using ZB.MOM.WW.OtOpcUa.Driver.FOCAS;

namespace ZB.MOM.WW.OtOpcUa.AdminUI.Components.Shared.Drivers.Pickers;

/// <summary>
/// The addressing spaces the manual FOCAS picker can compose. Mirrors the parseable subset of
/// <see cref="FocasAreaKind"/>: <see cref="FocasAreaKind.Fixed"/> is deliberately absent because a
/// fixed-tree path is discovered from the machine, not composed from parts — the picker's browse
/// tree supplies those.
/// </summary>
public enum FocasManualAddressKind
{
    /// <summary>PMC area — letter + byte + optional bit.</summary>
    Pmc,

    /// <summary>CNC parameter number + optional bit.</summary>
    Parameter,

    /// <summary>Macro variable number.</summary>
    Macro,
}

/// <summary>
/// Pure static helper that composes a canonical FOCAS address from the manual picker's parts.
/// Extracted so unit tests can call it without bUnit.
/// </summary>
/// <remarks>
///     <para>
///     <b>It builds through <see cref="FocasAddress"/> rather than formatting a string</b>, so what
///     it emits is parseable by construction and the two cannot drift.
///     </para>
///     <para>
///     It previously emitted <c>$"{group}:{parameterId}"</c> over a group list of
///     <c>axis/spindle/program/status</c> — none of which is a FOCAS addressing space — so the
///     picker's own default value, <c>axis:5</c>, was an address the driver rejects. Together with
///     the browse-commit defect this meant every UI-assisted authoring path produced unusable tags,
///     and only hand-typed addresses worked at all (Gitea #540).
///     </para>
/// </remarks>
public static class FocasAddressBuilder
{
    /// <summary>The PMC area letters the driver accepts, in the order the picker offers them.</summary>
    public static IReadOnlyList<string> PmcLetters { get; } =
        ["X", "Y", "F", "G", "R", "D", "C", "K", "A", "E", "T"];

    /// <summary>
    /// Composes the canonical FOCAS address string, or an empty string when the parts do not form a
    /// valid address (an out-of-range bit, a negative number, an unknown PMC letter).
    /// </summary>
    /// <param name="kind">Which addressing space the address is in.</param>
    /// <param name="pmcLetter">The PMC area letter; ignored unless <paramref name="kind"/> is
    /// <see cref="FocasManualAddressKind.Pmc"/>.</param>
    /// <param name="number">The PMC byte, parameter number or macro number.</param>
    /// <param name="bitIndex">Optional bit index — 0–7 for PMC, 0–31 for a parameter. Null for a
    /// whole-word address; always ignored for a macro, which has no bit form.</param>
    /// <returns>The canonical address, or an empty string when the parts are not addressable.</returns>
    public static string Build(
        FocasManualAddressKind kind, string? pmcLetter, int number, int? bitIndex)
    {
        FocasAddress? candidate = kind switch
        {
            FocasManualAddressKind.Pmc => new FocasAddress(
                FocasAreaKind.Pmc, (pmcLetter ?? "").Trim().ToUpperInvariant(), number, bitIndex),
            FocasManualAddressKind.Parameter => new FocasAddress(
                FocasAreaKind.Parameter, null, number, bitIndex),
            FocasManualAddressKind.Macro => new FocasAddress(
                FocasAreaKind.Macro, null, number, null),
            _ => null,
        };

        // Round-trip rather than trust the parts: the record accepts any values, the parser is the
        // authority on which of them address anything, and an empty result is what the picker shows
        // as "no address yet" instead of a plausible-looking string the driver would silently skip.
        return candidate?.Canonical is { } text && FocasAddress.TryParse(text) is not null ? text : "";
    }
}