using System;
using System.IO;
using System.Linq;
using System.Text;
using System.Collections.Generic;
using System.Reflection;
using AniNIX.Shared;

namespace AniNIX.Crypto {
    public class Workbench {
        public string inputText { get;  private set; }
        public string workSpace { get; private set; }
        public StringBuilder HelpText = new StringBuilder();
        public Dictionary<String,Cipher> SwitchCases = new Dictionary<String,Cipher>();
        // The workbench needs to maintain an instance of each ciphersuite for operation. 
        private List<Cipher> _ciphers = new List<Cipher>();
        // If this is true, we will prevent prompt and filesystem access.
        private bool _isBlind = false;

        /// <summary> 
        /// Read in a cipher either from a filename or from stdin
        /// <summary>
        /// <param name="line">user input</param>
        private void ReadCipher(String[] line) {
            // If a filename's not provided.
            if (line == null || line.Length !=2) {
                Console.WriteLine("Please paste your ciphertext. End your input with a trailing newline.");
                string readLn = Console.ReadLine();
                StringBuilder sb = new StringBuilder();
                //Read lines from stdin until a blank line is given.
                while (readLn != null && !String.IsNullOrWhiteSpace((readLn))) {
                    sb.AppendLine(readLn);
                    readLn=Console.ReadLine();
                }
                // The user's input is the trimmed sum of the lines.
                inputText = sb.ToString().Trim();
            } else { 
                // Try to read the file into the input.
                try { 
                    StringBuilder sb = new StringBuilder();
                    StreamReader fileReader = new StreamReader(line[1]);
                    String lineR = fileReader.ReadLine();
                    while (lineR != null) {
                        sb.AppendLine(lineR);
                        lineR = fileReader.ReadLine();
                    }
                    fileReader.Dispose();
                    fileReader = null;
                    inputText = sb.ToString().Trim();
                    Console.WriteLine(String.Format("Read {0}",line[1]));
                }
                // If there's a problem, input is null.
                catch (Exception e) {
                    Console.Error.WriteLine(e.Message);
                    inputText = null;
                }

            }
            workSpace = inputText;

        }        

        /// <summary>
        /// Create a new workbench from input.
        /// </summary> 
        /// <param name="args">the arguments provided for execution</param>
        public Workbench(string[] args) {
            // If args are null, read from STDIN.
            if (args.Length == 0) {
                ReadCipher(null);
                // If there's only one arg and that's --blind, set the blind option and read from stdin.
            } else if (args.Length == 1) {
                if (args[0].Equals("--blind")) {
                    this._isBlind = true;
                    ReadCipher(null);
                    // Otherwise, try to use the first argument as a filename.
                } else if (args[0].Equals("--help") || args[0].Equals("-h")) {
                } else {
                    String[] line = new String[2];
                    line[0] = "reread";
                    line[1] = args[0];
                    ReadCipher(line);            
                } 
                // Otherwise, give some help and exit.
            } else {
                Console.Error.WriteLine("The only argument allowed is a filename containing the ciphertext or --blind to block filesystem access.");
                System.Environment.Exit(1);
            }
            // Seed the helptext.
            HelpText.Append("Available commands:\n");
            // Don't tell users about things they can't use.
            if (!_isBlind) {
                HelpText.Append("reread           -- Read in a new cipher\n");
                HelpText.Append("write            -- write the workspace to a file\n");
            }
            HelpText.Append("reset            -- reset workspace to the ciphertext.\n");
            HelpText.Append("regex            -- Check for strings with the two regex arguments: [search] [filter]\n");
            HelpText.Append("links            -- show some helpful links\n");
            HelpText.Append("print            -- show the current workspace\n");
            HelpText.Append("display          -- alias of print\n");
            // Initialize the ciphersuites.
            Object[] cipherArgs = { (Object)this }; 
            foreach (Type cipherType in Assembly.GetAssembly(typeof(Cipher)).GetTypes()
                    .Where(myType => myType.IsClass && !myType.IsAbstract && myType.IsSubclassOf(typeof(Cipher)))) {
                _ciphers.Add((Cipher)Activator.CreateInstance(cipherType, cipherArgs));
            }
            HelpText.Append("exit             -- exit and show the result.\n");
            HelpText.Append("quit             -- alias of exit.\n");
            HelpText.Append("help             -- show this HelpText\n");
            HelpText.Append("\nYou can get help on any command by running \"<command> help\".\nSuppress printing the cipher with a trailing ;.\n\nCommand structure is: {module} {operation} [{keypart}]*\n\nExample commands:\n\"caesar encrypt 13\" -- Encrypt the input with a Caesarian cipher of offset 13.\n\"affine help\" -- Get help on the Affine cipher.\n\"simple stripspace\" -- Use the Simple module to remove spaces.\n\"analysis one-to-one\" -- Check if the workspace is a one-to-one correlation with the input.\n\n");
        }

