//$ Copyright 2015-22, Code Respawn Technologies Pvt Ltd - All Rights Reserved $//
using System.Collections.Generic;

namespace DungeonArchitect.Builders.Grid
{
    public class GridBuilderUtils
    {
        public static bool IsCorridor(CellType type)
        {
            return type == CellType.Corridor || type == CellType.CorridorPadding;
        }

        public static bool IsRoomCorridor(CellType typeA, CellType typeB)
        {
            return (typeA == CellType.Room && IsCorridor(typeB))
                || (typeB == CellType.Room && IsCorridor(typeA));
        }


        public static void GetRoomConnectionPointsForTiledMode(Rectangle bounds, ref List<IntVector> positions, bool skipCornersOnPathSelection)
        {
            int sx = bounds.X;
            int ex = bounds.X + bounds.Width;
            int sz = bounds.Z;
            int ez = bounds.Z + bounds.Length;
            if (skipCornersOnPathSelection)
            {
                sx++; sz++;
                ex--; ez--;
            }

            for (int x = sx; x < ex; x++)
            {
                positions.Add(new IntVector(x, 0, bounds.Z - 1));
                positions.Add(new IntVector(x, 0, bounds.Z + bounds.Length));
            }

            for (int z = sz; z < ez; z++)
            {
                positions.Add(new IntVector(bounds.X - 1, 0, z));
                positions.Add(new IntVector(bounds.X + bounds.Width, 0, z));
            }
        }


        public static bool AreAdjacentCellsReachable(GridDungeonModel gridModel, int cellIdA, int cellIdB)
        {
            var cellA = gridModel.GetCell(cellIdA);
            var cellB = gridModel.GetCell(cellIdB);

            if (cellA == null || cellB == null)
            {
                return false;
            }


            // If any one is a room, make sure we have a door between them
            if (cellA.CellType == CellType.Room || cellB.CellType == CellType.Room)
            {
                if (!gridModel.DoorManager.ContainsDoorBetweenCells(cellIdA, cellIdB))
                {
                    // We don't have a door between them and is blocked by a room wall
                    return false;
                }
            }

            // if their height is different, make sure we have a stair between them
            if (cellA.Bounds.Location.y != cellB.Bounds.Location.y)
            {
                if (!gridModel.ContainsStair(cellIdA, cellIdB))
                {
                    // Height difference with no stairs. not reachable
                    return false;
                }
            }

            // reachable
            return true;
        }

        /// <summary>
        /// Finds all the nearby tiles that belong to the same cluster
        /// </summary>
        /// <param name="gridModel"></param>
        /// <param name="corridorTileCellId"></param>
        /// <returns></returns>
        public static int[] GetCellCluster(GridDungeonModel gridModel, int sampleCellId)
        {
            var clusters = new List<int>();

            // Check if we are in a room.  Rooms don't need to be clustered as they form a single group
            var startCell = gridModel.GetCell(sampleCellId);
            if (startCell == null || startCell.CellType == CellType.Room)
            {
                clusters.Add(sampleCellId);
                return clusters.ToArray();
            }

            var visited = new HashSet<int>();
            var stack = new Stack<int>();
            stack.Push(sampleCellId);

            while (stack.Count > 0)
            {
                var topId = stack.Pop();
                if (visited.Contains(topId)) continue;
                visited.Add(topId);

                var top = gridModel.GetCell(topId);
                if (top == null) continue;
                if (top.CellType == CellType.Unknown || top.CellType == CellType.Room) continue;

                if (IsCorridor(top.CellType))
                {
                    clusters.Add(topId);
                }

                // search adjacent cells
                foreach (var adjacentId in top.AdjacentCells)
                {
                    // make sure the adjacent cell is reachable
                    if (AreAdjacentCellsReachable(gridModel, topId, adjacentId))
                    {
                        stack.Push(adjacentId);
                    }
                }
            }
            
            return clusters.ToArray();
        }

        public static void GetAdjacentCorridors(GridDungeonModel gridModel, int startCellId, ref List<int> OutConnectedCorridors, ref List<int> OutConnectedRooms)
        {
            OutConnectedCorridors.Clear();
            OutConnectedRooms.Clear();

            // search all nearby cells till we reach a dead end (or a room)
            var visited = new HashSet<int>();
            var stack = new Stack<int>();
            stack.Push(startCellId);

            while (stack.Count > 0)
            {
                var topId = stack.Pop();
                if (visited.Contains(topId)) continue;
                visited.Add(topId);

                var top = gridModel.GetCell(topId);
                if (top == null) continue;
                if (top.CellType == CellType.Unknown) continue;

                if (top.CellType == CellType.Room && top.Id != startCellId)
                {
                    OutConnectedRooms.Add(topId);
                    continue;
                }

                if (IsCorridor(top.CellType))
                {
                    OutConnectedCorridors.Add(topId);
                }

                // search adjacent cells
                foreach (var adjacentId in top.AdjacentCells)
                {
                    // make sure the adjacent cell is reachable
                    if (AreAdjacentCellsReachable(gridModel, topId, adjacentId))
                    {
                        stack.Push(adjacentId);
                    }
                }
            }
        }
    }

}