#region License Information
/* HeuristicLab
 * Copyright (C) 2002-2015 Heuristic and Evolutionary Algorithms Laboratory (HEAL)
 *
 * This file is part of HeuristicLab.
 *
 * HeuristicLab is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * HeuristicLab is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with HeuristicLab. If not, see <http://www.gnu.org/licenses/>.
 */
#endregion

using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using System.Reflection.Emit;

namespace HeuristicLab.Persistence {
  public sealed class TypeInfo {
    private Func<object> constructor;

    public Type Type { get; private set; }
    public ITransformer Transformer { get; private set; }
    public StorableTypeAttribute StorableTypeAttribute { get; private set; }
    public IEnumerable<ComponentInfo> Fields { get; private set; }
    public IEnumerable<ComponentInfo> Properties { get; private set; }
    public IEnumerable<MethodInfo> BeforeSerializationHooks { get; private set; }
    public IEnumerable<MethodInfo> AfterDeserializationHooks { get; private set; }
    public long Used { get; set; }

    public TypeInfo(Type type) {
      constructor = null;
      Type = type;
      Fields = Enumerable.Empty<ComponentInfo>();
      Properties = Enumerable.Empty<ComponentInfo>();
      BeforeSerializationHooks = Enumerable.Empty<MethodInfo>();
      AfterDeserializationHooks = Enumerable.Empty<MethodInfo>();
      Used = 0;
      Reflect();
    }
    public TypeInfo(Type type, ITransformer transformer)
      : this(type) {
      Transformer = transformer;
    }

    private void Reflect() {
      var type = Type;
      StorableTypeAttribute = StorableTypeAttribute.GetStorableTypeAttribute(type);
      if (StorableTypeAttribute != null) {
        // traverse type hierarchy from base type to sub types
        Stack<Type> types = new Stack<Type>();
        while (type != null) {
          types.Push(type);
          type = type.BaseType;
        }

        var fields = new List<ComponentInfo>();
        var properties = new List<ComponentInfo>();
        var beforeSerializationHooks = new List<MethodInfo>();
        var afterDeserializationHooks = new List<MethodInfo>();
        while (types.Count > 0) {
          type = types.Pop();
          if (StorableTypeAttribute.MemberSelection != StorableMemberSelection.AllProperties) {
            var fieldInfos = type.GetFields(BindingFlags.Instance | BindingFlags.DeclaredOnly | BindingFlags.Public | BindingFlags.NonPublic)
                                 .Where(x => !x.Name.StartsWith("<") && !x.Name.EndsWith("k__BackingField")); // exclude backing fields
            if (StorableTypeAttribute.MemberSelection == StorableMemberSelection.MarkedOnly)
              fieldInfos = fieldInfos.Where(x => StorableAttribute.IsStorable(x)).ToArray();
            foreach (var field in fieldInfos) {
              var attrib = StorableAttribute.GetStorableAttribute(field);
              var name = attrib == null || string.IsNullOrEmpty(attrib.Name) ? field.Name : attrib.Name;
              fields.Add(new ComponentInfo(type.Name + '.' + name, field, attrib, true, true));
            }
          }

          if (StorableTypeAttribute.MemberSelection != StorableMemberSelection.AllFields) {
            var propertyInfos = type.GetProperties(BindingFlags.Instance | BindingFlags.DeclaredOnly | BindingFlags.Public | BindingFlags.NonPublic).
                        Where(x => x.GetIndexParameters().Length == 0);  // exclude indexed properties
            if (StorableTypeAttribute.MemberSelection == StorableMemberSelection.MarkedOnly)
              propertyInfos = propertyInfos.Where(x => StorableAttribute.IsStorable(x)).ToArray();
            foreach (var property in propertyInfos) {
              var attrib = StorableAttribute.GetStorableAttribute(property);
              var name = attrib == null || string.IsNullOrEmpty(attrib.Name) ? property.Name : attrib.Name;
              properties.Add(new ComponentInfo(type.Name + '.' + name, property, attrib, property.CanRead, property.CanWrite));
            }
          }

          var methodInfos = type.GetMethods(BindingFlags.Instance | BindingFlags.DeclaredOnly | BindingFlags.Public | BindingFlags.NonPublic).
                            Where(x => StorableHookAttribute.IsStorableHook(x)).
                            Where(x => (x.ReturnType == typeof(void)) && (x.GetParameters().Length == 0));
          foreach (var method in methodInfos) {
            foreach (var attrib in StorableHookAttribute.GetStorableHookAttributes(method)) {
              if (attrib.HookType == HookType.BeforeSerialization)
                beforeSerializationHooks.Add(method);
              if (attrib.HookType == HookType.AfterDeserialization)
                afterDeserializationHooks.Add(method);
            }
          }
        }
        Fields = fields;
        Properties = properties;
        BeforeSerializationHooks = beforeSerializationHooks;
        AfterDeserializationHooks = afterDeserializationHooks;
      }
    }

    public Func<object> GetConstructor() {
      if (constructor != null) return constructor;

      // get storable constructor
      var ctor = Type.GetConstructors(BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic)
                     .Where(x => StorableConstructorAttribute.IsStorableConstructor(x))
                     .Where(x => (x.GetParameters().Length == 1) && (x.GetParameters()[0].ParameterType == typeof(bool)))
                     .FirstOrDefault();
      if (ctor != null) {
        DynamicMethod dm = new DynamicMethod("", typeof(object), null, Type, true);
        ILGenerator ilgen = dm.GetILGenerator();
        ilgen.Emit(OpCodes.Ldc_I4_1); // load true
        ilgen.Emit(OpCodes.Newobj, ctor);
        ilgen.Emit(OpCodes.Ret);
        constructor = (Func<object>)dm.CreateDelegate(typeof(Func<object>));
        return constructor;
      }

      // get default constructor
      ctor = Type.GetConstructor(BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic,
                                 null, Type.EmptyTypes, null);
      if (ctor != null) {
        DynamicMethod dm = new DynamicMethod("", typeof(object), null, Type, true);
        ILGenerator ilgen = dm.GetILGenerator();
        ilgen.Emit(OpCodes.Newobj, ctor);
        ilgen.Emit(OpCodes.Ret);
        constructor = (Func<object>)dm.CreateDelegate(typeof(Func<object>));
        return constructor;
      }

      throw new Exception("No storable constructor or parameterless constructor found.");
    }
  }
}