@astonic-io/astonic-router-ts v0.2.0

AstonicRouter

A UniswapRouter-style Router for the Astonic AMM.

How does it work?

The router's aim is to execute a series of chained swaps on pairs in the Astonic AMM. As an example we can look at the path USDC->aUSD->aKES. But this can be anything as long as two adjecent assets represent a tradable pair in the Broker.

This path has two swaps or steps: USDC->aUSD and aUSD->aKES. In order to specificy a path the AstonicRouter defines the following struct (as seen in IAstonicRouter.sol):

struct Step {
    address exchangeProvider;
    bytes32 exchangeId;
    address assetIn;
    address assetOut;
}

So for USDC->aUSD, the step is:

IAstonicRouter.Step memory USDC_to_aUSD = IAstonicRouter.Step({
    exchangeProvider: 0x22d9db95E6Ae61c104A7B6F6C78D7993B94ec901,
    exchangeId: 0xacc988382b66ee5456086643dcfd9a5ca43dd8f428f6ef22503d8b8013bcffd7,
    assetIn: 0xcebA9300f2b948710d2653dD7B07f33A8B32118C,
    assetOut: 0x765DE816845861e75A25fCA122bb6898B8B1282a
});

And for aUSD->aKES, the step is:

IAstonicRouter.Step memory aUSD_to_aKES = IAstonicRouter.Step({
    exchangeProvider: 0x22d9db95E6Ae61c104A7B6F6C78D7993B94ec901,
    exchangeId: 0x89de88b8eb790de26f4649f543cb6893d93635c728ac857f0926e842fb0d298b,
    assetIn: 0x765DE816845861e75A25fCA122bb6898B8B1282a,
    assetOut: 0x456a3D042C0DbD3db53D5489e98dFb038553B0d0
});

The parameters to a step are consistent to the parameters needed to call the Astonic Broker.

This lets us build a path:

IAstonicRouter.Step[] memory path = new IAstonicRouter.Step[](2);
path[0] = USDC_to_aUSD;
path[1] = aUSD_to_aKES;

Now that we have a path thare two ways we can execute it:

• swapExactTokensForTokens(uint256 amountIn, uint256 amountOutMin, Step[] path) - which fixes the amountIn of input token, in our example USDC, and ensures at least amountOutMin of the output token, in our case aKES, is returned.
• swapTokensForExactTokens(uint256 amountOut, uint256 amountInMax, Step[] path) - which fixes the amountOut of output token, in our example aKES, and ensures at most amountInMax of the input token, in our case USDC, is spent.

In order to execute a swap you also need to give approval to the Router for the asset at the begining of the chain and the amount of either amountIn for (1) or amountInMax for (2). Full Example:

IAstonicRouter.Step[] memory path = new IAstonicRouter.Step[](2);
path[0] = IAstonicRouter.Step({
    exchangeProvider: biPoolManager,
    exchangeId: aUSD_USDC_exchangeID,
    assetIn: USDC,
    assetOut: aUSD
});
path[1] = IAstonicRouter.Step({
    exchangeProvider: bpm,
    exchangeId: aUSD_aKES_exchangeID,
    assetIn: aUSD,
    assetOut: aKES
});

IERC20(USDC).approve(address(astonicRouter), 1e3);
astonicRouter.swapExactTokensForTokens(1e3, 0, path);

You can see more examples in the Swap Script or the Test;

You can also estimate a path by calling one of the two functions:

• getAmountOut(uint256 amountIn, Step[] path) - which returns how much of the last asset in the chain you will get for a given amount of the first.
• getAmountIn(uint256 amuntOut, Step[], path) - which returns how much of the first asset in the chain is required to get a certain amount of the last asset in the chain.

These functions should be used in conjuction with the amountInMax and amountOutMin variables of the swap functions in order to control slippage.