// Shatter Toolkit
// Copyright 2015 Gustav Olsson
using System.Collections.Generic;
using UnityEngine;

namespace ShatterToolkit.Examples
{
    public class OutlineCreator : MonoBehaviour
    {
        protected List<Vector3> points = new List<Vector3>();
        protected List<int> edges = new List<int>();
        protected List<int> triangles = new List<int>();
        protected List<int> triangleEdges = new List<int>();
        
        protected bool isTriangulated = false;
        protected bool isLoopClosed = false;
        protected int loopStart = 0;
        
        public int LoopPointCount
        {
            get { return points.Count - loopStart; }
        }
        
        public void Reset()
        {
            points.Clear();
            edges.Clear();
            triangles.Clear();
            triangleEdges.Clear();
            
            isTriangulated = false;
            isLoopClosed = false;
            loopStart = 0;
        }
        
        public void Update()
        {
            if (Input.GetMouseButtonDown(0))
            {
                if (isTriangulated)
                {
                    Reset();
                }
                
                // Add the mouse world position to the list of points
                Vector3 screenPosition = new Vector3(Input.mousePosition.x, Input.mousePosition.y, 10.0f);
                Vector3 worldPosition = Camera.main.ScreenToWorldPoint(screenPosition);
                
                points.Add(worldPosition);
                
                // Add an edge from the previous point to the new point
                if (LoopPointCount >= 2)
                {
                    edges.Add(points.Count - 2);
                    edges.Add(points.Count - 1);
                }
                
                // Set flag
                isLoopClosed = false;
            }
            else if (Input.GetMouseButtonDown(1))
            {
                if (LoopPointCount >= 3)
                {
                    // Add the last edge to close the current loop
                    edges.Add(points.Count - 1);
                    edges.Add(loopStart);
                    
                    // Set flag
                    isLoopClosed = true;
                    
                    // Start a new loop
                    loopStart = points.Count;
                }
            }
            
            if (Input.GetKeyDown(KeyCode.Space))
            {
                if (!isTriangulated && isLoopClosed)
                {
                    // Triangulate
                    int[] newEdges, newTriangles, newTriangleEdges;
                    
                    ITriangulator triangulator = new Triangulator(points, edges, Vector3.up);
                    
                    triangulator.Fill(out newEdges, out newTriangles, out newTriangleEdges);
                    
                    // Add the new edges and triangles
                    edges.AddRange(newEdges);
                    
                    triangles.AddRange(newTriangles);
                    
                    triangleEdges.AddRange(newTriangleEdges);
                    
                    // Set flag
                    isTriangulated = true;
                }
            }
        }
        
        public void OnGUI()
        {
            GUI.Box(new Rect(0, 0, 500, 100),   "Please turn on Gizmos!\n" +
                                                "Create an outline by left-clicking in a clockwise order on the screen.\n" +
                                                "Right-click to close a loop.\n" +
                                                "Create a hole by left-clicking in a counter-clockwise order inside a shape.\n" +
                                                "Be careful not to overlap edges.\n" +
                                                "Press SPACE to triangulate the closed loops!");
        }
        
        public void OnDrawGizmos()
        {
            Gizmos.color = Color.black;
            
            // Draw points
            for (int i = 0; i < points.Count; i++)
            {
                Gizmos.DrawSphere(points[i], 0.1f);
            }
            
            // Draw edges
            for (int i = 0; i < edges.Count / 2; i++)
            {
                int edge = i * 2;
                
                Gizmos.DrawLine(points[edges[edge + 0]], points[edges[edge + 1]]);
            }
            
            // Draw triangles
            for (int i = 0; i < triangles.Count / 3; i++)
            {
                int triangle = i * 3;
                
                Vector3 center = (points[triangles[triangle + 0]] + points[triangles[triangle + 1]] + points[triangles[triangle + 2]]) / 3.0f;
                
                // Draw a red line from the triangle center to first triangle edge
                Gizmos.color = Color.red;
                
                Gizmos.DrawLine(center, (points[edges[triangleEdges[triangle + 0] * 2 + 0]] + points[edges[triangleEdges[triangle + 0] * 2 + 1]]) * 0.5f);
                
                // Draw a green line from the triangle center to the second triangle edge
                Gizmos.color = Color.green;
                
                Gizmos.DrawLine(center, (points[edges[triangleEdges[triangle + 1] * 2 + 0]] + points[edges[triangleEdges[triangle + 1] * 2 + 1]]) * 0.5f);
                
                // Draw a blue line from the triangle center to the third triangle edge
                Gizmos.color = Color.blue;
                
                Gizmos.DrawLine(center, (points[edges[triangleEdges[triangle + 2] * 2 + 0]] + points[edges[triangleEdges[triangle + 2] * 2 + 1]]) * 0.5f);
            }
        }
    }
}