benilla-octo/crates/benilla-ui/src/script/object.rs

//! The FrameScript object model, frame side (RF-0023) — `CreateFrame`, the frame metatable +
//! wrapper cache, and the shared frame method surface (decision 0068 v1). The region side lives in
//! [`super::region`]; per-kind frame methods in their own modules ([`super::statusbar`], …),
//! dispatched by [`kind_method_registries`] before the shared table.
//!
//! A frame's Lua value is a table `T` with `T[0] = lightuserdata(id)` (the id encoding stands in for
//! RF-0023's `CScriptObject*`; see the module docs on ids) and one **shared** metatable whose
//! `__index` is a Rust function that dispatches a method name to its implementation. Wrappers are
//! cached in a Lua-side registry table keyed by id, so `GetParent()` (etc.) returns the *same* table
//! every time (stable identity). Named frames auto-publish to `_G`, non-overwriting (RF-0023). Region
//! leaves (`Texture`/`FontString`) use the same `T[0]` scheme but a *distinct* metatable (the "tag"
//! that separates their method surface from frames').
//!
//! The whole surface honors the MAXCSTACK discipline: the two metatables, the two method tables, and
//! the wrapper cache live in the Lua registry (named keys); Rust holds none of them across calls.

use std::ffi::c_void;

use mlua::{LightUserData, Lua, ObjectLike, Table, Value};

use super::binding_abi::optional_string;
use super::{Model, REG_FRAME_META, REG_FRAME_METHODS, REG_SCRIPTS, REG_WRAPPERS};
use crate::layout::Point;
use crate::order::{DrawLayer, Strata};
use crate::widget::{FrameHandle, FrameKind};

// The frame method-table clusters — split out purely for size (each module's own doc says what
// lives there); this file keeps the shared id/handle plumbing, `install`, and `CreateFrame`.
mod events_regions;
mod frame_state;
mod layout_methods;
pub(crate) use layout_methods::eff_scale;
pub(crate) mod movable;
pub(crate) mod toplevel;
pub(crate) use layout_methods::{anchor_bits_eq, anchor_retarget_is_structural};
pub(crate) use movable::{advance_move, advance_size, FrameMove, FrameSizing};

// ─────────────────────────────────────────────────────────────────────────────────────────────
// id ↔ lightuserdata
// ─────────────────────────────────────────────────────────────────────────────────────────────

pub(super) fn id_to_lud(id: u32) -> LightUserData {
    LightUserData(id as usize as *mut c_void)
}

/// Read the id out of a wrapper table's `T[0]` lightuserdata (RF-0023).
pub(crate) fn decode_id(this: &Table) -> mlua::Result<u32> {
    match this.raw_get::<Value>(0)? {
        Value::LightUserData(l) => Ok(l.0 as usize as u32),
        _ => Err(mlua::Error::runtime(
            "not a benilla frame/region object (missing T[0] identity)",
        )),
    }
}

/// Resolve `self` (a frame wrapper) to its live [`FrameHandle`].
pub(super) fn frame_handle_of(lua: &Lua, this: &Table) -> mlua::Result<FrameHandle> {
    let id = decode_id(this)?;
    let model = lua.app_data_ref::<Model>().expect("model app_data");
    model
        .id_to_frame
        .get(&id)
        .copied()
        .ok_or_else(|| mlua::Error::runtime("stale or invalid frame handle"))
}

// ─────────────────────────────────────────────────────────────────────────────────────────────
// Wrapper cache (RF-0023: lazy bind + named _G publish, non-overwriting)
// ─────────────────────────────────────────────────────────────────────────────────────────────

/// Get-or-create the wrapper table for a frame id, caching it and (if the frame is named and `_G`
/// has no such global yet) publishing it to `_G`. Callers must hold **no** model borrow (this takes
/// a short one to read the frame's name).
pub(super) fn frame_wrapper(lua: &Lua, id: u32) -> mlua::Result<Table> {
    let wrappers: Table = lua.named_registry_value(REG_WRAPPERS)?;
    if let Value::Table(t) = wrappers.get::<Value>(id)? {
        return Ok(t);
    }
    let t = lua.create_table()?;
    t.raw_set(0, Value::LightUserData(id_to_lud(id)))?;
    let meta: Table = lua.named_registry_value(REG_FRAME_META)?;
    t.set_metatable(Some(meta))?;
    wrappers.set(id, t.clone())?;

    let name: Option<String> = {
        let model = lua.app_data_ref::<Model>().expect("model app_data");
        model
            .id_to_frame
            .get(&id)
            .and_then(|h| model.arena.frame(*h))
            .and_then(|f| f.name.clone())
    };
    if let Some(name) = name {
        publish_global(lua, &name, &t)?;
    }
    Ok(t)
}

