using System.Collections.Generic;
using System.Collections;
using System.IO;
using UnityEngine;
using System;
using ES3Types;
using ES3Internal;

public abstract class ES3Writer : IDisposable
{
	public ES3Settings settings;
	protected HashSet<string> keysToDelete = new HashSet<string>();

	internal bool writeHeaderAndFooter = true;
	internal bool overwriteKeys = true;

    protected int serializationDepth = 0;

	#region ES3Writer Abstract Methods

	internal abstract void WriteNull();

    internal virtual void StartWriteFile()
    {
        serializationDepth++;
    }

    internal virtual void EndWriteFile()
    {
        serializationDepth--;
    }

    internal virtual void StartWriteObject(string name)
    {
        serializationDepth++;
    }

	internal virtual void EndWriteObject(string name)
    {
        serializationDepth--;
    }

	internal virtual void StartWriteProperty(string name)
    {
        if (name == null)
            throw new ArgumentNullException("Key or field name cannot be NULL when saving data.");
        ES3Debug.Log("<b>"+name +"</b> (writing property)", null, serializationDepth);
    }

	internal virtual void EndWriteProperty(string name)
    {
    }

    internal virtual void StartWriteCollection()
    {
        serializationDepth++;
    }

    internal virtual void EndWriteCollection()
    {
        serializationDepth--;
    }

    internal abstract void StartWriteCollectionItem(int index);
	internal abstract void EndWriteCollectionItem(int index);

	internal abstract void StartWriteDictionary();
	internal abstract void EndWriteDictionary();
	internal abstract void StartWriteDictionaryKey(int index);
	internal abstract void EndWriteDictionaryKey(int index);
	internal abstract void StartWriteDictionaryValue(int index);
	internal abstract void EndWriteDictionaryValue(int index);

	public abstract void Dispose();

	#endregion

	#region ES3Writer Interface abstract methods

	internal abstract void WriteRawProperty(string name, byte[] bytes);

	internal abstract void WritePrimitive(int value);
	internal abstract void WritePrimitive(float value);
	internal abstract void WritePrimitive(bool value);
	internal abstract void WritePrimitive(decimal value);
	internal abstract void WritePrimitive(double value);
	internal abstract void WritePrimitive(long value);
	internal abstract void WritePrimitive(ulong value);
	internal abstract void WritePrimitive(uint value);
	internal abstract void WritePrimitive(byte value);
	internal abstract void WritePrimitive(sbyte value);
	internal abstract void WritePrimitive(short value);
	internal abstract void WritePrimitive(ushort value);
	internal abstract void WritePrimitive(char value);
	internal abstract void WritePrimitive(string value);
	internal abstract void WritePrimitive(byte[] value);

	#endregion

	protected ES3Writer(ES3Settings settings, bool writeHeaderAndFooter, bool overwriteKeys)
	{
		this.settings = settings;
		this.writeHeaderAndFooter = writeHeaderAndFooter;
		this.overwriteKeys = overwriteKeys;
	}

	/* User-facing methods used when writing randomly-accessible Key-Value pairs. */
	#region Write(key, value) Methods

	internal virtual void Write(string key, Type type, byte[] value)
	{
		StartWriteProperty(key);
		StartWriteObject(key);
		WriteType(type);
		WriteRawProperty("value", value);
		EndWriteObject(key);
        EndWriteProperty(key);
		MarkKeyForDeletion(key);
	}

    /// <summary>Writes a value to the writer with the given key.</summary>
    /// <param name="key">The key which uniquely identifies this value.</param>
    /// <param name="value">The value we want to write.</param>
    public virtual void Write<T>(string key, object value)
    {
        if (typeof(T) == typeof(object))
        {
            if (value == null)
                Write(typeof(System.Object), key, null);
            else
                Write(value.GetType(), key, value);
        }
        else
            Write(typeof(T), key, value);
    }

