// SPDX-License-Identifier: MIT
// Klaytn Contract Library v1.0.0 (KIP/token/KIP37/extensions/KIP37Supply.sol)
// Based on OpenZeppelin Contracts v4.5.0 (token/ERC1155/extensions/ERC1155Supply.sol)
// https://github.com/OpenZeppelin/openzeppelin-contracts/releases/tag/v4.5.0

pragma solidity ^0.8.0;

import "../KIP37.sol";

/**
 * @dev Extension of KIP37 that adds tracking of total supply per id.
 *
 * Useful for scenarios where Fungible and Non-fungible tokens have to be
 * clearly identified. Note: While a totalSupply of 1 might mean the
 * corresponding is an NFT, there are no guarantees in this contract that no other token with the
 * same id are not going to be minted. Additional supply capping logic should be used for this.
 */
abstract contract KIP37Supply is KIP37 {
    mapping(uint256 => uint256) private _totalSupply;

    /**
     * @dev Total amount of tokens in with a given id.
     */
    function totalSupply(uint256 id) public view virtual returns (uint256) {
        return _totalSupply[id];
    }

    /**
     * @dev Indicates whether any token exist with a given id, or not.
     */
    function exists(uint256 id) public view virtual returns (bool) {
        return KIP37Supply.totalSupply(id) > 0;
    }

    /**
     * @dev See {KIP37-_beforeTokenTransfer}.
     */
    function _beforeTokenTransfer(
        address operator,
        address from,
        address to,
        uint256[] memory ids,
        uint256[] memory amounts,
        bytes memory data
    ) internal virtual override {
        super._beforeTokenTransfer(operator, from, to, ids, amounts, data);

        if (from == address(0)) {
            for (uint256 i = 0; i < ids.length; ++i) {
                _totalSupply[ids[i]] += amounts[i];
            }
        }

        if (to == address(0)) {
            for (uint256 i = 0; i < ids.length; ++i) {
                uint256 id = ids[i];
                uint256 amount = amounts[i];
                uint256 supply = _totalSupply[id];
                require(supply >= amount, "KIP37: burn amount exceeds totalSupply");
                unchecked {
                    _totalSupply[id] = supply - amount;
                }
            }
        }
    }
}