/// Publish a wrapper to `_G[name]`, non-overwriting (RF-0023).
pub(super) fn publish_global(lua: &Lua, name: &str, wrapper: &Table) -> mlua::Result<()> {
    let g = lua.globals();
    if g.get::<Value>(name)?.is_nil() {
        g.set(name, wrapper.clone())?;
    }
    Ok(())
}

// ─────────────────────────────────────────────────────────────────────────────────────────────
// String → enum parsing (the client's tables, transcribed in order.rs / layout.rs)
// ─────────────────────────────────────────────────────────────────────────────────────────────

pub(super) fn point_from_str(s: &str) -> Option<Point> {
    Some(match s.to_ascii_uppercase().as_str() {
        "TOPLEFT" => Point::TopLeft,
        "TOP" => Point::Top,
        "TOPRIGHT" => Point::TopRight,
        "LEFT" => Point::Left,
        "CENTER" => Point::Center,
        "RIGHT" => Point::Right,
        "BOTTOMLEFT" => Point::BottomLeft,
        "BOTTOM" => Point::Bottom,
        "BOTTOMRIGHT" => Point::BottomRight,
        _ => return None,
    })
}

/// The inverse of [`point_from_str`] (the client's point-id table `0x811a38`, names back out).
///
/// `pub(super)` because the REGION cluster reports the same names from the same table — one
/// spelling of the point set, not two (`region/layout.rs`'s `GetPoint`).
pub(super) fn point_name(p: Point) -> &'static str {
    match p {
        Point::TopLeft => "TOPLEFT",
        Point::Top => "TOP",
        Point::TopRight => "TOPRIGHT",
        Point::Left => "LEFT",
        Point::Center => "CENTER",
        Point::Right => "RIGHT",
        Point::BottomLeft => "BOTTOMLEFT",
        Point::Bottom => "BOTTOM",
        Point::BottomRight => "BOTTOMRIGHT",
    }
}

/// Every closed-vocabulary attribute parser **trims** before it matches (decision 1204).
///
/// Not tidiness: `zBar.xml:146` — a shipped, working 1.12 addon — declares
/// `frameStrata="BACKGROUND "` with a trailing space, and the real client took it. Ours refused,
/// the frame's whole `<Frames>` subtree went with it, and the addon never loaded. Whitespace is
/// never meaningful in an enum token, so trimming is both the lenient answer and the correct one;
/// it is applied at the three parsers rather than at the attribute read, because a `text=`
/// attribute's leading space IS meaningful and must not be touched.
fn enum_token(s: &str) -> String {
    s.trim().to_ascii_uppercase()
}

/// The reference's strata NAME table (`0x8119f8`) has eight rows, `BACKGROUND`..`TOOLTIP`; stratum
/// 0 (`WORLD`) has no name and no XML or Lua can put a frame there — the WorldFrame's constructor
/// is its only writer (decision 1984, wow-re `worldframe-widget.md` §4).
fn strata_from_str(s: &str) -> Option<Strata> {
    Some(match enum_token(s).as_str() {
        "BACKGROUND" => Strata::Background,
        "LOW" => Strata::Low,
        "MEDIUM" => Strata::Medium,
        "HIGH" => Strata::High,
        "DIALOG" => Strata::Dialog,
        "FULLSCREEN" => Strata::Fullscreen,
        "FULLSCREEN_DIALOG" => Strata::FullscreenDialog,
        "TOOLTIP" => Strata::Tooltip,
        "BLIZZARD" => Strata::Blizzard,
        _ => return None,
    })
}

pub(super) fn draw_layer_from_str(s: &str) -> Option<DrawLayer> {
    Some(match enum_token(s).as_str() {
        "BACKGROUND" => DrawLayer::Background,
        "BORDER" => DrawLayer::Border,
        "ARTWORK" => DrawLayer::Artwork,
        "OVERLAY" => DrawLayer::Overlay,
        "HIGHLIGHT" => DrawLayer::Highlight,
        _ => return None,
    })
}

/// The inverse of [`draw_layer_from_str`] — the token `GetDrawLayer` answers, in the client's own
/// spelling (uppercase, the five `<Layer level=>` names).
pub(super) fn draw_layer_name(l: DrawLayer) -> &'static str {
    match l {
        DrawLayer::Background => "BACKGROUND",
        DrawLayer::Border => "BORDER",
        DrawLayer::Artwork => "ARTWORK",
        DrawLayer::Overlay => "OVERLAY",
        DrawLayer::Highlight => "HIGHLIGHT",
    }
}

