using UnityEngine;
using UnityEngine.InputSystem;

/// <summary>
/// Simple camera movement controller for map navigation.
/// Supports WASD/arrow keys, right-click drag, and Q/E or mouse wheel zoom.
/// </summary>
[RequireComponent(typeof(Camera))]
public class MazeCameraController : MonoBehaviour
{
    [Header("Movement")]
    [SerializeField] private float moveSpeed = 20f;
    [SerializeField] private float dragSpeed = 1f;

    [Header("Zoom")]
    [SerializeField] private float zoomSpeed = 25f;
    [SerializeField] private float zoomMin = 5f;
    [SerializeField] private float zoomMax = 120f;

    [Header("Optional Bounds")]
    [SerializeField] private bool useBounds = false;
    [SerializeField] private Vector2 minBounds = new Vector2(-100f, -100f);
    [SerializeField] private Vector2 maxBounds = new Vector2(100f, 100f);

    private Camera cameraComponent;
    private Vector3 targetPosition;
    private Vector3 lastMousePosition;
    private bool isDragging;

    // Smooth zoom and pan to location
    private bool isSmoothlyCentering = false;
    private Vector3 smoothTargetPosition;
    private float smoothTargetZoom;
    private float smoothCenteringSpeed = 5f;
    private float smoothZoomSpeed = 3f;

    private void Awake()
    {
        cameraComponent = GetComponent<Camera>();
        targetPosition = transform.position;
    }

    private void Update()
    {
        if (isSmoothlyCentering)
        {
            UpdateSmoothCentering();
        }

        HandleKeyboardMovement();
        HandleMouseDrag();
        HandleZoom();
        ApplyPosition();
    }

    private void HandleKeyboardMovement()
    {
        var keyboard = Keyboard.current;
        if (keyboard == null)
        {
            return;
        }

        float horizontal = 0f;
        if (keyboard.aKey.isPressed || keyboard.leftArrowKey.isPressed)
        {
            horizontal -= 1f;
        }
        if (keyboard.dKey.isPressed || keyboard.rightArrowKey.isPressed)
        {
            horizontal += 1f;
        }

        float vertical = 0f;
        if (keyboard.sKey.isPressed || keyboard.downArrowKey.isPressed)
        {
            vertical -= 1f;
        }
        if (keyboard.wKey.isPressed || keyboard.upArrowKey.isPressed)
        {
            vertical += 1f;
        }

        if (horizontal != 0f || vertical != 0f)
        {
            isSmoothlyCentering = false; // Interrupt smooth zoom on manual movement
            Vector3 right = transform.right;
            Vector3 forward = Vector3.Cross(transform.right, Vector3.up).normalized;
            Vector3 worldMove = (right * horizontal + forward * vertical).normalized;
            // Use unscaledDeltaTime so camera movement is unaffected by simulation speed/pause
            targetPosition += worldMove * moveSpeed * Time.unscaledDeltaTime;
        }

        if (keyboard.qKey.isPressed)
        {
            isSmoothlyCentering = false; // Interrupt smooth zoom on manual zoom
            Zoom(-zoomSpeed * Time.unscaledDeltaTime);
        }
        else if (keyboard.eKey.isPressed)
        {
            isSmoothlyCentering = false; // Interrupt smooth zoom on manual zoom
            Zoom(zoomSpeed * Time.unscaledDeltaTime);
        }
    }

    private void HandleMouseDrag()
    {
        var mouse = Mouse.current;
        if (mouse == null)
        {
            return;
        }

        if (mouse.rightButton.wasPressedThisFrame)
        {
            isSmoothlyCentering = false; // Interrupt smooth zoom on manual drag
            isDragging = true;
            Vector2 position = mouse.position.ReadValue();
            lastMousePosition = new Vector3(position.x, position.y, 0f);
        }

        if (mouse.rightButton.wasReleasedThisFrame)
        {
            isDragging = false;
        }

        if (isDragging && mouse.rightButton.isPressed)
        {
            Vector2 position = mouse.position.ReadValue();
            Vector3 currentMousePosition = new Vector3(position.x, position.y, 0f);
            if (currentMousePosition != lastMousePosition)
            {
                Vector3 dragDelta = GetDragWorldDelta(lastMousePosition, currentMousePosition);
                targetPosition += dragDelta * dragSpeed;
                lastMousePosition = currentMousePosition;
            }
        }
    }

    private void HandleZoom()
    {
        var mouse = Mouse.current;
        if (mouse != null)
        {
            float scroll = mouse.scroll.ReadValue().y;
            if (scroll != 0f)
            {
                isSmoothlyCentering = false; // Interrupt smooth zoom on manual zoom
                Zoom(-scroll * zoomSpeed * Time.unscaledDeltaTime);
            }
        }
    }

    private void Zoom(float amount)
    {
        if (cameraComponent.orthographic)
        {
            cameraComponent.orthographicSize = Mathf.Clamp(cameraComponent.orthographicSize + amount, zoomMin, zoomMax);
        }
        else
        {
            cameraComponent.fieldOfView = Mathf.Clamp(cameraComponent.fieldOfView + amount, zoomMin, zoomMax);
        }
    }

