Sylpheed/crates/sylpheed-formats/tests/ui_prm_primitives_disc.rs

//! `.prm` elements are untextured quads, and the declaration table says so.
//!
//! Every composite the port draws is missing them: they carry no sprite, so
//! `compose` skips them. What they are was settled statically on 2026-08-19 —
//! see `docs/re/structures/ui-prm-primitives.md`. This pins the three facts the
//! decoding rests on, and is disc-gated like the rest of the corpus.

use std::path::{Path, PathBuf};

use sylpheed_formats::{pak::PakArchive, ratc, ui_layout};

fn disc_root() -> Option<PathBuf> {
    if let Ok(p) = std::env::var("SYLPHEED_DISC") {
        let p = PathBuf::from(p);
        if p.join("dat").is_dir() {
            return Some(p);
        }
    }
    let default = Path::new(
        "/home/fabi/RE - Project Sylpheed/Project Sylpheed - Arc of Deception (USA, Europe) (En,Ja)",
    );
    if default.join("dat").is_dir() {
        return Some(default.to_path_buf());
    }
    None
}

fn for_each_build(root: &Path, mut f: impl FnMut(&str, &[u8])) {
    let mut paks: Vec<PathBuf> = std::fs::read_dir(root.join("dat"))
        .expect("dat/")
        .flatten()
        .map(|e| e.path())
        .filter(|p| p.extension().and_then(|s| s.to_str()) == Some("pak"))
        .collect();
    paks.sort();
    for p in &paks {
        let name = p.file_name().unwrap().to_string_lossy().to_string();
        let Ok(arc) = PakArchive::open(p) else { continue };
        for e in arc.entries() {
            let Ok(bytes) = arc.read(e) else { continue };
            if ratc::is_ratc(&bytes) {
                f(&name, &bytes);
            }
        }
    }
}

/// **Bit `0x10` of `kind` means "untextured primitive", and it is exact.**
///
/// This is the point of the whole item: the primitive-ness is a *decoded field*,
/// not a guess from the `.prm` file extension. Over every screen build on the
/// disc, `kind & 0x10` and a `.prm` name agree with **zero** exceptions in
/// either direction — so a port can classify without parsing names.
///
/// Also pinned here because it is the same sweep: no `.prm` element has a RATC
/// child of its own name. All 369 of them are payload-less, which is what
/// "untextured" means concretely — there is nothing in the bundle to draw.
#[test]
fn kind_bit_0x10_means_prm_exactly_and_prm_carries_no_payload() {
    let Some(root) = disc_root() else {
        eprintln!("SKIP: extracted disc not found (set SYLPHEED_DISC to enable)");
        return;
    };
    let (mut prm, mut prm_without_bit, mut bit_without_prm, mut with_child) = (0, 0, 0, 0);
    let (mut full_screen, mut sized) = (0, 0);
    for_each_build(&root, |pak, bytes| {
        let Some(build) = ui_layout::parse_build(bytes) else {
            return;
        };
        if build.from_fallback {
            return;
        }
        let kids = ratc::parse(bytes).unwrap_or_default();
        for el in &build.elements {
            let is_prm = el.name.to_ascii_lowercase().ends_with(".prm");
            let has_bit = el.kind & 0x10 != 0;
            if is_prm && !has_bit {
                prm_without_bit += 1;
                eprintln!("{pak}: {} is .prm without bit 0x10", el.name);
            }
            if has_bit && !is_prm {
                bit_without_prm += 1;
                eprintln!("{pak}: {} has bit 0x10 but is not .prm", el.name);
            }
            if !is_prm {
                continue;
            }
            prm += 1;
            if kids.iter().any(|c| c.name == el.name) {
                with_child += 1;
                eprintln!("{pak}: {} has a payload child", el.name);
            }
            sized += 1;
            if (el.pivot_x * 2, el.pivot_y * 2) == (1280, 720) {
                full_screen += 1;
            }
        }
    });
    assert!(prm > 300, "only {prm} `.prm` elements — the sweep did not run");
    assert_eq!(prm_without_bit, 0, "a `.prm` element without kind bit 0x10");
    assert_eq!(bit_without_prm, 0, "kind bit 0x10 on something that is not `.prm`");
    assert_eq!(with_child, 0, "a `.prm` element with a payload child");
    // 361 of 369 are exactly the design space; the handful that are not are
    // small coloured quads (844x600, and two degenerate 0x720).
    assert!(
        full_screen * 10 > sized * 9,
        "only {full_screen}/{sized} `.prm` elements are full-screen"
    );
    eprintln!("{prm} `.prm` elements: all kind&0x10, none with a payload, {full_screen} full-screen");
}

/// **A `.prm` fade quad cannot be drawn at `Element::rest()`** — the pose that
/// rule picks would black out the screen.
///
/// The title's `pteff00.prm` is a screen transition: opaque black at t=12,
/// transparent by t=64, held transparent to t=74, opaque black again on the way
/// out. What the title screen sits at is the transparent plateau. `rest()` picks
/// by longest dwell to the next keyframe's time, which lands on an *endpoint* of
/// the fade — an opaque black full-screen quad, painted last in the measured
/// order, i.e. the whole screen.
///
/// This test states the defect rather than hiding it: it asserts the shape of
/// the group (so the reasoning stays checkable) and that `rest()` returns the
/// opaque frame (so that when the resting rule is fixed, this test fails and
/// someone reads the note above instead of rediscovering it).
#[test]
fn the_title_fade_quad_is_a_transition_and_rest_picks_the_wrong_end() {
    let Some(root) = disc_root() else {
        eprintln!("SKIP: extracted disc not found (set SYLPHEED_DISC to enable)");
        return;
    };
    let arc = PakArchive::open(root.join("dat").join("GP_TITLE.pak")).expect("GP_TITLE.pak");
    let mut checked = 0usize;
    for e in arc.entries() {
        let Ok(bytes) = arc.read(e) else { continue };
        let Some(build) = ui_layout::parse_build(&bytes) else {
            continue;
        };
        for el in &build.elements {
            if el.name != "pteff00.prm" || el.keyframes.len() != 4 {
                continue;
            }
            checked += 1;
            let a: Vec<u32> = el.keyframes.iter().map(|k| k.fade >> 24).collect();
            assert_eq!(
                a,
                vec![0xff, 0x00, 0x00, 0xff],
                "the fade group is opaque → transparent → transparent → opaque"
            );
            assert_eq!(
                el.rest().map(|k| k.fade),
                Some(0xff00_0000),
                "rest() still picks an endpoint of the fade — if this now returns \
                 the transparent plateau the resting rule has been fixed and the \
                 note on this test is stale"
            );
        }
    }
    assert!(checked >= 3, "found {checked} title fade quads, expected several");
}