using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;

namespace MultiWheelC.TrajectoryPlanning.EMPlanner;

/// <summary>
/// 供成功规划结果发布的时间参数化轨迹；本类型只施加结构约束，世界空间复核由上游服务完成，点序列、元数据和终端语义在发布后保持不可变。
/// </summary>
public sealed class EmTrajectory
{
    /// <summary>
    /// 创建可发布的轨迹并复制点列表容器。元数据和每个点对象按引用保存、调用方仍拥有它们；传入列表可随后修改而不影响 <see cref="Points"/>，且 null 或空列表会抛出异常。
    /// </summary>
    public EmTrajectory(EmTrajectoryMetadata metadata, IReadOnlyList<EmTrajectoryPoint> points)
    {
        if (metadata == null)
            throw new ArgumentNullException(nameof(metadata));
        if (points == null)
            throw new ArgumentNullException(nameof(points));
        if (points.Count == 0)
            throw new ArgumentException("A published trajectory requires at least one point.", nameof(points));

        var copy = new List<EmTrajectoryPoint>(points.Count);
        for (int index = 0; index < points.Count; index++)
        {
            if (points[index] == null)
                throw new ArgumentException("Trajectory points cannot contain null values.", nameof(points));
            copy.Add(points[index]);
        }

        Metadata = metadata;
        Points = new ReadOnlyCollection<EmTrajectoryPoint>(copy);
    }

    /// <summary>
    /// 轨迹的不可变发布元数据引用；构造时必须非 null，未在本类中深拷贝。
    /// </summary>
    public EmTrajectoryMetadata Metadata { get; }

    /// <summary>
    /// 按调用方提供顺序保存的只读点列表；列表容器为构造时复制的快照，至少包含一个非 null 点，时间单调性由上游验证保证而非本构造器检查。
    /// </summary>
    public IReadOnlyList<EmTrajectoryPoint> Points { get; }
}