using System.Collections.Generic;
using AcDream.Core.Chat;
using AcDream.UI.Abstractions.Panels.Settings;

namespace AcDream.App.UI.Layout;

/// <summary>
/// Pure port of <c>gmConfigUI::SetMouseTurningDefaults @0x0049E8F0</c> — the
/// Gameplay tab's "Use Mouse Turning Settings" button
/// (<c>docs/research/2026-08-10-keyboard-config-and-gameplay-tab.md</c> §4.4).
/// A one-shot "apply the recommended mouse-turning values" macro over six
/// options: five CLIENT-LOCAL preferences
/// (<see cref="CameraTurningSettings"/>) plus one server-synced bit
/// (<c>PlayerOption.UseMouseTurning</c>, NOT modeled here — the caller
/// threads the current/target value in and reads
/// <see cref="Result.UseMouseTurningChanged"/> back out to decide whether to
/// send <c>SetSingleCharacterOption (0x0005)</c>).
///
/// <para>
/// Byte-verified per-value conditions (research doc §4.4, the MSVC
/// <c>fcomp</c>/<c>fnstsw</c>/<c>jnp</c> idiom — the body runs when the
/// CURRENT value differs from the macro's target, exact float equality, no
/// epsilon): Stiffness → 0.95 iff <c>≠ 0.95</c>; AdjustmentSpeed → 50.0 iff
/// <c>≠ 50.0</c>; MouseLookSensitivity → 0.7 iff <c>≠ 0.7</c>; AlignToSlope
/// → off iff currently on; InvertMouseLookYAxis → on iff currently off;
/// UseMouseTurning → on iff currently off. Retail's directional bool
/// conditions (<c>== 1</c> / <c>== 0</c>) are behaviourally identical to a
/// plain inequality against the fixed target for a two-state bool, so this
/// port uses <c>!=</c> uniformly.
/// </para>
///
/// <para>
/// Retail emits one retail-verbatim chat line PER CHANGED value (never for
/// an already-at-target value) and finishes with
/// <c>SaveCurrentValues()</c> (the caller's job — the macro's target page is
/// the Config tab's own <see cref="OptionPage"/>, which this class does not
/// know about).
/// </para>
/// </summary>
public static class MouseTurningSettingsMacro
{
    public readonly record struct Result(
        CameraTurningSettings Updated,
        bool UseMouseTurningChanged,
        IReadOnlyList<string> ChatLines);

    /// <summary>
    /// Computes the macro's outcome. Pure — no I/O, no side effects; the
    /// caller applies <see cref="Result.Updated"/> (persist + live apply),
    /// sends the wire bit if <see cref="Result.UseMouseTurningChanged"/>,
    /// and emits <see cref="Result.ChatLines"/> through the interface-text
    /// seam, in that order (retail's own call order at
    /// <c>0x0049E924</c>-<c>0x0049EB57</c>).
    /// </summary>
    public static Result Compute(CameraTurningSettings current, bool useMouseTurningCurrent)
    {
        CameraTurningSettings target = CameraTurningSettings.MouseTurningTarget;
        var lines = new List<string>();

        float stiffness = current.Stiffness;
        if (stiffness != target.Stiffness)
        {
            lines.Add(OptionsPanelText.CameraStiffnessChanged(stiffness, target.Stiffness));
            stiffness = target.Stiffness;
        }

        float adjustmentSpeed = current.AdjustmentSpeed;
        if (adjustmentSpeed != target.AdjustmentSpeed)
        {
            lines.Add(OptionsPanelText.CameraAdjustmentChanged(adjustmentSpeed, target.AdjustmentSpeed));
            adjustmentSpeed = target.AdjustmentSpeed;
        }

        float sensitivity = current.MouseLookSensitivity;
        if (sensitivity != target.MouseLookSensitivity)
        {
            lines.Add(OptionsPanelText.MouseSensitivityChanged(sensitivity, target.MouseLookSensitivity));
            sensitivity = target.MouseLookSensitivity;
        }

        bool alignToSlope = current.AlignToSlope;
        if (alignToSlope != target.AlignToSlope)
        {
            lines.Add(OptionsPanelText.AlignToSlopeChanged);
            alignToSlope = target.AlignToSlope;
        }

        bool invertY = current.InvertMouseLookYAxis;
        if (invertY != target.InvertMouseLookYAxis)
        {
            lines.Add(OptionsPanelText.InvertMouseLookAxesChanged);
            invertY = target.InvertMouseLookYAxis;
        }

        // UseMouseTurning's target is always ON (true) — retail's
        // `== 0` condition ("currently off").
        bool useMouseTurningChanged = useMouseTurningCurrent != true;
        if (useMouseTurningChanged)
            lines.Add(OptionsPanelText.TurnToFaceCameraChanged);

        return new Result(
            new CameraTurningSettings(stiffness, adjustmentSpeed, sensitivity, alignToSlope, invertY),
            useMouseTurningChanged,
            lines);
    }
}