# Atomic Swaps

In order to do an atomic swap with someone, you will first have to
agree on what tokens you wish to swap. For example, let's say you want
to swap `40` `ANON` for your counterparty's `20` `DAWN`. You can do
this tutorial with a real counterparty or with yourself. This tutorial
assumes the counterparty is yourself, but we will indicate which steps
differ so you should be able to do the tutorial with a real
counterparty as well.

The swap uses one coin per party so the counterparty only sees the
single coin you're using, not your other coins.

> Note: A "coin" is a single cryptographic record. Your wallet balance
> is the sum of all coins you own, and each coin must be spent
> entirely.

You must use a coin worth the exact amount you want to swap. To create
a smaller coin denomination, send yourself the amount you want to swap.
Then check you have a spendable coin to swap with. Note that the coin
overview might look very different depending on your activity:

```shell
drk> wallet coins

 Coin            | Spent | Token ID        | Aliases | Value                    | Spend Hook | User Data | Spent TX
-----------------+-------+-----------------+---------+--------------------------+------------+-----------+-----------------
 EGV6rS...pmmm6H | true  | 241vAN...KcLssb | DRK     | 2000000000 (20)          | -          | -         | fbbd7a...5f2b19
...
 H6Bc49...Zb6k8h | false | {TOKEN2}        | DAWN    | 2000000000 (20)          | -          | -         | -
 47QnyR...1T7igm | true  | {TOKEN1}        | ANON    | 4269000000 (42.69)       | -          | -         | 47b481...b07395
 5UUJbH...trdQHY | false | {TOKEN1}        | ANON    | 4000000000 (40)          | -          | -         | -
 EEneNB...m6mxTC | false | 241vAN...KcLssb | DRK     | 1999442971 (19.97253683) | -          | -         | -
```

You'll have to initiate the swap and build your half of the swap tx:

```shell
drk> otc init 40.0:20.0 ANON:DAWN > half_swap
```

Then you can send this `half_swap` file to the counterparty and they
can create the other half and sign it by running:

```shell
drk> otc join < half_swap > full_swap
```

The counterparty can now send it back to you. Finally, to make the swap
transaction valid, you need to sign it as well.

> Note: If you are doing this tutorial by yourself, you don't need to
> send the `half_swap` or `full_swap` file anywhere, and can just
> create the `full_swap` followed by the `signed_swap` directly.

```shell
drk> otc sign < full_swap > signed_swap
```

Now that the swap is signed, one of the parties (or a third one)
must attach the corresponding fee:

```shell
drk> attach-fee < signed_swap > full_swap_with_fee
```

Since a new call has been added to the transaction, both parties
must re-sign the full_swap_with_fee file, one by one.

Party A:

```shell
drk> otc sign < full_swap_with_fee > signed_full_swap_with_fee
```

Party B:

```shell
drk> otc sign < signed_full_swap_with_fee > swap.tx
```

Now the complete swap transaction can be broadcast:

```shell
drk> broadcast < swap.tx

[mark_tx_spend] Processing transaction: d2a5e288e6ba44583ee12db9c7a0ed154c736d1aa841d70c7d3fa121c92dfc69
[mark_tx_spend] Found Money contract in call 0
[mark_tx_spend] Found Money contract in call 1
Broadcasting transaction...
Transaction ID: d2a5e288e6ba44583ee12db9c7a0ed154c736d1aa841d70c7d3fa121c92dfc69
```

On success, you should see a transaction ID. This transaction will now
be in the mempool, and you should wait until it's confirmed.

![pablo-waiting2](img/pablo2.jpg)

After a while you should see the change in balances in your wallet:

```shell
drk> wallet balance

 Token ID                                     | Aliases | Balance
----------------------------------------------+---------+-------------
 241vANigf1Cy3ytjM1KHXiVECxgxdK4yApddL8KcLssb | DRK     | 19.96835727
 {TOKEN1}                                     | ANON    | 40
 {TOKEN2}                                     | DAWN    | 20
```

Since in this example we did an atomic swap with ourself, the balances are
unchanged. We can confirm it actually happened successfully by checking
our coins:

```shell
drk> wallet coins

 Coin            | Spent | Token ID        | Aliases | Value                    | Spend Hook | User Data | Spent TX
-----------------+-------+-----------------+---------+--------------------------+------------+-----------+-----------------
 EGV6rS...pmmm6H | true  | 241vAN...KcLssb | DRK     | 2000000000 (20)          | -          | -         | fbbd7a...5f2b19
...
 EEneNB...m6mxTC | true  | 241vAN...KcLssb | DRK     | 1999442971 (19.97253683) | -          | -         | d2a5e2...2dfc69
 H6Bc49...Zb6k8h | true  | {TOKEN2}        | DAWN    | 2000000000 (20)          | -          | -         | d2a5e2...2dfc69
 5UUJbH...trdQHY | true  | {TOKEN1}        | ANON    | 4000000000 (40)          | -          | -         | d2a5e2...2dfc69
 4zwzZf...uMbVir | false | {TOKEN2}        | DAWN    | 2000000000 (20)          | -          | -         | -
 BrqQuk...FcwW6d | false | {TOKEN1}        | ANON    | 4000000000 (40)          | -          | -         | -
 EEneNB...m6mxTC | false | 241vAN...KcLssb | DRK     | 1999442971 (19.96834924) | -          | -         | -
```

Here you can see there are two entries for the tokens we used in the
swap: `40.00` `ANON` and `20.00` `DAWN` . The first entry shows the
`Spent` flag as `true` and the second entry shows the `Spent` flag as
`false`. This means the transaction was successful. Since we are
swapping with ourself, we successfully spent the coins in the first
half of the transaction, and re-minted them to ourselves in the second
half of the transaction.

If you're testing atomic swaps with a counterparty and you can see
their tokens, that means the swap was successful.  In case you still
see your old tokens, that could mean that the swap transaction has not
yet been confirmed.
