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Interactions with Mettalex DEX will require the ability to call some Mettalex smart contract events:
Mint L/S Position tokens from coin tokens (i.e. USDT);
Redeem L/S token pair for coin tokens;
Redeem single Position token for coin tokens if contract is settled.
This means that each user needs to call different methods accordingly to the liquidity pool they want to interact with (i.e. Mettalex Vault, LPs pool or AMM pool).
Possible Events: Mettalex Vault
The possible scenarios a user can face when operating with position tokens in the Mettalex Vault are the following: 
Allowance
allowance (address owner, address spender)
This method returns the remaining number of tokens the spender address is allowed to spend on behalf of the owner address through the method transferFrom. This value is zero by default. This value changes when approve or transferFrom are called.
Approve
approve (address spender, uint256 amount)
This method sets an amount uint256 of tokens as the allowance of the spender address over the caller's tokens. It returns a boolean value indicating whether the operation succeeded or not.
BalanceOf
balanceOf (address account)
Returns the amount of tokens owned by the account.
IncreaseAllowance
increaseAllowance (address spender, uint256 addedValue)
This method is called when the user wants to increase the allowance related to his address. uint256 indicates the value added to the existing allowance.
DecreaseAllowance
decreaseAllowance (address spender, uint256 subtractedValue)
This method is called when the user wants to decrease the allowance related to his address. uint256 indicates the value subtracted to the existing allowance.
MintPositions
mintPositions (uint256 _quantityToMint)
This method is called to mint new position tokens where uint256 indicates the amount of positions to be minted and transferred to the user’s account.
MintFromCollateralAmount
mintFromCollateralAmount(uint256 _collateralAmount)
This method is called to mint new position tokens depending on the amount of collateral deposited. The amount of collateral to be deposited is given by uint256.
RedeemPositions
redeemPositions (address _to, uint256 _redeemQuantity)
This method allows the user to redeem the collateral to send to the sender address.
The method is called to redeem the given amount of positions held by the user. The address the user wants to use to transfer the collateral redeemed is indicated by address _to. The amount of positions to redeem is given by uint256.
SettlePosition
settlePositions ()
This method allows the users to settle by returning collateral and burning position tokens.
BulkSettlePositions
bulkSettlePositions (address[] calldata _settlers)
This method allows the users to settle multiple accounts by returning collateral and burning position tokens. The parameter address[] indicates the array of user accounts to be settled.
TotalSupply
totalSupply ()
Returns the amount of tokens in existence.
Transfer
transfer (address recipient, uint256 amount)
This method is called when a user wants to move an amount uint256 of tokens from the caller's account to the recipient address. This method returns a boolean value indicating whether the operation succeeded or not.
TransferFrom
transferFrom (address sender, address recipient, uint256 amount)
When this method is called it generates a transfer event in which the user wants to move an amount uint256 of tokens from the sender address to recipient address using the allowance mechanism. The amount transferred will be deducted from the caller's allowance. This method returns a boolean value indicating if the operation succeeded.
Possible Events: LPs pool
The scenario a liquidity provider can face when operating with the LPs pool can be the following:
Deposit
deposit (uint _amount)
This method allows users who want to provide liquidity to deposit the quantity of liquidity desired into the pool. uint _amount indicates the amount of liquidity to be deposited.
Withdraw
withdraw (uint256 _amount)
With this method users who want to withdraw their liquidity from the LPs pool. uint256 _amount indicates the amount of liquidity the user wants to withdraw.
WithdrawAll
withdrawAll ()
With this method the user can withdraw all of their liquidity from the LPs pool.
Earn
earn ()
This method transfers money from the vault to the autonomous market maker contract in order to earn trading fees from the supplied funds.
GetPricePerFullShare
getPricePerFullShare ()
This method is called when the user wants to get the price for the entire amount of liquidity he owns in the liquidity pool.
Possible Events: Autonomous Market Maker
ClaimFees
claimFee (address _to)
This method is called to claim the fee accumulated by the vault. The parameter address _to indicates the address to transfer the fees accrued.
GetExpectedOutAmount
getExpectedOutAmount (address fromToken, address toToken, uint256 fromTokenAmount)
returns (uint256 tokensReturned, uint256 priceImpact)
This method is called to get the expected amount of tokens (i.e. uint256 fromTokemAmount) given out in a swap operation from the fromToken address to the toToken address. This method returns the amount of tokens returned to the user’s account (i.e. uint256 tokensReturned) and the price impact due to the operation (i.e. uint256 priceImpact).
GetExpectedInAmount
getExpectedInAmount (address fromToken, address toToken, uint256 toTokenAmount)
returns (uint256 tokensReturned, uint256 priceImpact)
This method is called to get the expected amount of tokens (i.e. uint256 toTokemAmount) received in a swap operation from the fromToken address to the toToken address. This method returns the amount of tokens returned to the account (i.e. uint256 tokensReturned) and the price impact due to the operation (i.e. uint256 priceImpact).
GetSwapFee
getSwapFee ()
It shows the fee related to the swap operation.
GetBalance
getBalance (address token)
It is used in order to get the balance of tokens owned by the address.
HandleBreach
handleBreach ()
Settle all Long and Short tokens held by the contract in case of Commodity breach.
IsBound
isBound (address token)
Used to check if the token is bounded to the balancer pool connected with the strategy. token is the address of the token. It returns the status of the token, that is if it is bounded to the balancer pool or not.
SwapExactAmountIn
swapExactAmountIn (address tokenIn, uint256 tokenAmountIn, address tokenOut, uint256 minAmountOut, uint256 maxPrice)
   returns (uint256 tokenAmountOut, uint256 spotPriceAfter 
This method is called when the user wants to trade an amount uint256 tokenAmountIn of tokenIn taken by the pool, in exchange for an amount uint256 minAmountOut of tokenOut given to the user from the pool, with a maximum marginal price equal to uint 256 maxPrice. 
This method returns the amount of tokens taken out from the user’s account (i.e. uint256 tokenAmountOut) and the new spot price after the swap operation (i.e. uint256 spotPriceAfter).
UpdateSpotAndNormalizeWeights
updateSpotAndNormalizeWeights ()
It is called to rebalance the Balancer pool according to the new spot price updated in Vault.
UpdateOracle
updateOracle (address _newOracle)
This method changes the address of the Oracle contract. Address is the new Oracle address.
UpdateSpot
updateSpot (uint256 _price)
This method updates the spot price of an asset. uint256 is the new updated price. The update can take place only if the arbitration price is within the contract bounds otherwise the contract settles.
UpdateCommodityAfterBreach
updateCommodityAfterBreach (address _vault, address _ltk, address _stk)
This method is called to update the contract addresses after a band breach occurs. address _vault is the vault address whereas address _ltk and address _stk are respectively the Long and Short token addresses.
Fetch.ai’s Stop-Loss agent for DeFi Liquidity Providers
Trading Strategies with Derivatives
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Contents
Possible Events: Mettalex Vault
Possible Events: LPs pool
Possible Events: Autonomous Market Maker