//------------------------------------------------------------------------------
// <copyright file="CodeIdentifier.cs" company="Microsoft">
//     Copyright (c) Microsoft Corporation.  All rights reserved.
// </copyright>
// <owner current="true" primary="true">[....]</owner>                                                                
//------------------------------------------------------------------------------

namespace System.Xml.Serialization {
    
    using System;
    using System.Text;
    using System.Collections;
    using System.IO;
    using System.Globalization;
    using System.Diagnostics;
    using System.CodeDom;
    using System.CodeDom.Compiler;
    using Microsoft.CSharp;
    
    /// <include file='doc\CodeIdentifier.uex' path='docs/doc[@for="CodeIdentifier"]/*' />
    ///<internalonly/>
    /// <devdoc>
    ///    <para>[To be supplied.]</para>
    /// </devdoc>
    public class CodeIdentifier {
        internal static CodeDomProvider csharp = new CSharpCodeProvider();
        internal const int MaxIdentifierLength = 511;

        [Obsolete("This class should never get constructed as it contains only static methods.")]
        public CodeIdentifier() {
        }

        /// <include file='doc\CodeIdentifier.uex' path='docs/doc[@for="CodeIdentifier.MakePascal"]/*' />
        /// <devdoc>
        ///    <para>[To be supplied.]</para>
        /// </devdoc>
        public static string MakePascal(string identifier) {
            identifier = MakeValid(identifier);
            if (identifier.Length <= 2)
                return identifier.ToUpper(CultureInfo.InvariantCulture);
            else if (char.IsLower(identifier[0]))
                return char.ToUpper(identifier[0], CultureInfo.InvariantCulture).ToString(CultureInfo.InvariantCulture) + identifier.Substring(1);
            else
                return identifier;
        }
        
        /// <include file='doc\CodeIdentifier.uex' path='docs/doc[@for="CodeIdentifier.MakeCamel"]/*' />
        /// <devdoc>
        ///    <para>[To be supplied.]</para>
        /// </devdoc>
        public static string MakeCamel(string identifier) {
            identifier = MakeValid(identifier);
            if (identifier.Length <= 2)
                return identifier.ToLower(CultureInfo.InvariantCulture);
            else if (char.IsUpper(identifier[0]))
                return char.ToLower(identifier[0], CultureInfo.InvariantCulture).ToString(CultureInfo.InvariantCulture) + identifier.Substring(1);
            else
                return identifier;
        }
        
        /// <include file='doc\CodeIdentifier.uex' path='docs/doc[@for="CodeIdentifier.MakeValid"]/*' />
        /// <devdoc>
        ///    <para>[To be supplied.]</para>
        /// </devdoc>
        public static string MakeValid(string identifier) {
            StringBuilder builder = new StringBuilder();
            for (int i = 0; i < identifier.Length && builder.Length < MaxIdentifierLength; i++) {
                char c = identifier[i];
                if (IsValid(c)) {
                    if (builder.Length == 0 && !IsValidStart(c)) {
                        builder.Append("Item");
                    }
                    builder.Append(c);
                }
            }
            if (builder.Length == 0) return "Item";
            return builder.ToString();
        }

        internal static string MakeValidInternal(string identifier) {
            if (identifier.Length > 30) {
                return "Item";
            }
            return MakeValid(identifier);
        }

        static bool IsValidStart(char c) {

            // the given char is already a valid name character
#if DEBUG
                // use exception in the place of Debug.Assert to avoid throwing asserts from a server process such as aspnet_ewp.exe
                if (!IsValid(c)) throw new ArgumentException(Res.GetString(Res.XmlInternalErrorDetails, "Invalid identifier character " + ((Int16)c).ToString(CultureInfo.InvariantCulture)), "c");
#endif

            // First char cannot be a number
            if (Char.GetUnicodeCategory(c) == UnicodeCategory.DecimalDigitNumber)
                return false;
            return true;
        }

