using FarseerPhysics.Common;
using FarseerPhysics.Common.PolygonManipulation;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Graphics;
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Voronoi2;

namespace Barotrauma.RuinGeneration
{
    abstract class RuinShape
    {
        protected Rectangle rect;

        public Rectangle Rect
        {
            get { return rect; }
        }


        public int DistanceFromEntrance
        {
            get;
            protected set;
        }

        public List<Line> Walls;

        public virtual void CreateWalls() { }

        public Alignment GetLineAlignment(Line line)
        {
            if (line.A.Y == line.B.Y)
            {
                if (line.A.Y > rect.Center.Y && line.B.Y > rect.Center.Y)
                {
                    return Alignment.Bottom;
                }
                else if (line.A.Y < rect.Center.Y && line.B.Y < rect.Center.Y)
                {
                    return Alignment.Top;
                }
            }
            else
            {
                if (line.A.X < rect.Center.X && line.B.X < rect.Center.X)
                {
                    return Alignment.Left;
                }
                else if (line.A.X > rect.Center.X && line.B.X > rect.Center.X)
                {
                    return Alignment.Right;
                }
            }

            return Alignment.Center;
        }

         /// <summary>
        /// Goes through a list of line segments and "clips off" all parts of the lines that are inside the rectangle
        /// </summary>
        public void SplitLines(Rectangle rectangle)
        {
            List<Line> newLines = new List<Line>();

            foreach (Line line in Walls)
            {
                if (line.A.X == line.B.X) //vertical line
                {
                    //line doesn't intersect the rectangle
                    if (rectangle.X > line.A.X || rectangle.Right < line.A.X ||
                        rectangle.Y > line.B.Y || rectangle.Bottom < line.A.Y)
                    {
                        newLines.Add(line);
                    }
                    else if (line.A.Y > rectangle.Y && line.B.Y < rectangle.Bottom)
                    {
                        continue;
                    }
                    //point A is within the rectangle -> cut a portion from the top of the line
                    else if (line.A.Y >= rectangle.Y && line.A.Y <= rectangle.Bottom)
                    {
                        newLines.Add(new Line(new Vector2(line.A.X, rectangle.Bottom), line.B, line.Type));
                    }
                    //point B is within the rectangle -> cut a portion from the bottom of the line
                    else if (line.B.Y >= rectangle.Y && line.B.Y <= rectangle.Bottom)
                    {
                        newLines.Add(new Line(line.A, new Vector2(line.A.X, rectangle.Y), line.Type));
                    }
                    //rect is in between the lines -> split the line into two
                    else
                    {
                        newLines.Add(new Line(line.A, new Vector2(line.A.X, rectangle.Y), line.Type));
                        newLines.Add(new Line(new Vector2(line.A.X, rectangle.Bottom), line.B, line.Type));
                    }
                }
                else if (line.A.Y == line.B.Y) //horizontal line
                {
                    //line doesn't intersect the rectangle
                    if (rectangle.X > line.B.X || rectangle.Right < line.A.X ||
                        rectangle.Y > line.A.Y || rectangle.Bottom < line.A.Y)
                    {

                        newLines.Add(line);
                    }
                    else if (line.A.X > rectangle.X && line.B.X < rectangle.Right)
                    {
                        continue;
                    }
                    //point A is within the rectangle -> cut a portion from the left side of the line
                    else if (line.A.X >= rectangle.X && line.A.X <= rectangle.Right)
                    {
                        newLines.Add(new Line(new Vector2(rectangle.Right, line.A.Y), line.B, line.Type));
                    }
                    //point B is within the rectangle -> cut a portion from the right side of the line
                    else if (line.B.X >= rectangle.X && line.B.X <= rectangle.Right)
                    {
                        newLines.Add(new Line(line.A, new Vector2(rectangle.X, line.A.Y), line.Type));
                    }
                    //rect is in between the lines -> split the line into two
                    else
                    {
                        newLines.Add(new Line(line.A, new Vector2(rectangle.X, line.A.Y), line.Type));
                        newLines.Add(new Line(new Vector2(rectangle.Right, line.A.Y), line.B, line.Type));
                    }
                }
                else
                {
                    DebugConsole.ThrowError("Error in StructureGenerator.SplitLines - lines must be axis aligned");
                }

            }

            Walls = newLines;
        }
    }

        struct Line
        {
            public readonly Vector2 A, B;

            public readonly RuinStructureType Type;

            public Line(Vector2 a, Vector2 b, RuinStructureType type)
            {
                Debug.Assert(a.X <= b.X);
                Debug.Assert(a.Y <= b.Y);

