//! Layer 1 of docs/RUST.md's "Three test layers": the real transcript
//! screen, over the real bench fixture, at the phone's size and density,
//! driven by `iris::harness` with no window, no compositor and no GPU.
//!
//! Every gesture here is a file under `touch/` -- see
//! `flick-120hz.touch` for why the *shape* of the delivery is the whole
//! point, and why the emulator cannot produce it (a `ui-trace` swipe is
//! many evenly-spaced events; a finger at 120Hz is five samples in
//! 20ms).

use ai_app::ui::fixture::{PHONE_FRAME_MS, PHONE_SCALE, phone_size};
use iris::harness::{Harness, TouchScript};
use iris::prelude::*;

/// The screen open on the fixture, framed twice: once to draw, once for
/// `LazySpan::repair_anchor` to resolve the opening `snap_end` into a real
/// anchor, which is what every assertion about scroll position reads.
fn opened() -> (Harness, ai_app::ui::TranscriptScreen) {
    let mut h = Harness::new(phone_size(), PHONE_SCALE);
    let opened = ai_app::ui::fixture::open(&mut h.rsc, &mut h.state).expect("the fixture folds");
    h.frame(0);
    h.frame(PHONE_FRAME_MS);
    (h, opened.screen)
}

fn script(name: &str, text: &str) -> TouchScript {
    TouchScript::parse(text).unwrap_or_else(|e| panic!("{name}: {e}"))
}

fn offset(h: &mut Harness, screen: &ai_app::ui::TranscriptScreen) -> String {
    (screen.list)(&mut h.rsc).anchor_position_display()
}

/// (a) and (b) together, because the second is only meaningful if the
/// first happened: the recorded flick must release with a real velocity
/// (`GestureOutcome::Released(Some(v))`, which is the only thing that
/// puts a value in `Scroll::fling_velocity`), and the list must then
/// actually travel and stop on the spline's own schedule.
#[test]
fn a_recorded_flick_releases_with_a_velocity_and_flings_the_list() {
    let (mut h, screen) = opened();
    let before = offset(&mut h, &screen);

    let flick = script("flick-120hz", include_str!("../touch/flick-120hz.touch"));
    h.replay(&flick);

    let velocity = (screen.list)(&mut h.rsc)
        .fling_velocity()
        .expect("the flick must release as a pan with a velocity, not a tap");
    // Compose's own answer for this recording's five samples, printed by
    // `iris/benches/velocity_reference.py` -- not a number read off this
    // code. **Positive** because the flick runs *down* the screen and a
    // delta now carries the finger's own direction the whole way, from the
    // gesture through `Selection::drag` (which passes it straight to
    // `Scroll::fling`) to the anchor. It read -15250 while the transcript
    // negated the velocity on its way into a `LazySpan` whose anchor
    // offset ran the other way; the magnitude is the number that came from
    // `velocity_reference.py` and it has not changed.
    // The 2026-09-07 before/after: the old average estimator read
    // 12250px/s here, which is the fling Iris reported as too slow.
    assert!(
        (velocity - 15_250.0).abs() < 20.0,
        "expected ~15250px/s from velocity_reference.py, got {velocity}"
    );

    // `iris/benches/fling_spline_reference.py`'s own line for this exact
    // case -- `density=2.55 v=15250.0: distance=11057.424px
    // duration=2.0716s`. **Not** `FlingCalculator::new(PHONE_SCALE)`,
    // which is the calculator under test: bounding a fling with the thing
    // being measured is the "compared the code with itself" shape 73f956f
    // found in the spline's own tests, and it left this one able to fail
    // in the "ran too long" direction only -- never in the "stopped dead"
    // direction, which is what Iris actually reported
    // (review, 2026-09-07's T1).
    const REFERENCE_MS: u64 = 2071;
    const REFERENCE_PX: f32 = 11057.0;
    let end = flick.end_ms() + REFERENCE_MS * 2;
    let mut settled_at = None;
    let mut t = flick.end_ms();
    // Travel in pixels, measured from a row's own on-screen extent, since
    // `LazySpan` has no travel accessor and this needs none: follow whatever
    // row is under the viewport's middle until it leaves, then pick
    // another. Deliberately an *under*-count -- the frame a row leaves on
    // contributes nothing -- which is why it is only ever a lower bound.
    let middle = phone_size().y / 2.0;
    let mut travelled = 0.0f32;
    let mut tracked: Option<(RowKey, f32)> = None;
    while t <= end {
        h.frame(t);
        let list = (screen.list)(&mut h.rsc);
        tracked =
            match tracked.and_then(|(key, was)| list.extent(key).map(|(now, _)| (key, was, now))) {
                Some((key, was, now)) => {
                    travelled += (now - was).abs();
                    Some((key, now))
                }
                None => list
                    .key_at(middle)
                    .and_then(|key| list.extent(key).map(|(top, _)| (key, top))),
            };
        if settled_at.is_none() && !(screen.list)(&mut h.rsc).is_scrolling() {
            settled_at = Some(t);
        }
        t += PHONE_FRAME_MS;
    }