/// A widget tag or `CreateFrame` type string → its [`FrameKind`], case- and separator-insensitive
/// ([`enum_token`]). Public because it is the ONE mapping: `benilla-app`'s `frame_flag_gate` sweep
/// needs it to ask the engine whether a tag is mouse-enabled by construction, and a second copy
/// there is exactly what drifted.
pub fn frame_kind_from_tag(s: &str) -> Option<FrameKind> {
    frame_kind_from_str(s)
}

fn frame_kind_from_str(s: &str) -> Option<FrameKind> {
    Some(match enum_token(s).as_str() {
        "FRAME" => FrameKind::Frame,
        // The world frame's own registered type (decision 1983; `0x495948` in the registration
        // batch, the one row passing `1` as its third argument).
        "WORLDFRAME" => FrameKind::WorldFrame,
        // `TaxiRouteFrame` — a registered `CreateFrame` type that is a `CSimpleFrame` and NOTHING
        // else, so it maps to `Frame` rather than earning a kind (decision 1828; wow-re
        // `ui/scratch/taxiroute-widget-type.md`). Factory `0x495ba0` allocates `0x314`, the same
        // size the plain-`<Frame>` factory `0x6eec10` allocates for the same base ctor `0x769090`,
        // and the ctor `0x506950` adds no field. Its vtables are the base's length exactly (36 + 11
        // slots), so it declares no new virtual; it overrides four slots, of which two are lifetime
        // plumbing and the other two — `EmitLayer 0x506a60` and a scale hook `0x506ac0` — are DEAD
        // in 5875: the paint callback `0x506a90` tail-calls `0x506aa0`, which is a bare `ret`, and
        // every module global it would fill is written by nothing.
        //
        // Mapping it to `Frame` is therefore the faithful answer, not a 1203 shortcut — and it is
        // faithful in the strong sense that `GetObjectType()` must return **"Frame"** and
        // `IsObjectType("TaxiRouteFrame")` must be **false**: `0x484800` is not overridden, so the
        // name lives only in the 22-entry tag→factory registry and never becomes a class identity.
        // The flight-path lines are plain `<Texture>` children the FrameXML creates and rotates
        // with the 8-argument `SetTexCoord` we already support; `TaxiRouteFrame.cpp` is a vestigial
        // C++ renderer that draws nothing.
        "TAXIROUTEFRAME" => FrameKind::Frame,
        "BUTTON" => FrameKind::Button,
        "CHECKBUTTON" => FrameKind::CheckButton,
        // A real registered type (`0x4959a6`), not an alias for Button — decision 1799. Registering
        // it AS a Button would load `LootFrame.xml` and leave every row dead, because 1.12 has no
        // Lua verb for "take slot N": `LootSlot` is the bind-confirm continuation, hard-wired to
        // `flag = 1`.
        "LOOTBUTTON" => FrameKind::LootButton,
        "EDITBOX" => FrameKind::EditBox,
        "STATUSBAR" => FrameKind::StatusBar,
        "SLIDER" => FrameKind::Slider,
        "SCROLLFRAME" => FrameKind::ScrollFrame,
        "MODEL" => FrameKind::Model,
        "PLAYERMODEL" => FrameKind::PlayerModel,
        "DRESSUPMODEL" => FrameKind::DressUpModel,
        "TABARDMODEL" => FrameKind::TabardModel,
        "MESSAGEFRAME" => FrameKind::MessageFrame,
        "SCROLLINGMESSAGEFRAME" => FrameKind::ScrollingMessageFrame,
        "COLORSELECT" => FrameKind::ColorSelect,
        "SIMPLEHTML" => FrameKind::SimpleHtml,
        "MOVIEFRAME" => FrameKind::MovieFrame,
        "GAMETOOLTIP" => FrameKind::GameTooltip,
        "MINIMAP" => FrameKind::Minimap,
        "COOLDOWN" => FrameKind::Cooldown,
        _ => return None,
    })
}

/// A Lua number-ish → f32 (nil/other → 0.0), for offset/color args.
pub(super) fn as_f32(v: &Value) -> f32 {
    match v {
        Value::Number(n) => *n as f32,
        Value::Integer(i) => *i as f32,
        _ => 0.0,
    }
}

