// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;


// Define the contract
contract BlockchainBasedSecurity {
    // State variables
    address public admin; // Address of the admin
    address[] public trustedControllers; // List of trusted controllers
    string[] private messages; // List of messages sent by controllers
    mapping(address => bool) private isTrustedController; // Mapping to check if an address is a trusted controller
    mapping(address => bool) private blacklist; // Mapping to check if an address is blacklisted


    // Events
    event ControllerRegistered(address indexed controller); // Event emitted when a controller is registered
    event ControllerDeleted(address indexed controller); // Event emitted when a controller is deleted
    event MessageSent(address indexed sender, string message); // Event emitted when a message is sent
    event Blacklisted(address indexed controller); // Event emitted when a controller is blacklisted


    // Constructor to set the admin as the contract deployer
    constructor() {
        admin = msg.sender;
    }


    // Modifier to allow only the admin to execute certain functions
    modifier onlyAdmin() {
        require(msg.sender == admin, "Only Admin is Allowed to Add new Controllers");
        _;
    }


    // Modifier to allow only trusted controllers to execute certain functions
    modifier onlyTrustedController() {
        require(isTrustedController[msg.sender], "Only Trusted Controllers can send messages");
        _;
    }


    // Function to register a new controller, only callable by the admin
    function registerController(address id) public onlyAdmin {
        require(id != address(0), "Invalid address"); // Ensure the address is valid
        require(!isTrustedController[id], "Controller is already registered"); // Ensure the controller is not already registered
        trustedControllers.push(id); // Add the controller to the list
        isTrustedController[id] = true; // Mark the controller as trusted
        emit ControllerRegistered(id); // Emit the ControllerRegistered event
    }


    // Function to remove a specific controller, only callable by the admin
    function removeSpecificController(address controller) public onlyAdmin {
        require(isTrustedController[controller], "Controller is not registered"); // Ensure the controller is registered
        for (uint i = 0; i < trustedControllers.length; i++) { // Loop through the list of controllers
            if (trustedControllers[i] == controller) { // Find the controller to remove
                trustedControllers[i] = trustedControllers[trustedControllers.length - 1]; // Replace it with the last controller
                trustedControllers.pop(); // Remove the last controller
                break; // Exit the loop
            }
        }
        isTrustedController[controller] = false; // Mark the controller as not trusted
        emit ControllerDeleted(controller); // Emit the ControllerDeleted event
    }
}