using System.Collections.Generic;

namespace InteractiveVideo
{
    /// <summary>
    /// All tracked object states for one video frame.
    /// Loaded frames are sparse (tracking may run at a lower rate than the video); the manager
    /// resolves a video frame into a frame like this by nearest lookup or interpolation.
    /// </summary>
    public sealed class TrackingFrame
    {
        public long Frame;
        public readonly List<TrackedObjectInstance> Objects = new List<TrackedObjectInstance>(8);

        /// <summary>Linear search: frames hold a handful of objects, a dictionary would allocate on rebuild.</summary>
        public bool TryGet(string trackId, out TrackedObjectInstance instance)
        {
            for (int i = 0; i < Objects.Count; i++)
            {
                if (Objects[i].TrackId == trackId)
                {
                    instance = Objects[i];
                    return true;
                }
            }
            instance = null;
            return false;
        }

        public int IndexOf(string trackId)
        {
            for (int i = 0; i < Objects.Count; i++)
                if (Objects[i].TrackId == trackId) return i;
            return -1;
        }
    }
}