// ─────────────────────────────────────────────────────────────────────────────────────────────
// install — build the method tables, metatables, CreateFrame, and registry roots
// ─────────────────────────────────────────────────────────────────────────────────────────────

pub(super) fn install(lua: &Lua) -> mlua::Result<()> {
    // The wrapper cache + the per-frame script tables (Lua-side roots — the MAXCSTACK discipline).
    lua.set_named_registry_value(REG_WRAPPERS, lua.create_table()?)?;
    lua.set_named_registry_value(REG_SCRIPTS, lua.create_table()?)?;

    install_frame_methods(lua)?;
    super::region::install(lua)?;
    super::statusbar::install(lua)?;
    super::button::install(lua)?;
    super::editbox::install(lua)?;
    // AFTER every table above exists: collapse the 19 Region-map names to one shared
    // implementation each, so a method pulled off a frame works on a texture (decision 1501).
    super::region_map::install(lua)?;

    // Shared frame metatable: __index is a Rust dispatcher over the frame method table (RF-0023),
    // checking the frame's *kind-specific* method table first. Per-kind resolution matters beyond
    // correctness: addons duck-type widgets (`if frame.SetValue then …`), so a plain frame must
    // resolve `SetValue` to nil — one shared table would make every frame quack like every widget.
    let frame_meta = lua.create_table()?;
    let frame_index = lua.create_function(|lua, (this, key): (Table, Value)| {
        for reg in kind_method_registries(lua, &this) {
            let methods: Table = lua.named_registry_value(reg)?;
            let v = methods.get::<Value>(key.clone())?;
            if !v.is_nil() {
                return Ok(v);
            }
        }
        let methods: Table = lua.named_registry_value(REG_FRAME_METHODS)?;
        methods.get::<Value>(key)
    })?;
    frame_meta.set("__index", frame_index)?;
    lua.set_named_registry_value(REG_FRAME_META, frame_meta.clone())?;
    // RF-0023 publishes the shared metatable as _G["__framescript_meta"].
    lua.globals().set("__framescript_meta", frame_meta)?;

    // CreateFrame(kind, name?, parent?, inherits?) — a global (RF-0024's factory is the loader's;
    // this is the runtime one). `inherits` (4th) applies a registered template to the frame this
    // call just made, through `crate::loader::apply_template`.
    let create_frame = lua.create_function(create_frame)?;
    lua.globals().set("CreateFrame", create_frame)?;

    // GetScreenWidth/Height — the screen-root rect in UI units (the ref's tooltip side-pick reads
    // them: ContainerFrameItemButton_OnEnter anchors LEFT when the slot sits in the right half).
    lua.globals().set(
        "GetScreenWidth",
        lua.create_function(|lua, ()| {
            let model = lua.app_data_ref::<Model>().expect("model");
            Ok(model.screen.width())
        })?,
    )?;
    lua.globals().set(
        "GetScreenHeight",
        lua.create_function(|lua, ()| {
            let model = lua.app_data_ref::<Model>().expect("model");
            Ok(model.screen.height())
        })?,
    )?;

    // SetupFullscreenScale(frame) — the registered binding `0x48c270` the stock WorldMapFrame.xml,
    // CinematicFrame.xml and UIOptionsFrame.xml call from OnShow (decision 1980; wow-re
    // `system/ui/scratch/setup-fullscreen-scale.md`, VERIFIED at the bytes): the frame's scale
    // becomes `min(0.75 · a, 1.0)` for the CONFIGURED aspect `a` — the `gxResolution` width over
    // height (the `widescreen` CVar's default of 1 selects it; at 0 the aspect is 4:3 and the
    // scale 1) — and nothing else is written: no anchor, size or position, and `UIParent`'s
    // scale never enters. It is the same `CSimpleFrame::SetScale` the Lua method calls. The
    // window's aspect is the configured one here (the UI-unit rect keeps the pixel ratio); NaN
    // takes the 1.0 leg as the reference's `fcomp` does. The three raises are the binding's own.
    lua.globals().set(
        "SetupFullscreenScale",
        lua.create_function(|lua, frame: Value| {
            let Value::Table(frame) = frame else {
                return Err(mlua::Error::runtime("Usage: SetupFullscreenScale(frame)"));
            };
            if decode_id(&frame).is_err() {
                return Err(mlua::Error::runtime(
                    "SetupFullscreenScale(): Couldn't find 'this' in frame object",
                ));
            }
            if frame_handle_of(lua, &frame).is_err() {
                return Err(mlua::Error::runtime(
                    "SetupFullscreenScale(): Wrong object type, expected frame",
                ));
            }
            let scale = {
                let model = lua.app_data_ref::<Model>().expect("model");
                fullscreen_scale(model.screen.width() / model.screen.height())
            };
            frame.call_method::<()>("SetScale", scale)
        })?,
    )?;

