OpenNest/OpenNest.Core/CNC/HeadRaise.cs

using System;
using System.Collections.Generic;
using System.Linq;

namespace OpenNest.CNC
{
    /// <summary>
    /// A rapid the head must make raised because it passes over parts already cut, which may have
    /// tipped. Plan Cutting marks such a rapid only when no route avoids the crossing, and always
    /// marks the rapid out of a cutout's slug after its lead-out (see docs/cutting-planner.md): a
    /// <see cref="Marker"/> comment immediately before the <see cref="RapidMove"/>, or before the
    /// <see cref="SubProgramCall"/> whose arrival rapid it is, since a sub-program may be shared and
    /// is never marked itself. Rapid checks accept a crossing on a marked rapid. Posts write their machine's head raise before every marked rapid,
    /// and refuse to post a marked program when they have none, since the rapid is unsafe head down.
    /// See docs/cutting-planner.md.
    /// </summary>
    public static class HeadRaise
    {
        /// <summary>The comment immediately before a rapid made with the head raised.</summary>
        public const string Marker = "HEAD RAISE";

        public static bool IsMarker(ICode code) => code is Comment { Value: Marker };

        /// <summary>Whether <paramref name="program"/>'s own codes hold a marker.</summary>
        public static bool IsMarked(Program program)
        {
            if (program?.Codes == null)
                return false;
            foreach (var code in program.Codes)
                if (IsMarker(code))
                    return true;
            return false;
        }

        /// <summary>
        /// For each of <paramref name="codes"/>, whether it is a rapid made with the head raised, or a
        /// sub-program call whose arrival rapid is. A marker must be followed directly by a rapid or
        /// a call; anything else is a malformed program (<see cref="ArgumentException"/>), since a
        /// post could raise before the wrong move.
        /// </summary>
        public static bool[] RaisedMask(IReadOnlyList<ICode> codes)
        {
            ArgumentNullException.ThrowIfNull(codes);
            var mask = new bool[codes.Count];
            for (var i = 0; i < codes.Count; i++)
            {
                if (!IsMarker(codes[i]))
                    continue;
                if (i + 1 >= codes.Count || codes[i + 1] is not (RapidMove or SubProgramCall))
                    throw new ArgumentException("A head-raise marker is not followed by a rapid.");
                mask[i + 1] = true;
            }
            return mask;
        }

        /// <summary>
        /// A copy of <paramref name="program"/> with a marker before each of its own codes at
        /// <paramref name="rapids"/>, which must be rapids or sub-program calls not marked already.
        /// </summary>
        public static Program Mark(Program program, IReadOnlyCollection<int> rapids)
        {
            ArgumentNullException.ThrowIfNull(program);
            ArgumentNullException.ThrowIfNull(rapids);
            var marked = RaisedMask(program.Codes);
            var copy = (Program)program.Clone();
            for (var i = copy.Codes.Count - 1; i >= 0; i--)
            {
                if (!rapids.Contains(i))
                    continue;
                if (copy.Codes[i] is not (RapidMove or SubProgramCall) || marked[i])
                    throw new ArgumentException("Only an unmarked rapid or sub-program call can be marked for a head raise.");
                copy.Codes.Insert(i, new Comment(Marker));
            }
            return copy;
        }

        /// <summary>
        /// Refuses a nest a post cannot write, before any output is created: a marked rapid needs
        /// the post's head-raise code, and its markers must be well formed.
        /// </summary>
        public static void EnsurePostable(Nest nest, bool hasCode, string postName) =>
            PostMarkers.EnsurePostable(nest, hasCode, IsMarked, program => RaisedMask(program.Codes),
                name => $"{name} has rapids that must raise the head over parts already cut, but "
                    + $"the {postName} post has no head-raise code. Enter it in \"Head raise\" in "
                    + $"the {postName} Settings dialog, which opens when you post.");
    }
}