diff --git a/cli.js b/cli.js
index cc54c90..c73a89a 100644
--- a/cli.js
+++ b/cli.js
@@ -1,44 +1,13 @@
 #!/usr/bin/env node
-import checkEnvVariables from './src/utils/checkEnvVariables.js';
-import checkInputPath from './src/utils/checkInputPath.js';
+
+import checkEnv from './src/utils/checks/checkEnvVariables.js';
+import checkPath from './src/utils/checks/checkInputPath.js';
 import fetchFiles from './src/utils/fetchFiles.js';
-import validateAudioFiles from './src/services/fileService.js';
-import recognizeAudioFiles from './src/services/musicRecognitionService.js';
-import retrieveMetadata from './src/services/metadataRetrievalService.js';
-
-const { ACOUSTID_API_KEY, SPOTIFY_CLIENT_ID, SPOTIFY_CLIENT_SECRET } = process.env;
-
-async function main() {
-  try {
-    // Check for required environment variables
-    // checkEnvVariables();
-    // Check for required input path
-    const inputPath = process.argv[[2]];
-    checkInputPath(inputPath);
-    // Preferred service can be provided
-    const service = process.argv[[3]] || undefined;
-
-    // Resolve the input path to get array of file paths (handles one or more files)
-    const files = await fetchFiles(inputPath);
-    // Process the resolved paths to confirm and prepare the audio file for metadata recognition
-    const audioFiles = await validateAudioFiles(files);
-    // Recognize the content of the audio file and obtain the corresponding Spotify track ID
-    const audioIds = await recognizeAudioFiles(audioFiles, service);
-    // Fetch the audio metadata from Spotify using the recognized track IDs
-    const audioMetadata = await retrieveMetadata(audioIds, service);
-    console.log(audioMetadata);
-    // Write the fetched metadata into the audio file
-    // const processedAudioFiles = await fileController.writeMetadata(audioMetadata, audioFiles);
-  } catch (e) {
-    console.error('An error occurred inside cli.js:', e);
-    process.exit(1);
-  }
-}
-
-main().catch((error) => {
-  console.error(`Execution error: ${error.message}`);
-  process.exit(1);
-});
+import validateFiles from './src/services/fileService.js';
+import recognizeFiles from './src/services/musicRecognitionService.js';
+import retrieveMetadataService from './src/services/metadata/metadataRetrievalService.js';
+import normalizeMetadataService from './src/services/metadata/normalizers/metadataNormalizerService.js';
+import writeMetadataService from './src/services/metadata/metadataWritingService.js';
 
 process.on('uncaughtException', (error) => {
   console.error('Uncaught Exception:', error);
@@ -49,3 +18,69 @@ process.on('unhandledRejection', (reason, promise) => {
   console.error('Unhandled Rejection at:', promise, 'reason:', reason);
   process.exit(1);
 });
+
+// Check for required environment variables at the start
+checkEnv();
+
+/**
+ * The main function that serves as the entry point for the CLI tool.
+ * @param {string} inputPath - The file system path to the audio files to be processed.
+ * @param {string} [service] - Optional; name of the service to use for audio recognition.
+ */
+async function main(inputPath, service) {
+  // Fetch the paths to audio files. This can handle a directory of files or a single file.
+  // `fetchFiles` resolves the path(s) and returns an array of file paths.
+  const files = await fetchFiles(inputPath);
+
+  // Validate the audio files at provided paths. This step checks their format,
+  // returning a filtered list of valid audio files.
+  const audioFiles = await validateFiles(files);
+
+  // Perform the audio file recognition. This step takes the valid audio files and
+  // uses an audio recognition service to identify each track, associating it with a unique ID.
+  const filesWithIds = await recognizeFiles(audioFiles, service);
+
+  // Retrieve the metadata for the recognized audio files. This involves fetching
+  // data such as titles, artists, albums, etc., based on the previously obtained track IDs.
+  const filesWithMetadata = await retrieveMetadataService(filesWithIds, service);
+
+  // Normalize the fetched metadata. Data normalization involves converting all the
+  // metadata to a standard format or schema, ensuring consistency across all data points.
+  const normalizedMetadata = await normalizeMetadataService(filesWithMetadata, service);
+
+  // Write the normalized metadata into the audio files. This step actually updates each
+  // audio file with the correct metadata, so it's correctly recognized by media players.
+  await writeMetadataService(normalizedMetadata);
+}
+
+/**
+ * Executes the main functionality of the command-line interface.
+ *
+ * This function parses command-line arguments to retrieve the input path and the
+ * optional service argument. It then passes those arguments to the main function for further processing.
+ *
+ * If an error occurs during the execution of the main function or the input path
+ * validation fails, it catches the error and exits the process with a status code of 1.
+ */
+function runCli() {
+  try {
+    // Note: Ensure your argument indices are correct.
+    // If this is run with `npm run analyze -- <path>`, indices should be [[1]] and [[2]]
+    // Validates the input path (second CLI argument)
+    const inputPath = process.argv[[2]];
+    checkPath(inputPath);
+
+    // Optionally selects a service (third CLI argument)
+    const service = process.argv[[3]] || undefined;
+
+    // Invoke the main function with the input path and service
+    main(inputPath, service);
+  } catch (error) {
+    // Log the error message to the console
+    console.error('An error occurred:', error.message);
+    // Terminate the process with an error status code
+    process.exit(1);
+  }
+}
+
+runCli();