    // GetCursorPosition() → x, y — the last cursor position the host fed (`mouse_move`/
    // `mouse_button`), UI units y-up like every other coordinate read — the SCREEN's units, which
    // is what the reference hands Lua too; a caller inside a scaled frame divides by its
    // `GetEffectiveScale()` (the reference's own `MouseIsOver` does, and the stock world map at
    // a scale under 1 is the case that made the division load-bearing here — decision 1985). The
    // world map polls this every OnUpdate for hover/click math.
    lua.globals().set(
        "GetCursorPosition",
        lua.create_function(|lua, ()| {
            let model = lua.app_data_ref::<Model>().expect("model");
            Ok(model.cursor_pos)
        })?,
    )?;

    // The modifier-key mirror ([`UiScript::set_modifiers`], fed by the app's input pass before
    // any mouse event each frame) — the reference handlers fork on these at click time
    // (ContainerFrame.lua's shift-split / ctrl-dressup, ActionBarFrame.xml's shift-pickup,
    // SpellBookFrame.lua's shift-pickup). Era booleans, not 1.12's 1/nil — the house API target
    // (decision 0068); every transcribed `if IsShiftKeyDown()` reads both identically.
    for (name, pick) in [
        ("IsShiftKeyDown", 0usize),
        ("IsControlKeyDown", 1),
        ("IsAltKeyDown", 2),
    ] {
        lua.globals().set(
            name,
            lua.create_function(move |lua, ()| {
                let model = lua.app_data_ref::<Model>().expect("model");
                let m = [model.modifiers.0, model.modifiers.1, model.modifiers.2];
                Ok(m[pick])
            })?,
        )?;
    }

    Ok(())
}

/// The registry keys of a frame's kind-specific method tables, in resolution order — the `__index`
/// dispatcher walks them before the shared table, mirroring the client's class chain (CheckButton
/// resolves through Button's map, RF-28). Empty for plain kinds (and for anything that isn't a live
/// frame, e.g. a region wrapper passing through).
fn kind_method_registries(lua: &Lua, this: &Table) -> &'static [&'static str] {
    let Ok(id) = decode_id(this) else { return &[] };
    let model = lua.app_data_ref::<Model>().expect("model app_data");
    let Some(h) = model.id_to_frame.get(&id) else {
        return &[];
    };
    match model.arena.frame(*h).map(|f| f.kind) {
        Some(FrameKind::StatusBar) => &[super::statusbar::REG_STATUSBAR_METHODS],
        Some(FrameKind::EditBox) => &[super::editbox::REG_EDITBOX_METHODS],
        Some(FrameKind::ScrollingMessageFrame) => {
            &[super::messageframe::REG_SCROLLINGMESSAGEFRAME_METHODS]
        }
        // Its SIBLING, with its own table — not a fallthrough to the scrolling one. Until this arm
        // existed a `<MessageFrame>` resolved no kind-specific method at all, which is what blocked
        // `EasyCopy`, `QuestHistory` and `QuestItem` on `UIErrorsFrame:AddMessage` (three of the
        // corpus's six method-class blockers) and made `SetInsertMode` unreachable.
        Some(FrameKind::MessageFrame) => &[super::messageframe::REG_MESSAGEFRAME_METHODS],
        Some(FrameKind::ScrollFrame) => &[super::scrollframe::REG_SCROLLFRAME_METHODS],
        Some(FrameKind::SimpleHtml) => &[super::simplehtml::REG_SIMPLEHTML_METHODS],
        Some(FrameKind::Slider) => &[super::slider::REG_SLIDER_METHODS],
        Some(FrameKind::ColorSelect) => &[super::colorselect::REG_COLORSELECT_METHODS],
        Some(FrameKind::Button) => &[super::button::REG_BUTTON_METHODS],
        // One method of its own, then all of Button's — the miss order of `0x4c1be0`, which probes
        // its own 1-entry map `0xb71b64` and tail-calls `Button`'s `0x782c90`.
        Some(FrameKind::LootButton) => &[
            super::loot::REG_LOOTBUTTON_METHODS,
            super::button::REG_BUTTON_METHODS,
        ],
        Some(FrameKind::CheckButton) => &[
            super::button::REG_CHECKBUTTON_METHODS,
            super::button::REG_BUTTON_METHODS,
        ],
        // The Model pane's own surface. Its absence is what stopped pfUI — and, through pfUI's
        // embedded copies, pfQuest, pfQuest-turtle and ShaguDPS — on `SetModel` after the whole
        // rest of their UI had already built (`super::modelframe`'s header).
        Some(FrameKind::Model) => &[super::modelframe::REG_MODEL_METHODS],
        // The chain, not a repetition: `CGCharacterModelBase`'s lookup `0x506260` probes its own
        // 3-entry map and on a miss tail-calls `CSimpleModel`'s `0x76f870`. Order is the miss
        // order — three names of its own, then all 23 of `Model`'s.
        Some(FrameKind::PlayerModel) => &[
            super::modelframe::REG_PLAYERMODEL_METHODS,
            super::modelframe::REG_MODEL_METHODS,
        ],
        // Three of its own, then PlayerModel's three, then Model's 23: `CGDressUpModelFrame`'s
        // lookup probes `0x84f190` and misses into `CGCharacterModelBase`'s `0x506260`, which
        // misses into `CSimpleModel`'s `0x76f870` (1969).
        Some(FrameKind::DressUpModel) => &[
            super::dressup::REG_DRESSUPMODEL_METHODS,
            super::modelframe::REG_PLAYERMODEL_METHODS,
            super::modelframe::REG_MODEL_METHODS,
        ],
        // Ten of its own (`0x84ee40`), then PlayerModel's three, then Model's 23 — the same
        // derived → base probe as its sibling (1977).
        Some(FrameKind::TabardModel) => &[
            super::tabard::REG_TABARDMODEL_METHODS,
            super::modelframe::REG_PLAYERMODEL_METHODS,
            super::modelframe::REG_MODEL_METHODS,
        ],
        Some(FrameKind::Minimap) => &[super::minimap::REG_MINIMAP_METHODS],
        Some(FrameKind::Cooldown) => &[super::cooldown::REG_COOLDOWN_METHODS],
        Some(FrameKind::GameTooltip) => &[super::tooltip::REG_TOOLTIP_METHODS],
        _ => &[],
    }
}