        static bool IsValid(char c) {
            UnicodeCategory uc = Char.GetUnicodeCategory(c);
            // each char must be Lu, Ll, Lt, Lm, Lo, Nd, Mn, Mc, Pc
            // 
            switch (uc) {
            case UnicodeCategory.UppercaseLetter:        // Lu
            case UnicodeCategory.LowercaseLetter:        // Ll
            case UnicodeCategory.TitlecaseLetter:        // Lt
            case UnicodeCategory.ModifierLetter:         // Lm
            case UnicodeCategory.OtherLetter:            // Lo
            case UnicodeCategory.DecimalDigitNumber:     // Nd
            case UnicodeCategory.NonSpacingMark:         // Mn
            case UnicodeCategory.SpacingCombiningMark:   // Mc
            case UnicodeCategory.ConnectorPunctuation:   // Pc
                break;
            case UnicodeCategory.LetterNumber:
            case UnicodeCategory.OtherNumber:
            case UnicodeCategory.EnclosingMark:
            case UnicodeCategory.SpaceSeparator:
            case UnicodeCategory.LineSeparator:
            case UnicodeCategory.ParagraphSeparator:
            case UnicodeCategory.Control:
            case UnicodeCategory.Format:
            case UnicodeCategory.Surrogate:
            case UnicodeCategory.PrivateUse:
            case UnicodeCategory.DashPunctuation:
            case UnicodeCategory.OpenPunctuation:
            case UnicodeCategory.ClosePunctuation:
            case UnicodeCategory.InitialQuotePunctuation:
            case UnicodeCategory.FinalQuotePunctuation:
            case UnicodeCategory.OtherPunctuation:
            case UnicodeCategory.MathSymbol:
            case UnicodeCategory.CurrencySymbol:
            case UnicodeCategory.ModifierSymbol:
            case UnicodeCategory.OtherSymbol:
            case UnicodeCategory.OtherNotAssigned:
                return false;
            default:
#if DEBUG
                        // use exception in the place of Debug.Assert to avoid throwing asserts from a server process such as aspnet_ewp.exe
                        throw new ArgumentException(Res.GetString(Res.XmlInternalErrorDetails, "Unhandled category " + uc), "c");
#else
                return false;
#endif
            }
            return true;
        }

        internal static void CheckValidIdentifier(string ident) {
            if (!CodeGenerator.IsValidLanguageIndependentIdentifier(ident))
                throw new ArgumentException(Res.GetString(Res.XmlInvalidIdentifier, ident), "ident");
        }

        internal static string GetCSharpName(string name) {
            //

            return EscapeKeywords(name.Replace('+', '.'), csharp);
        }

        static int GetCSharpName(Type t, Type[] parameters, int index, StringBuilder sb) {
            if (t.DeclaringType != null && t.DeclaringType != t) {
                index = GetCSharpName(t.DeclaringType, parameters, index, sb);
                sb.Append(".");
            }
            string name = t.Name;
            int nameEnd = name.IndexOf('`');
            if (nameEnd < 0) {
                nameEnd = name.IndexOf('!');
            }
            if (nameEnd > 0) {
                EscapeKeywords(name.Substring(0, nameEnd), csharp, sb);
                sb.Append("<");
                int arguments = Int32.Parse(name.Substring(nameEnd+1), CultureInfo.InvariantCulture) + index;
                for (; index < arguments; index++) {
                    sb.Append(GetCSharpName(parameters[index]));
                    if (index < arguments -1) {
                        sb.Append(",");
                    }
                }
                sb.Append(">");
            }
            else {
                EscapeKeywords(name, csharp, sb);
            }
            return index;
        }

        internal static string GetCSharpName(Type t) {
            int rank = 0;
            while (t.IsArray) {
                t = t.GetElementType();
                rank++;
            }
            StringBuilder sb = new StringBuilder();
            sb.Append("global::");
            string ns = t.Namespace;
            if (ns != null && ns.Length > 0) {
                string[] parts = ns.Split(new char[] {'.'});
                for (int i = 0; i < parts.Length; i++) {
                    EscapeKeywords(parts[i], csharp, sb);
                    sb.Append(".");
                }
            }

            Type[] arguments = t.IsGenericType || t.ContainsGenericParameters ? t.GetGenericArguments() : new Type[0];
            GetCSharpName(t, arguments, 0, sb);
            for (int i = 0; i < rank; i++) {
                sb.Append("[]");
            }
            return sb.ToString();
        }

        //
        /*
        internal static string GetTypeName(string name, CodeDomProvider codeProvider) {
            return codeProvider.GetTypeOutput(new CodeTypeReference(name));
        }
        */

        static void EscapeKeywords(string identifier, CodeDomProvider codeProvider, StringBuilder sb) {
            if (identifier == null || identifier.Length == 0) 
                return;
            string originalIdentifier = identifier;
            int arrayCount = 0;
            while (identifier.EndsWith("[]", StringComparison.Ordinal)) {
                arrayCount++;
                identifier = identifier.Substring(0, identifier.Length - 2);
            }
            if (identifier.Length > 0) {
                CheckValidIdentifier(identifier);
                identifier = codeProvider.CreateEscapedIdentifier(identifier);
                sb.Append(identifier);
            }
            for (int i = 0; i < arrayCount; i++) {
                sb.Append("[]");
            }
        }

        static string EscapeKeywords(string identifier, CodeDomProvider codeProvider) {
            if (identifier == null || identifier.Length == 0) return identifier;
            string originalIdentifier = identifier;
            string[] names = identifier.Split(new char[] {'.', ',', '<', '>'});
            StringBuilder sb = new StringBuilder();
            int separator = -1;
            for (int i = 0; i < names.Length; i++) {
                if (separator >= 0) {
                    sb.Append(originalIdentifier.Substring(separator, 1));
                }
                separator++;
                separator += names[i].Length;
                string escapedName = names[i].Trim();
                EscapeKeywords(escapedName, codeProvider, sb);
            }
            if (sb.Length != originalIdentifier.Length)
                return sb.ToString();
            return originalIdentifier;
        }
    }
}