using System;
using System.Collections.Generic;
using GeometryTD.UI;
using UnityEngine;
using UnityEngine.InputSystem;
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,
            Func<int, bool> isTowerAtMaxLevel,
            int upgradeCost,
            int destroyGain,
            out CombatSelectFormUserData userData)
        {
            userData = null;
            if (tilemap == null || !TryGetPointerWorldPosition(tilemap, mapTransform, out Vector3 worldPosition,
                    out Vector2 screenPosition))
            {
                return false;
            }

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

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

            userData = new CombatSelectFormUserData
            {
                ClickObjectType = clickObjectType,
                ScreenPosition = resolvedScreenPosition,
                WorldPosition = worldPosition,
                CellPosition = clickedCell,
                TowerEntityId = towerEntityId,
                IsTowerAtMaxLevel = towerEntityId != 0 && isTowerAtMaxLevel != null && isTowerAtMaxLevel(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 screenPosition)
        {
            worldPosition = Vector3.zero;
            screenPosition = Vector2.zero;

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

            Mouse mouse = Mouse.current;
            if (mouse == null)
            {
                return false;
            }

            Vector2 pointerPosition = mouse.position.ReadValue();
            Ray ray = mainCamera.ScreenPointToRay(pointerPosition);
            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);
            screenPosition = BuildScreenPosition(pointerPosition);
            return true;
        }

        private static Vector2 BuildScreenPosition(Vector3 pointerScreenPosition)
        {
            return new Vector2(pointerScreenPosition.x, pointerScreenPosition.y);
        }

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

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

            Vector3 cellCenterWorld = tilemap.GetCellCenterWorld(cellPosition);
            Vector3 cellScreenPosition = mainCamera.WorldToScreenPoint(cellCenterWorld);
            if (cellScreenPosition.z < 0f)
            {
                return fallbackScreenPosition;
            }

            return BuildScreenPosition(cellScreenPosition);
        }
    }
}