using System;
using System.Collections.Generic;
using GeometryTD.UI;
using UnityEngine;
using UnityEngine.Tilemaps;

namespace GeometryTD.Entity
{
    public sealed class CombatSelectInputService
    {
        public bool TryBuildUserData(Tilemap tilemap, Transform mapTransform,
            IReadOnlyDictionary<Vector3Int, int> towerEntityIdByFoundationCell, Func<Vector3Int, bool> isFoundationCell,
            int upgradeCost, int destroyGain, out CombatSelectFormUserData userData)
        {
            userData = null;
            if (tilemap == null || !TryGetPointerWorldPosition(tilemap, mapTransform, out Vector3 worldPosition,
                    out Vector2 contentPosition))
            {
                return false;
            }

            Vector3Int clickedCell = tilemap.WorldToCell(worldPosition);
            CombatSelectClickObjectType clickObjectType = CombatSelectClickObjectType.None;
            int towerEntityId = 0;
            Vector2 resolvedContentPosition = contentPosition;

            if (towerEntityIdByFoundationCell != null &&
                towerEntityIdByFoundationCell.TryGetValue(clickedCell, out int occupiedTowerEntityId))
            {
                clickObjectType = CombatSelectClickObjectType.Tower;
                towerEntityId = occupiedTowerEntityId;
                resolvedContentPosition = BuildContentPositionFromCell(tilemap, clickedCell, contentPosition);
            }
            else if (isFoundationCell != null && isFoundationCell(clickedCell))
            {
                clickObjectType = CombatSelectClickObjectType.Foundation;
                resolvedContentPosition = BuildContentPositionFromCell(tilemap, clickedCell, contentPosition);
            }

            userData = new CombatSelectFormUserData
            {
                ClickObjectType = clickObjectType,
                ContentPosition = resolvedContentPosition,
                WorldPosition = worldPosition,
                CellPosition = clickedCell,
                TowerEntityId = towerEntityId,
                UpgradeCost = Mathf.Max(0, upgradeCost),
                DestroyGain = Mathf.Max(0, destroyGain)
            };
            return true;
        }

        private static bool TryGetPointerWorldPosition(Tilemap tilemap, Transform mapTransform, out Vector3 worldPosition,
            out Vector2 contentPosition)
        {
            worldPosition = Vector3.zero;
            contentPosition = Vector2.zero;

            Camera mainCamera = GameEntry.Scene != null ? GameEntry.Scene.MainCamera : Camera.main;
            if (mainCamera == null)
            {
                return false;
            }

            Ray ray = mainCamera.ScreenPointToRay(Input.mousePosition);
            float mapPlaneZ = tilemap != null ? tilemap.transform.position.z : (mapTransform != null ? mapTransform.position.z : 0f);
            Vector3 planeNormal = mainCamera.transform.forward.sqrMagnitude > Mathf.Epsilon
                ? -mainCamera.transform.forward
                : Vector3.forward;
            Plane mapPlane = new Plane(planeNormal, new Vector3(0f, 0f, mapPlaneZ));
            if (!mapPlane.Raycast(ray, out float enterDistance))
            {
                return false;
            }

            worldPosition = ray.GetPoint(enterDistance);
            contentPosition = BuildContentPosition(Input.mousePosition);
            contentPosition = new Vector2((int)contentPosition.x, (int)contentPosition.y);
            contentPosition = new Vector2(contentPosition.x + 0.5f, contentPosition.y + 0.5f);
            return true;
        }

        private static Vector2 BuildContentPosition(Vector3 pointerScreenPosition)
        {
            return new Vector2(
                pointerScreenPosition.x - Screen.width * 0.5f,
                pointerScreenPosition.y - Screen.height * 0.5f);
        }

        private static Vector2 BuildContentPositionFromCell(Tilemap tilemap, Vector3Int cellPosition,
            Vector2 fallbackContentPosition)
        {
            if (tilemap == null)
            {
                return fallbackContentPosition;
            }

            Camera mainCamera = GameEntry.Scene != null ? GameEntry.Scene.MainCamera : Camera.main;
            if (mainCamera == null)
            {
                return fallbackContentPosition;
            }

            Vector3 cellCenterWorld = tilemap.GetCellCenterWorld(cellPosition);
            Vector3 cellScreenPosition = mainCamera.WorldToScreenPoint(cellCenterWorld);
            Vector2 contentPosition = BuildContentPosition(cellScreenPosition);
            contentPosition = new Vector2((int)contentPosition.x, (int)contentPosition.y);
            return new Vector2(contentPosition.x + 0.5f, contentPosition.y + 0.5f);
        }
    }
}