using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.IO;
using System.Diagnostics;

namespace IP_Camera_Cleanup
{
    class Program
    {
        public enum ExitCodes
        {
            Success,
            InvalidArgument = -1,
            FailedRate = -2
        }
        public static IEnumerable<string> Exemptions;


        static bool silent = false;
        static void Main(string[] args)
        {
            string folderPath = "";
            string fileTypeString = "*.mp4";
            int daysOld = 30;

            if (args.Contains("\\f")) // Specify the folder path
            {
                int flagIndex = Array.IndexOf(args, "\\f");
                if(flagIndex + 1 < args.Length)
                {
                    folderPath = args[flagIndex + 1];
                }
                else
                {
                    throw new ArgumentException("Missing or invalid source folder parameter.");
                }
                
            }
            if (args.Where((s) => s == "\\s").Count() > 0)
            {
                // run in silent mode
                silent = true;
            }
            if (args.Contains("\\d")) // specify the age of the file in days
            {
                int flagIndex = Array.IndexOf(args, "\\d");
                if (flagIndex + 1 < args.Length && !args[flagIndex +1].StartsWith("\\"))
                {
                    daysOld = int.Parse(args[flagIndex + 1]);
                }
                else
                {
                    throw new ArgumentException("Missing or invalid file age parameter.");
                }
            }
            if (args.Contains("\\t")) // specify the file type to search for
            {
                int flagIndex = Array.IndexOf(args, "\\t");
                if (flagIndex + 1 < args.Length && !args[flagIndex + 1].StartsWith("\\") && args[flagIndex + 1].StartsWith("*."))
                {
                    fileTypeString = args[flagIndex + 1];
                }
                else
                {
                    throw new ArgumentException("Missing or invalid file type parameter.");
                }
            }
            //else
            //{
            //    Console.WriteLine("Invalid option. Valid options are: \'\\f\' {folder path}");
            //    Console.WriteLine("Enter a folder path or press \'q\' to exit");
            //    folderPath = Console.ReadLine();
            //}
            if (folderPath == "q")
            {
                Environment.ExitCode = (int)ExitCodes.InvalidArgument;
            }
            else if(folderPath != "")
            {
                using (FileStream fs = File.Open(".\\Exemptions.lst", FileMode.OpenOrCreate, FileAccess.ReadWrite))
                {
                    byte[] exemptionsBytes = new byte[fs.Length];
                    fs.Read(exemptionsBytes, 0, exemptionsBytes.Length);
                    Console.WriteLine("Exemptions file Loaded");
                    Exemptions = Encoding.Unicode.GetString(exemptionsBytes, 0, exemptionsBytes.Length)
                        .Replace("\r\n", "\n").Split('\n').Where(x => x != "");
                }
                // Hard-coded exemptions, to prevent bad behaviour
                Exemptions = Exemptions.Concat(new List<string> {"System Volume Information", "$RECYCLE.BIN", "C:\\Windows", "hiberfil.sys", "pagefile.sys", "swapfile.sys"});

                foreach (var item in Exemptions)
                {
                    Console.WriteLine(item);
                }

                Result result = DeleteAllFiles(folderPath, daysOld, fileTypeString);
                using (EventLog eventLog = new EventLog("Application"))
                {
                    eventLog.Source = "Application";
                    if (result.Percentage < 0.75f) // Exit with an error code if more than 25% of files failed
                    {
                        eventLog.WriteEntry(string.Format("File Cleanup failed to delete {0}% ({1}/{2}) files.", (int)((1f-result.Percentage)*100), result.Failed ,result.Count), EventLogEntryType.Warning);
                        Environment.Exit((int)ExitCodes.FailedRate);
                    }
                    else
                    {
                        eventLog.WriteEntry(string.Format("File Cleanup successfully deleted {0}/{1} files ({2}%)",result.Count-result.Failed,result.Count,(int)(result.Percentage * 100)), EventLogEntryType.Information);
                        Environment.Exit(0);
                    }
                    