                A = a;
                B = b;
                Type = type;
            }
        }  

    class Ruin
    {
        private List<BTRoom> rooms;
        private List<Corridor> corridors;

        private List<Line> walls;

        private List<RuinShape> allShapes;

        public List<RuinShape> RuinShapes
        {
            get { return allShapes; }
        }

        public Rectangle Area
        {
            get;
            private set;
        }

        public Ruin(VoronoiCell closestPathCell, List<VoronoiCell> caveCells, Rectangle area)
        {
            Area = area;

            corridors = new List<Corridor>();
            rooms = new List<BTRoom>();

            walls = new List<Line>();

            allShapes = new List<RuinShape>();

            Generate(closestPathCell, caveCells, area);
        }
             
        public void Generate(VoronoiCell closestPathCell, List<VoronoiCell> caveCells, Rectangle area)
        {
            corridors.Clear();
            rooms.Clear();

            //area = new Rectangle(area.X, area.Y - area.Height, area.Width, area.Height);

            int iterations = Rand.Range(3, 4, false);

            float verticalProbability = Rand.Range(0.4f, 0.6f, false);
            
            BTRoom baseRoom = new BTRoom(area);

            rooms = new List<BTRoom> { baseRoom };

            for (int i = 0; i < iterations; i++)
            {
                rooms.ForEach(l => l.Split(0.3f, verticalProbability));

                rooms = baseRoom.GetLeaves();
            }

            foreach (BTRoom leaf in rooms)
            {
                leaf.Scale
                    (
                        new Vector2(Rand.Range(0.5f, 0.9f, false), Rand.Range(0.5f, 0.9f, false))
                    );
            }
            
            baseRoom.GenerateCorridors(200, 256, corridors);

            walls = new List<Line>();

            rooms.ForEach(leaf => 
            { 
                leaf.CreateWalls();
                //walls.AddRange(leaf.Walls); 
            });

            //---------------------------

            BTRoom entranceRoom = null;
            float shortestDistance = 0.0f;
            foreach (BTRoom leaf in rooms)
            {
                float distance = Vector2.Distance(leaf.Rect.Center.ToVector2(), closestPathCell.Center);
                if (entranceRoom == null || distance < shortestDistance)
                {
                    entranceRoom = leaf;
                    shortestDistance = distance;
                }
            }

            rooms.Remove(entranceRoom);

            //var startCell = closestPathCell;

            //Rectangle startCellRect = new Rectangle(
            //    (int)startCell.edges.Min(e => Math.Min(e.point1.X, e.point2.X)),
            //    (int)startCell.edges.Min(e => Math.Min(e.point1.Y, e.point2.Y)),
            //    (int)startCell.edges.Max(e => Math.Max(e.point1.X, e.point2.X)),
            //    (int)startCell.edges.Max(e => Math.Max(e.point1.Y, e.point2.Y)));

            //startCellRect.Width = startCellRect.Width - startCellRect.X;
            //startCellRect.Height = startCellRect.Height - startCellRect.Y;

            //int startX = Math.Min(entranceRoom.Rect.Center.X, startCellRect.Center.X);
            //int endX = Math.Max(entranceRoom.Rect.Right, startCellRect.Right);

            //int startY = Math.Min(entranceRoom.Rect.Center.Y, startCellRect.Center.Y);
            //int endY = Math.Max(entranceRoom.Rect.Bottom, startCellRect.Bottom);

            //if (entranceRoom.Rect.X > startCellRect.X && entranceRoom.Rect.Right < startCellRect.Right)
            //{
            //    corridors.Add(new Corridor(new Rectangle(entranceRoom.Rect.Center.X, startY, 128, endY - startY)));
            //}
            //else if (entranceRoom.Rect.Y > startCellRect.Y && entranceRoom.Rect.Bottom < startCellRect.Bottom)
            //{
            //    corridors.Add(new Corridor(new Rectangle(startX, entranceRoom.Rect.Center.Y, endX - startX, 128)));
            //}
            //else
            //{
            //    corridors.Add(new Corridor(new Rectangle(startX, entranceRoom.Rect.Center.Y, endX - startX, 128)));
            //    corridors.Add(new Corridor(new Rectangle(endX, startY, 128, endY - startY)));
            //}

            //---------------------------

            foreach (BTRoom leaf in rooms)
            {
                foreach (Corridor corridor in corridors)
                {
                    leaf.SplitLines(corridor.Rect);
                }

                walls.AddRange(leaf.Walls);
            }


            foreach (Corridor corridor in corridors)
            {
                List<Line> corridorWalls = new List<Line>();
                
                corridor.CreateWalls();

                foreach (BTRoom leaf in rooms)
                {
                    corridor.SplitLines(leaf.Rect);
                }

                foreach (Corridor corridor2 in corridors)
                {
                    if (corridor == corridor2) continue;
                    corridor.SplitLines(corridor2.Rect);
                }


                walls.AddRange(corridor.Walls);
            }

            //leaves.Remove(entranceRoom);

