WIP CurveRecipe

[dantop114]

Some considerations about this WIP:

• _bake was written supposing that IPie.calcTokensForAmount() returns (_, uint256[] amounts) where amounts contains the amount of _inputToken to spend for each underlying asset
• Does IPie.joinPool(uint256) receive the amount of _inputToken from which thepie is baked/minted?

Now some considerations about the implementation and possible edits:

• Gas consumption will be huge on this (basically ICurveExchange.get_best_rate requires a lot of gas). We should think about exposing a pure function as: getBestPools(address _inputToken, address[] _outputTokens) that returns something like address[] pools, representing the best pools. This can be encoded (like in UniPieRecipe) and passed in the data field to bake.

[dantop114]

Last commit adds a script to estimate gas for get_best_rate function in Swap Curve contract in scripts/curveExchangeTest.ts.

Results from the script:

Curve Swap contract address: 0xD1602F68CC7C4c7B59D686243EA35a9C73B0c6a2
Gas estimation for get_best_rate: 1603971
Best pool is 0x06364f10B501e868329afBc005b3492902d6C763 receiving 99925715633714086595 DAI

So gas cost for get_best_rate should be 1603971. In CurveRecipe contract, this function is called n times (where n is the number of underlying tokens). Supposing a price of 100 gwei gas price: 1603971 * 100 gwei = 160397100 gwei = 0,1603971 ETH (just for a single call to get_best_rate)