        /// <summary> 
        /// Convert this workbench into a readable string.
        /// </summary>
        public override String ToString() {
            StringBuilder currentStatus = new StringBuilder();
            currentStatus.Append("Input:\n");
            currentStatus.Append(this.inputText);
            currentStatus.Append("\n");
            currentStatus.Append("Workspace:\n");
            currentStatus.Append(this.workSpace);
            return currentStatus.ToString();
        }

        /// <summary>
        /// Display this workbench to stdout with colors.
        /// </summary>
        //  <param name="verbose">Set to true if you want verbose prints.
        public void Print() { Print(false); }
        public void Print(bool verbose) {
            Console.ForegroundColor = ConsoleColor.Red;
            Console.WriteLine("Input:");
            Console.ResetColor();
            Console.WriteLine(this.inputText);
            Console.ForegroundColor = ConsoleColor.Red;
            Console.WriteLine("Workspace:");
            Console.ResetColor();
            if (verbose) return;
            List<String> topletters = Analysis.GetMostCommonLetters(workSpace).Take(5).ToList();//cyan
            List<String> bigrams = Analysis.Top(Analysis.GetSubstrings(workSpace,2)); //yellow
            List<String> trigrams = Analysis.Top(Analysis.GetSubstrings(workSpace,3));//magenta
            for (int i = 0; i < workSpace.Length; i++) {
                if (i < workSpace.Length-1 && workSpace[i] == workSpace[i+1]) {
                    Console.ForegroundColor = ConsoleColor.Green;
                    Console.Write(workSpace[i++]);

                } else if (i < workSpace.Length-2 && trigrams.Contains(workSpace.Substring(i,3))) {
                    Console.ForegroundColor = ConsoleColor.Magenta;
                    Console.Write(workSpace[i++]);
                    Console.Write(workSpace[i++]);
                } else if (i < workSpace.Length-1 && bigrams.Contains(workSpace.Substring(i,2))) {
                    Console.ForegroundColor = ConsoleColor.Yellow;
                    Console.Write(workSpace[i++]);
                } else if (topletters.Contains(workSpace[i].ToString())) {
                    Console.ForegroundColor = ConsoleColor.Cyan;
                } 
                Console.Write(workSpace[i]);
                Console.ResetColor();
            }
            Console.WriteLine(); 
        }
        
        /// <summary>
        /// Show some helpful links.
        /// </summary>
        public static void HelpfulLinks() {
            StringBuilder linksText = new StringBuilder();
            linksText.Append("http://www.visca.com/regexdict/ -- RegEx word dictionary\n");
            linksText.Append("http://rumkin.com/tools/cipher/ -- Cipher tools\n");
            linksText.Append("http://norvig.com/mayzner.html  -- Frequency analysis\n");
            Console.Write(linksText.ToString());
        }

        /// <summary>
        /// Save the workspace to a file
        /// </summary>
        /// <param name="workSpace"> what to write </param>
        /// <param name="line"> user input, which should include a file</param>
        public void WriteWorkspace(String workSpace, String[] line) {
            // Require a filename.
            if (line == null || line.Length != 2) {
                Console.Error.WriteLine("Need a file.");
                return;
            }
            try {
                // If we are actually given a file, write the workspace to a file and close.
                StreamWriter fileWriter = new StreamWriter(line[1],false);
                fileWriter.WriteLine(workSpace);
                fileWriter.Dispose();
                fileWriter = null;
                Console.WriteLine(String.Format("Wrote file {0}",line[1]));
            } catch (Exception e) {
                // Let the user know the file's not writeable.
                Console.WriteLine(String.Format("Couldn't write file.\n{0}",e.Message));
            }
        }

