/*

    Copyright 2020 DODO ZOO.
    SPDX-License-Identifier: Apache-2.0

*/

pragma solidity 0.6.9;
pragma experimental ABIEncoderV2;

import {DVMVault} from "./DVMVault.sol";
import {DecimalMath} from "../../lib/DecimalMath.sol";
import {IDODOCallee} from "../../intf/IDODOCallee.sol";

contract DVMFunding is DVMVault {
    function buyShares(address to) external preventReentrant returns (uint256) {
        uint256 baseInput = getBaseInput();
        uint256 quoteInput = getQuoteInput();
        require(baseInput > 0, "NO_BASE_INPUT");
        uint256 baseReserve = _BASE_RESERVE_; // may save gas? 待确认
        uint256 quoteReserve = _QUOTE_RESERVE_;
        uint256 mintAmount;
        // case 1. initial supply
        if (baseReserve == 0 && quoteReserve == 0) {
            mintAmount = baseInput;
        }
        // case 2. supply when quote reserve is 0
        if (baseReserve > 0 && quoteReserve == 0) {
            uint256 mintRatio = DecimalMath.divFloor(baseInput, baseReserve);
            mintAmount = DecimalMath.mulFloor(totalSupply, mintRatio);
        }
        // case 3. normal case
        if (baseReserve > 0 && quoteReserve > 0) {
            uint256 baseInputRatio = DecimalMath.divFloor(baseInput, baseReserve);
            uint256 quoteInputRatio = DecimalMath.divFloor(quoteInput, quoteReserve);
            uint256 mintRatio = baseInputRatio > quoteInputRatio ? quoteInputRatio : baseInputRatio;
            // 在提币的时候向下取整。因此永远不会出现，balance为0但totalsupply不为0的情况
            // 但有可能出现，reserve>0但totalSupply=0的场景
            uint256 totalShare = totalSupply;
            if (totalShare > 0) {
                mintAmount = DecimalMath.mulFloor(totalShare, mintRatio);
            } else {
                mintAmount = baseInput;
            }
        }
        _mint(to, mintAmount);
        _sync();
    }

    function sellShares(
        address to,
        uint256 shareAmount,
        bytes calldata data
    ) external preventReentrant returns (uint256) {
        require(_SHARES_[msg.sender] >= shareAmount, "SHARES_NOT_ENOUGH");
        (uint256 baseBalance, uint256 quoteBalance) = getVaultBalance();
        uint256 totalShares = totalSupply;
        _burn(msg.sender, shareAmount);
        uint256 baseAmount = baseBalance.mul(shareAmount).div(totalShares);
        uint256 quoteAmount = quoteBalance.mul(shareAmount).div(totalShares);
        _transferBaseOut(to, baseAmount);
        _transferQuoteOut(to, quoteAmount);
        _sync();
        if (data.length > 0)
            IDODOCallee(msg.sender).DVMSellShareCall(
                to,
                shareAmount,
                baseAmount,
                quoteAmount,
                data
            );
    }
}