    private Vector3 GetDragWorldDelta(Vector3 previousScreenPosition, Vector3 currentScreenPosition)
    {
        Plane dragPlane = new Plane(-transform.forward, transform.position);
        Ray previousRay = cameraComponent.ScreenPointToRay(previousScreenPosition);
        Ray currentRay = cameraComponent.ScreenPointToRay(currentScreenPosition);

        if (dragPlane.Raycast(previousRay, out float previousDistance) && dragPlane.Raycast(currentRay, out float currentDistance))
        {
            Vector3 previousWorld = previousRay.GetPoint(previousDistance);
            Vector3 currentWorld = currentRay.GetPoint(currentDistance);
            return previousWorld - currentWorld;
        }

        return Vector3.zero;
    }

    private void ApplyPosition()
    {
        Vector3 newPosition = targetPosition;
        if (useBounds)
        {
            newPosition.x = Mathf.Clamp(newPosition.x, minBounds.x, maxBounds.x);
            newPosition.z = Mathf.Clamp(newPosition.z, minBounds.y, maxBounds.y);
        }

        transform.position = newPosition;
    }

    /// <summary>
    /// Smoothly zooms and pans the camera to a specific room
    /// </summary>
    /// <param name="room">The room to zoom to</param>
    /// <param name="zoomPadding">Multiplier for room size (1.0 = exactly room size, 1.3 = 30% larger)</param>
    /// <param name="transitionDuration">Time to complete the zoom/pan in seconds</param>
    public void ZoomToRoom(MazeRoom room, float zoomPadding = 1.3f, float transitionDuration = 0.5f)
    {
        if (room == null) return;

        // Stop any previous zoom to prevent stacking
        isSmoothlyCentering = false;

        // Calculate room center in world space (XZ plane only - don't change camera height Y)
        Vector2Int roomCenter = room.GetCenter();
        Vector3 roomCenterXZ = new Vector3(roomCenter.x + 0.5f, targetPosition.y, roomCenter.y + 0.5f); // Keep Y unchanged

        // Calculate required zoom level to fit room with padding
        float roomWidth = room.Width;
        float roomHeight = room.Height;
        float maxRoomDim = Mathf.Max(roomWidth, roomHeight) * zoomPadding;

        // Adjust for camera aspect ratio
        float requiredZoom = maxRoomDim / (2f * Mathf.Tan(cameraComponent.fieldOfView * Mathf.Deg2Rad / 2f));
        if (cameraComponent.orthographic)
        {
            requiredZoom = maxRoomDim * 0.5f;
        }

        // Set smooth transition targets
        smoothTargetPosition = roomCenterXZ; // Pan to room center on XZ plane only
        smoothTargetZoom = Mathf.Clamp(requiredZoom, zoomMin, zoomMax);
        smoothCenteringSpeed = 1f / transitionDuration;
        isSmoothlyCentering = true;
    }

    /// <summary>
    /// Updates the smooth camera transition toward target position and zoom
    /// </summary>
    private void UpdateSmoothCentering()
    {
        // Smooth pan to target position - use unscaledDeltaTime so it works while paused/slow
        float posDist = Vector3.Distance(targetPosition, smoothTargetPosition);
        if (posDist > 0.01f)
        {
            targetPosition = Vector3.Lerp(targetPosition, smoothTargetPosition, smoothCenteringSpeed * Time.unscaledDeltaTime);
        }
        else
        {
            targetPosition = smoothTargetPosition; // Snap to target
        }

        // Smooth zoom to target
        float currentZoom = cameraComponent.orthographic ? cameraComponent.orthographicSize : cameraComponent.fieldOfView;
        float zoomDist = Mathf.Abs(currentZoom - smoothTargetZoom);

        if (zoomDist > 0.01f)
        {
            if (cameraComponent.orthographic)
            {
                cameraComponent.orthographicSize = Mathf.Lerp(cameraComponent.orthographicSize, smoothTargetZoom, smoothZoomSpeed * Time.unscaledDeltaTime);
            }
            else
            {
                cameraComponent.fieldOfView = Mathf.Lerp(cameraComponent.fieldOfView, smoothTargetZoom, smoothZoomSpeed * Time.unscaledDeltaTime);
            }
        }
        else
        {
            // Snap to target zoom
            if (cameraComponent.orthographic)
            {
                cameraComponent.orthographicSize = smoothTargetZoom;
            }
            else
            {
                cameraComponent.fieldOfView = smoothTargetZoom;
            }
        }

        // Check if we've reached both targets
        posDist = Vector3.Distance(targetPosition, smoothTargetPosition);
        currentZoom = cameraComponent.orthographic ? cameraComponent.orthographicSize : cameraComponent.fieldOfView;
        zoomDist = Mathf.Abs(currentZoom - smoothTargetZoom);

        if (posDist < 0.01f && zoomDist < 0.01f)
        {
            isSmoothlyCentering = false;
        }
    }

}