// ==========================================================================
// 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>
    /// The ClassManager is responsible for creating and managing instances
    /// that implement the Python type objects that reflect managed classes.
    ///
    /// Each managed type reflected to Python is represented by an instance
    /// of a concrete subclass of ClassBase. Each instance is associated with
    /// a generated Python type object, whose slots point to static methods 
    /// of the managed instance's class. 
    /// </summary>

    internal class ClassManager {

        static Dictionary<Type, ClassBase> cache;
        static Type dtype;

        private ClassManager() {}

        static ClassManager() {
            cache = new Dictionary<Type, ClassBase>(128);
            // SEE: http://msdn.microsoft.com/en-us/library/96b1ayy4%28VS.90%29.aspx
            // ""All delegates inherit from MulticastDelegate, which inherits from Delegate.""
            // Was Delegate, which caused a null MethodInfo returned from GetMethode("Invoke")
            // and crashed on Linux under Mono.
            dtype = typeof(System.MulticastDelegate);
        }

        //====================================================================
        // Return the ClassBase-derived instance that implements a particular 
        // reflected managed type, creating it if it doesn't yet exist.
        //====================================================================

        internal static ClassBase GetClass(Type type) {
            ClassBase cb = null;
            cache.TryGetValue(type, out cb);
            if (cb != null) {
                return cb;
            }
            cb = CreateClass(type);
            cache.Add(type, cb);
            return cb;
        }


        //====================================================================
        // Create a new ClassBase-derived instance that implements a reflected
        // managed type. The new object will be associated with a generated
        // Python type object.
        //====================================================================

        private static ClassBase CreateClass(Type type) {

            // First, we introspect the managed type and build some class
            // information, including generating the member descriptors 
            // that we'll be putting in the Python class __dict__.

            ClassInfo info = GetClassInfo(type);

            // Next, select the appropriate managed implementation class.
            // Different kinds of types, such as array types or interface
            // types, want to vary certain implementation details to make
            // sure that the type semantics are consistent in Python.

            ClassBase impl;

            // Check to see if the given type extends System.Exception. This
            // lets us check once (vs. on every lookup) in case we need to 
            // wrap Exception-derived types in old-style classes

            if (type.ContainsGenericParameters) {
                impl = new GenericType(type);
            }

            else if (type.IsSubclassOf(dtype)) {
                impl = new DelegateObject(type);
            }

            else if (type.IsArray) {
                impl = new ArrayObject(type);
            }

            else if (type.IsInterface) {
                impl = new InterfaceObject(type);
            }

            else if (type == typeof(Exception) || 
                    type.IsSubclassOf(typeof(Exception))) {
                impl = new ExceptionClassObject(type);
            }

            else {
                impl = new ClassObject(type);
            }

            impl.indexer = info.indexer;

            // Now we allocate the Python type object to reflect the given
            // managed type, filling the Python type slots with thunks that
            // point to the managed methods providing the implementation.


            IntPtr tp = TypeManager.GetTypeHandle(impl, type);
            impl.tpHandle = tp;

            // Finally, initialize the class __dict__ and return the object.
            IntPtr dict = Marshal.ReadIntPtr(tp, TypeOffset.tp_dict);


            IDictionaryEnumerator iter = info.members.GetEnumerator();
            while(iter.MoveNext()) {
                ManagedType item = (ManagedType)iter.Value;
                string name = (string)iter.Key;
                Runtime.PyDict_SetItemString(dict, name, item.pyHandle);
            }

            // If class has constructors, generate an __doc__ attribute.
					
            IntPtr doc;
			Type marker = typeof(DocStringAttribute);
			Attribute[] attrs = (Attribute[])type.GetCustomAttributes(marker, false);
            if (attrs.Length == 0) {
            	doc = IntPtr.Zero;
			}
			else {
				DocStringAttribute attr = (DocStringAttribute)attrs[0];
				string docStr = attr.DocString;
            	doc = Runtime.PyString_FromString(docStr);
                Runtime.PyDict_SetItemString(dict, "__doc__", doc);
                Runtime.Decref(doc);
			}

            ClassObject co = impl as ClassObject;
            // If this is a ClassObject AND it has constructors, generate a __doc__ attribute.
            // required that the ClassObject.ctors be changed to internal
            if (co != null) {
                if (co.ctors.Length > 0) {
                    // Implement Overloads on the class object
                    ConstructorBinding ctors = new ConstructorBinding(type, tp, co.binder);
                    // ExtensionType types are untracked, so don't Incref() them.
                    // XXX deprecate __overloads__ soon...
                    Runtime.PyDict_SetItemString(dict, "__overloads__", ctors.pyHandle);
                    Runtime.PyDict_SetItemString(dict, "Overloads", ctors.pyHandle);
					
                    if (doc == IntPtr.Zero) {
                    	doc = co.GetDocString();
	                    Runtime.PyDict_SetItemString(dict, "__doc__", doc);
	                    Runtime.Decref(doc);
	                }
				}
			}

            return impl;
        }




        private static ClassInfo GetClassInfo(Type type) {
            ClassInfo ci = new ClassInfo(type);
            Hashtable methods = new Hashtable();
            ArrayList list;
            MethodInfo meth;
            ManagedType ob;
            String name;
            Object item;
            Type tp;
            int i, n;

            // This is complicated because inheritance in Python is name 
            // based. We can't just find DeclaredOnly members, because we
            // could have a base class A that defines two overloads of a
            // method and a class B that defines two more. The name-based
            // descriptor Python will find needs to know about inherited
            // overloads as well as those declared on the sub class.

