// SPDX-License-Identifier: GPL-3.0
pragma solidity ^0.6.12;

//import "hardhat/console.sol";

import {Math} from "@openzeppelin/contracts/math/Math.sol";
import {SafeERC20} from "@openzeppelin/contracts/token/ERC20/SafeERC20.sol";
import {SafeMath} from "@openzeppelin/contracts/math/SafeMath.sol";
import {IDetailedERC20} from "../../interfaces/IDetailedERC20.sol";
import {IVaultAdapter} from "../../interfaces/IVaultAdapter.sol";
import "hardhat/console.sol";

/// @title Pool
///
/// @dev A library which provides the Vault data struct and associated functions.
library Vault {
  using Vault for Data;
  using Vault for List;
  using SafeERC20 for IDetailedERC20;
  using SafeMath for uint256;

  struct Data {
    IVaultAdapter adapter;
    uint256 totalDeposited;
  }

  struct List {
    Data[] elements;
  }

  /// @dev Gets the total amount of assets deposited in the vault.
  ///
  /// @return the total assets.
  function totalValue(Data storage _self) internal view returns (uint256) {
    return _self.adapter.totalValue();
  }

  /// @dev Gets the token that the vault accepts.
  ///
  /// @return the accepted token.
  function token(Data storage _self) internal view returns (IDetailedERC20) {
    return IDetailedERC20(_self.adapter.token());
  }

  /// @dev Deposits funds from the caller into the vault.
  ///
  /// @param _amount the amount of funds to deposit.
  function deposit(Data storage _self, uint256 _amount) internal returns (uint256) {
    // Push the token that the vault accepts onto the stack to save gas.
    IDetailedERC20 _token = _self.token();

    _token.safeTransfer(address(_self.adapter), _amount);
    _self.adapter.deposit(_amount);
    _self.totalDeposited = _self.totalDeposited.add(_amount);

    return _amount;
  }

  /// @dev Deposits the entire token balance of the caller into the vault.
  function depositAll(Data storage _self) internal returns (uint256) {
    IDetailedERC20 _token = _self.token();
    return _self.deposit(_token.balanceOf(address(this)));
  }

  /// @dev Withdraw deposited funds from the vault.
  ///
  /// @param _recipient the account to withdraw the tokens to.
  /// @param _amount    the amount of tokens to withdraw.
  function withdraw(Data storage _self, address _recipient, uint256 _amount) internal returns (uint256, uint256) {
    (uint256 _withdrawnAmount, uint256 _decreasedValue) = _self.directWithdraw(_recipient, _amount);
    _self.totalDeposited = _self.totalDeposited.sub(_decreasedValue);
    return (_withdrawnAmount, _decreasedValue);
  }

  /// @dev Directly withdraw deposited funds from the vault.
  ///
  /// @param _recipient the account to withdraw the tokens to.
  /// @param _amount    the amount of tokens to withdraw.
  function directWithdraw(Data storage _self, address _recipient, uint256 _amount) internal returns (uint256, uint256) {
    IDetailedERC20 _token = _self.token();

    uint256 _startingBalance = _token.balanceOf(_recipient);
    uint256 _startingTotalValue = _self.totalValue();

    _self.adapter.withdraw(_recipient, _amount);

    uint256 _endingBalance = _token.balanceOf(_recipient);
    uint256 _withdrawnAmount = _endingBalance.sub(_startingBalance);

    uint256 _endingTotalValue = _self.totalValue();
    uint256 _decreasedValue = _startingTotalValue.sub(_endingTotalValue);

    return (_withdrawnAmount, _decreasedValue);
  }

  /// @dev Withdraw all the deposited funds from the vault.
  ///
  /// @param _recipient the account to withdraw the tokens to.
  function withdrawAll(Data storage _self, address _recipient) internal returns (uint256, uint256) {
    return _self.withdraw(_recipient, _self.totalDeposited);
  }

  /// @dev Harvests yield from the vault.
  ///
  /// @param _recipient the account to withdraw the harvested yield to.
  function harvest(Data storage _self, address _recipient) internal returns (uint256, uint256) {
    if (_self.totalValue() <= _self.totalDeposited) {
      return (0, 0);
    }
    uint256 _withdrawAmount = _self.totalValue().sub(_self.totalDeposited);
    return _self.directWithdraw(_recipient, _withdrawAmount);
  }

  /// @dev Adds a element to the list.
  ///
  /// @param _element the element to add.
  function push(List storage _self, Data memory _element) internal {
    _self.elements.push(_element);
  }

  /// @dev Gets a element from the list.
  ///
  /// @param _index the index in the list.
  ///
  /// @return the element at the specified index.
  function get(List storage _self, uint256 _index) internal view returns (Data storage) {
    return _self.elements[_index];
  }

  /// @dev Gets the last element in the list.
  ///
  /// This function will revert if there are no elements in the list.
  ///
  /// @return the last element in the list.
  function last(List storage _self) internal view returns (Data storage) {
    return _self.elements[_self.lastIndex()];
  }

  /// @dev Gets the index of the last element in the list.
  ///
  /// This function will revert if there are no elements in the list.
  ///
  /// @return the index of the last element.
  function lastIndex(List storage _self) internal view returns (uint256) {
    uint256 _length = _self.length();
    return _length.sub(1, "Vault.List: empty");
  }

  /// @dev Gets the number of elements in the list.
  ///
  /// @return the number of elements.
  function length(List storage _self) internal view returns (uint256) {
    return _self.elements.length;
  }
}