using System;
using System.Collections.Generic;
using System.Text;
using System.IO;
using System.Collections;
using System.Reflection;
using System.Xml;

namespace Persistence {

  #region Tokens
  public interface ISerializationToken {
  }
  public class BeginToken : ISerializationToken {
    public DataMemberAccessor Accessor;
    public int Id;
    public BeginToken(DataMemberAccessor accessor, int id) {
      this.Accessor = accessor;
      this.Id = id;
    }    
  }
  public class EndToken : ISerializationToken {
    public DataMemberAccessor Accessor;
    public int Id;
    public EndToken(DataMemberAccessor accessor, int id) {
      this.Accessor = accessor;
      this.Id = id;
    }    
  }
  public class PrimitiveToken : ISerializationToken {
    public DataMemberAccessor accessor;
    public object Data;
    public PrimitiveToken(DataMemberAccessor accessor, object data) {
      this.accessor =  accessor;
      this.Data = data;
    }    
  }
  public class ReferenceToken : ISerializationToken {
    public string Name;
    public int Id;
    public ReferenceToken(string name, int id) {
      this.Name = name;
      this.Id = id;
    }    
  }
  public class NullReferenceToken : ISerializationToken {
    public string Name;
    public NullReferenceToken(string name) {
      this.Name = name;
    }
  }
  #endregion

  #region Primitives
  public interface IPrimitiveSerializer {
    Type Type { get; }
    object Serialize(object o);
    object DeSerialize(object o);
  }
  public class String2XMLSerializer : IPrimitiveSerializer {
    public Type Type { get { return typeof(string); } }
    public object Serialize(object o) {
      return "<![CDATA[" +
        ((string)o).Replace("]]>", "]]]]><![CDATA[>") +
        "]]>";
    }
    public object DeSerialize(object o) {
      StringBuilder sb = new StringBuilder();
      foreach (string s in ((string)o).Split(
        new string[] { "<![CDATA[", "]]>" },
        StringSplitOptions.RemoveEmptyEntries)) {
        sb.Append(s);
      }
      return sb.ToString();
    }
  }
  public class Int2XMLSerializer : IPrimitiveSerializer {
    public Type Type { get { return typeof(int); } }
    public object Serialize(object o) {
      return ((int)o).ToString();
    }
    public object DeSerialize(object o) {
      return int.Parse((string)o);
    }
  }
  #endregion

  #region Custom
  public interface ICustomSerializer {
    bool CanSerialize(Type type);
    IEnumerable Serialize(object o);
    object DeSerialize(IEnumerable o, Type t);
  }
  public class EnumerableSerializer : ICustomSerializer {
    public bool CanSerialize(Type type) {
      if (type.GetInterface("IEnumerable") == null)
        return false;
      if (type.GetMethod("GetEnumerator", new Type[] {}) == null)
        return false;
      MethodInfo addMethod = type.GetMethod("Add");
      if (addMethod == null)
        return false;
      if (addMethod.GetParameters().Length != 1)
        return false;
      return true;
    }
    public IEnumerable Serialize(object o) {
      return (IEnumerable)o;
    }
    public object DeSerialize(IEnumerable objects, Type t) {
      object instance = Activator.CreateInstance(t);
      foreach (object o in objects) {
        t.GetMethod("Add").Invoke(instance, new object[] { o });
      }
      return instance;
    }
  }
  public class ArraySerializer : ICustomSerializer {    

    public bool CanSerialize(Type type) {
      return type.IsArray;      
    }

    public IEnumerable Serialize(object array) {
      foreach (object o in (Array)array) {
        yield return o;
      }
    }

    public object DeSerialize(IEnumerable elements, Type t) {
      List<object> allElements = new List<object>();
      foreach (object obj in elements) {
        allElements.Add(obj);
      }
      Array array = 
        Array.CreateInstance(t.GetElementType(), allElements.Count);
      for (int i = 0; i < array.Length; i++) {
        array.SetValue(allElements[i], i);
      }
      return array;
    }

  }  
  #endregion

  public class Serializer : IEnumerable<ISerializationToken> {

    private object obj;
    private string rootName;
    private Dictionary<object, int> obj2id;
    private Dictionary<Type, IPrimitiveSerializer> primitiveSerializers;
    private List<ICustomSerializer> customSerializers;

    public Serializer(object obj, IEnumerable<IPrimitiveSerializer> primitiveSerializers) :
      this(obj, primitiveSerializers, "ROOT") { }

    public Serializer(object obj, IEnumerable<IPrimitiveSerializer> primitiveSerializers, string rootName) {
      this.obj = obj;
      this.rootName = rootName;
      this.primitiveSerializers = new Dictionary<Type,IPrimitiveSerializer>();
      foreach (IPrimitiveSerializer serializer in primitiveSerializers) {
        this.primitiveSerializers.Add(serializer.Type, serializer);
      }
      this.customSerializers = new List<ICustomSerializer>();
      customSerializers.Add(new EnumerableSerializer());
      customSerializers.Add(new ArraySerializer());
      this.obj2id = new Dictionary<object, int>();
      obj2id.Add(new object(), 0);      
    }    