    /// <summary>Writes a value to the writer with the given key, using the given type rather than the generic parameter.</summary>
    /// <param name="key">The key which uniquely identifies this value.</param>
    /// <param name="value">The value we want to write.</param>
    /// <param name="type">The type we want to use for the header, and to retrieve an ES3Type.</param>
    [System.ComponentModel.EditorBrowsable(System.ComponentModel.EditorBrowsableState.Never)]
	public virtual void Write(Type type, string key, object value)
	{ 
		StartWriteProperty(key);
		StartWriteObject(key);
		WriteType(type);
		WriteProperty("value", value, ES3TypeMgr.GetOrCreateES3Type(type), settings.referenceMode);
		EndWriteObject(key);
        EndWriteProperty(key);
		MarkKeyForDeletion(key);
	}

	#endregion

	#region Write(value) & Write(value, ES3Type) Methods

	/// <summary>Writes a value to the writer. Note that this should only be called within an ES3Type.</summary>
	/// <param name="value">The value we want to write.</param>
	/// <param name="memberReferenceMode">Whether we want to write UnityEngine.Object fields and properties by reference, by value, or both.</param>
	[System.ComponentModel.EditorBrowsable(System.ComponentModel.EditorBrowsableState.Never)]
	public virtual void Write(object value, ES3.ReferenceMode memberReferenceMode = ES3.ReferenceMode.ByRef)
	{
		if(value == null){	WriteNull(); return; }

        var type = ES3TypeMgr.GetOrCreateES3Type(value.GetType());
		Write(value, type, memberReferenceMode);
	}

	[System.ComponentModel.EditorBrowsable(System.ComponentModel.EditorBrowsableState.Never)]
	public virtual void Write(object value, ES3Type type, ES3.ReferenceMode memberReferenceMode = ES3.ReferenceMode.ByRef)
	{
        // Note that we have to check UnityEngine.Object types for null by casting it first, otherwise
        // it will always return false.
        if (value == null || (ES3Reflection.IsAssignableFrom(typeof(UnityEngine.Object), value.GetType()) && value as UnityEngine.Object == null))
        {
            WriteNull();
            return;
        }

        // Deal with System.Objects
        if (type == null || type.type == typeof(object))
        {
            var valueType = value.GetType();
            type = ES3TypeMgr.GetOrCreateES3Type(valueType);

            if(type == null)
                throw new NotSupportedException("Types of " + valueType + " are not supported. Please see the Supported Types guide for more information: https://docs.moodkie.com/easy-save-3/es3-supported-types/");

            if (!type.isCollection && !type.isDictionary)
            {
                StartWriteObject(null);
                WriteType(valueType);

                type.Write(value, this);

                EndWriteObject(null);
                return;
            }
        }

		if(type == null)
			throw new ArgumentNullException("ES3Type argument cannot be null.");
        if (type.isUnsupported)
        {
            if(type.isCollection || type.isDictionary)
                throw new NotSupportedException(type.type + " is not supported because it's element type is not supported. Please see the Supported Types guide for more information: https://docs.moodkie.com/easy-save-3/es3-supported-types/");
            else
                throw new NotSupportedException("Types of " + type.type + " are not supported. Please see the Supported Types guide for more information: https://docs.moodkie.com/easy-save-3/es3-supported-types/");
        }

        if (type.isPrimitive || type.isEnum)
            type.Write(value, this);
        else if (type.isCollection)
        {
            StartWriteCollection();
            ((ES3CollectionType)type).Write(value, this, memberReferenceMode);
            EndWriteCollection();
        }
        else if (type.isDictionary)
        {
            StartWriteDictionary();
            ((ES3DictionaryType)type).Write(value, this, memberReferenceMode);
            EndWriteDictionary();
        }
        else
        {
            if (type.type == typeof(GameObject))
                ((ES3Type_GameObject)type).saveChildren = settings.saveChildren;

