// ==========================================================================
// This software is subject to the provisions of the Zope Public License,
// Version 2.0 (ZPL).  A copy of the ZPL should accompany this distribution.
// THIS SOFTWARE IS PROVIDED "AS IS" AND ANY AND ALL EXPRESS OR IMPLIED
// WARRANTIES ARE DISCLAIMED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
// WARRANTIES OF TITLE, MERCHANTABILITY, AGAINST INFRINGEMENT, AND FITNESS
// FOR A PARTICULAR PURPOSE.
// ==========================================================================

using System;
using System.Runtime.InteropServices;
using System.Collections.Generic;
using System.Collections;
using System.Reflection;
using System.Security;

namespace Python.Runtime {

    /// <summary>
    /// This class is responsible for efficiently maintaining the bits 
    /// of information we need to support aliases with 'nice names'.
    /// </summary>

    internal class GenericUtil {

        static Dictionary<string, Dictionary<string, List<string>>> mapping;

        private GenericUtil() {}

        static GenericUtil() {
            mapping = new 
                Dictionary<string, Dictionary<string, List<string>>>();
        }

        //====================================================================
        // Register a generic type that appears in a given namespace.
        //====================================================================

        internal static void Register(Type t) {
            Dictionary<string, List<string>> nsmap = null;
            //for Anonymous type, there is no namespace
            if (t.Namespace == null) return;

            mapping.TryGetValue(t.Namespace, out nsmap);
            if (nsmap == null) {
                nsmap = new Dictionary<string, List<string>>();
                mapping[t.Namespace] = nsmap;
            }
            string basename = t.Name;
            int tick = basename.IndexOf("`");
            if (tick > -1) {
                basename = basename.Substring(0, tick);
            }
            List<string> gnames = null;
            nsmap.TryGetValue(basename, out gnames);
            if (gnames == null) {
                gnames = new List<string>();
                nsmap[basename] = gnames;
            }
            gnames.Add(t.Name);
        }

        //====================================================================
        // xxx
        //====================================================================

        public static List<string> GetGenericBaseNames(string ns) {
            Dictionary<string, List<string>> nsmap = null;
            mapping.TryGetValue(ns, out nsmap);
            if (nsmap == null) {
                return null;
            }
            List<string> names = new List<string>();
            foreach (string key in nsmap.Keys) {
                names.Add(key);
            }
            return names;
        }

        //====================================================================
        // xxx
        //====================================================================

        public static List<Type> GenericsForType(Type t) {
            Dictionary<string, List<string>> nsmap = null;
            mapping.TryGetValue(t.Namespace, out nsmap);
            if (nsmap == null) {
                return null;
            }

            string basename = t.Name;
            int tick = basename.IndexOf("`");
            if (tick > -1) {
                basename = basename.Substring(0, tick);
            }

            List<string> names = null;
            nsmap.TryGetValue(basename, out names);
            if (names == null) {
                return null;
            }

            List<Type> result = new List<Type>();
            foreach (string name in names) {
                string qname = t.Namespace + "." + name;
                Type o = AssemblyManager.LookupType(qname);
                if (o != null) {
                    result.Add(o);
                }
            }

            return result;
        }

        //====================================================================
        // xxx
        //====================================================================

        public static string GenericNameForBaseName(string ns, string name) {
            Dictionary<string, List<string>> nsmap = null;
            mapping.TryGetValue(ns, out nsmap);
            if (nsmap == null) {
                return null;
            }
            List<string> gnames = null;
            nsmap.TryGetValue(name, out gnames);
            if (gnames == null) {
                return null;
            }
            if (gnames.Count > 0) {
                return gnames[0];
            }
            return null;
        }


    }



}