// SPDX-License-Identifier: MIT
pragma solidity >=0.7.6 <0.9;

import "@openzeppelin/contracts/token/ERC20/IERC20.sol";

library CollateralType {
    enum Class {
        NONE, // unused
        POOL, // pool collateral type
        VAULT // usable as vault collateral
    }

    // Collateral token is uniquely identified by the pair (collateralClass, token).
    struct Data {
        // The kind of collateral for this token.
        CollateralType.Class collateralClass;
        // The ERC20 token contract for this collateral type.
        IERC20 token;
        // Same as token.decimals(), when that exists.
        uint256 decimals;
        // Token invalidation time. Must be 0 on creation.
        uint256 validUntil;
        // When `true`, the FTSO with symbol `assetFtsoSymbol` returns asset price relative to this token
        // (such FTSO's will probably exist for major stablecoins).
        // When `false`, the FTSOs with symbols `assetFtsoSymbol` and `tokenFtsoSymbol` give asset and token
        // price relative to the same reference currency and the asset/token price is calculated as their ratio.
        bool directPricePair;
        // FTSO symbol for the asset, relative to this token or a reference currency
        // (it depends on the value of `directPricePair`).
        string assetFtsoSymbol;
        // FTSO symbol for this token in reference currency.
        // Used for asset/token price calculation when `directPricePair` is `false`.
        // Otherwise it is irrelevant to asset/token price calculation, but if it is nonempty,
        // it is still used in calculation of challenger and confirmation rewards
        // (otherwise we assume it approximates the value of USD and pay directly the USD amount in vault collateral).
        string tokenFtsoSymbol;
        // Minimum collateral ratio for healthy agents.
        uint256 minCollateralRatioBIPS;
        // Minimum collateral ratio for agent in CCB (Collateral call band).
        // If the agent's collateral ratio is less than this, skip the CCB and go straight to liquidation.
        // A bit smaller than minCollateralRatioBIPS.
        uint256 ccbMinCollateralRatioBIPS;
        // Minimum collateral ratio required to get agent out of liquidation.
        // Will always be greater than minCollateralRatioBIPS.
        uint256 safetyMinCollateralRatioBIPS;
    }
}