            StartWriteObject(null);

            if (type.isES3TypeUnityObject)
                ((ES3UnityObjectType)type).WriteObject(value, this, memberReferenceMode);
            else
                type.Write(value, this);
            EndWriteObject(null);
        }
	}

    internal virtual void WriteRef(UnityEngine.Object obj)
    {
        WriteRef(obj, ES3ReferenceMgrBase.referencePropertyName);
    }

    internal virtual void WriteRef(UnityEngine.Object obj, string propertyName)
    {
        WriteRef(obj, ES3ReferenceMgrBase.referencePropertyName, ES3ReferenceMgrBase.Current);
    }

    internal virtual void WriteRef(UnityEngine.Object obj, string propertyName, ES3ReferenceMgrBase refMgr)
    {
        if (refMgr == null)
            throw new InvalidOperationException($"An Easy Save 3 Manager is required to save references. To add one to your scene, exit playmode and go to Tools > Easy Save 3 > Add Manager to Scene. Object being saved by reference is {obj.GetType()} with name {obj.name}.");

        // Get the reference ID, if it exists, and store it.
        long id = refMgr.Get(obj);
        // If reference ID doesn't exist, create reference.
        if (id == -1)
            id = refMgr.Add(obj);
        WriteProperty(propertyName, id.ToString());
    }

    #endregion

    /* Writes a property as a name value pair. */
    #region WriteProperty(name, value) methods

    /// <summary>Writes a field or property to the writer. Note that this should only be called within an ES3Type.</summary>
    /// <param name="name">The name of the field or property.</param>
    /// <param name="value">The value we want to write.</param>
    public virtual void WriteProperty(string name, object value)
	{
        WriteProperty(name, value, settings.memberReferenceMode);
	}

	/// <summary>Writes a field or property to the writer. Note that this should only be called within an ES3Type.</summary>
	/// <param name="name">The name of the field or property.</param>
	/// <param name="value">The value we want to write.</param>
	/// <param name="memberReferenceMode">Whether we want to write the property by reference, by value, or both.</param>
	public virtual void WriteProperty(string name, object value, ES3.ReferenceMode memberReferenceMode)
	{
        if (SerializationDepthLimitExceeded())
            return;

        StartWriteProperty(name); 
        Write(value, memberReferenceMode); 
        EndWriteProperty(name);
	}

    /// <summary>Writes a field or property to the writer. Note that this should only be called within an ES3Type.</summary>
    /// <param name="name">The name of the field or property.</param>
    /// <param name="value">The value we want to write.</param>
    public virtual void WriteProperty<T>(string name, object value)
    {
        WriteProperty(name, value, ES3TypeMgr.GetOrCreateES3Type(typeof(T)), settings.memberReferenceMode);
    }

    [System.ComponentModel.EditorBrowsable(System.ComponentModel.EditorBrowsableState.Never)]
	public virtual void WriteProperty(string name, object value, ES3Type type)
	{ 
		WriteProperty(name, value, type, settings.memberReferenceMode);
	}

    [System.ComponentModel.EditorBrowsable(System.ComponentModel.EditorBrowsableState.Never)]
	public virtual void WriteProperty(string name, object value, ES3Type type, ES3.ReferenceMode memberReferenceMode)
	{
        if (SerializationDepthLimitExceeded())
            return;

        StartWriteProperty(name); 
        Write(value, type, memberReferenceMode); 
        EndWriteProperty(name);
	}

	[System.ComponentModel.EditorBrowsable(System.ComponentModel.EditorBrowsableState.Never)]
	public virtual void WritePropertyByRef(string name, UnityEngine.Object value)
	{
        if (SerializationDepthLimitExceeded())
            return;

        StartWriteProperty(name);
		if(value == null)
        { 
            WriteNull(); 
            return; };
		StartWriteObject(name);
		WriteRef(value);
		EndWriteObject(name);
		EndWriteProperty(name);
	}

