.. _collect_limit_order:

collect limit order
================================

here, we provide a simple example to fetch limit orders of iZiSwap from an user's address, and select one of them to collect

The full example code of this chapter can be spotted `here <https://github.com/izumiFinance/izumi-iZiSwap-sdk/blob/main/example/limitOrder/collectLimitOrder.ts>`_.


1. fetch limit orders
---------------------

.. code-block:: typescript
    :linenos:

    const chain:BaseChain = initialChainTable[ChainId.BSC]
    const rpc = 'https://bsc-dataseed2.defibit.io/'
    const web3 = new Web3(new Web3.providers.HttpProvider(rpc))
    const account =  web3.eth.accounts.privateKeyToAccount(privateKey)

    const limitOrderAddress = '0x9Bf8399c9f5b777cbA2052F83E213ff59e51612B'
    const limitOrderManager = getLimitOrderManagerContract(limitOrderAddress, web3)


    const testAAddress = '0xCFD8A067e1fa03474e79Be646c5f6b6A27847399'
    const testBAddress = '0xAD1F11FBB288Cd13819cCB9397E59FAAB4Cdc16F'

    const testA = await fetchToken(testAAddress, chain, web3)
    const testB = await fetchToken(testBAddress, chain, web3)
    const fee = 2000 // 2000 means 0.2%

    // fetch limit order
    const {activeOrders, deactiveOrders} = await fetchLimitOrderOfAccount(
        chain, web3, limitOrderManager, '0xD0B1c02E8A6CA05c7737A3F4a0EEDe075fa4920C', [testA]
    )

the code above is nearly the same as :ref:`fetch_limit_order`, you can view more detailed explains though this link

2. select an order to collect and get calling
-------------------------------------------------------------

first, select an order or your own

.. code-block:: typescript
    :linenos:

    const activeOrderAt2 = activeOrders[2]

second, get calling of decrease the limit order

.. code-block:: typescript
    :linenos:

    const orderIdx = activeOrderAt2.idx
    const gasPrice = '5000000000'
    const params: CollectLimOrderParam = {
        orderIdx,
        tokenX: activeOrderAt2.tokenX,
        tokenY: activeOrderAt2.tokenY,
        collectDecAmount: activeOrderAt2.sellingDec,
        collectEarnAmount: '1'
    }
    // dec limit order of orderIdx
    const {collectLimitOrderCalling, options} = getCollectLimitOrderCall(
        limitOrderManager,
        account.address,
        chain,
        params,
        gasPrice
    )

We should notice that, if tokenX or tokenY is chain token (like `ETH` on ethereum or `BNB` on bsc),
we should specify one field in `params` to indicate sdk collecting in form of `Chain Token`
or collecting in form of `Wrapped Chain Token` (like `WETH` on ethereum or `WBNB` on bsc).

In the sdk version 1.1.* or before, one should specify a field named `strictERC20Token` to indicate that.
`true` for collecting token in form of `Wrapped Chain Token`, `false` for collecting in form of `Chain Token`.
In the sdk version 1.2.* or later, you have two ways to indicate sdk. 

The first way is as before, specifing `strictERC20Token` field.
The second way is specifing `strictERC20Token` as undefined and specifying the corresponding token in this param as 
`WETH` or `ETH`.


3.  estimate gas (optional)
---------------------------
of course you can skip this step if you don't want to limit gas.

.. code-block:: typescript
    :linenos:

    const gasLimit = await collectLimitOrderCalling.estimateGas(options)

4. finally, send transaction!
------------------------------

for metamask or other explorer's wallet provider, you can easily write 

.. code-block:: typescript
    :linenos:

    await collectLimitOrderCalling.send({...options, gas: gasLimit})

otherwise, if you run codes in console, you could use following code

.. code-block:: typescript
    :linenos:

    const signedTx = await web3.eth.accounts.signTransaction(
        {
            ...options,
            to: limitOrderAddress,
            data: collectLimitOrderCalling.encodeABI(),
            gas: new BigNumber(gasLimit * 1.1).toFixed(0, 2),
        }, 
        privateKey
    )
    // nonce += 1;
    const tx = await web3.eth.sendSignedTransaction(signedTx.rawTransaction);

after this step, we have successfully collect a limit order (if no revert occurred).