missing way to run commands and ensuring valid arguments in command so giberish doesnt run

lib/commandLineParser.cpp

@@ -0,0 +1,67 @@
+#include "commandLineParser.h"
+#include <iostream>
+#include <stdexcept> // for std::invalid_argument
+
+//implement hashmap for the code
+CLI::CLI(int argc, char** argv){
+    try{
+        if (arc < 2) {
+            throw std::invalid_argument("Error: No input file provided.\n
+                                         Usage: <program> <input_file>");
+        }
+        //sets program info
+        programName = argv[0];
+        inputFile = argv[1]
+
+        //checks that file has correct file extension
+        if(!(CLI::IsMarkupFile(inputFile))) {
+            throw std::invalid_argument("Error: Invalid file extension. Expected a '.md' (Markdown) file.");
+        }
+        //stores remaining arguments
+        for (int i = 1; i < argc; i++){
+            args.push_back(argv[i]);
+        }
+        }
+    catch (const std::invalid_argument& e) {
+        std::cerr << e.what() << "\n";
+        PrintHelp();
+        std::exit(EXIT_FAILURE);
+    }
+    }
+
+bool CLI::IsMarkupFile(const std::string& filename) {
+    //markdown file extension
+    const std::string requiredExtension = ".md";
+    //checks to see if it can even include extension
+    if (filename.size() <= requiredExtension.size()) {
+        return false;
+    }
+    // Extracts the last N characters of the filename (where N is the length of the required extension)
+    // and checks if they match the required file extension (e.g., ".md").
+    //
+    // Example:
+    //   filename = "notes.md"
+    //   requiredExtension = ".md"
+    //   filename.substr(filename.size() - requiredExtension.size()) == ".md" → true
+    //
+    // Reference: https://en.cppreference.com/w/cpp/string/basic_string/substr
+    return filename.substr(filename.size() - requiredExtension.size()) == requiredExtension;
+}
+
+
+//place to run commands but IDK IF WE SHOULD USE A HASMAP or how we are going to get each method to run
+void CLI::RunCommands(){
+    for (int i = 0; i < args.size(); i++){
+
+    }    
+}
+
+void CLI::PrintHelp() const{
+    std::cout << "Usage:\n"
+              << " " << programName << " <input_file> REQUIRED\n"
+              << "Flags:\n"
+              << " --o, --output <outputFile>, optional output filename\n"
+              << " --w, --watch, enables watchdog\n"
+              << " --s, --stop, stops watchdog\n";
+}
+