    IEnumerator IEnumerable.GetEnumerator() {
      return this.GetEnumerator();
    }

    public IEnumerator<ISerializationToken> GetEnumerator() {
      DataMemberAccessor rootAccessor = new DataMemberAccessor(
        this.rootName, obj.GetType(), null, () => this.obj, null);
      IEnumerator<ISerializationToken> iterator = Serialize(rootAccessor);
      while (iterator.MoveNext())
        yield return iterator.Current;      
    }

    private IEnumerator<ISerializationToken> Serialize(DataMemberAccessor accessor) {
      object value = accessor.Get();      
      if (value == null) {
        yield return new NullReferenceToken(accessor.Name);
      } else if (this.primitiveSerializers.ContainsKey(value.GetType())) {
        yield return new PrimitiveToken(accessor, this.primitiveSerializers[value.GetType()].Serialize(value));
      } else if (this.obj2id.ContainsKey(value)) {
        yield return new ReferenceToken(accessor.Name, this.obj2id[value]);
      } else {
        int id = obj2id.Count;
        this.obj2id.Add(value, id);
        yield return new BeginToken(accessor, id);
        ICustomSerializer customSerializer = this.FindCustomSerializer(value.GetType());
        if (customSerializer != null) {
          foreach (object obj in customSerializer.Serialize(value)) {
            IEnumerator<ISerializationToken> iterator = this.Serialize(new DataMemberAccessor(obj));
            while (iterator.MoveNext())
              yield return iterator.Current;            
          }
        } else { // composite serialization
          foreach (KeyValuePair<string, DataMemberAccessor> mapping in
            StorableAttribute.GetAutostorableAccessors(value)) {
            IEnumerator<ISerializationToken> iterator = this.Serialize(mapping.Value);
            while (iterator.MoveNext())
              yield return iterator.Current;
          }
        }
        yield return new EndToken(accessor, id);        
      }
    }    

    private ICustomSerializer FindCustomSerializer(Type type) {
      foreach (ICustomSerializer s in customSerializers) {
        if (s.CanSerialize(type))
          return s;
      }
      return null;
    }                
  }

  public class DeSerializer {

    interface IAccessibleObject {
      object Obj { get; }
    }

    class CustomObject : IAccessibleObject {
      public object Obj { get { return this.obj; } }
      private object obj;
      public List<object> customValues;
      public CustomObject(object obj) {
        this.obj = obj;
        this.customValues = new List<object>();
      }
      public void AddValue(object value) {
        customValues.Add(value);
      }
    }

    class CompositeObject : IAccessibleObject{
      public object Obj { get { return this.obj; } }
      public object obj;
      public Dictionary<string, DataMemberAccessor> accessorDict;
      public CompositeObject(object obj, Dictionary<string, DataMemberAccessor> accessorDict) {
        this.obj = obj;
        this.accessorDict = new Dictionary<string, DataMemberAccessor>();        
        foreach (KeyValuePair<string, DataMemberAccessor> pair in accessorDict) {
          this.accessorDict.Add(
            pair.Value.Name,
            pair.Value);
        }
      }
      public void SetValue(string name, object value) {
        accessorDict[name].Set(value);        
      }
      public void SetAllDefaultValues() {
        throw new NotImplementedException();
      }
    }

    private delegate void Handler(IParseToken token);

    private Dictionary<int, object> id2obj;
    private Dictionary<Type, Handler> handlers;
    private Stack<IAccessibleObject> compositeStack;    

    private Dictionary<Type, IPrimitiveSerializer> primitiveSerializers;
    private List<ICustomSerializer> customSerializers;

    public DeSerializer(
        IEnumerable<IPrimitiveSerializer> primitiveSerializers,
        IEnumerable<ICustomSerializer> customSerializers) {
      id2obj = new Dictionary<int, object>();
      compositeStack = new Stack<IAccessibleObject>();
      handlers = new Dictionary<Type, Handler>();
      handlers.Add(typeof(CompositeStart), new Handler(CompositeStartHandler));
      handlers.Add(typeof(CompositeEnd), new Handler(CompositeEndHandler));
      handlers.Add(typeof(Primitive), new Handler(PrimitiveHandler));
      handlers.Add(typeof(Reference), new Handler(ReferenceHandler));
      handlers.Add(typeof(Null), new Handler(NullHandler));
      // TODO: make this configurable
      this.primitiveSerializers = new Dictionary<Type, IPrimitiveSerializer>();
      foreach (IPrimitiveSerializer ps in primitiveSerializers) {
        this.primitiveSerializers.Add(ps.Type, ps);
      }
      this.customSerializers = new List<ICustomSerializer>(customSerializers);
     