	/// <summary>Writes a private property to the writer. Note that this should only be called within an ES3Type.</summary>
	/// <param name="name">The name of the property.</param>
	/// <param name="objectContainingProperty">The object containing the property we want to write.</param>
	public void WritePrivateProperty(string name, object objectContainingProperty)
	{
		var property = ES3Reflection.GetES3ReflectedProperty(objectContainingProperty.GetType(), name);
		if(property.IsNull)
			throw new MissingMemberException("A private property named "+ name + " does not exist in the type "+objectContainingProperty.GetType());
		WriteProperty(name, property.GetValue(objectContainingProperty), ES3TypeMgr.GetOrCreateES3Type(property.MemberType));
	}

	/// <summary>Writes a private field to the writer. Note that this should only be called within an ES3Type.</summary>
	/// <param name="name">The name of the field.</param>
	/// <param name="objectContainingField">The object containing the property we want to write.</param>
	public void WritePrivateField(string name, object objectContainingField)
	{
		var field = ES3Reflection.GetES3ReflectedMember(objectContainingField.GetType(), name);
		if(field.IsNull)
			throw new MissingMemberException("A private field named "+ name + " does not exist in the type "+objectContainingField.GetType());
		WriteProperty(name,field.GetValue(objectContainingField), ES3TypeMgr.GetOrCreateES3Type(field.MemberType));
	}

	[System.ComponentModel.EditorBrowsable(System.ComponentModel.EditorBrowsableState.Never)]
	public void WritePrivateProperty(string name, object objectContainingProperty, ES3Type type)
	{
		var property = ES3Reflection.GetES3ReflectedProperty(objectContainingProperty.GetType(), name);
		if(property.IsNull)
			throw new MissingMemberException("A private property named "+ name + " does not exist in the type "+objectContainingProperty.GetType());
		WriteProperty(name, property.GetValue(objectContainingProperty), type);
	}

	[System.ComponentModel.EditorBrowsable(System.ComponentModel.EditorBrowsableState.Never)]
	public void WritePrivateField(string name, object objectContainingField, ES3Type type)
	{
		var field = ES3Reflection.GetES3ReflectedMember(objectContainingField.GetType(), name);
		if(field.IsNull)
			throw new MissingMemberException("A private field named "+ name + " does not exist in the type "+objectContainingField.GetType());
		WriteProperty(name,field.GetValue(objectContainingField), type);
	}

	[System.ComponentModel.EditorBrowsable(System.ComponentModel.EditorBrowsableState.Never)]
	public void WritePrivatePropertyByRef(string name, object objectContainingProperty)
	{
		var property = ES3Reflection.GetES3ReflectedProperty(objectContainingProperty.GetType(), name);
		if(property.IsNull)
			throw new MissingMemberException("A private property named "+ name + " does not exist in the type "+objectContainingProperty.GetType());
		WritePropertyByRef(name, (UnityEngine.Object)property.GetValue(objectContainingProperty));
	}

	[System.ComponentModel.EditorBrowsable(System.ComponentModel.EditorBrowsableState.Never)]
	public void WritePrivateFieldByRef(string name, object objectContainingField)
	{
		var field = ES3Reflection.GetES3ReflectedMember(objectContainingField.GetType(), name);
		if(field.IsNull)
			throw new MissingMemberException("A private field named "+ name + " does not exist in the type "+objectContainingField.GetType());
		WritePropertyByRef(name, (UnityEngine.Object)field.GetValue(objectContainingField));
	}

	[System.ComponentModel.EditorBrowsable(System.ComponentModel.EditorBrowsableState.Never)]
	public void WriteType(Type type)
	{
		WriteProperty(ES3Type.typeFieldName, ES3Reflection.GetTypeString(type));
	}

	#endregion

	#region Create methods

	/// <summary>Creates a new ES3Writer.</summary>
	/// <param name="filePath">The relative or absolute path of the file we want to write to.</param>
	/// <param name="settings">The settings we want to use to override the default settings.</param>
	public static ES3Writer Create(string filePath, ES3Settings settings)
	{
		return Create(new ES3Settings(filePath, settings));
	}

