using System;
using System.Collections.Generic;

namespace UnityEngine.XR.ARFoundation
{
    /// <summary>
    /// Event arguments for the <see cref="ARParticipantManager.participantsChanged"/> event.
    /// </summary>
    [Obsolete("ARParticipantsChangedEventArgs has been deprecated in AR Foundation version 6.0. Use ARTrackablesChangedEventArgs<TTrackable> instead.", false)]
    public struct ARParticipantsChangedEventArgs : IEquatable<ARParticipantsChangedEventArgs>
    {
        /// <summary>
        /// The list of <see cref="ARParticipant"/>s added since the last event.
        /// </summary>
        public List<ARParticipant> added { get; private set; }

        /// <summary>
        /// The list of <see cref="ARParticipant"/>s udpated since the last event.
        /// </summary>
        public List<ARParticipant> updated { get; private set; }

        /// <summary>
        /// The list of <see cref="ARParticipant"/>s removed since the last event.
        /// </summary>
        public List<ARParticipant> removed { get; private set; }

        /// <summary>
        /// Constructs an <see cref="ARParticipantsChangedEventArgs"/>.
        /// </summary>
        /// <param name="added">The list of <see cref="ARParticipant"/>s added since the last event.</param>
        /// <param name="updated">The list of <see cref="ARParticipant"/>s updated since the last event.</param>
        /// <param name="removed">The list of <see cref="ARParticipant"/>s removed since the last event.</param>
        public ARParticipantsChangedEventArgs(
            List<ARParticipant> added,
            List<ARParticipant> updated,
            List<ARParticipant> removed)
        {
            this.added = added;
            this.updated = updated;
            this.removed = removed;
        }

        /// <summary>
        /// Generates a hash suitable for use with containers like `HashSet` and `Dictionary`.
        /// </summary>
        /// <returns>A hash code generated from this object's fields.</returns>
        public override int GetHashCode() => HashCodeUtil.Combine(
            HashCodeUtil.ReferenceHash(added),
            HashCodeUtil.ReferenceHash(updated),
            HashCodeUtil.ReferenceHash(removed));

        /// <summary>
        /// Tests for equality.
        /// </summary>
        /// <param name="obj">The `object` to compare against.</param>
        /// <returns>`True` if <paramref name="obj"/> is of type <see cref="ARParticipantsChangedEventArgs"/> and
        /// <see cref="Equals(ARParticipantsChangedEventArgs)"/> also returns `true`; otherwise `false`.</returns>
        public override bool Equals(object obj) => (obj is ARParticipantsChangedEventArgs) && Equals((ARParticipantsChangedEventArgs)obj);

        int GetCount(List<ARParticipant> list) => list != null ? list.Count : 0;

        /// <summary>
        /// Generates a string suitable for debugging. The string contains the number of added, updated, and removed participants.
        /// </summary>
        /// <returns>A string suitable for debug logging.</returns>
        public override string ToString() => $"Added: {GetCount(added)}, Updated: {GetCount(updated)}, Removed: {GetCount(removed)}";

        /// <summary>
        /// Tests for equality.
        /// </summary>
        /// <param name="other">The other <see cref="ARParticipantsChangedEventArgs"/> to compare against.</param>
        /// <returns><c>true</c> if <paramref name="other"/> is equal to this <see cref="ARParticipantsChangedEventArgs"/>.</returns>
        public bool Equals(ARParticipantsChangedEventArgs other)
        {
            return
                ReferenceEquals(added, other.added) &&
                ReferenceEquals(updated, other.updated) &&
                ReferenceEquals(removed, other.removed);
        }
        /// <summary>
        /// Tests for equality. Same as <see cref="Equals(ARParticipantsChangedEventArgs)"/>.
        /// </summary>
        /// <param name="lhs">The left-hand side of the comparison.</param>
        /// <param name="rhs">The right-hand side of the comparison.</param>
        /// <returns><c>true</c> if <paramref name="lhs"/> is equal to <paramref name="rhs"/>.</returns>
        public static bool operator ==(ARParticipantsChangedEventArgs lhs, ARParticipantsChangedEventArgs rhs) => lhs.Equals(rhs);

        /// <summary>
        /// Tests for inequality. Same as <c>!</c><see cref="Equals(ARParticipantsChangedEventArgs)"/>.
        /// </summary>
        /// <param name="lhs">The left-hand side of the comparison.</param>
        /// <param name="rhs">The right-hand side of the comparison.</param>
        /// <returns><c>true</c> if <paramref name="lhs"/> is not equal to <paramref name="rhs"/>.</returns>
        public static bool operator !=(ARParticipantsChangedEventArgs lhs, ARParticipantsChangedEventArgs rhs) => !lhs.Equals(rhs);
    }
}