interface IOracle is IModule {

    function init(address baseToken) external;
    function update(address token) external;
    function indexToken() external view returns(address);

    /**
     @param token ERC20 token
     @param amountTokens quantity, token native precision
     @param amountUsd US dollar equivalent, precision 18
     @param volatility metric for future use-cases
     */
    function read(address token, uint amountTokens) external view returns(uint amountUsd, uint volatility);

    /**
     @param token ERC20 token
     @param amountTokens token quantity, token native precision
     @param amountUsd US dollar equivalent, precision 18
     @param volatility metric for future use-cases
     */    
    function amountRequired(address token, uint amountUsd) external view returns(uint amountTokens, uint volatility);

    /**
     @notice converts normalized precision-18 amounts to token native precision amounts, truncates low-order values
     @param token ERC20 token contract
     @param amountNormal quantity, precision 18
     @param amountTokens quantity scaled to token precision
     */    
    function normalizedToTokens(address token, uint amountNormal) external view returns(uint amountTokens);

    /**
     @notice converts token native precision amounts to normalized precision-18 amounts
     @param token ERC20 token contract
     @param amountNormal quantity, precision 18
     @param amountTokens quantity scaled to token precision
     */  
    function tokensToNormalized(address token, uint amountTokens) external view returns(uint amountNormal);
}
function tokensToNormalized(address token, uint amountTokens) external view returns(uint amountNormal);

/**
 @notice converts token native precision amounts to normalized precision-18 amounts
 @param token ERC20 token contract
 @param amountNormal quantity, precision 18
 @param amountTokens quantity scaled to token precision
 */