using System;

using System.Collections.Generic;

using System.Text;



namespace Hanhud.Utils

{

    /// <summary>

    /// Provides shared helper functionality for working with Windows process command-lines.

    /// </summary>

    public static class CWindowsCommandLineHelper

    {

        /// <summary>

        /// Performs escaping and quoting of arguments where necessary to

        /// build up a command-line suitable for use with the

        /// <see cref="Process.Start" /> method.

        /// </summary>

        /// <param name="arguments">The arguments to be included on the command-line.</param>

        /// <returns>The resulting command-line.</returns>

        public static string FormatCommandLine(params string[] arguments)

        {

            arguments = (string[])arguments.Clone();

            for (int index = 0; index < arguments.Length; index++)

            {

                arguments[index] = GetQuotedArgument(arguments[index]);

            }

            return string.Join(" ", arguments);

        }



        private static string GetQuotedArgument(string argument)

        {

            // The method reads the input argument backwards and builds

            // the result in reverse-character order.

            StringBuilder resultBuilder = new StringBuilder();



            // If the text has whitespace, it must be surrounded in quotes.

            bool surroundingQuotesRequired = HasWhitespace(argument);



            // This flag tracks whether the last character processed was a

            // quote or a backslash that belongs to a sequence of backslashes

            // that immediately precede a quote.

            bool precedingQuote = false;



            // If surrounding quotes are required, start with one.

            // This means that any slashes at the end must be doubled up,

            // so we must also set the precedingQuote flag.

            if (surroundingQuotesRequired)

            {

                resultBuilder.Append('"');

                precedingQuote = true;

            }



            // Read the argument string backwards, escaping any quotes and backslashes

            // where necessary (backslashes are OK unless in a sequence preceding a quote).

            for (int index = argument.Length - 1; index >= 0; index--)

            {

                char character = argument[index];

                resultBuilder.Append(character);



                if (character == '"')

                {

                    precedingQuote = true;

                    resultBuilder.Append('\\');

                }

                else if (character == '\\' && precedingQuote)

                {

                    resultBuilder.Append('\\');

                }

                else

                {

                    precedingQuote = false;

                }

            }



            // If surrounding quotes are required, add one.

            if (surroundingQuotesRequired)

            {

                resultBuilder.Append('"');

            }



            // Reverse the result and we're done.

            return Reverse(resultBuilder.ToString());

        }



        private static bool HasWhitespace(string argument)

        {

            // Iterate over the string and return true if it contains any whitespace characters.

            foreach (char character in argument)

            {

                if (char.IsWhiteSpace(character))

                {

                    return true;

                }

            }

            return false;

        }



        private static string Reverse(string input)

        {

            // Convert the string to a character array, reverse the order

            // and convert it back.

            char[] array = input.ToCharArray();

            Array.Reverse(array);

            return new string(array);

        }

    }

}