/// `CreateFrame(kind, name?, parent?, inherits?)` — the runtime frame factory.
///
/// The fourth argument is a **template name list**, and honouring it is what makes
/// `CreateFrame("Button", "MyButton", UIParent, "UIPanelButtonTemplate")` — the corpus's most
/// common single line — produce a button with art, regions, scripts and a fired `OnLoad` rather
/// than an empty frame. The frame is created first and decorated second
/// ([`crate::loader::apply_template`]), in that order and never the other way: the template's own
/// `OnLoad` must be able to see the frame's real name, and `$parent` inside the template must
/// resolve against **the caller's** name, not the template's.
///
/// An **unresolvable** template name raises `CreateFrame(): Couldn't find inherited node "%s"` and
/// creates nothing — the reference's own behaviour, byte-verified (`0x7061dd` → `luaL_error`, which
/// never returns). A template that resolves but is *unusable in some other way* — declared without
/// `virtual="true"`, or of a shape that does not fit the kind asked for — is still a warning plus a
/// working frame, because the registry lookup itself succeeded and that is the only thing the miss
/// branch tests.
pub(super) fn create_frame(
    lua: &Lua,
    (kind, name, parent, inherits): (String, Option<Value>, Option<Value>, Option<Value>),
) -> mlua::Result<Table> {
    let frame_kind = frame_kind_from_str(&kind)
        .ok_or_else(|| mlua::Error::runtime(format!("CreateFrame: unknown frame type '{kind}'")))?;
    // The WorldFrame's registry record is a ONE-SHOT: the reference unlinks and releases it the
    // moment the first `<WorldFrame>` is instantiated (`0x6ee439`), so a second one — from any
    // XML, or `CreateFrame("WorldFrame")` — takes the lookup's miss leg, `Unknown frame type`
    // (decision 1984). The loader reaches this through the same global, so it covers both.
    if frame_kind == FrameKind::WorldFrame
        && lua
            .app_data_ref::<Model>()
            .expect("model app_data")
            .world_frame_made
    {
        return Err(mlua::Error::runtime(format!(
            "CreateFrame: unknown frame type '{kind}'"
        )));
    }
    // **`name` and `inherits` are `lua_tostring` positions, and a NUMBER is a string to it.**
    // `0x7060b0` reads both through `0x6f3690` with no type guard at all, so `CreateFrame("Frame",
    // 5)` names the frame `"5"` — a `Value::String`-only match drops it (wow-re
    // `ui/scratch/xml-template-name-lookup.md` §5.2).
    //
    // The fourth argument's quirk, which is real and reads like a bug in the client: `lua_tostring`
    // runs at `0x70613f` **before** the `cmp 4` gate, and `0x6f7cb1 mov dword ptr [esi],0x4`
    // retags the number's stack slot **in place** — so by the time the tag is tested it IS a
    // string. `CreateFrame("Frame", nil, nil, 5)` therefore raises `Couldn't find inherited node
    // "5"`, while `f:CreateTexture(nil, nil, 5)` silently ignores the 5, because the region
    // constructors ask `lua_type` first and never coerce. Same value, opposite outcome, decided by
    // argument order alone — which is why this is spelled out rather than shared with them.
    let name: Option<String> = name.as_ref().and_then(|v| optional_string(lua, v));
    let template: Option<String> = inherits.as_ref().and_then(|v| optional_string(lua, v));

