using System.Collections;
using System.Collections.Generic;
using GeoAPI.Geometries;

namespace GisSharpBlog.NetTopologySuite.Planargraph
{
    /// <summary>
    /// A map of <see cref="Node">nodes</see>, indexed by the coordinate of the node.
    /// </summary>   
    public class NodeMap
    {
        private readonly IDictionary nodeMap = new Dictionary<ICoordinate, Node>();

        /// <summary>
        /// Returns the Nodes in this NodeMap, sorted in ascending order
        /// by angle with the positive x-axis.
        /// </summary>
        public ICollection Values
        {
            get
            {
                return nodeMap.Values;
            }
        }

        /// <summary>
        /// Returns the number of Nodes in this NodeMap.
        /// </summary>
        public int Count
        {
            get
            {
                return nodeMap.Count;
            }
        }

        /// <summary>
        /// Adds a node to the map, replacing any that is already at that location.
        /// </summary>
        /// <param name="n"></param>
        /// <returns>The added node.</returns>
        public Node Add(Node n)
        {
            nodeMap[n.Coordinate] = n;
            return n;
        }

        /// <summary>
        /// Removes the Node at the given location, and returns it (or null if no Node was there).
        /// </summary>
        /// <param name="pt"></param>
        /// <returns></returns>
        public Node Remove(ICoordinate pt)
        {
            Node node = (Node) nodeMap[pt];
            nodeMap.Remove(pt);
            return node;
        }

        /// <summary>
        /// Returns the Node at the given location, or null if no Node was there.
        /// </summary>
        /// <param name="coord"></param>
        /// <returns></returns>
        public Node Find(ICoordinate coord)
        {
            return (Node) nodeMap[coord];
        }

        /// <summary>
        /// Returns an Iterator over the Nodes in this NodeMap, sorted in ascending order
        /// by angle with the positive x-axis.
        /// </summary>
        public IEnumerator GetEnumerator()
        {
            return nodeMap.Values.GetEnumerator();
        }
    }
}