using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using TransportGame.Business;
using TransportGame.Model;
using TransportGame.Model.Road;
using TransportGame.Utils;

namespace TransportGame.Generator
{
    public class BuildingGenerator
    {
        Random random = new Random();

        private float LotSquareMinSize { get { return ConfigManager.Buildgen.LotSquareMinSize; } }
        private float LotSquareMaxSize { get { return ConfigManager.Buildgen.LotSquareMaxSize; } }
        private float LotSpacing { get { return ConfigManager.Buildgen.LotSpacing; } }

        private Map map;
        QuadTree<RoadNode> nodeTree;
        QuadTree<BuildingLot> lotTree;

        private void AllocateLots()
        {
            // Generate lots for every segment
            foreach (var pair in map.RoadNetwork.ArticulationSegments)
            {
                bool didSomething;
                var segment = pair.Value;
                var dir = segment.Direction;
                var perp = dir.RotateDeg(90);

                float width0 = ConfigManager.Roadgen.SidewalkWidth + ConfigManager.Roadgen.LaneWidth * segment.LanesTo1;
                float width1 = ConfigManager.Roadgen.SidewalkWidth + ConfigManager.Roadgen.LaneWidth * segment.LanesTo2;

                Vector2 start = segment.Terminal1.Position;
                Vector2 end = segment.Terminal2.Position;
                Vector2 posL = start, posR = start, nposL, nposR;
                int attempts = 0;

                do
                {
                    didSomething = false;
                    float sizeL = random.NextSingle(LotSquareMinSize, LotSquareMaxSize), sizeR = random.NextSingle(LotSquareMinSize, LotSquareMaxSize);
                    nposL = posL + dir * sizeL;
                    nposR = posR + dir * sizeR;

                    // Left side
                    if ((posL - end).LengthSq >= sizeL * sizeL)
                    {
                        didSomething = true;

                        // Build lot squares
                        Vector2[] left = new Vector2[4];
                        left[0] = posL + perp * (width0 + LotSpacing + sizeL);
                        left[1] = posL + perp * (width0 + LotSpacing);
                        left[2] = nposL + perp * (width0 + LotSpacing);
                        left[3] = nposL + perp * (width0 + LotSpacing + sizeL);

                        BuildingLot lot = new BuildingLot(sizeL, left);

                        if (CanAllocate(posL, lot))
                            lotTree.Add(lot);

                        // Advance
                        posL = nposL;
                    }

                    // Right side
                    if ((posR - end).LengthSq >= sizeR * sizeR)
                    {
                        didSomething = true;
                        
                        // Build lot squares
                        Vector2[] right = new Vector2[4];
                        right[0] = posR - perp * (width1 + LotSpacing + sizeR);
                        right[1] = posR - perp * (width1 + LotSpacing);
                        right[2] = nposR - perp * (width1 + LotSpacing);
                        right[3] = nposR - perp * (width1 + LotSpacing + sizeR);

                        BuildingLot lot = new BuildingLot(sizeR, right);

                        if (CanAllocate(posL, lot))
                            lotTree.Add(lot);

                        // Advance
                        posR = nposR;
                    }

                    if (!didSomething)
                        attempts++;

                } while (attempts < ConfigManager.Buildgen.MaxLotAttempts);
            }

            // Done
            map.BuildingLots = lotTree.ToList();
        }

        private bool CanAllocate(Vector2 pos, BuildingLot lot0)
        {
            if (lot0.Points.Any(p => !lotTree.Boundary.Contains(p)))
                return false;

            // Test other lots
            Rectangle lotArea = new Rectangle(
                pos.X - 2f * LotSquareMaxSize, 
                pos.Y - 2f * LotSquareMaxSize,
                pos.X + 2f * LotSquareMaxSize,
                pos.Y + 2f * LotSquareMaxSize);

            foreach (var lot in lotTree.Query(lotArea))
            {
                if (BuildingLot.DoesIntersect(lot0, lot))
                    return false;
            }

