# BEX userCmd Explained

## Background
We have this BEX transaction: https://bartio.beratrail.io/tx/0x113c50e59148c06aeac42a91ab11df4436a2c9b1b0febaebad93f9d905ff9256

It does 2 things:
1) Creates a new pool
2) Adds liquidity to the pool

## Issue
It is unclear to developers how `userCmd` is being encoded to achieve this functionality. Developers who wish to perform these actions programmatically require an understanding of how to interact with `userCmd` at a deeper level.

## Reviewing Frontend Call

It's helpful to see what the UI (closed source) does to build the transaction:

Call path indexes have been highlighted to show which proxy sidecars are invoked.

## Step 1 - MultiPath

At the highest level, `userCmd` is called with the arguments `[6, multiCmd]`

We see in the [contract code](https://github.com/berachain/CrocSwap-protocol/blob/mainL2/contracts/mixins/StorageLayout.sol#L200) that `6` corresponds to `MULTICALL_PROXY_IDX`

In `MultiPath.sol`, the `cmdCode` is `2`, corresponding to [two commands](https://github.com/berachain/CrocSwap-protocol/blob/mainL2/contracts/callpaths/MultiPath.sol#L29) we wish to make.

Each call's code + command is serialized and separately called:

    
    (, uint8 code1, bytes memory cmd1, uint8 code2, bytes memory cmd2) =
    abi.decode(cmd, (uint8, uint8, bytes, uint8, bytes));
    
    callUserCmdMem(code1, cmd1);
    callUserCmdMem(code2, cmd2);

## Step 2 - Pool Creation

The first command has a `callPath = 3`, relating to the [`ColdProxy`](https://github.com/berachain/CrocSwap-protocol/blob/mainL2/contracts/mixins/StorageLayout.sol#L197)

The first argument of the `initiPoolInfo.calldata` has a specific `ColdPath` code, which is `71`, calling the [`initPool`](https://github.com/berachain/CrocSwap-protocol/blob/mainL2/contracts/callpaths/ColdPath.sol#L91) function

The remaining calldata is further decoded as follows:

(, address base, address quote, uint256 poolIdx, uint128 price) =
            abi.decode(cmd, (uint8, address,address,uint256,uint128));

## Step 3 - Add Liquidity

Things should be straightforward at this point. The second `MultiPath` code is `128`, corresponding to the liquidity provision command [here](https://github.com/berachain/CrocSwap-protocol/blob/mainL2/contracts/callpaths/WarmPath.sol#L49).

## Appendix
### Calldata Decoded

Function: userCmd(uint16, bytes)
MethodID: 0xa15112f9

[0]: 0000000000000000000000000000000000000000000000000000000000000006
// callpath (6 for MultiPath)

[1]: 0000000000000000000000000000000000000000000000000000000000000040
// Offset to the cmd data

[2]: 00000000000000000000000000000000000000000000000000000000000002e0
// Length of the cmd data

[3]: 0000000000000000000000000000000000000000000000000000000000000002
// Number of commands (2)

[4]: 0000000000000000000000000000000000000000000000000000000000000003
// First command code (3 for ColdPath)

[5]: 00000000000000000000000000000000000000000000000000000000000000a0
// Offset to first command data

[6]: 0000000000000000000000000000000000000000000000000000000000000080
// Length of first command data

[7]: 0000000000000000000000000000000000000000000000000000000000000160
// Offset to second command data

[8]: 00000000000000000000000000000000000000000000000000000000000000a0
// Length of second command data

[9]: 0000000000000000000000000000000000000000000000000000000000000047
// Command code for initPool (71 in decimal, which is 0x47 in hex)

[10]: 0000000000000000000000004dc594ce9752af1290402d2d9fd8eb0b6c863bd6
// Base token address for pool initialization

[11]: 000000000000000000000000b2292e4b23b21bf44455b3ffeca9d25eacc07a7c
// Quote token address for pool initialization

[12]: 0000000000000000000000000000000000000000000000000000000000008ca0
// Pool index (36000) for pool initialization

[13]: 0000000000000000000000000000000000000000000000016a09e667f3bd0000
// Initial price (1.600000000000000000 in fixed-point representation) for pool initialization

[14]: 0000000000000000000000000000000000000000000000000000000000000160
// Offset to second command data

[15]: 000000000000000000000000000000000000000000000000000000000000001f
// Second command code (31 for MINT_AMBIENT_BASE_LP in WarmPath)

[16]: 0000000000000000000000004dc594ce9752af1290402d2d9fd8eb0b6c863bd6
// Base token address for liquidity addition

[17]: 000000000000000000000000b2292e4b23b21bf44455b3ffeca9d25eacc07a7c
// Quote token address for liquidity addition

[18]: 0000000000000000000000000000000000000000000000000000000000008ca0
// Pool index (36000) for liquidity addition

[19]: 0000000000000000000000000000000000000000000000000000000000000000
// Bid tick (0) for liquidity addition

[20]: 0000000000000000000000000000000000000000000000000000000000000000
// Ask tick (0) for liquidity addition

[21]: 0000000000000000000000000000000000000000019d2d3d4200d9a7a37fb727
// Amount of liquidity to add

[22]: 0000000000000000000000000000000000000000000000016a09e667f3bd0000
// Lower price limit (1.6) for liquidity addition

[23]: 0000000000000000000000000000000000000000000000016a09e667f3bd0000
// Upper price limit (1.6) for liquidity addition

[24]: 0000000000000000000000000000000000000000000000000000000000000000
// Reserve flags (0) for liquidity addition

[25]: 0000000000000000000000002b15c8526162163a12fcda6d75f4dab13d02da5f
// LP conduit address for liquidity addition

### Transaction Summary

#### 1. Initialize Pool
The first command (code 3) calls the ColdPath contract to initialize the pool:

- Base token: 0x4dc594ce9752af1290402d2d9fd8eb0b6c863bd6
- Quote token: 0xb2292e4b23b21bf44455b3ffeca9d25eacc07a7c
- Pool ID: 36000
- Initial price: 1.600000000000000000

#### 2. Add Liquidity
The second command (code 128) calls the WarmPath contract to mint liquidity:

- Base token: 0x4dc594ce9752af1290402d2d9fd8eb0b6c863bd6
- Quote token: 0xb2292e4b23b21bf44455b3ffeca9d25eacc07a7c
- Pool ID: 36000
- Bid tick: 0
- Ask tick: 0
- Liquidity: 8223039985483627371447
- Lower limit: 1.600000000000000000
- Upper limit: 1.600000000000000000
- Reserve flags: 0
- LP Conduit: 0x2b15c8526162163a12fcda6d75f4dab13d02da5f