// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.8.0;

import "./IERC1155.sol";
import "./IERC1155MetadataURI.sol";
import "./IERC1155Receiver.sol";
import "../../utils/Context.sol";
import "../../introspection/ERC165.sol";
import "../../math/SafeMath.sol";
import "../../utils/Address.sol";

contract ERC1155 is Context, ERC165, IERC1155, IERC1155MetadataURI {
using Address for address;

// Mapping from token ID to account balances
mapping(uint256 => mapping(address => uint256)) private _balances;

// Mapping from account to operator approvals
mapping(address => mapping(address => bool)) private _operatorApprovals;

// Used as the URI for all token types by relying on ID substitution, e.g. https://token-cdn-domain/{id}.json
string private _uri;

/**
 * @dev See {_setURI}.
 */
constructor(string memory uri_) {
    _setURI(uri_);
}

function supportsInterface(bytes4 interfaceId) public view virtual override(ERC165, IERC165) returns (bool) {
    return
        interfaceId == type(IERC1155).interfaceId ||
        interfaceId == type(IERC1155MetadataURI).interfaceId ||
        super.supportsInterface(interfaceId);
}


function uri(uint256) public view virtual override returns (string memory) {
    return _uri;
}


function balanceOf(address account, uint256 id) public view virtual override returns (uint256) {
    require(account != address(0), "ERC1155: address zero is not a valid owner");
    return _balances[id][account];
}


function balanceOfBatch(address[] memory accounts, uint256[] memory ids)
    public
    view
    virtual
    override
    returns (uint256[] memory)
{
    require(accounts.length == ids.length, "ERC1155: accounts and ids length mismatch");

    uint256[] memory batchBalances = new uint256[](accounts.length);

    for (uint256 i = 0; i < accounts.length; ++i) {
        batchBalances[i] = balanceOf(accounts[i], ids[i]);
    }

    return batchBalances;
}


function setApprovalForAll(address operator, bool approved) public virtual override {
    _setApprovalForAll(_msgSender(), operator, approved);
}


function isApprovedForAll(address account, address operator) public view virtual override returns (bool) {
    return _operatorApprovals[account][operator];
}


function safeTransferFrom(
    address from,
    address to,
    uint256 id,
    uint256 amount,
    bytes memory data
) public virtual override {
    require(
        from == _msgSender() || isApprovedForAll(from, _msgSender()),
        "ERC1155: caller is not owner nor approved"
    );
    _safeTransferFrom(from, to, id, amount, data);
}


function safeBatchTransferFrom(
    address from,
    address to,
    uint256[] memory ids,
    uint256[] memory amounts,
    bytes memory data
) public virtual override {
    require(
        from == _msgSender() || isApprovedForAll(from, _msgSender()),
        "ERC1155: transfer caller is not owner nor approved"
    );
    _safeBatchTransferFrom(from, to, ids, amounts, data);
}


function _safeTransferFrom(
    address from,
    address to,
    uint256 id,
    uint256 amount,
    bytes memory data
) internal virtual {
    require(to != address(0), "ERC1155: transfer to the zero address");

    address operator = _msgSender();
    uint256[] memory ids = _asSingletonArray(id);
    uint256[] memory amounts = _asSingletonArray(amount);

    _beforeTokenTransfer(operator, from, to, ids, amounts, data);

    uint256 fromBalance = _balances[id][from];
    require(fromBalance >= amount, "ERC1155: insufficient balance for transfer");
     {
        _balances[id][from] = fromBalance - amount;
    }
    _balances[id][to] += amount;

    emit TransferSingle(operator, from, to, id, amount);

    _afterTokenTransfer(operator, from, to, ids, amounts, data);

    _doSafeTransferAcceptanceCheck(operator, from, to, id, amount, data);
}


function _safeBatchTransferFrom(
    address from,
    address to,
    uint256[] memory ids,
    uint256[] memory amounts,
    bytes memory data
) internal virtual {
    require(ids.length == amounts.length, "ERC1155: ids and amounts length mismatch");
    require(to != address(0), "ERC1155: transfer to the zero address");

    address operator = _msgSender();

    _beforeTokenTransfer(operator, from, to, ids, amounts, data);

    for (uint256 i = 0; i < ids.length; ++i) {
        uint256 id = ids[i];
        uint256 amount = amounts[i];

        uint256 fromBalance = _balances[id][from];
        require(fromBalance >= amount, "ERC1155: insufficient balance for transfer");
         {
            _balances[id][from] = fromBalance - amount;
        }
        _balances[id][to] += amount;
    }

    emit TransferBatch(operator, from, to, ids, amounts);

    _afterTokenTransfer(operator, from, to, ids, amounts, data);

    _doSafeBatchTransferAcceptanceCheck(operator, from, to, ids, amounts, data);
}


function _setURI(string memory newuri) internal virtual {
    _uri = newuri;
}


function _mint(
    address to,
    uint256 id,
    uint256 amount,
    bytes memory data
) internal virtual {
    require(to != address(0), "ERC1155: mint to the zero address");

    address operator = _msgSender();
    uint256[] memory ids = _asSingletonArray(id);
    uint256[] memory amounts = _asSingletonArray(amount);