        /// <summary>
        /// Interact with the user.
        /// </summary>
        public void Run() {
            // Display the header.
            Console.ForegroundColor = ConsoleColor.Red;            
            Console.WriteLine("### Welcome to the AniNIX/CryptoWorkbench ###");
            Console.ResetColor();
            Console.WriteLine("Type help for assistance.\n");
            Print();
            try { 
                // Set the initial command to be show the helptext.
                string command = "";
                string read = "";
                string[] line;
                bool showCipher=true;

                // Until the user exits...
                while (command != "exit" && command != "quit") {
                    // parse shell-type command unification with semicolons
                    foreach (String executable in read.Split(';')) {

                        // If the command is only whitespace, continue and don't show the cipher.
                        if (String.IsNullOrWhiteSpace(executable)) {
                            showCipher = false; // if the last nonwhitespace character is a semicolon, we won't bother printing.
                            continue;
                        }

                        // Otherwise we will show the cipehr.
                        showCipher = true;
                        line = executable.Trim().Split(' '); 
                        command = line[0];
                        // Command is first space-delimited entry.
                        switch (command) {
                            case "reread":
                                if (!_isBlind) ReadCipher(line);
                                break;
                            case "write":
                                if (!_isBlind) WriteWorkspace(workSpace,line);
                                break;
                            case "reset":
                                this.workSpace = this.inputText;
                                Console.Clear();
                                Console.WriteLine("Reset.");
                                break;
                            case "links": 
                                HelpfulLinks();
                                break;
                            case "regex":
                                try {
                                    if (line.Length == 3) { 
                                        Console.Write(ExecuteCommand.Run(String.Format("bash /opt/aninix/CryptoWorkbench/regex-lookup.bash \"{0}\" \"{1}\"",line[1].Replace("\\","\\\\").Replace("$","\\$"),line[2].Replace("\\","\\\\").Replace("$","\\$"))));
                                    } else if (line.Length == 2) {
                                        Console.Write(ExecuteCommand.Run(String.Format("bash /opt/aninix/CryptoWorkbench/regex-lookup.bash \"{0}\"",line[1].Replace("\\","\\\\").Replace("$","\\$"))));
                                        Console.WriteLine(); 
                                    } else {
                                        Console.Error.WriteLine("Need at least one search term.");
                                    }
                                } catch (Exception e) {
                                    Console.Error.WriteLine(e.ToString());
                                }
                                break;
                            case "help":
                                Console.WriteLine(HelpText.ToString());
                                break;
                            case "display":
                            case "print":
                                showCipher = true;
                                break;
                            case "exit": 
                            case "quit":
                                throw new Exception("");
                            default: 
                                try {
                                    workSpace = SwitchCases[command].RunCommand(this.workSpace,this.inputText,line); 
                                } catch (Exception e) { 
                                    e.ToString();
                                    Console.Error.WriteLine("Command not found.");
                                }
                                break;
                        }
                    }

                    // Show the cipher if the user asked.
                    if (showCipher) Print();
                    // Display an AniNIX-standard prompt.
                    Console.Write("\nCW ");
                    Console.ForegroundColor = ConsoleColor.Red;
                    Console.Write("|");
                    Console.ResetColor();
                    Console.Write("> ");
                    read = Console.ReadLine().Trim();
                }
                // If we run into trouble, tell the user.
            } catch (Exception e) {
                Console.Error.WriteLine(e.Message);
            }

            // When we exit, show the result to the user.
            finally { 
                Console.WriteLine("\nFinal result:");
                this.Print();
            }
        }


        /// <summary> 
        /// Create  and execute a workbench program.
        /// </summary>
        public static void Main(string[] args) {
            Workbench cw = new Workbench(args);
            try {
                cw.Run();
            } catch (NullReferenceException e) {
                Console.Error.WriteLine(String.Format("Caught {0}",e.GetType().ToString()));
            }
        }
    }
}