using System.Collections.Generic;
using UnityEngine;

namespace MazeGen
{
    /// <summary>
    /// Single entry point for milestone 1: drop this on one empty GameObject in the scene
    /// and press Play. It creates the generator, agent and path visualizer, spawns the
    /// start room(s), and lets you click yellow exit markers to walk the agent through them.
    /// </summary>
    [RequireComponent(typeof(MazeGenerator))]
    public class MazeSceneBuilder : MonoBehaviour
    {
        [SerializeField, Min(1)] private int startRoomCount = 1;
        [SerializeField] private float startRoomSpread = 6f;

        private MazeGenerator _generator;
        private MazeAgentController _agentController;
        private PathVisualizer _pathVisualizer;
        private MazeCameraController _cameraController;

        private readonly Dictionary<int, ExitMarker> _exitMarkers = new Dictionary<int, ExitMarker>();

        private void Awake()
        {
            _generator = GetComponent<MazeGenerator>();
            _generator.RoomGenerated += OnRoomGenerated;
            _generator.ExitAdded += OnExitAdded;

            var agentGO = new GameObject("Agent");
            agentGO.transform.SetParent(transform, false);
            _agentController = agentGO.AddComponent<MazeAgentController>();
            _agentController.Initialize(_generator);

            var pathGO = new GameObject("PathVisualizer");
            pathGO.transform.SetParent(transform, false);
            pathGO.AddComponent<LineRenderer>();
            _pathVisualizer = pathGO.AddComponent<PathVisualizer>();

            var cam = Camera.main;
            if (cam != null)
            {
                _cameraController = cam.GetComponent<MazeCameraController>();
                if (_cameraController == null)
                    _cameraController = cam.gameObject.AddComponent<MazeCameraController>();
            }
        }

        private void Start()
        {
            Room firstStartRoom = null;
            for (int i = 0; i < startRoomCount; i++)
            {
                float angle = startRoomCount > 1 ? (360f / startRoomCount) * i : 0f;
                Vector2 pos = startRoomCount > 1
                    ? new Vector2(Mathf.Cos(angle * Mathf.Deg2Rad), Mathf.Sin(angle * Mathf.Deg2Rad)) * startRoomSpread
                    : Vector2.zero;

                var room = _generator.GenerateStartRoom(pos);
                firstStartRoom ??= room;
            }

            // Milestone 1: single agent spawns in the first start room.
            _agentController.Spawn(firstStartRoom);
            _agentController.Agent.RoomEntered += room => _pathVisualizer.AppendPoint(room.Position);
            _agentController.Agent.RoomEntered += room => _cameraController?.FocusOn(room.Position);
            _agentController.Agent.ReachedExitRoom += room => Debug.Log($"[MazeGen] Agent reached the exit room (id {room.Id})!");
            _pathVisualizer.AppendPoint(firstStartRoom.Position);
            _cameraController?.SnapTo(firstStartRoom.Position);
            RefreshMarkerVisuals();
        }

        private void OnRoomGenerated(Room room)
        {
            var roomGO = new GameObject($"Room_{room.Id}_{room.Kind}");
            roomGO.transform.SetParent(transform, false);
            roomGO.AddComponent<RoomView>().Initialize(room);

            foreach (var exit in room.Exits)
                SpawnExitMarker(room, exit);
        }

        private void OnExitAdded(Room room, Exit exit)
        {
            SpawnExitMarker(room, exit);
            RefreshMarkerVisuals();
        }

        private void SpawnExitMarker(Room room, Exit exit)
        {
            var markerGO = new GameObject($"Exit_{exit.Id}");
            markerGO.transform.SetParent(transform, false);
            var marker = markerGO.AddComponent<ExitMarker>();
            marker.Initialize(room, exit);
            _exitMarkers[exit.Id] = marker;
        }

        private void Update()
        {
            if (!MazeInput.WasLeftClickedThisFrame()) return;

            Camera cam = Camera.main;
            if (cam == null) return;

            Ray ray = cam.ScreenPointToRay(MazeInput.GetPointerScreenPosition());
            RaycastHit2D hit = Physics2D.GetRayIntersection(ray, Mathf.Infinity);
            if (hit.collider != null && hit.collider.TryGetComponent(out ExitMarker marker))
                OnExitClicked(marker.ExitData);
        }

        private void OnExitClicked(Exit exit)
        {
            if (_agentController.Agent == null || exit.OwnerRoomId != _agentController.Agent.CurrentRoom.Id)
            {
                Debug.Log("[MazeGen] That exit isn't reachable from your current room.");
                return;
            }

            if (_agentController.TryUseExit(exit))
                RefreshMarkerVisuals();
        }

        private void RefreshMarkerVisuals()
        {
            Room currentRoom = _agentController.Agent?.CurrentRoom;
            MazeAgent agent = _agentController.Agent;
            foreach (var marker in _exitMarkers.Values)
                marker.UpdateVisual(currentRoom, agent);
        }
    }
}