using System;

namespace AcDream.Core.Physics;

/// <summary>
/// L.2a slice 1 (2026-05-12) — runtime-toggleable physics probe flags.
/// Initialized from env vars at process start; flippable at runtime via
/// the DebugPanel mirror (or by direct assignment). Log call sites read
/// these statics so a checkbox toggle takes effect on the next resolve
/// without relaunching.
///
/// <para>
/// L.2d slice 1 (2026-05-13) adds <see cref="ProbeBuildingEnabled"/> +
/// the <see cref="LastBspHitPoly"/> diagnostic side-channel. Future
/// slices may fold the older <c>ACDREAM_DUMP_*</c> env vars into this
/// class for unified runtime toggling. Until then, those older flags
/// remain sticky-at-startup per their original implementation.
/// </para>
/// </summary>
public static class PhysicsDiagnostics
{
    /// <summary>
    /// When true, <see cref="PhysicsEngine.ResolveWithTransition"/> emits
    /// one structured <c>[resolve]</c> line per call: input + target +
    /// output position/cell, grounded state, contact-plane status,
    /// collision-normal validity, walkable polygon status, moving entity
    /// id. Initial state from <c>ACDREAM_PROBE_RESOLVE=1</c>.
    /// </summary>
    public static bool ProbeResolveEnabled { get; set; } =
        Environment.GetEnvironmentVariable("ACDREAM_PROBE_RESOLVE") == "1";

    /// <summary>
    /// When true, every change to <c>PlayerMovementController.CellId</c>
    /// emits one <c>[cell-transit]</c> line: old → new cell, current
    /// world position, reason tag (<c>resolver</c> / <c>teleport</c>).
    /// Initial state from <c>ACDREAM_PROBE_CELL=1</c>.
    /// </summary>
    public static bool ProbeCellEnabled { get; set; } =
        Environment.GetEnvironmentVariable("ACDREAM_PROBE_CELL") == "1";

    /// <summary>
    /// L.2d slice 1 (2026-05-13). When true, every BSP-shadow-entry hit
    /// attributed by <c>TransitionTypes.FindObjCollisions</c> emits a
    /// multi-line <c>[resolve-bldg]</c> entry: which part (partIdx vs 0),
    /// physics-BSP root radius vs visual AABB radius, world-space entity
    /// origin, and the specific hit polygon's vertices in both
    /// object-local and world space. Designed to distinguish the three
    /// L.2d hypotheses (wrong BSP loaded / over-registered parts /
    /// BSPQuery flaw) from a single Holtburg-doorway capture.
    ///
    /// <para>
    /// Also gates a one-time <c>[entity-source]</c> log line at every
    /// <c>ShadowObjects.Register(...)</c> call site in <c>GameWindow</c>
    /// — makes <c>entityId=0xA9B479</c> in a probe line greppable to its
    /// source registration within the same log file.
    /// </para>
    ///
    /// <para>
    /// Initial state from <c>ACDREAM_PROBE_BUILDING=1</c>. Mirrorable
    /// via <c>DebugVM.ProbeBuilding</c> when <c>ACDREAM_DEVTOOLS=1</c>.
    /// </para>
    ///
    /// <para>
    /// Spec: <c>docs/superpowers/specs/2026-05-13-l2d-cbuildingobj-collision-design.md</c>.
    /// </para>
    /// </summary>
    public static bool ProbeBuildingEnabled { get; set; } =
        Environment.GetEnvironmentVariable("ACDREAM_PROBE_BUILDING") == "1";

    /// <summary>
    /// L.2d slice 1 (2026-05-13). Diagnostic side-channel: the
    /// <see cref="ResolvedPolygon"/> that <see cref="BSPQuery"/>
    /// recorded for the most recent collision-normal write.
    /// <see cref="TransitionTypes.FindObjCollisions"/> clears this to
    /// <see langword="null"/> before each shadow-entry test and reads it
    /// back after, so emitting the <c>[resolve-bldg]</c> probe line can
    /// reference the actual hit poly without plumbing an out-param
    /// through BSPQuery's recursive private methods.
    ///
    /// <para>
    /// Written by <see cref="BSPQuery"/> only when
    /// <see cref="ProbeBuildingEnabled"/> is true, so this stays
    /// zero-cost in normal play. Cylinder collisions leave this
    /// <see langword="null"/> — the probe line emits
    /// <c>hitPoly: n/a (cylinder)</c> in that case.
    /// </para>
    ///
    /// <para>
    /// Not threadsafe — physics runs on a single thread. If that
    /// changes, this needs <c>[ThreadStatic]</c> or rethink. Deviation
    /// from spec component 4 (which described an out-param); the
    /// side-channel keeps BSPQuery's signature stable and the diagnostic
    /// path off the production code surface.
    /// </para>
    /// </summary>
    public static ResolvedPolygon? LastBspHitPoly { get; set; }

    /// <summary>
    /// B.6 slice 1 (2026-05-14) — baseline trace for the local-player
    /// server-initiated auto-walk path (issue #63). When true, the
    /// following events emit one-line <c>[autowalk-*]</c> logs:
    /// <list type="bullet">
    ///   <item><description><c>[autowalk-out]</c> on every <c>SendUse</c>
    ///     / <c>SendPickUp</c> the local player issues — these are the
    ///     packets that may trigger ACE's server-side <c>CreateMoveToChain</c>
    ///     when the target is out of <c>WithinUseRadius</c>.</description></item>
    ///   <item><description><c>[autowalk-mt]</c> on every inbound
    ///     <c>UpdateMotion</c> for the local player — captures the
    ///     <c>MovementType + MoveToPath + speed/runRate</c> ACE sends.</description></item>
    ///   <item><description><c>[autowalk-up]</c> on every inbound
    ///     <c>UpdatePosition</c> for the local player — answers "what's
    ///     ACE's broadcast cadence during auto-walk?"</description></item>
    /// </list>
    /// Initial state from <c>ACDREAM_PROBE_AUTOWALK=1</c>.
    ///
    /// <para>
    /// Spec: <c>docs/superpowers/specs/2026-05-14-phase-b6-design.md</c>
    /// §"Required investigation".
    /// </para>
    /// </summary>
    public static bool ProbeAutoWalkEnabled { get; set; } =
        Environment.GetEnvironmentVariable("ACDREAM_PROBE_AUTOWALK") == "1";

    /// <summary>
    /// 2026-05-16. Logs one line per `IsUseableTarget` call that takes
    /// the null-useability fallback path (creature pass / BF_DOOR pass /
    /// BF_LIFESTONE pass / etc.). Used to measure how often ACE's seed
    /// DB ships entities without `_useability` set — settles whether
    /// the fallback is live code or theoretical defense.
    ///
    /// <para>
    /// Retail has NO fallback; null/zero useability blocks Use entirely
    /// (acclient_2013_pseudo_c.txt:402923 ItemHolder::UseObject —
    /// IsUseable==0 falls through to "cannot be used" branch). Our
    /// fallback exists because ACE genuinely sends null for many seed
    /// weenies. The probe quantifies "many".
    /// </para>
    ///
    /// <para>Toggle via env var <c>ACDREAM_PROBE_USEABILITY_FALLBACK=1</c>
    /// or DebugPanel checkbox.</para>
    /// </summary>
    public static bool ProbeUseabilityFallbackEnabled { get; set; } =
        Environment.GetEnvironmentVariable("ACDREAM_PROBE_USEABILITY_FALLBACK") == "1";
}