using System;
using System.IO;
using System.Linq;
using System.Collections.Generic;

namespace Speedometer {
    class Program {
    	static string DirPath = @"testFolder";
    	static int CycleNum = 10;

        static void Main(string[] args) {
        	for (int i = 0, len = args.Length; i < len; i++) {
        		var arg = args[i];
        		var argLen = arg.Length;
        		if (arg == "--") {
        			break;
        		}

        		arg = arg.TrimStart('-');
        		if (argLen == arg.Length) {
        			break;
        		}

        		var flag = arg;
        		switch (flag) {
        			case "help":
        			case "h":
        				Console.WriteLine("speedometer [-h] [-d dir] [-cycles num]");
        				return;
        			case "dir":
        			case "d":
        				i++;
        				if (i >= len) {
        					Console.Error.WriteLine($"Expected -{flag} argument.");
        					Environment.Exit(1);
        					return;
        				}
        				DirPath = args[i];
        				continue;
        			case "cycles":
        			case "c":
        				i++;
        				if (i >= len) {
        					Console.Error.WriteLine($"Expected -{flag} argument.");
        					Environment.Exit(1);
        					return;
        				}
        				if (!Int32.TryParse(args[i], out CycleNum)) {
        					Console.Error.WriteLine($"Cannot parse -{flag} argument.");
        					Environment.Exit(1);
        					return;
        				}
        			continue;
        			default:
        				Console.Error.WriteLine($"Unknown option {flag}");
        				Environment.Exit(1);
        				return;
        		}
        	}
            double creationTime = 0;
            // Creating and filling the directory.
            if (!Directory.Exists(DirPath)) {
            	try {
        			Directory.CreateDirectory(DirPath);
        		}
        		catch(DirectoryNotFoundException dirEx) {
            		Console.WriteLine("An error occured: " + dirEx.Message);
					throw new DirectoryNotFoundException("Wrong folder path");
            	}
        		catch(IOException IOEx) {
                	Console.WriteLine("An error occured: " + IOEx.Message);
                	throw new IOException("Specified path is a file");
            	}
            	finally {
    				Environment.Exit(1);
				}
        	}
        	Console.WriteLine($"Directory was made sucessefully!");

            if (IsDirectoryEmpty(DirPath)) {
                creationTime = fillFolder(DirPath);
        	}

            DirectoryInfo di = new DirectoryInfo(DirPath);
            long bytesNum = 0;
            double overallTime = 0;
            var time1 = DateTime.Now;
            FileInfo[] df = di.GetFiles();
            Random rnd = new Random();
           	// int[] seen;
            for (int i = 0; i < CycleNum; i++) {
            	//getting the info about the random file
                string randomFile = GetRandomFile(ref df, ref rnd);
                FileInfo fi = new FileInfo(randomFile);
                bytesNum += fi.Length;

                //calculating the time required to read this file
                var t1 = DateTime.Now;
                File.ReadAllText(randomFile);
                var t2 = DateTime.Now;
                TimeSpan sp = t2 - t1;
                overallTime += sp.TotalSeconds;
            }
            var time2 = DateTime.Now;
            TimeSpan span = time2 - time1;
            double cycleTime = span.TotalSeconds;

            ShowResults(overallTime, cycleTime, bytesNum, DirPath, creationTime);
        }
        static void ShowResults(double overallTime, double cycleTime, long bytesNum, string fp, double creationTime) {
        	Console.WriteLine("Sys name: " + Environment.MachineName);
        	Console.WriteLine("Folder path: " + fp);
        	if (creationTime != 0)
        		Console.WriteLine("Time taken to create the directory: " + creationTime);
        	else
        		Console.WriteLine("The directory has already existed");
        	Console.WriteLine("Number of bytes in read files: " + bytesNum);
        	Console.WriteLine("Time spent to process the cycle: " + cycleTime);
        	Console.WriteLine("Speed of reading files in byte/sec: " + (bytesNum/overallTime));
        }
        static string GetRandomFile(ref FileInfo[] df, ref Random rnd) {
        	int i = rnd.Next(0, df.Length);
        	return df[i].ToString();
        }
        static bool IsDirectoryEmpty(string fp) {
            return !Directory.EnumerateFileSystemEntries(fp).Any();
        }
        static double fillFolder(string fp) {
            var orig = fp;
            var data = new byte[5 * 1024 * 1024];
            var t1 = DateTime.Now;
            for (var i = 0; i < 1000; i++) {
                fp = orig + "/File" + i;
                File.WriteAllBytes(fp, data);
            }
            var t2 = DateTime.Now;
            TimeSpan sp = t2 - t1;
            return sp.TotalSeconds;
        }
    }
}