organising.sol

// SPDX-License-Identifier: MIT
pragma solidity >= 0.5.0 < 0.9.0;
contract EventContract{
    struct Event{
    address organiser;
    string name;
    uint date;
    uint price;
    uint ticketCount;
    uint ticketRemain;
    }
 mapping(uint=>Event) public events;
 mapping(address=>mapping(uint=>uint)) public tickets;
 uint public nextId;

 function createEvent(string memory name,uint date,uint price,uint ticketCount) external{
     require(date>block.timestamp,"you can organize event for future date");
     require(ticketCount>0,"you can organise only if you create more than 0 tickets");

     events[nextId]=Event(msg.sender,name,date,price,ticketCount,ticketCount);
    nextId++;
    }

    function buyTicket(uint id,uint quantity) external payable{
        require(events[id].date!=0,"no event exist");
        require(events[id].date>block.timestamp,"event has already occured");
        Event storage _event=events[id];
        require(msg.value==(_event.price*quantity),"ether is not enough");
        require(_event.ticketRemain>=quantity,"not enough tickets");
        _event.ticketRemain-=quantity;
        tickets[msg.sender][id]+=quantity;
    }

    function transferTicket(uint id,uint quantity,address to) external{
        require(events[id].date!=0,"no event exist");
        require(events[id].date>block.timestamp,"event has already occured");
        require(tickets[msg.sender][id]>=quantity,"you don't have enough tickets");
        tickets[msg.sender][id]-=quantity;
        tickets[to][id]+=quantity;
    }

}