                }
                
            }
        }
        static Result DeleteAllFiles(string folderPath, int daysOld, string fileTypeString)
        {
            // Cleaner option for enumerating files
            if (silent)
            {
                long count = 0; // Calling Count() on validFiles would force enumeration of all values. Light-weight method is to just record how many we've iterated through. We're in silent so logging the total files found can be retrospective
                long failiures = 0;

                var rootDirs = Directory.EnumerateDirectories(folderPath, "*", SearchOption.TopDirectoryOnly).Where(x => Exemptions.All(e => !x.Contains(e)));

                foreach (var dir in rootDirs)
                {
                    try
                    {
                        IEnumerable<string> files = Directory.EnumerateFiles(dir, fileTypeString, SearchOption.AllDirectories).Where(x => IsDateOlder(x, daysOld));
                        foreach (var file in files)
                        {
                            count++;
                            try
                            {
                                File.Delete(file);
                            }
                            catch
                            {
                                failiures++;
                            }
                        }
                    }
                    catch (Exception e)
                    {
                        using (EventLog eventLog = new EventLog("Application"))
                        {
                            eventLog.Source = "Application";
                            eventLog.WriteEntry("Failed to enumerate files: " + e, EventLogEntryType.Error, 2222, 1);
                        }
                    }
                }
                if (failiures == 0)
                {
                    return new Result() { Count = count, Failed = 0, Percentage = 1f };
                }
                else
                {
                    return new Result() { Count = count, Failed = failiures, Percentage = 1 - failiures / (float)count };
                }
            }
            else
            {
                // Old implementation is left here
                List<string> validFiles = FindFiles(folderPath).Where((s) => IsDateOlder(s, daysOld)).ToList();
                Console.WriteLine("Deleting {0} files...", validFiles.Count());
                int completeSize = validFiles.Count().ToString().Length;
                int position = 0;
                int failiures = 0;
                foreach (string file in validFiles)
                {
                    int Cursor_y = Console.CursorTop;
                    try
                    {
                        string line = new string(' ', completeSize - position.ToString().Length) + position;
                        Console.Write(line);
                        Console.SetCursorPosition(0, Cursor_y);
                        File.Delete(file);
                        position++;
                    }
                    catch (Exception e)
                    {
                        Console.WriteLine("Could not delete {0}: {1}", file, e);
                        position++;
                        failiures++;
                    }
                }
                if (failiures == 0)
                {
                    return new Result() { Count = validFiles.Count, Failed = failiures, Percentage = 1f };
                }
                else
                {
                    return new Result() { Count = validFiles.Count, Failed = failiures, Percentage = 0f};
                }
            }

            
        }
        static List<string> FindFiles(string FolderPath)
        {
            List<string> currentFound = new List<string>();
            try
            {
                // Only enumerate files that aren't included in the exemptions
                currentFound.AddRange(Directory.EnumerateFiles(FolderPath, "*.mp4", SearchOption.TopDirectoryOnly)
                    .Where((s) => Exemptions.All((e) => !s.Contains(e)))
                    .ToList());
                foreach (string path in Directory.EnumerateDirectories(FolderPath).Where((s) => Exemptions.All((e) => !s.Contains(e))))
                {
                    currentFound.AddRange(FindFiles(path));
                }
            }
            catch (Exception e)
            {
                using (EventLog eventLog = new EventLog("Application"))
                {
                    eventLog.Source = "Application";
                    eventLog.WriteEntry("Failed to enumerate files in " + FolderPath, EventLogEntryType.Error, 101, 1);
                }
                if (!silent)
                {
                    Console.WriteLine(e);
                }
            }
            
            
            return currentFound;
        }

        static bool IsDateOlder(string fileName, int daysOld)
        {
            try
            {
                if (!Exemptions.Contains(fileName))
                {
                    FileInfo fileInfo = new FileInfo(fileName);
                    return (DateTime.UtcNow.Subtract(fileInfo.LastWriteTimeUtc) > new TimeSpan(daysOld, 0, 0, 0));
                }

            }
            catch { }
            return false;
        }
    }
    class Result
    {
        public float Percentage { get; set; }
        public long Count { get; set; }
        public long Failed { get; set; }
    }
}