// ==================================================================================================================                                                                                          

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//   MBBY   BBB.   8BBB   :BBB  BBB .BBUBB  BB1  BBBi   kBBB  BBBM     BBBjBBBr    BBB1     

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//BBBB      iBBB  BBBBBBBBBE    EBBBB  ,BBBB     MBBBBBBBM   BBB,    iBBB  .BBB2 :BBBBBBB7  

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//               LBBj

//

// Apworks Application Development Framework

// Copyright (C) 2010-2011 apworks.codeplex.com.

// Licensed under the Apache License, Version 2.0 (the "License");

// you may not use this file except in compliance with the License.

// You may obtain a copy of the License at

//    http://www.apache.org/licenses/LICENSE-2.0

// Unless required by applicable law or agreed to in writing, software

// distributed under the License is distributed on an "AS IS" BASIS,

// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

// See the License for the specific language governing permissions and

// limitations under the License.

// ================================================================================================================== 





using System;

using System.Reflection;

using System.Security.Cryptography;

using System.Text;



namespace Apworks

{

    /// <summary>

    /// Represents the utility class used by Apworks.

    /// </summary>

    public static class Utils

    {

        #region Private Constants

        private const int InitialPrime = 23;

        private const int FactorPrime = 29;

        #endregion



        #region Internal Extension Methods

        /// <summary>

        /// Gets the signature string.

        /// </summary>

        /// <param name="type">The type.</param>

        /// <returns>The signature string.</returns>

        public static string GetSignature(this Type type)

        {

            StringBuilder sb = new StringBuilder();



            if (type.IsGenericType)

            {

                sb.Append(type.GetGenericTypeDefinition().FullName);

                sb.Append("[");

                int i = 0;

                var genericArgs = type.GetGenericArguments();

                foreach (var genericArg in genericArgs)

                {

                    sb.Append(genericArg.GetSignature());

                    if (i != genericArgs.Length - 1)

                        sb.Append(", ");

                    i++;

                }

                sb.Append("]");

            }

            else

            {

                if (!string.IsNullOrEmpty(type.FullName))

                    sb.Append(type.FullName);

                else if (!string.IsNullOrEmpty(type.Name))

                    sb.Append(type.Name);

                else

                    sb.Append(type.ToString());



            }

            return sb.ToString();

        }

        /// <summary>

        /// Gets the signature string.

        /// </summary>

        /// <param name="method">The method.</param>

        /// <returns>The signature string.</returns>

        public static string GetSignature(this MethodInfo method)

        {

            StringBuilder sb = new StringBuilder();

            Type returnType = method.ReturnType;

            sb.Append(method.ReturnType.GetSignature());

            sb.Append(" ");

            sb.Append(method.Name);

            if (method.IsGenericMethod)

            {

                sb.Append("[");

                var genericTypes = method.GetGenericArguments();

                int i = 0;

                foreach (var genericType in genericTypes)

                {

                    sb.Append(genericType.GetSignature());

                    if (i != genericTypes.Length - 1)

                        sb.Append(", ");

                    i++;

                }

                sb.Append("]");

            }

            sb.Append("(");

            var parameters = method.GetParameters();

            if (parameters != null && parameters.Length > 0)

            {

                int i = 0;

                foreach (var parameter in parameters)

                {

                    sb.Append(parameter.ParameterType.GetSignature());

                    if (i != parameters.Length - 1)

                        sb.Append(", ");

                    i++;

                }

            }

            sb.Append(")");

            return sb.ToString();

        }

        #endregion



        #region Public Methods

        /// <summary>

        /// Gets the hash code for an object based on the given array of hash

        /// codes from each property of the object.

        /// </summary>

        /// <param name="hashCodesForProperties">The array of the hash codes

        /// that are from each property of the object.</param>

        /// <returns>The hash code.</returns>

        public static int GetHashCode(params int[] hashCodesForProperties)

        {

            unchecked

            {

                int hash = InitialPrime;

                foreach (var code in hashCodesForProperties)

                    hash = hash * FactorPrime + code;

                return hash;

            }

        }

        /// <summary>

        /// Generates a unique identifier represented by a <see cref="System.String"/> value

        /// with the specified length.

        /// </summary>

        /// <param name="length">The length of the identifier to be generated.</param>

        /// <returns>The unique identifier represented by a <see cref="System.String"/> value.</returns>

        public static string GetUniqueIdentifier(int length)

        {

            int maxSize = length;

            char[] chars = new char[62];

            string a;

            a = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890";

            chars = a.ToCharArray();

            int size = maxSize;

            byte[] data = new byte[1];

            RNGCryptoServiceProvider crypto = new RNGCryptoServiceProvider();

            crypto.GetNonZeroBytes(data);

            size = maxSize;

            data = new byte[size];

            crypto.GetNonZeroBytes(data);

            StringBuilder result = new StringBuilder(size);

            foreach (byte b in data)

            {

                result.Append(chars[b % (chars.Length - 1)]);

            }

            // Unique identifiers cannot begin with 0-9

            if (result[0] >= '0' && result[0] <= '9')

            {

                return GetUniqueIdentifier(length);

            }

            return result.ToString();

        }

        #endregion

    }

}