using System;
using System.Collections.Generic;

namespace SchematicDrawing
{
    public class Graph
    {
        IList<GNode> nodes;
        GNode currentNode;

        public Graph()
        {
            nodes = new List<GNode>();
        }

        public void Clear()
        {
            nodes.Clear();
        }

        /// <summary>
        /// Add a node to the list of graph nodes
        /// </summary>
        /// <param name="node">Graph node</param>
        public void AddNode(GNode node)
        {
            nodes.Add(node);
        }

        /// <summary>
        /// Add an edge to the list of edges of node1.
        /// </summary>
        /// <param name="node1">Node 1 (start)</param>
        /// <param name="node2">NOde 2 (end)</param>
        /// <param name="defaultDist">Default distance (when closed)</param>
        /// <param name="routeCouple">Way the route affects this edge</param>
        /// <returns>Added graph edge</returns>
        public GEdge AddEdge(GNode node1, GNode node2, int defaultDist, RouteCouple routeCouple = RouteCouple.None)
        {
            GEdge gedge = new GEdge(node1, node2, defaultDist, routeCouple);
            node1.AddEdge(gedge);
            return gedge;
        }

        /// <summary>
        /// Run Dijkstra shortest path algorithm to determine schematic drawing coloring
        /// </summary>
        /// <param name="startNode">Start node</param>
        /// <param name="secondaryStartNodes">List of secondary start nodes</param>
        public void RunDijkstraAlgo(GNode startNode, IList<GNode> secondaryStartNodes = null)
        {
            if (nodes == null || startNode == null || !nodes.Contains(startNode)) return;

            /// Reset all nodes
            foreach (var node in nodes) node.Reset();

            startNode.Dist = 0;
            if (secondaryStartNodes != null) foreach (var ssn in secondaryStartNodes) ssn.Dist = 10000;
            currentNode = startNode;

            int minDistance = int.MaxValue;
            do
            {
                /// Consider all unvisited neighbors of the current node
                foreach (var e in currentNode.Edges)
                {
                    int distViaCurrNode = (e.Dist == int.MaxValue) ? int.MaxValue : currentNode.Dist + e.Dist;
                    if (!e.EndNode.Visited && distViaCurrNode < e.EndNode.Dist)
                    {
                        e.EndNode.Dist = distViaCurrNode;
                    }
                }
                currentNode.Visited = true;

                /// Find new current node from all unvisited nodes
                currentNode = null;
                minDistance = int.MaxValue;
                foreach (var n in nodes)
                {
                    if (!n.Visited && n.Dist < minDistance)
                    {
                        minDistance = n.Dist;
                        currentNode = n;
                    }
                }
            }
            while (minDistance < int.MaxValue && currentNode != null);
        }
    }
}