    // Resolve the parent handle (a wrapper table, or a name string) under a short read borrow.
    //
    // **The name-string arm is OURS, and the reference RAISES on it** — `0x7060b0` asks
    // `lua_type` three times and `cmp eax,5`: a table is the parent, nil/absent means no parent,
    // and a string takes the error leg (`xml-template-name-lookup.md` §5.2's per-position table).
    //
    // It is **parked, not pruned**, on the same footing as `TEXTURE_ONLY_METHODS`' tail three: the
    // §5 established *that* it raises but did not quote the message, and inventing the text of a
    // client error is exactly what decision 1721 was written about — a plausible string in the
    // voice of a finding. Measured meanwhile: **zero** call sites pass a string parent, in the
    // 109-folder corpus or in our own FrameXML, so the superset is unreachable in practice and
    // removing it blind would buy nothing. Pruning it needs the message, not more confidence.
    let parent_handle: Option<FrameHandle> = {
        let model = lua.app_data_ref::<Model>().expect("model app_data");
        match &parent {
            Some(Value::Table(t)) => decode_id(t)
                .ok()
                .and_then(|id| model.id_to_frame.get(&id).copied()),
            Some(Value::String(s)) => s.to_str().ok().and_then(|n| model.arena.lookup(n.as_ref())),
            _ => None,
        }
    };

    // A 4th argument that is present but neither a string nor a number is **silently ignored by
    // the reference** — `lua_tostring` returns NULL for it and the `cmp 4` gate then falls into
    // the ordinary construction path. So this is a benilla-only diagnostic and stays a WARNING,
    // never a raise: it tells a reader something was dropped without changing what runs.
    if template.is_none() {
        if let Some(v) = inherits.as_ref().filter(|v| !v.is_nil()) {
            let mut model = lua.app_data_mut::<Model>().expect("model app_data");
            model.warnings.push(format!(
                "CreateFrame: the 4th argument (inherits) must be a template-name string, got {}; \
                 ignored for '{}'",
                v.type_name(),
                name.as_deref().unwrap_or("<unnamed>")
            ));
        }
    }

    // ── THE TEMPLATE LOOKUP HAPPENS HERE — before anything is constructed or published ──────────
    //
    // `0x7061dd` calls the registry lookup `0x6ee6f0` and, on NULL, falls into
    // `luaL_error(L, "CreateFrame(): Couldn't find inherited node \"%s\"")` at `0x7061ed`. That
    // never returns — `luaG_errormsg`/`luaD_throw` contain no `ret` at all and end in `longjmp`, so
    // the `xor eax,eax; ret` after the call is dead code. The frame is **not created**, no global
    // is published, and the calling statement is abandoned; the error is ordinary Lua propagation
    // and `pcall`-catchable, which is how the widget dispatcher (`0x704f10`, every handler under
    // `lua_pcall`) turns it into one dead handler rather than a dead client.
    //
    // We used to warn and hand back a usable bare frame, and the doc above said the reference
    // "creates the frame anyway". That claim is refuted at the bytes. It is the same class as 1249:
    // a failure the client reports and we swallowed — and swallowing is the worse half, because the
    // addon then runs on a frame with none of the art, regions or scripts it asked for and fails
    // later, somewhere unrelated.
    //
    // Ordering is the carved part, not a detail: the miss branch precedes the synthetic-node build
    // (`0x706208`) and the `name` store (`0x70622d`), so a miss leaves no partial widget and no
    // orphan global behind. Doing this after construction would leave both.
    if let Some(t) = template.as_deref().filter(|t| !t.is_empty()) {
        let known = {
            let model = lua.app_data_ref::<Model>().expect("model app_data");
            let templates = model.framexml_templates.borrow();
            // One name, verbatim, folded — the law `framexml::expand` resolves under.
            templates.contains_key(t) || templates.keys().any(|k| k.eq_ignore_ascii_case(t))
        };
        if !known {
            return Err(mlua::Error::runtime(format!(
                "CreateFrame(): Couldn't find inherited node \"{t}\""
            )));
        }
    }

