MP3 Reader - C# Programming Exercise

// Import the necessary namespaces for file handling
using System;
using System.IO;
using System.Text;

class MP3Reader
{
    // Main method where the program starts
    static void Main(string[] args)
    {
        // Ensure the user provided the correct number of arguments
        if (args.Length != 1)
        {
            Console.WriteLine("Usage: MP3Reader ");
            return;
        }

        string mp3File = args[0];

        // Check if the file exists
        if (!File.Exists(mp3File))
        {
            Console.WriteLine("Error: The file does not exist.");
            return;
        }

        try
        {
            // Open the MP3 file in read-only mode
            using (FileStream fs = new FileStream(mp3File, FileMode.Open, FileAccess.Read))
            {
                // Move to the last 128 bytes where the ID3v1 tag is located
                fs.Seek(-128, SeekOrigin.End);

                // Read the last 128 bytes into a buffer
                byte[] tagBuffer = new byte[128];
                fs.Read(tagBuffer, 0, 128);

                // Check if the tag header is "TAG" (ID3v1 header identifier)
                string tagHeader = Encoding.ASCII.GetString(tagBuffer, 0, 3);
                if (tagHeader != "TAG")
                {
                    Console.WriteLine("No ID3v1 tag found in this MP3 file.");
                    return;
                }

                // Extract the information from the ID3v1 tag
                string title = TrimString(Encoding.ASCII.GetString(tagBuffer, 3, 30));
                string artist = TrimString(Encoding.ASCII.GetString(tagBuffer, 33, 30));
                string album = TrimString(Encoding.ASCII.GetString(tagBuffer, 63, 30));
                string year = TrimString(Encoding.ASCII.GetString(tagBuffer, 93, 4));
                string comment = TrimString(Encoding.ASCII.GetString(tagBuffer, 97, 30));

                // Genre is stored as a byte, so we read it and map it to a genre
                byte genreByte = tagBuffer[127];
                string genre = GetGenreName(genreByte);

                // Display the extracted information
                Console.WriteLine("ID3v1 Tag Information:");
                Console.WriteLine($"Title: {title}");
                Console.WriteLine($"Artist: {artist}");
                Console.WriteLine($"Album: {album}");
                Console.WriteLine($"Year: {year}");
                Console.WriteLine($"Comment: {comment}");
                Console.WriteLine($"Genre: {genre}");
            }
        }
        catch (Exception ex)
        {
            Console.WriteLine($"An error occurred: {ex.Message}");
        }
    }

    // Helper function to trim trailing spaces from strings
    static string TrimString(string input)
    {
        return input.TrimEnd('\0', ' ');
    }

    // Helper function to map genre byte to genre name
    static string GetGenreName(byte genreByte)
    {
        // 80 predefined genres from the ID3v1 specification
        string[] genres = new string[]
        {
            "Blues", "Classic Rock", "Country", "Dance", "Disco", "Funk", "Grunge", "Hip-Hop", 
            "Jazz", "Metal", "New Age", "Oldies", "Other", "Pop", "R&B", "Rap", "Reggae", 
            "Rock", "Techno", "Industrial", "Alternative", "Ska", "Death Metal", "Pranks", 
            "Soundtrack", "Euro-Techno", "Pop-Folk", "Pop-Funk", "Fusion", "Trance", "Video", 
            "Rock & Roll", "Hard Rock", "Alternative Rock", "Christian", "Country Rock", 
            "Dance Hall", "Death Metal", "Disco House", "Eurodance", "Groove", "House", 
            "Indie", "Minimal", "Reggaeton", "Techno Trance", "Hardcore", "Dubstep", "Trap", 
            "Ambient", "Chill-out", "House Techno", "Synthwave", "Nu Disco", "Electro", 
            "Future Bass", "Deep House", "Indie Dance", "Funk", "Folk", "Reggae Dub", "Jazz Funk",
            "K-Pop", "J-Pop", "Blues Rock", "Soul", "Acoustic", "Folk Rock", "Gospel", "Pop Rock", 
            "Soul", "Folk", "Punk", "Post Punk", "Ska Punk", "Riot Grrl", "Country Blues", "Blues Rock", 
            "Latin Jazz", "Experimental", "Avant-garde", "Jazzy Funk", "Electropop", "Acid Jazz", 
            "Post-Rock", "Noise", "Jazz Rock", "Math Rock", "Psychedelic Rock", "Pop Punk", 
            "Southern Rock", "Folk Punk", "Indie Pop", "Jazz Blues", "Folk Soul", "Indie R&B", 
            "Blues Soul", "Electro-Rock", "Garage Rock"
        };

        // Return the genre name based on the genre byte
        if (genreByte >= 0 && genreByte < genres.Length)
        {
            return genres[genreByte];
        }
        else
        {
            return "Unknown";
        }
    }
}