	/// <summary>Creates a new ES3Writer.</summary>
	/// <param name="settings">The settings we want to use to override the default settings.</param>
	public static ES3Writer Create(ES3Settings settings)
	{
		return Create(settings, true, true, false);
	}

	// Implicit Stream Methods.
	internal static ES3Writer Create(ES3Settings settings, bool writeHeaderAndFooter, bool overwriteKeys, bool append)
	{
		var stream = ES3Stream.CreateStream(settings, (append ? ES3FileMode.Append : ES3FileMode.Write));
		if(stream == null)
			return null;
		return Create(stream, settings, writeHeaderAndFooter, overwriteKeys);
	}

	// Explicit Stream Methods.

	internal static ES3Writer Create(Stream stream, ES3Settings settings, bool writeHeaderAndFooter, bool overwriteKeys)
	{
		if(stream.GetType() == typeof(MemoryStream))
		{
			settings = (ES3Settings)settings.Clone();
			settings.location = ES3.Location.InternalMS;
		}

		// Get the baseWriter using the given Stream.
		if(settings.format == ES3.Format.JSON)
			return new ES3JSONWriter(stream, settings, writeHeaderAndFooter, overwriteKeys);
        else
			return null;
	}

    #endregion

    /*
     * Checks whether serialization depth limit has been exceeded
     */
    [System.ComponentModel.EditorBrowsable(System.ComponentModel.EditorBrowsableState.Never)]
    protected bool SerializationDepthLimitExceeded()
    {
        if (serializationDepth > settings.serializationDepthLimit)
        {
            ES3Debug.LogWarning("Serialization depth limit of " + settings.serializationDepthLimit + " has been exceeded, indicating that there may be a circular reference.\nIf this is not a circular reference, you can increase the depth by going to Window > Easy Save 3 > Settings > Advanced Settings > Serialization Depth Limit");
            return true;
        }
        return false;
    }

    /*
	 * 	Marks a key for deletion.
	 * 	When merging files, keys marked for deletion will not be included.
	 */
    [System.ComponentModel.EditorBrowsable(System.ComponentModel.EditorBrowsableState.Never)]
	public virtual void MarkKeyForDeletion(string key)
	{
		keysToDelete.Add(key);
	}

	/*
	 * 	Merges the contents of the non-temporary file with this ES3Writer,
	 * 	ignoring any keys which are marked for deletion.
	 */
	protected void Merge()
	{
		using(var reader = ES3Reader.Create(settings))
		{
			if(reader == null)
				return;
			Merge(reader);
		}
	}

	/*
	 * 	Merges the contents of the ES3Reader with this ES3Writer,
	 * 	ignoring any keys which are marked for deletion.
	 */
	protected void Merge(ES3Reader reader)
	{
		foreach(KeyValuePair<string,ES3Data> kvp in reader.RawEnumerator)
			if(!keysToDelete.Contains(kvp.Key) || kvp.Value.type == null) // Don't add keys whose data is of a type which no longer exists in the project.
				Write(kvp.Key, kvp.Value.type.type, kvp.Value.bytes);
	}

	/// <summary>Stores the contents of the writer and overwrites any existing keys if overwriting is enabled.</summary>
	public virtual void Save()
	{
		Save(overwriteKeys);
	}

	/// <summary>Stores the contents of the writer and overwrites any existing keys if overwriting is enabled.</summary>
	/// <param name="overwriteKeys">Whether we should overwrite existing keys.</param>
	public virtual void Save(bool overwriteKeys)
	{
		if(overwriteKeys)
			Merge();
		EndWriteFile();
		Dispose();

		// If we're writing to a location which can become corrupted, rename the backup file to the file we want.
		// This prevents corrupt data.
        if(settings.location == ES3.Location.File || settings.location == ES3.Location.PlayerPrefs)
		    ES3IO.CommitBackup(settings);
	}
}