public Command parseInput() throws ChatException {
        switch (this.type) {
        case "bye":
            return new ExitCommand();
        case "list":
            return new ListCommand();
        case "help":
            return new HelpCommand();
        case "todo":
            String todoRegex = "^(\\w+)(\\s)(.+)";
            Pattern todoPattern = Pattern.compile(todoRegex);
            Matcher todoMatcher = todoPattern.matcher(input);
            if (todoMatcher.find()) {
                String description = todoMatcher.group(3);
                return new TodoCommand(description);
            } else {
                throw new ChatException("Input does not match expected format: todo <task>");
            }
        case "deadline":
            String deadlineRegex = "^(\\w+) (.+?)\\/by (.+)$";
            Pattern deadlinePattern = Pattern.compile(deadlineRegex);
            Matcher deadlineMatcher = deadlinePattern.matcher(input);
            if (deadlineMatcher.find()) {
                String description = deadlineMatcher.group(2);
                String toTime = deadlineMatcher.group(3);
                return new DeadlineCommand(description, toTime);
            } else {
                throw new ChatException("Input does not match expected format: deadline <task> /by <time>");
            }
        case "event":
            String eventRegex = "^(\\w+) (.+?) \\/from (.+?) \\/to (.+)$";
            Pattern eventPattern = Pattern.compile(eventRegex);
            Matcher eventMatcher = eventPattern.matcher(input);
            if (eventMatcher.find()) {
                String description = eventMatcher.group(2);
                String fromTime = eventMatcher.group(3);
                String toTime = eventMatcher.group(4);
                return new EventCommand(description, fromTime, toTime);
            } else {
                throw new ChatException("Input does not match expected format: event <task> /from <time> /to <time>");
            }
        case "mark":
            String markRegex = "^(\\w+) (\\d+)";
            Pattern markPattern = Pattern.compile(markRegex);
            Matcher markMatcher = markPattern.matcher(input);
            if (markMatcher.find()) {
                String number = markMatcher.group(2);
                return new MarkCommand(number);
            } else {
                throw new ChatException("Input does not match expected format: mark <number>");
            }
        case "unmark":
            String unmarkRegex = "^(\\w+) (\\d+)";
            Pattern unmarkPattern = Pattern.compile(unmarkRegex);
            Matcher unmarkMatcher = unmarkPattern.matcher(input);
            if (unmarkMatcher.find()) {
                String number = unmarkMatcher.group(2);
                return new UnmarkCommand(number);
            } else {
                throw new ChatException("Input does not match expected format: unmark <number>");
            }
        case "delete":
            String deleteRegex = "^(\\w+) (\\d+)";
            Pattern deletePattern = Pattern.compile(deleteRegex);
            Matcher deleteMatcher = deletePattern.matcher(input);
            if (deleteMatcher.find()) {
                String number = deleteMatcher.group(2);
                return new DeleteCommand(number);
            } else {
                throw new ChatException("Input does not match expected format: delete <number>");
            }
        case "find":
            String findRegex = "^(\\w+)(\\s)(.+)";
            Pattern findPattern = Pattern.compile(findRegex);
            Matcher findMatcher = findPattern.matcher(input);
            if (findMatcher.find()) {
                String keyword = findMatcher.group(3);
                return new FindCommand(keyword);
            } else {
                throw new ChatException("Input does not match expected format: find <keyword>");
            }
        default:
            throw new ChatException("Command not found, type help for a list of commands");
        }
    }

    /**
     * The main method that starts the application.
     * It performs initial setup by greeting the user, loading the task list from a file,
     * and then enters a loop to process user commands until an exit command is issued.
     */