/*
 * Copyright (c) Meta Platforms, Inc. and affiliates.
 * All rights reserved.
 *
 * Licensed under the Oculus SDK License Agreement (the "License");
 * you may not use the Oculus SDK except in compliance with the License,
 * which is provided at the time of installation or download, or which
 * otherwise accompanies this software in either electronic or hard copy form.
 *
 * You may obtain a copy of the License at
 *
 * https://developer.oculus.com/licenses/oculussdk/
 *
 * Unless required by applicable law or agreed to in writing, the Oculus SDK
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

using System;

/// <summary>
/// Represents a "space" in the Oculus Runtime.
/// </summary>
public readonly struct OVRSpace : IEquatable<OVRSpace>
{
	/// <summary>
	/// A runtime handle associated with this <see cref="OVRSpace"/>. This could change between subsequent sessions
	/// or apps.
	/// </summary>
	public ulong Handle { get; }

	/// <summary>
	/// Retrieve the universally unique identifier (UUID) associated with this <see cref="OVRSpace"/>.
	/// </summary>
	/// <remarks>
	/// Every space that can be persisted will have a UUID associated with it. UUIDs are consistent across different
	/// sessions and apps.
	///
	/// The UUID of a space does not change over time, but not all spaces are guaranteed to have a UUID.
	/// </remarks>
	/// <param name="uuid">If successful, the uuid associated with this <see cref="OVRSpace"/>, otherwise, `Guid.Empty`.
	/// </param>
	/// <returns>Returns `true` if the uuid could be retrieved, otherwise `false`.</returns>
	public bool TryGetUuid(out Guid uuid) => OVRPlugin.GetSpaceUuid(Handle, out uuid);

	/// <summary>
	/// Indicates whether this <see cref="OVRSpace"/> represents a valid space (vs a default constructed
	/// <see cref="OVRSpace"/>).
	/// </summary>
	public bool Valid => Handle != 0;

	/// <summary>
	/// Constructs an <see cref="OVRSpace"/> object from an existing runtime handle and UUID.
	/// </summary>
	/// <remarks>
	/// This constructor does not create a new space. An <see cref="OVRSpace"/> is a wrapper for low-level functionality
	/// in the Oculus Runtime. To create a new spatial anchor, use <see cref="OVRSpatialAnchor"/>.
	/// </remarks>
	/// <param name="handle">The runtime handle associated with the space.</param>
	public OVRSpace(ulong handle) => Handle = handle;

	/// <summary>
	/// Generates a string representation of this <see cref="OVRSpace"/> of the form
	/// "0xYYYYYYYY"
	/// where "Y" are the hexadecimal digits of the <see cref="Handle"/>.
	/// </summary>
	/// <returns>Returns a string representation of this <see cref="OVRSpace"/>.</returns>
	public override string ToString() => $"0x{Handle:x8}";

	public bool Equals(OVRSpace other) => Handle == other.Handle;

	public override bool Equals(object obj) => obj is OVRSpace other && Equals(other);

	public override int GetHashCode() => Handle.GetHashCode();

	public static bool operator== (OVRSpace lhs, OVRSpace rhs) => lhs.Handle == rhs.Handle;

	public static bool operator!= (OVRSpace lhs, OVRSpace rhs) => lhs.Handle != rhs.Handle;

	public static implicit operator OVRSpace(ulong handle) => new OVRSpace(handle);

	public static implicit operator ulong(OVRSpace space) => space.Handle;
}