            // Test nearby roads
            Rectangle roadArea = new Rectangle(
                pos.X - 1.1f * ConfigManager.Roadgen.HighwaySegmentLength,
                pos.Y - 1.1f * ConfigManager.Roadgen.HighwaySegmentLength,
                pos.X + 1.1f * ConfigManager.Roadgen.HighwaySegmentLength,
                pos.Y + 1.1f * ConfigManager.Roadgen.HighwaySegmentLength);

            foreach (var node in nodeTree.Query(roadArea))
            {
                foreach (var segment in node.ArticulationSegments)
                {
                    if (BuildingLot.DoesIntersect(lot0, segment.AsLineSegment()))
                        return false;
                }
                
            }

            return true;
        }

        private void GenerateBuildings()
        {
            foreach (var lot in map.BuildingLots)
                map.Buildings.Add(GenerateBuilding(lot));
        }

        Polygon GeneratePrimitivePolygon(BuildingLot lot)
        {
            List<Vector2> points = new List<Vector2>();
            int sides = random.Next(4, 7);                    // Number of sides
            float angle = 2 * (float)Math.PI / sides;         // Angle between sides
            bool ok;

            do
            {
                // Reset
                ok = true;
                points.Clear();

                // Generate radius, start position and direction
                float radius = random.NextSingle(lot.Size * 0.25f, lot.Size * 0.5f);  // Length of a side
                Vector2 current = lot.Position + new Vector2(random.NextSingle(-lot.Size / 2, lot.Size / 2), random.NextSingle(-lot.Size / 2, lot.Size / 2));
                Vector2 dir = new Vector2(random.NextSingle(), random.NextSingle()).Normalized * radius;

                // Generate polygon
                for (int i = 0; i < sides; i++)
                {
                    points.Add(current);

                    // Make sure every point is inside
                    if (!lot.IsInside(current))
                    {
                        ok = false;
                        break;
                    }

                    current = current + dir;
                    dir = dir.Rotate(angle);
                }
            } while (!ok);
            
            return new Polygon(points);
        }

        private Building GenerateBuilding(BuildingLot lot)
        {
            Building b = new Building();

            int levelCount = random.Next(1, ConfigManager.Buildgen.MaxBuildingLevels);
            b.LevelHeights = new float[levelCount];
            b.Polygons = new Polygon[levelCount][];

            for (int i = levelCount - 1; i >= 0; --i)
            {
                List<Polygon> polys = new List<Polygon>();
                
                for (int j = 0; j < 1 + random.Next(ConfigManager.Buildgen.MaxPolygonsPerLevel); j++)
                    polys.Add(GeneratePrimitivePolygon(lot));

                if (i + 1 < levelCount)
                {
                    polys.AddRange(b.Polygons[i + 1]);
                    b.LevelHeights[i] = random.NextSingle(0, b.LevelHeights[i + 1]);
                }
                else
                {
                    b.LevelHeights[i] = random.NextSingle(ConfigManager.Buildgen.MinBuildingHeight, ConfigManager.Buildgen.MaxBuildingHeight) * map.GetPopulation(lot.Position);
                }

                for (int j = 0; j < random.Next(ConfigManager.Buildgen.MaxPolygonsPerLevel); j++)
                    polys.Add(GeneratePrimitivePolygon(lot));

                b.Polygons[i] = polys.ToArray();
            }

            return b;
        }

        public void Generate(Map map)
        {
            this.map = map;
            map.Buildings = new List<Building>();
            
            // Construct node tree
            nodeTree = new QuadTree<RoadNode>(0, 0, map.Width, map.Height);
            foreach (var pair in map.RoadNetwork.Nodes)
                nodeTree.Add(pair.Value);

            lotTree = new QuadTree<BuildingLot>(0, 0, map.Width, map.Height);

            // Allocate lots
            AllocateLots();

            GenerateBuildings();
        }
    }
}