            BindingFlags flags = BindingFlags.Static | 
                                 BindingFlags.Instance | 
                                 BindingFlags.Public | 
                                 BindingFlags.NonPublic;

            MemberInfo[] info = type.GetMembers(flags);
            Hashtable local = new Hashtable();
            ArrayList items = new ArrayList();
            MemberInfo m;

            // Loop through once to find out which names are declared
            for (i = 0; i < info.Length; i++) {
                m = info[i];
                if (m.DeclaringType == type) {
                    local[m.Name] = 1;
                }
            }

            // Now again to filter w/o losing overloaded member info
            for (i = 0; i < info.Length; i++) {
                m = info[i];
                if (local[m.Name] != null) {
                    items.Add(m);
                }
            }

            if (type.IsInterface) {
                // Interface inheritance seems to be a different animal: 
                // more contractual, less structural.  Thus, a Type that
                // represents an interface that inherits from another 
                // interface does not return the inherited interface's 
                // methods in GetMembers. For example ICollection inherits 
                // from IEnumerable, but ICollection's GetMemebers does not 
                // return GetEnumerator.
                //
                // Not sure if this is the correct way to fix this, but it 
                // seems to work. Thanks to Bruce Dodson for the fix.

                Type[] inheritedInterfaces = type.GetInterfaces();

                for (i = 0; i < inheritedInterfaces.Length; ++i) {
                    Type inheritedType = inheritedInterfaces[i];
                    MemberInfo[] imembers = inheritedType.GetMembers(flags);
                    for (n = 0; n < imembers.Length; n++) {
                        m = imembers[n];
                        if (local[m.Name] == null) {
                            items.Add(m);
                        }
                    }
                }
            }

            for (i = 0; i < items.Count; i++) {

                MemberInfo mi = (MemberInfo)items[i];

                switch(mi.MemberType) {

                case MemberTypes.Method:
                    meth = (MethodInfo) mi;
                    if (!(meth.IsPublic || meth.IsFamily || 
                          meth.IsFamilyOrAssembly))
                        continue;
                    name = meth.Name;
                    item = methods[name];
                    if (item == null) {
                        item = methods[name] = new ArrayList();
                    }
                    list = (ArrayList) item;
                    list.Add(meth);
                    continue;

                case MemberTypes.Property:
                    PropertyInfo pi = (PropertyInfo) mi;

                    MethodInfo mm = null;
                    try {
                        mm = pi.GetGetMethod(true);
                        if (mm == null) {
                            mm = pi.GetSetMethod(true);
                        }
                    }
                    catch (SecurityException) {
                        // GetGetMethod may try to get a method protected by
                        // StrongNameIdentityPermission - effectively private.
                        continue;
                    }

                    if (mm == null) {
                        continue;
                    }

                    if (!(mm.IsPublic || mm.IsFamily || mm.IsFamilyOrAssembly))
                        continue;

                    // Check for indexer
                    ParameterInfo[] args = pi.GetIndexParameters();
                    if (args.GetLength(0) > 0) {
                        Indexer idx = ci.indexer;
                        if (idx == null) {
                            ci.indexer = new Indexer();
                            idx = ci.indexer;
                        }
                        idx.AddProperty(pi);
                        continue;
                    }

                    ob = new PropertyObject(pi);
                    ci.members[pi.Name] = ob;
                    continue;

                case MemberTypes.Field:
                    FieldInfo fi = (FieldInfo) mi;
                    if (!(fi.IsPublic || fi.IsFamily || fi.IsFamilyOrAssembly))
                        continue;
                    ob = new FieldObject(fi);
                    ci.members[mi.Name] = ob;
                    continue;

                case MemberTypes.Event:
                    EventInfo ei = (EventInfo)mi;
                    MethodInfo me = ei.GetAddMethod(true);
                    if (!(me.IsPublic || me.IsFamily || me.IsFamilyOrAssembly))
                        continue;
                    ob = new EventObject(ei);
                    ci.members[ei.Name] = ob;
                    continue;

                case MemberTypes.NestedType:
                    tp = (Type) mi;
                    if (!(tp.IsNestedPublic || tp.IsNestedFamily || 
                          tp.IsNestedFamORAssem))
                        continue;
                    ob = ClassManager.GetClass(tp);
                    ci.members[mi.Name] = ob;
                    continue;

                }
            }

            IDictionaryEnumerator iter = methods.GetEnumerator();

            while(iter.MoveNext()) {
                name = (string) iter.Key;
                list = (ArrayList) iter.Value;

                MethodInfo[] mlist = (MethodInfo[])list.ToArray(
                                                   typeof(MethodInfo)
                                                   );

                ob = new MethodObject(name, mlist);
                ci.members[name] = ob;
            }

            return ci;

        }


    }        


    internal class ClassInfo {

        internal ClassInfo(Type t) {
            members = new Hashtable();
            indexer = null;
        }

        public Hashtable members;
        public Indexer indexer;
    }



}