            BTRoom.CalculateDistancesFromEntrance(entranceRoom, corridors);

            allShapes = GenerateStructures(caveCells);
        }

        private List<RuinShape> GenerateStructures(List<VoronoiCell> caveCells)
        {
            List<RuinShape> shapes = new List<RuinShape>(rooms);
            shapes.AddRange(corridors);

            //MapEntityPrefab hullPrefab = MapEntityPrefab.list.Find(m => m.Name == "Hull");

            foreach (RuinShape leaf in shapes)
            {
                foreach (Line wall in leaf.Walls)
                {
                    var structurePrefab = RuinStructure.GetRandom(leaf is BTRoom ? RuinStructureType.Wall : RuinStructureType.CorridorWall, leaf.GetLineAlignment(wall));
                    if (structurePrefab == null) continue;

                    float radius = (wall.A.X == wall.B.X) ? (structurePrefab.Prefab as StructurePrefab).Size.X * 0.5f : (structurePrefab.Prefab as StructurePrefab).Size.Y * 0.5f;

                    Rectangle rect = new Rectangle(
                        (int)(wall.A.X - radius), 
                        (int)(wall.B.Y + radius), 
                        (int)((wall.B.X - wall.A.X) + radius*2.0f), 
                        (int)((wall.B.Y - wall.A.Y) + radius*2.0f));

                    var structure = new Structure(rect, structurePrefab.Prefab as StructurePrefab, null);
                    structure.MoveWithLevel = true;
                    structure.SetCollisionCategory(Physics.CollisionLevel);
                }


                var background = RuinStructure.GetRandom(RuinStructureType.Back, Alignment.Center);
                if (background == null) continue;

                Rectangle backgroundRect = new Rectangle(leaf.Rect.X, leaf.Rect.Y + leaf.Rect.Height, leaf.Rect.Width, leaf.Rect.Height);

                new Structure(backgroundRect, (background.Prefab as StructurePrefab), null).MoveWithLevel = true;

            }

            for (int i = 0; i < shapes.Count*2; i++ )
            {
                Alignment[] alignments = new Alignment[] { Alignment.Top, Alignment.Bottom, Alignment.Right, Alignment.Left, Alignment.Center };

                var prop = RuinStructure.GetRandom(RuinStructureType.Prop, alignments[Rand.Int(alignments.Length, false)]);

                Vector2 size = (prop.Prefab is StructurePrefab) ? (prop.Prefab as StructurePrefab).Size : Vector2.Zero;

                var shape = shapes[Rand.Int(shapes.Count, false)];

                Vector2 position = shape.Rect.Center.ToVector2();
                if (prop.Alignment.HasFlag(Alignment.Top))
                {
                    position = new Vector2(Rand.Range(shape.Rect.X+size.X, shape.Rect.Right - size.X, false), shape.Rect.Bottom - 64);
                }
                else if (prop.Alignment.HasFlag(Alignment.Bottom))
                {
                    position = new Vector2(Rand.Range(shape.Rect.X + size.X, shape.Rect.Right - size.X, false), shape.Rect.Top + 64);
                }
                else if (prop.Alignment.HasFlag(Alignment.Right))
                {
                    position = new Vector2(shape.Rect.Right - 64, Rand.Range(shape.Rect.Y + size.X, shape.Rect.Bottom - size.Y, false));
                }
                else if (prop.Alignment.HasFlag(Alignment.Left))
                {
                    position = new Vector2(shape.Rect.X + 64, Rand.Range(shape.Rect.Y + size.X, shape.Rect.Bottom - size.Y, false));
                }

                if (prop.Prefab is ItemPrefab)
                {
                    var item = new Item(prop.Prefab as ItemPrefab, position, null);
                    item.MoveWithLevel = true;
                }
                else
                {
                    new Structure(new Rectangle(
                        (int)(position.X - size.X/2.0f), (int)(position.Y + size.Y/2.0f),
                        (int)size.X, (int)size.Y),
                        prop.Prefab as StructurePrefab, null).MoveWithLevel = true;
                }
            }

            return shapes;
        }
                
        public void Draw(SpriteBatch spriteBatch)
        {
            //foreach (BTRoom room in leaves)
            //{
            //    GUI.DrawRectangle(spriteBatch, room.Rect, Color.White);
            //}

            //foreach (Corridor corr in corridors)
            //{
            //    GUI.DrawRectangle(spriteBatch, corr.Rect, Color.Blue);
            //}

            foreach (Line line in walls)
            {
                GUI.DrawLine(spriteBatch, new Vector2(line.A.X, -line.A.Y), new Vector2(line.B.X, -line.B.Y), Color.Red, 0.0f, 10);
            }
        }

    }
}