_address).for && Signer::address_of(account) != offer_address;
aborts_if Timestamp::now_seconds() < global<Offer<Offered>>(offer_address).time_lock;
include Timestamp::AbortsIfTimestampNotExists;

Function exists_at

Returns true if an offer of type Offered exists at offer_address.

public fun exists_at<Offered: store>(offer_address: address): bool
Implementation 
public fun exists_at<Offered: store>(offer_address: address): bool {
    exists<Offer<Offered>>(offer_address)
}
Specification 
aborts_if false;

Function address_of

Returns the address of the Offered type stored at offer_address. Fails if no such Offer exists.

public fun address_of<Offered: store>(offer_address: address): address
Implementation 
public fun address_of<Offered: store>(offer_address: address): address acquires Offer {
    borrow_global<Offer<Offered>>(offer_address).for
}
Specification 
aborts_if !exists<Offer<Offered>>(offer_address);

Function take_offer

Take Offer and put to signer's Collection.

public(script) fun take_offer<Offered: store>(signer: signer, offer_address: address)
Implementation 
public(script) fun take_offer<Offered: store>(
    signer: signer,
    offer_address: address,
) acquires Offer {
    let offered = redeem<Offered>(&signer, offer_address);
    Collection2::put(&signer, Signer::address_of(&signer), offered);
}
Specification 
pragma verify = false;

Module Specification

pragma verify = true;
pragma aborts_if_is_strict = true;