using System;
using System.Collections.Generic;
using System.Linq;
using OpenNest.CNC;

namespace OpenNest;

/// <summary>Exact immutable CNC motion values. Rapid moves retain contour/hole boundaries; arcs are not tessellated.</summary>
public sealed record PartGeometryMotion(CodeType Type, double X, double Y, double CenterX,
    double CenterY, RotationType Rotation, LayerType Layer, bool Suppressed);

/// <summary>
/// Owned geometry only: no Drawing, quantity, events, or mutable CNC references are retained.
/// This initial boundary supports flat rapid/linear/arc programs and rejects other instructions explicitly.
/// Coordinates and mode are preserved without normalization, rounding, or polygon approximation.
/// </summary>
public sealed class PartGeometrySnapshot
{
    private PartGeometrySnapshot(Mode mode, IEnumerable<PartGeometryMotion> motions)
    {
        Mode = mode;
        Motions = NestJob.Own(motions);
    }

    public Mode Mode { get; }
    public IReadOnlyList<PartGeometryMotion> Motions { get; }

    /// <summary>Copies supported motion geometry immediately; later program edits cannot affect this snapshot.</summary>
    public static PartGeometrySnapshot FromProgram(Program program)
    {
        ArgumentNullException.ThrowIfNull(program);
        var motions = program.Codes.Select(code => code switch
        {
            ArcMove arc => new PartGeometryMotion(arc.Type, arc.EndPoint.X, arc.EndPoint.Y,
                arc.CenterPoint.X, arc.CenterPoint.Y, arc.Rotation, arc.Layer, arc.Suppressed),
            LinearMove line => new PartGeometryMotion(line.Type, line.EndPoint.X, line.EndPoint.Y,
                0, 0, default, line.Layer, line.Suppressed),
            RapidMove rapid => new PartGeometryMotion(rapid.Type, rapid.EndPoint.X, rapid.EndPoint.Y,
                0, 0, default, default, rapid.Suppressed),
            _ => throw new NotSupportedException("Geometry snapshots currently support only flat rapid/linear/arc programs.")
        });
        return new PartGeometrySnapshot(program.Mode, motions);
    }
}