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contracts...Lootbox.sol

pragma solidity >=0.8.0 <0.9.0;

/** 
 * @title Lootbox
 * @dev Matrix lootbox contract
 */

import "@openzeppelin/contracts/token/ERC1155/ERC1155.sol";
import "@openzeppelin/contracts/token/ERC1155/utils/ERC1155Holder.sol";
// import "https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/token/ERC1155/ERC1155.sol";
// import "https://github.com/OpenZeppelin/openzeppelin-contracts/blob/v3.4.0/contracts/token/ERC1155/ERC1155Holder.sol";
// import "https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/token/ERC1155/presets/ERC1155PresetMinterPauser.sol";

contract Lootbox is ERC1155Holder {
    // NULL is for depleted items; fungible tokens not yet implemented     
    enum TokenType{ NULL, NONFUNGIBLE, SEMIFUNGIBLE, FUNGIBLE }
     
    
    // pity indicates whether an item is in the pity pool
    struct LootboxItem {
        TokenType tokenType;
        ERC1155Token token;
        string name;
        uint32 unitWeight;
        bool pity;
    }
    
    struct ERC1155Token {
        address contractAddress;
        uint id;
    }
    
    LootboxItem[] public pool; // list of LootboxItems is the Lootbox pool
    uint public pityNumber = 9; // guaranteed pity roll every this often + 1
    
    // maps id to rate ranges
    // width of range, inclusive. is the total weight (i.e. unit weight for NFTs, unit weight * qty for SFTs)
    // open function generates a random int and checks which range it falls in
    mapping(uint => uint32[2]) private normalRates;
    mapping(uint => uint32[2]) private pityRates;
    
    mapping(address => uint) public pityCounter; // counts rolls to pity for each lootbox opening address
     
    // random integer between 1 and rangeEnd, inclusive
    function _fakeRandint(uint rangeEnd) private view returns (uint randint_) {
        randint_ = (uint(keccak256(abi.encodePacked(block.timestamp, block.difficulty))) % rangeEnd) + 1;
    }
    
    // end of normalRates ranges
    function _rangeEnd() private view returns (uint rangeEnd_) {
        if (pool.length == 0) return 0;
        for (uint i=pool.length-1; i>=0; i--) {
            if (i==0 && pool[0].tokenType == TokenType.NULL) return 0;
            if (pool[i].tokenType == TokenType.NULL) continue;
            rangeEnd_ = normalRates[i][1];
            break;
        }
    }
    
    // end of pityRates ranges
    function _pityRangeEnd() private view returns (uint rangeEnd_) {
        if (pool.length == 0) return 0;
        for (uint i=pool.length-1; i>=0; i--) {
            if (i==0 && pool[0].tokenType == TokenType.NULL) return 0;
            if (i==0 && !pool[0].pity) return 0;
            if (pool[i].tokenType == TokenType.NULL) continue;
            if (!pool[i].pity) continue;
            rangeEnd_ = pityRates[i][1];
            break;
        }
    }
    
    function addNft(string memory _name, uint32 _weight, bool _pity, address _tokenContract, uint _tokenId) public {
        
        ERC1155 tokenContract = ERC1155(_tokenContract);
        require(tokenContract.balanceOf(msg.sender, _tokenId)>0);
        tokenContract.safeTransferFrom(msg.sender, address(this), _tokenId, 1, "");
        
        uint32 rangeEnd = uint32(_rangeEnd()+1);
        uint32 pityRangeEnd = uint32(_pityRangeEnd()+1);
        
        ERC1155Token memory tokenData = ERC1155Token({contractAddress: _tokenContract, id: _tokenId});
        LootboxItem memory item = LootboxItem({tokenType: TokenType.NONFUNGIBLE, token: tokenData, name: _name, unitWeight: _weight, pity: _pity});
        
        pool.push(item);
        normalRates[pool.length-1] = [rangeEnd, rangeEnd+_weight-1];
        
        if (_pity) {
            pityRates[pool.length-1] = [pityRangeEnd, pityRangeEnd+_weight-1];
        }
    }
    
    // added item not in pity pool by default
    function addNft(string memory _name, uint32 _weight, address _tokenContract, uint _tokenId) public {
        addNft(_name, _weight, false, _tokenContract, _tokenId);
    }
    
    function addSft(string memory _name, uint32 _weight, uint32 _qty, bool _pity, address _tokenContract, uint _tokenId) public {
        
