using System;
using System.Collections.Generic;
using System.Text;
using System.IO;
using System.Collections;

namespace TextFileStats
{
    class Program
    {
        static void Main(string[] args)
        {
            string file = "placeholder";
            bool isValid = false;

            if (args.Length > 0)
            {
                if (File.Exists(args[0]))
                {
                    file = args[0];
                    isValid = true;
                }
            }

            while (!isValid)
            {
                Console.Write("Enter the path to the file: ");
                file = Console.ReadLine();

                if (!File.Exists(file))
                {
                    Console.WriteLine("The specified file \"{0}\" does not exist!", file);
                    Console.WriteLine("Press [ ENTER ] to re-enter");
                    Console.ReadLine();
                }
                else
                {
                    isValid = true;
                }

                Console.Clear();
            }

            Dictionary<char, int> characters = new Dictionary<char, int>();
            Dictionary<string, int> words = new Dictionary<string, int>();

            string[] lines = File.ReadAllLines(file);

            Console.WriteLine("Read file {0} with {1} lines of text", file, lines.Length);

            foreach (string str in lines)
            {
                foreach (char ch in str)
                {
                    if (characters.ContainsKey(ch))
                    {
                        characters[ch] += 1;
                    }
                    else
                    {
                        characters.Add(ch, 1);
                    }
                }

                string[] wordArray = str.Split(' ');

                foreach (string curStr in wordArray)
                {
                    if (words.ContainsKey(curStr))
                    {
                        words[curStr] += 1;
                    }
                    else
                    {
                        words.Add(curStr, 1);
                    }
                }
            }

            Console.WriteLine();

            Console.WriteLine("Unique Words Read: {0}", words.Count);
            Console.WriteLine("Unique Characters Read: {0}", characters.Count);
            Console.WriteLine("Please wait... Generating statistics...");
            Console.WriteLine();

            TextWriter tw = new StreamWriter("statistics.txt");

            tw.WriteLine("-- Frequency Statistics Start --");
            tw.WriteLine("-- Word Count Statistics Start --");
            tw.WriteLine();
            foreach (KeyValuePair<string,int> entry in words)
            {
                tw.WriteLine(entry.Key + " = " + entry.Value);
            }

            tw.WriteLine();
            tw.WriteLine("-- Word Count Statistics End --");
            tw.WriteLine("-- Character Count Statistics Start --");
            tw.WriteLine();

            foreach (KeyValuePair<char,int> entry in characters)
            {
                tw.WriteLine(entry.Key + " = " + entry.Value);
            }

            tw.WriteLine();
            tw.WriteLine("-- Character Count Statistics End --");
            tw.WriteLine("-- Frequency Statistics End --");

            tw.Close();

            Console.WriteLine("Detailed statistics generated at file location: \n" +
                Directory.GetCurrentDirectory() + "\\statistics.txt");

            Console.WriteLine();
            Console.WriteLine("Press [ ENTER ] to exit");
            Console.ReadLine();
        }
    }
}