using System;
using System.Collections.Generic;
using UnityEngine;

namespace XNode
{
    /// <summary> Base class for all node graphs </summary>
    [Serializable]
    public abstract class NodeGraph : ScriptableObject
    {
        /// <summary>
        ///     All nodes in the graph.
        ///     <para />
        ///     See: <see cref="AddNode{T}" />
        /// </summary>
        [SerializeField] public List<Node> nodes = new List<Node>();

        /// <summary> Add a node to the graph by type (convenience method - will call the System.Type version) </summary>
        public T AddNode<T>() where T : Node
        {
            return AddNode(typeof(T)) as T;
        }

        /// <summary> Add a node to the graph by type </summary>
        public virtual Node AddNode(Type type)
        {
            Node.graphHotfix = this;
            Node node = CreateInstance(type) as Node;
            node.graph = this;
            nodes.Add(node);
            return node;
        }

        /// <summary> Creates a copy of the original node in the graph </summary>
        public virtual Node CopyNode(Node original)
        {
            Node.graphHotfix = this;
            Node node = Instantiate(original);
            node.graph = this;
            node.ClearConnections();
            nodes.Add(node);
            return node;
        }

        /// <summary> Safely remove a node and all its connections </summary>
        /// <param name="node"> The node to remove </param>
        public virtual void RemoveNode(Node node)
        {
            node.ClearConnections();
            nodes.Remove(node);
            if (Application.isPlaying)
            {
                Destroy(node);
            }
        }

        /// <summary> Remove all nodes and connections from the graph </summary>
        public virtual void Clear()
        {
            if (Application.isPlaying)
            {
                for (int i = 0; i < nodes.Count; i++)
                {
                    if (nodes[i] != null)
                    {
                        Destroy(nodes[i]);
                    }
                }
            }

            nodes.Clear();
        }

        /// <summary> Create a new deep copy of this graph </summary>
        public virtual NodeGraph Copy()
        {
            // Instantiate a new nodegraph instance
            NodeGraph graph = Instantiate(this);
            // Instantiate all nodes inside the graph
            for (int i = 0; i < nodes.Count; i++)
            {
                if (nodes[i] == null)
                {
                    continue;
                }

                Node.graphHotfix = graph;
                Node node = Instantiate(nodes[i]);
                node.graph = graph;
                graph.nodes[i] = node;
            }

            // Redirect all connections
            for (int i = 0; i < graph.nodes.Count; i++)
            {
                if (graph.nodes[i] == null)
                {
                    continue;
                }

                foreach (NodePort port in graph.nodes[i].Ports)
                {
                    port.Redirect(nodes, graph.nodes);
                }
            }

            return graph;
        }

        protected virtual void OnDestroy()
        {
            // Remove all nodes prior to graph destruction
            Clear();
        }

        #region Attributes

        /// <summary> Automatically ensures the existance of a certain node type, and prevents it from being deleted. </summary>
        [AttributeUsage(AttributeTargets.Class, AllowMultiple = true)]
        public class RequireNodeAttribute : Attribute
        {
            public Type type0;
            public Type type1;
            public Type type2;

            /// <summary> Automatically ensures the existance of a certain node type, and prevents it from being deleted </summary>
            public RequireNodeAttribute(Type type)
            {
                type0 = type;
                type1 = null;
                type2 = null;
            }

            /// <summary> Automatically ensures the existance of a certain node type, and prevents it from being deleted </summary>
            public RequireNodeAttribute(Type type, Type type2)
            {
                type0 = type;
                type1 = type2;
                this.type2 = null;
            }

            /// <summary> Automatically ensures the existance of a certain node type, and prevents it from being deleted </summary>
            public RequireNodeAttribute(Type type, Type type2, Type type3)
            {
                type0 = type;
                type1 = type2;
                this.type2 = type3;
            }

            public bool Requires(Type type)
            {
                if (type == null)
                {
                    return false;
                }

                if (type == type0)
                {
                    return true;
                }

                if (type == type1)
                {
                    return true;
                }

                if (type == type2)
                {
                    return true;
                }

                return false;
            }
        }

        #endregion
    }
}