    // Create in the arena, mint the id, seed a default layout input. All under one write borrow.
    let id = {
        let mut model = lua.app_data_mut::<Model>().expect("model app_data");
        let h = model.arena.create(frame_kind, name, parent_handle);
        if frame_kind == FrameKind::WorldFrame {
            model.world_frame_made = true;
        }
        // The client's CreateFrame inheritance (the ctor doc's "loader/CreateFrame concern" —
        // widget/mod.rs `create`): a child enters its PARENT's stratum at the parent's level + 1.
        // The ctor's bare MEDIUM/0 left a DIALOG-strata popup drawing its own translucent
        // backdrop OVER its buttons (the children stayed in MEDIUM — the abandon dialog's dark
        // buttons, pixel-diffed against the raw art). An explicit frameStrata/frameLevel attr
        // still overrides right after (apply_attrs).
        if let Some(p) = parent_handle {
            if let Some((pstrata, plevel)) = model.arena.frame(p).map(|f| (f.strata, f.level)) {
                model.arena.set_frame_strata(h, pstrata);
                model.arena.set_frame_level(h, plevel + 1, false);
            }
        }
        let id = model.frame_id(h);
        model.layout_inputs.entry(h).or_default();
        id
    };

    // The wrapper exists (and, if named, is published to `_G`) BEFORE the template runs — a
    // template's `OnLoad` fires inside this call, and the reference's addons rely on both facts:
    // `local b = CreateFrame(...)` hands back a frame whose OnLoad has already run, and that
    // handler can reach itself by name.
    let wrapper = frame_wrapper(lua, id)?;
    if let Some(template) = template {
        let messages = crate::loader::apply_template(lua, &wrapper, &kind, &template);
        if !messages.is_empty() {
            let mut model = lua.app_data_mut::<Model>().expect("model app_data");
            model.warnings.extend(messages);
        }
    }
    Ok(wrapper)
}

// ─────────────────────────────────────────────────────────────────────────────────────────────
// Frame method surface — the table itself is built by the three clusters above
// ─────────────────────────────────────────────────────────────────────────────────────────────

/// Build the shared frame method table from the five clusters ([`frame_state`], [`layout_methods`],
/// [`events_regions`], [`movable`], [`toplevel`]) and publish it to the registry.
fn install_frame_methods(lua: &Lua) -> mlua::Result<()> {
    let m = lua.create_table()?;
    frame_state::install(lua, &m)?;
    layout_methods::install(lua, &m)?;
    events_regions::install(lua, &m)?;
    movable::install(lua, &m)?;
    toplevel::install(lua, &m)?;
    lua.set_named_registry_value(REG_FRAME_METHODS, m)?;
    Ok(())
}

/// `0x48c270`'s law: `g = 0.75 · aspect`, and the scale is `g` below 1.0, else 1.0 — NaN lands on
/// the 1.0 leg (the `fcomp` compare fails every ordered test).
pub(crate) fn fullscreen_scale(aspect: f32) -> f32 {
    let g = 0.75 * aspect;
    if g < 1.0 {
        g
    } else {
        1.0
    }
}

#[cfg(test)]
mod fullscreen_scale_tests {
    use super::fullscreen_scale;
    use crate::script::UiScript;

    #[test]
    fn the_scale_is_three_quarters_of_the_aspect_capped_at_one() {
        assert_eq!(fullscreen_scale(4.0 / 3.0), 1.0);
        assert_eq!(fullscreen_scale(16.0 / 9.0), 1.0);
        assert!((fullscreen_scale(5.0 / 4.0) - 0.9375).abs() < 1e-6);
        assert_eq!(fullscreen_scale(f32::NAN), 1.0);
    }

    #[test]
    fn the_verb_scales_the_frame_and_raises_its_three_strings() {
        let mut s = UiScript::new().unwrap();
        s.set_screen_size(1280.0, 1024.0);
        s.run(r#"f = CreateFrame("Frame", "FS") SetupFullscreenScale(f)"#)
            .unwrap();
        assert!((s.eval::<f64>("return f:GetScale()").unwrap() - 0.9375).abs() < 1e-6);
        s.set_screen_size(1600.0, 900.0);
        s.run("SetupFullscreenScale(f)").unwrap();
        assert_eq!(s.eval::<f64>("return f:GetScale()").unwrap(), 1.0);
        for (call, needle) in [
            (
                "SetupFullscreenScale()",
                "Usage: SetupFullscreenScale(frame)",
            ),
            (
                "SetupFullscreenScale(7)",
                "Usage: SetupFullscreenScale(frame)",
            ),
            (
                "SetupFullscreenScale({})",
                "Couldn't find 'this' in frame object",
            ),
            (
                "SetupFullscreenScale(f:CreateTexture())",
                "Wrong object type, expected frame",
            ),
        ] {
            let err = s.run(call).unwrap_err().to_string();
            assert!(err.contains(needle), "{call}: {err}");
        }
    }
}