        ERC1155 tokenContract = ERC1155(_tokenContract);
        require(tokenContract.balanceOf(msg.sender, _tokenId)>0);
        tokenContract.safeTransferFrom(msg.sender, address(this), _tokenId, _qty, "");
        
        uint32 rangeEnd = uint32(_rangeEnd()+1);
        uint32 pityRangeEnd = uint32(_pityRangeEnd()+1);
        
        ERC1155Token memory tokenData = ERC1155Token({contractAddress: _tokenContract, id: _tokenId});
        LootboxItem memory item = LootboxItem({tokenType: TokenType.SEMIFUNGIBLE, token: tokenData, name: _name, unitWeight: _weight, pity: _pity});
        
        pool.push(item);
        normalRates[pool.length-1] = [rangeEnd, rangeEnd+(_weight*_qty)-1];
        
        
        
        if (_pity) {
            pityRates[pool.length-1] = [pityRangeEnd, pityRangeEnd+(_weight*_qty)-1];
        }
    }
    
    // added item not in pity pool by default
    function addSft(string memory _name, uint32 _weight, uint32 _qty, address _tokenContract, uint _tokenId) public {
        addSft(_name, _weight, _qty, false, _tokenContract, _tokenId);
    }
    
    function _removeItem(uint _index) private {
        LootboxItem storage toRemove = pool[_index];
        
        // change ranges of all other items first because unitWeight may be deleted
        if (pool.length>0 && _index<pool.length-1) { // if removed item is not the last item
            for (uint i=_index+1; i<pool.length; i++) {
                if (pool[i].tokenType == TokenType.NULL) continue;
                normalRates[i][0] -= toRemove.unitWeight;
                normalRates[i][1] -= toRemove.unitWeight;
                
                if (pool[i].pity) {
                    pityRates[i][0] -= toRemove.unitWeight;
                    pityRates[i][1] -= toRemove.unitWeight;
                }
            }
        }

        // remove relevant item
        if (toRemove.tokenType == TokenType.SEMIFUNGIBLE) { // remove 1 unit if more is left
            if (normalRates[_index][1] >= normalRates[_index][0] + toRemove.unitWeight) {
                normalRates[_index][1] -= toRemove.unitWeight;
                if (toRemove.pity) pityRates[_index][1] -= toRemove.unitWeight;
            } else { // when item is completely depleted
                pool[_index].tokenType = TokenType.NULL;
            }
        } else if (toRemove.tokenType == TokenType.NONFUNGIBLE) {
           pool[_index].tokenType = TokenType.NULL;
        } else revert("Trying to remove null item");
    }
    
    function _open() private returns (LootboxItem memory item_) {
        uint rangeEnd = _rangeEnd();
        if (rangeEnd == 0) revert("Box empty");
        uint32 randIndex = uint32(_fakeRandint(rangeEnd));
        for (uint i=0; i<pool.length; i++) {
            if (pool[i].tokenType == TokenType.NULL) continue;
            if (randIndex <= normalRates[i][1]) {
                item_ = pool[i];
                ERC1155 tokenContract = ERC1155(item_.token.contractAddress);
                tokenContract.safeTransferFrom(address(this), msg.sender, item_.token.id, 1, "");
                _removeItem(i);
                break;
            }
        }
    }
    
    function _pityOpen() private returns (LootboxItem memory item_) {
        uint rangeEnd = _pityRangeEnd();
        if (rangeEnd == 0) revert("Pity pool empty");
        uint32 randIndex = uint32(_fakeRandint(rangeEnd));
        for (uint i=0; i<pool.length; i++) {
            if (pool[i].tokenType == TokenType.NULL) continue;
            if (!pool[i].pity) continue;
            if (randIndex <= pityRates[i][1]) {
                item_ = pool[i];
                ERC1155 tokenContract = ERC1155(item_.token.contractAddress);
                tokenContract.safeTransferFrom(address(this), msg.sender, item_.token.id, 1, "");
                _removeItem(i);
                break;
            }
        }
    }
    
    function open() public returns (LootboxItem memory item_) {
        if (pityCounter[msg.sender] >= pityNumber) { // pity roll
            pityCounter[msg.sender] = 0;
            // if pity pool empty, draws from normal pool
            if (_pityRangeEnd() != 0) {
                item_ = _pityOpen();
            } else {
                item_ = _open();
            }
        } else { // normal roll
            pityCounter[msg.sender] += 1;
            item_ = _open();
        }
    }

 }