    _beforeTokenTransfer(operator, address(0), to, ids, amounts, data);

    _balances[id][to] += amount;
    emit TransferSingle(operator, address(0), to, id, amount);

    _afterTokenTransfer(operator, address(0), to, ids, amounts, data);

    _doSafeTransferAcceptanceCheck(operator, address(0), to, id, amount, data);
}


function _mintBatch(
    address to,
    uint256[] memory ids,
    uint256[] memory amounts,
    bytes memory data
) internal virtual {
    require(to != address(0), "ERC1155: mint to the zero address");
    require(ids.length == amounts.length, "ERC1155: ids and amounts length mismatch");

    address operator = _msgSender();

    _beforeTokenTransfer(operator, address(0), to, ids, amounts, data);

    for (uint256 i = 0; i < ids.length; i++) {
        _balances[ids[i]][to] += amounts[i];
    }

    emit TransferBatch(operator, address(0), to, ids, amounts);

    _afterTokenTransfer(operator, address(0), to, ids, amounts, data);

    _doSafeBatchTransferAcceptanceCheck(operator, address(0), to, ids, amounts, data);
}


function _burn(
    address from,
    uint256 id,
    uint256 amount
) internal virtual {
    require(from != address(0), "ERC1155: burn from the zero address");

    address operator = _msgSender();
    uint256[] memory ids = _asSingletonArray(id);
    uint256[] memory amounts = _asSingletonArray(amount);

    _beforeTokenTransfer(operator, from, address(0), ids, amounts, "");

    uint256 fromBalance = _balances[id][from];
    require(fromBalance >= amount, "ERC1155: burn amount exceeds balance");
     {
        _balances[id][from] = fromBalance - amount;
    }

    emit TransferSingle(operator, from, address(0), id, amount);

    _afterTokenTransfer(operator, from, address(0), ids, amounts, "");
}


function _burnBatch(
    address from,
    uint256[] memory ids,
    uint256[] memory amounts
) internal virtual {
    require(from != address(0), "ERC1155: burn from the zero address");
    require(ids.length == amounts.length, "ERC1155: ids and amounts length mismatch");

    address operator = _msgSender();

    _beforeTokenTransfer(operator, from, address(0), ids, amounts, "");

    for (uint256 i = 0; i < ids.length; i++) {
        uint256 id = ids[i];
        uint256 amount = amounts[i];

        uint256 fromBalance = _balances[id][from];
        require(fromBalance >= amount, "ERC1155: burn amount exceeds balance");
         {
            _balances[id][from] = fromBalance - amount;
        }
    }

    emit TransferBatch(operator, from, address(0), ids, amounts);

    _afterTokenTransfer(operator, from, address(0), ids, amounts, "");
}


function _setApprovalForAll(
    address owner,
    address operator,
    bool approved
) internal virtual {
    require(owner != operator, "ERC1155: setting approval status for self");
    _operatorApprovals[owner][operator] = approved;
    emit ApprovalForAll(owner, operator, approved);
}

function _beforeTokenTransfer(
    address operator,
    address from,
    address to,
    uint256[] memory ids,
    uint256[] memory amounts,
    bytes memory data
) internal virtual {}


function _afterTokenTransfer(
    address operator,
    address from,
    address to,
    uint256[] memory ids,
    uint256[] memory amounts,
    bytes memory data
) internal virtual {}

function _doSafeTransferAcceptanceCheck(
    address operator,
    address from,
    address to,
    uint256 id,
    uint256 amount,
    bytes memory data
) private {
    if (to.isContract()) {
        try IERC1155Receiver(to).onERC1155Received(operator, from, id, amount, data) returns (bytes4 response) {
            if (response != IERC1155Receiver.onERC1155Received.selector) {
                revert("ERC1155: ERC1155Receiver rejected tokens");
            }
        } catch Error(string memory reason) {
            revert(reason);
        } catch {
            revert("ERC1155: transfer to non ERC1155Receiver implementer");
        }
    }
}

function _doSafeBatchTransferAcceptanceCheck(
    address operator,
    address from,
    address to,
    uint256[] memory ids,
    uint256[] memory amounts,
    bytes memory data
) private {
    if (to.isContract()) {
        try IERC1155Receiver(to).onERC1155BatchReceived(operator, from, ids, amounts, data) returns (
            bytes4 response
        ) {
            if (response != IERC1155Receiver.onERC1155BatchReceived.selector) {
                revert("ERC1155: ERC1155Receiver rejected tokens");
            }
        } catch Error(string memory reason) {
            revert(reason);
        } catch {
            revert("ERC1155: transfer to non ERC1155Receiver implementer");
        }
    }
}

function _asSingletonArray(uint256 element) private pure returns (uint256[] memory) {
    uint256[] memory array = new uint256[](1);
    array[0] = element;

    return array;
}

}