using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using UnityEngine;

/// <summary>
/// This sample expands on the basic scene manager and adds the following features:
///   * Spawn a prefab for the wall, ceiling, floor elements and set 2D dimensions
///   * Spawn a fallback object for all other semantic labels and set 3D dimensions
///   * Update the location of all anchors at some frequency with new tracking info
/// </summary>
/// <remarks>
/// The prefabs in this class are scaled to dimensions 1, however, you will need to
/// consider the dimension within your prefab to scale correctly. Additionally, in
/// order to avoid stretching, you may consider 9-slicing.
///
/// Scene anchors are tracked independently and can change as new tracking information
/// becomes available. It may be better for your use case to consider a single
/// tracking point and only update that. This will keep the relative positions of
/// all objects consistent, while also updating the location with new tracking data.
/// </remarks>
public class PrefabSceneManager : MonoBehaviour
{
    public GameObject WallPrefab;
    public GameObject CeilingPrefab;
    public GameObject FloorPrefab;
    public GameObject FallbackPrefab;
    public float UpdateFrequencySeconds = 5;

    List<(GameObject,OVRLocatable)> _locatableObjects = new List<(GameObject,OVRLocatable)>();

    void Start()
    {
        SceneManagerHelper.RequestScenePermission();

        LoadSceneAsync();
        StartCoroutine(UpdateAnchorsPeriodically());
    }

    async void LoadSceneAsync()
    {
        // fetch all rooms, with a SceneCapture fallback
        var rooms = new List<OVRAnchor>();
        await OVRAnchor.FetchAnchorsAsync<OVRRoomLayout>(rooms);
        if (rooms.Count == 0)
        {
            var sceneCaptured = await SceneManagerHelper.RequestSceneCapture();
            if (!sceneCaptured)
                return;

            await OVRAnchor.FetchAnchorsAsync<OVRRoomLayout>(rooms);
        }

        // fetch room elements, create objects for them
        var tasks = rooms.Select(async room =>
        {
            var roomObject = new GameObject($"Room-{room.Uuid}");
            if (!room.TryGetComponent(out OVRAnchorContainer container))
                return;
            if (!room.TryGetComponent(out OVRRoomLayout roomLayout))
                return;

            var children = new List<OVRAnchor>();
            await container.FetchChildrenAsync(children);
            await CreateSceneAnchors(roomObject, roomLayout, children);
        }).ToList();
        await Task.WhenAll(tasks);
    }

    async Task CreateSceneAnchors(GameObject roomGameObject,
        OVRRoomLayout roomLayout, List<OVRAnchor> anchors)
    {
        roomLayout.TryGetRoomLayout(out var ceilingUuid,
            out var floorUuid, out var wallUuids);

        // iterate over all anchors as async tasks
        var tasks = anchors.Select(async anchor =>
        {
            // can we locate it in the world?
            if (!anchor.TryGetComponent(out OVRLocatable locatable))
                return;
            await locatable.SetEnabledAsync(true);

            // check room layout information and assign prefab
            // it would also be possible to use the semantic label
            var prefab = FallbackPrefab;
            if (anchor.Uuid == floorUuid)
                prefab = FloorPrefab;
            else if (anchor.Uuid == ceilingUuid)
                prefab = CeilingPrefab;
            else if (wallUuids.Contains(anchor.Uuid))
                prefab = WallPrefab;

            // get semantic classification for object name
            var label = "other";
            if (anchor.TryGetComponent(out OVRSemanticLabels labels))
                label = labels.Labels;

            // create container object
            var gameObject = new GameObject(label);
            gameObject.transform.SetParent(roomGameObject.transform);
            var helper = new SceneManagerHelper(gameObject);
            helper.SetLocation(locatable);

            // instantiate prefab & set 2D dimensions
            var model = Instantiate(prefab, gameObject.transform);
            if (anchor.TryGetComponent(out OVRBounded2D bounds2D) &&
                bounds2D.IsEnabled)
            {
                model.transform.localScale = new Vector3(
                    bounds2D.BoundingBox.size.x,
                    bounds2D.BoundingBox.size.y,
                    0.01f);
            }

            // we will set volume dimensions for the non-room elements
            if (prefab == FallbackPrefab)
            {
                if (anchor.TryGetComponent(out OVRBounded3D bounds3D) &&
                    bounds3D.IsEnabled)
                {
                    model.transform.localPosition = new Vector3(0, 0,
                        -bounds3D.BoundingBox.size.z / 2);
                    model.transform.localScale = bounds3D.BoundingBox.size;
                }
            }

            // save game object and locatable for updating later
            _locatableObjects.Add((gameObject, locatable));
        }).ToList();

        await Task.WhenAll(tasks);
    }

    IEnumerator UpdateAnchorsPeriodically()
    {
        while (true) {
            foreach (var (gameObject, locatable) in _locatableObjects)
            {
                var helper = new SceneManagerHelper(gameObject);
                helper.SetLocation(locatable);
            }

            yield return new WaitForSeconds(UpdateFrequencySeconds);
        }
    }
}