    }
    public object DeSerialize(IEnumerable<IParseToken> tokens) {
      foreach (IParseToken token in tokens) {
        handlers[token.GetType()].Invoke(token);
      }
      return compositeStack.Pop().Obj;
    }
    private void CompositeStartHandler(IParseToken token) {
      CompositeStart start = (CompositeStart)token;
      object instance = null;
      if (this.FindCustomSerializer(start.Type) != null) {
        instance = new object();
        compositeStack.Push(new CustomObject(instance));
        id2obj.Add(start.Id, instance);
        // TODO: add warning proxy
      } else {
        instance = Activator.CreateInstance(start.Type);
        Dictionary<string, DataMemberAccessor> accessorDict =
        StorableAttribute.GetAutostorableAccessors(instance);
        compositeStack.Push(new CompositeObject(instance, accessorDict));
        id2obj.Add(start.Id, instance);
      }
    }
    private void CompositeEndHandler(IParseToken token) {
      CompositeEnd end = (CompositeEnd)token;      
      ICustomSerializer customSerializer = this.FindCustomSerializer(end.Type);
      if (customSerializer != null) {
        CustomObject customObject = (CustomObject)compositeStack.Pop();  
        this.SetValue(end.Name,
          customSerializer.DeSerialize(customObject.customValues, end.Type));
      } else {
        CompositeObject compositeObject = (CompositeObject)compositeStack.Pop();
        this.SetValue(end.Name, compositeObject.obj);
      }
    }
    private ICustomSerializer FindCustomSerializer(Type type) {
      foreach (ICustomSerializer serializer in customSerializers) {
        if (serializer.CanSerialize(type))
          return serializer;
      }
      return null;
    }
    private void PrimitiveHandler(IParseToken token) {
      Primitive primitive = (Primitive)token;
      object value = primitiveSerializers[primitive.Type].DeSerialize(primitive.SerializedValue);
      this.SetValue(primitive.Name, value);     
    }
    private void ReferenceHandler(IParseToken token) {
      Reference reference = (Reference)token;      
      this.SetValue(reference.Name, this.id2obj[reference.Id]);            
    }
    private void NullHandler(IParseToken token) {
      Null nil = (Null)token;
      this.SetValue(nil.Name, null);      
    }
    private void SetValue(string name, object value) {
       if (compositeStack.Count == 0) {
        compositeStack.Push(new CompositeObject(value, new Dictionary<string,DataMemberAccessor>()));
       } else {
         object accessibleObject = compositeStack.Peek();
         if ( accessibleObject is CompositeObject ) {
           ((CompositeObject)accessibleObject).SetValue(name, value);
         } else if (accessibleObject is CustomObject) {           
           ((CustomObject)accessibleObject).AddValue(value);
         }
      }      
    }
  }

  public class XmlFormatter {

    delegate string Formatter(ISerializationToken token);

    private Dictionary<Type, Formatter> formatters;
    private int depth;

    public XmlFormatter() {
      this.formatters = new Dictionary<Type,Formatter>();
      this.formatters.Add(typeof(BeginToken), new Formatter(FormatBegin));
      this.formatters.Add(typeof(EndToken), new Formatter(FormatEnd));
      this.formatters.Add(typeof(PrimitiveToken), new Formatter(FormatData));
      this.formatters.Add(typeof(ReferenceToken), new Formatter(FormatReference));
      this.formatters.Add(typeof(NullReferenceToken), new Formatter(FormatNullReference));
      this.depth = 0;
    }
    
    public string Format(ISerializationToken token) {
      return formatters[token.GetType()](token);
    }

    private string Prefix {
      get { return new string(' ', this.depth*2); }
    }

    private string FormatBegin(ISerializationToken token) {
      BeginToken beginToken = (BeginToken)token;
      string result =
        String.Format("{0}<COMPOSITE name=\"{1}\" type=\"{2}\" id=\"{3}\">\n",
          this.Prefix, beginToken.Accessor.Name, beginToken.Accessor.Type, beginToken.Id);
      this.depth += 1;
      return result;
    }

    private string FormatEnd(ISerializationToken token) {
      EndToken endToken = (EndToken)token;
      this.depth -= 1;
      return Prefix + "</COMPOSITE>\n";
    }

