using System.Collections.Generic;
using UnityEngine;

namespace InteractiveVideo
{
    /// <summary>
    /// Identity of a tracked thing in a video: who or what it is.
    /// This never changes across frames. Per-frame state lives in <see cref="TrackedObjectInstance"/>.
    /// </summary>
    public sealed class TrackedObject
    {
        /// <summary>Stable track id used by the frames, e.g. "person_01".</summary>
        public string Id;
        /// <summary>Category, e.g. "person" or "object".</summary>
        public string Type;
        /// <summary>Display name, e.g. "Father".</summary>
        public string Name;

        /// <summary>True when this definition was created because a frame referenced an id the file never declared.</summary>
        public bool IsImplicit;

        public override string ToString() => string.IsNullOrEmpty(Name) ? Id : $"{Name} ({Id})";
    }

    /// <summary>
    /// The state of one tracked object at one point in time: where it is and what it is doing.
    /// Coordinates are TRACKING coordinates (normalised 0..1, Y down). Convert with <see cref="VideoCoordinates"/>.
    /// Instances belonging to loaded frames are immutable in practice; the tracking manager also owns a pool of
    /// instances it rewrites every frame when interpolating, so never cache a reference across frames.
    /// </summary>
    public sealed class TrackedObjectInstance
    {
        public string TrackId;
        /// <summary>Resolved identity. Never null after loading (an implicit definition is created for unknown ids).</summary>
        public TrackedObject Definition;

        /// <summary>Bounding box in tracking coordinates (xMin, yMin = top-left; Y grows downwards).</summary>
        public Rect Bounds;
        /// <summary>Polygon in tracking coordinates. Reused buffer; may have fewer than 3 points (then it is not hit-testable).</summary>
        public readonly List<Vector2> Polygon = new List<Vector2>(64);

        public bool Visible = true;
        public bool Occluded;
        public float Confidence = 1f;
        /// <summary>Semantic per-frame information, e.g. "drinking water". May be null.</summary>
        public string Action;

        /// <summary>The video frame this state describes (the tracked frame, or the interpolated video frame).</summary>
        public long Frame;

        public bool HasPolygon => Polygon.Count >= 3;
        public string Name => Definition != null && !string.IsNullOrEmpty(Definition.Name) ? Definition.Name : TrackId;

        public void CopyFrom(TrackedObjectInstance other)
        {
            TrackId = other.TrackId;
            Definition = other.Definition;
            Bounds = other.Bounds;
            Polygon.Clear();
            Polygon.AddRange(other.Polygon);
            Visible = other.Visible;
            Occluded = other.Occluded;
            Confidence = other.Confidence;
            Action = other.Action;
            Frame = other.Frame;
        }
    }
}