using System;
using System.Collections.Generic;
using EscapeRoomEngine.Engine.Runtime.Modules;
using EscapeRoomEngine.Engine.Runtime.Requirements;
using UnityEngine;
using Logger = EscapeRoomEngine.Engine.Runtime.Utilities.Logger;
using LogType = EscapeRoomEngine.Engine.Runtime.Utilities.LogType;
using Object = UnityEngine.Object;

namespace EscapeRoomEngine.Engine.Runtime
{
    public class Space
    {
        /// <summary>
        /// The room relative (<i>RR</i>) dimensions of this space.
        /// </summary>
        internal readonly Dimensions rrDimensions;
        internal readonly Room room;
        
        /// <summary>
        /// A list of all modules.
        /// </summary>
        internal List<Module> Modules { get; } = new(2);
        /// <summary>
        /// A list of all staged and added modules.
        /// </summary>
        internal List<Module> AllModules
        {
            get
            {
                var modules = new List<Module>(Modules);
                if (_stagedModules.Count > 0)
                {
                    modules.AddRange(_stagedModules);
                }
                return modules;
            }
        }
        
        private GameObject _spaceObject, _spaceTiles;
        private List<Module> _stagedModules = new();

        internal Space(Room room, Passage entrance)
        {
            this.room = room;
            rrDimensions = GenerateSpaceDimensions(
                entrance,
                Engine.DefaultEngine.theme.minRoomSize,
                Engine.DefaultEngine.theme.playSpace);
            
            // connect the space to its passage
            entrance.ConnectTo(new DoorModule(this,
                ((DoorModuleDescription)entrance.fromOut.description).connectedDoorDescription));
            Modules.Add(entrance.toIn);
        }

        internal bool AddModuleWithRequirements(Module module)
        {
            var requirementsFulfilled = module.CheckRequirements();
            if (requirementsFulfilled)
            {
                // add all previously staged modules first ...
                for (var i = _stagedModules.Count - 1; i >= 0; i--)
                {
                    Modules.Add(_stagedModules[i]);
                }
                
                // ... and then add the module itself
                Modules.Add(module);
            }
            
            // always clear the staged modules. if a module isn't added, its corresponding staged modules should be discarded
            _stagedModules = new List<Module>();

            return requirementsFulfilled;
        }

        /// <summary>
        /// Stage a module if its requirements are currently met. It will be added as soon as the next module is added by <see cref="AddModuleWithRequirements"/>.
        /// </summary>
        /// <param name="module">The module to stage</param>
        /// <returns>Whether the requirements were met and the module was staged</returns>
        internal bool StageModuleWithRequirements(Module module)
        {
            var requirementsFulfilled = module.CheckRequirements();
            if (requirementsFulfilled)
            {
                _stagedModules.Add(module);
            }

            return requirementsFulfilled;
        }

        internal void InstantiateSpace(Transform parent, string name)
        {
            _spaceObject = new GameObject($"Space {name}");
            _spaceObject.transform.SetParent(parent, false);
            _spaceObject.transform.localPosition = new Vector3(rrDimensions.x, 0, rrDimensions.z);
            
            // build the space floor out of tiles
            _spaceTiles = new GameObject($"Space Geometry");
            _spaceTiles.transform.SetParent(_spaceObject.transform, false);
            _spaceTiles.isStatic = true;
            for (var z = 0; z < rrDimensions.length; z++)
            {
                for (var x = 0; x < rrDimensions.width; x++)
                {
                    var left = x == 0;
                    var right = x == rrDimensions.width - 1;
                    var bottom = z == 0;
                    var top = z == rrDimensions.length - 1;
                    
                    TileLocation location;
                    if (bottom)
                        location = left ? TileLocation.SW : right ? TileLocation.SE : TileLocation.S;
                    else if (top)
                        location = left ? TileLocation.NW : right ? TileLocation.NE : TileLocation.N;
                    else
                        location = left ? TileLocation.W : right ? TileLocation.E : TileLocation.C;
                    
                    var tileObject = Object.Instantiate(Engine.DefaultEngine.theme.spaceTile, _spaceTiles.transform, false);
                    tileObject.transform.localPosition = new Vector3(x, 0, z);
                    tileObject.showTile = location;
                }
            }

            // instantiate all modules inside this space
            Modules.ForEach(module => module.InstantiateModule(_spaceObject.transform));
        }

        /// <summary>
        /// Convert a position relative to this space to one relative to the room.
        /// </summary>
        /// <param name="srPosition">The space relative (<i>SR</i>) position that should be converted to a room relative (<i>RR</i>) position.</param>
        internal Vector2Int ToRoomRelative(Vector2Int srPosition) => srPosition + rrDimensions.Position;
        /// <summary>
        /// Convert a position relative to the room to one relative to this space.
        /// </summary>
        /// <param name="rrPosition">The room relative (<i>RR</i>) position that should be converted to a space relative (<i>SR</i>) position.</param>
        internal Vector2Int ToSpaceRelative(Vector2Int rrPosition) => rrPosition - rrDimensions.Position;

        /// <summary>
        /// Generate space dimensions that fit the required size constraints and cover the position of the entrance.
        /// </summary>
        /// <returns>The generated room relative (<i>RR</i>) dimensions.</returns>
        private static Dimensions GenerateSpaceDimensions(Passage entrance, Vector2Int minSize, Vector2Int availableSpace)
        {
            var xMin = -1;
            var xMax = -1;
            var zMin = -1;
            var zMax = -1;
            var position = entrance.rrPosition;
            var door = entrance.fromOut;

            // fix the side the door is facing away from
            switch (door.orientation)
            {
                case Orientation.North:
                    zMin = position.y;
                    zMax = Utilities.Utilities.RandomInclusive(zMin + minSize.y, availableSpace.y);
                    break;
                case Orientation.East:
                    xMin = position.x;
                    xMax = Utilities.Utilities.RandomInclusive(xMin + minSize.x, availableSpace.x);
                    break;
                case Orientation.South:
                    zMax = position.y + 1;
                    zMin = Utilities.Utilities.RandomInclusive(0, zMax - minSize.y);
                    break;
                case Orientation.West:
                    xMax = position.x + 1;
                    xMin = Utilities.Utilities.RandomInclusive(0, xMax - minSize.x);
                    break;
                default:
                    throw new ArgumentOutOfRangeException();
            }

            // calculate remaining values if they haven't been covered by the switch statement yet
            if(xMin == -1)
                xMin = Utilities.Utilities.RandomInclusive(0, Math.Min(position.x, availableSpace.x - minSize.x));
            if(xMax == -1)
                xMax = Utilities.Utilities.RandomInclusive(Math.Max(position.x + 1, xMin + minSize.x), availableSpace.x);
            if(zMin == -1)
                zMin = Utilities.Utilities.RandomInclusive(0, Math.Min(position.y, availableSpace.y - minSize.y));
            if(zMax == -1)
                zMax = Utilities.Utilities.RandomInclusive(Math.Max(position.y + 1, zMin + minSize.y), availableSpace.y);

            var dimensions = new Dimensions(xMax - xMin, zMax - zMin, xMin, zMin);
            
            Logger.Log($"Generated space dimensions {dimensions} from entrance position {position}", LogType.RoomGeneration);
            
            return dimensions;
        }
    }
}