    private string FormatData(ISerializationToken token) {
      PrimitiveToken dataToken = (PrimitiveToken)token;
      return String.Format("{0}<PRIMITIVE name=\"{1}\" type=\"{2}\">{3}</PRIMITIVE>\n",
        this.Prefix, dataToken.accessor.Name, dataToken.accessor.Type, dataToken.Data);      
    }

    private string FormatReference(ISerializationToken token) {
      ReferenceToken refToken = (ReferenceToken)token;
      return String.Format("{0}<REFERENCE name=\"{1}\" ref=\"{2}\"/>\n",
        this.Prefix, refToken.Name, refToken.Id);      
    }

    private string FormatNullReference(ISerializationToken token) {
      NullReferenceToken nullRefToken = (NullReferenceToken)token;
      return String.Format("{0}<NULL name=\"{1}\"/>\n",
        this.Prefix, nullRefToken.Name);
    }


  }

  #region parsing tokens
  public interface IParseToken { }
  public class CompositeStart : IParseToken {
    public string Name;
    public Type Type;    
    public int Id;
    public CompositeStart(string name, Type type, int id) {
      this.Name = name;
      this.Type = type;
      this.Id = id;      
    }
  }
  public class CompositeEnd : IParseToken {
    public string Name;
    public Type Type;    
    public int Id;
    public CompositeEnd(string name, Type type, int id) {
      this.Name = name;
      this.Type = type;
      this.Id = id;      
    }
  }
  public class Primitive : IParseToken {
    public string Name;
    public Type Type;
    public string SerializedValue;
    public Primitive(string name, Type type, string serilaizedValue) {
      this.Name = name;
      this.Type = type;
      this.SerializedValue = serilaizedValue;
    }
  }
  public class Reference : IParseToken {
    public string Name;
    public int Id;
    public Reference(string name, int id) {
      this.Name = name;
      this.Id = id;
    }
  }
  public class Null : IParseToken {
    public string Name;
    public Null(string name) {
      this.Name = name;
    }
  }
  #endregion


  public class XmlParser : IEnumerable<IParseToken> {

    private XmlReader reader;
    private delegate IEnumerator<IParseToken> Handler();
    private Dictionary<string, Handler> handlers;

    public XmlParser(StreamReader input) {
      XmlReaderSettings settings = new XmlReaderSettings();
      settings.ConformanceLevel = ConformanceLevel.Document;
      settings.IgnoreWhitespace = true;
      settings.IgnoreComments = true;
      this.reader = XmlReader.Create(input, settings);
      this.handlers = new Dictionary<string, Handler>();
      this.handlers.Add("PRIMITIVE", new Handler(ParsePrimitive));
      this.handlers.Add("COMPOSITE", new Handler(ParseComposite));
      this.handlers.Add("REFERENCE", new Handler(ParseReference));
      this.handlers.Add("NULL", new Handler(ParseNull));
    }
    public IEnumerator<IParseToken> GetEnumerator() {
      while (this.reader.Read()) {
        if (!reader.IsStartElement()) {          
          break;
        }
        IEnumerator<IParseToken> iterator;
        try {                      
            iterator = handlers[reader.Name].Invoke();          
        } catch (KeyNotFoundException) {          
          throw new InvalidOperationException(String.Format(
            "No handler for XML tag \"{0}\" installed",
            reader.Name));
        }
        while (iterator.MoveNext()) {
          yield return iterator.Current;
        }
      }      
    }
    private IEnumerator<IParseToken> ParsePrimitive() {
      yield return new Primitive(
        this.reader.GetAttribute("name"),
        Type.GetType(this.reader.GetAttribute("type")),
        this.reader.ReadString());      
    }
    private IEnumerator<IParseToken> ParseComposite() {
      string name = this.reader.GetAttribute("name");
      Type type = Type.GetType(this.reader.GetAttribute("type"));
      int id = int.Parse(this.reader.GetAttribute("id"));
      yield return new CompositeStart(name, type, id);        
      IEnumerator<IParseToken> iterator = this.GetEnumerator();
      while (iterator.MoveNext())
        yield return iterator.Current;
      yield return new CompositeEnd(name, type, id);      
    }
    private IEnumerator<IParseToken> ParseReference() {
      yield return new Reference(
        this.reader.GetAttribute("name"),
        int.Parse(this.reader.GetAttribute("ref")));      
    }
    private IEnumerator<IParseToken> ParseNull() {
      yield return new Null(this.reader.GetAttribute("name"));      
    }        
    IEnumerator IEnumerable.GetEnumerator() {
      return this.GetEnumerator();
    }    
  }  
}