    let after = offset(&mut h, &screen);
    assert_ne!(
        before, after,
        "the fling ticks must have moved the list off where the flick left it"
    );
    let settled_at = settled_at.expect("the fling must stop on its own, not run forever");
    let ran_for = settled_at - flick.end_ms();
    // Both directions. The lower bound is the one that fails when a fling
    // settles on its first tick; the upper is the one that was here.
    assert!(
        ran_for >= REFERENCE_MS - PHONE_FRAME_MS * 2,
        "the fling stopped after {ran_for}ms against the spline reference's {REFERENCE_MS}ms"
    );
    assert!(
        ran_for <= REFERENCE_MS + PHONE_FRAME_MS * 2,
        "the fling ran {ran_for}ms against the spline reference's {REFERENCE_MS}ms"
    );
    // 80% of the reference, against 10527px measured today -- the 5%
    // shortfall is the frames a tracked row leaves the screen on. A fling
    // that moves one row's worth fails this; scaling `tick_fling`'s delta
    // by 0.01 reports 111px, which is how it was confirmed to fail in the
    // direction the bug goes.
    assert!(
        travelled >= REFERENCE_PX * 0.8,
        "the fling travelled {travelled:.0}px against the spline reference's {REFERENCE_PX:.0}px"
    );
}

/// The half the flick fix had no reason to touch: a tap must decide
/// `Tapped`, which means no velocity anywhere and nothing moved.
#[test]
fn a_tap_on_a_row_moves_nothing() {
    let (mut h, screen) = opened();
    let before = offset(&mut h, &screen);

    h.replay(&script("tap", include_str!("../touch/tap.touch")));

    assert_eq!(
        (screen.list)(&mut h.rsc).fling_velocity(),
        None,
        "a tap must not fling"
    );
    // Frames it would have moved in, had anything been moving.
    h.frames_until(100, 400, PHONE_FRAME_MS);
    assert_eq!(before, offset(&mut h, &screen), "a tap must scroll nothing");
    assert_eq!(
        h.state.opened_urls,
        Vec::<String>::new(),
        "no link was under this tap"
    );
}

/// A press held past `LONG_PRESS` and then dragged selects text rather
/// than panning -- the other branch of the same arbiter the flick goes
/// through.
#[test]
fn a_long_press_and_drag_selects_text() {
    let (mut h, screen) = opened();
    let before = offset(&mut h, &screen);

    h.replay(&script(
        "long-press",
        include_str!("../touch/long-press.touch"),
    ));

    let selected = screen
        .selected_text(&mut h.rsc)
        .expect("a long-press then drag must leave text selected");
    assert!(
        !selected.trim().is_empty(),
        "the selection covered no characters: {selected:?}"
    );
    assert_eq!(
        before,
        offset(&mut h, &screen),
        "a selection must not also pan the list"
    );
}

/// The composer sits on whatever the platform says the bottom of usable
/// space is -- the keyboard's inset while it is open
/// (`Composer::set_bottom_inset`, the path Android's
/// `on_insets_changed` feeds). Checked here rather than on the emulator
/// because it is a layout fact, and the emulator costs minutes.
#[test]
fn the_composer_sits_above_a_simulated_ime_inset() {
    let (mut h, screen) = opened();
    let height = h.size().y;
    let field_bottom = |h: &mut Harness| {
        h.render
            .window_region(&screen.composer.field, &h.rsc)
            .expect("the composer field is on screen")
            .bot_right
            .y
    };

    let closed = field_bottom(&mut h);
    assert!(
        closed <= height,
        "the composer is off the bottom of the window even with no keyboard: {closed} > {height}"
    );

    // A Gboard-sized keyboard on this surface. Any real number would do;
    // what matters is that the bar clears it.
    let ime = 1000.0;
    screen.composer.set_bottom_inset(&mut h.rsc, ime);
    h.frame(PHONE_FRAME_MS * 2);

    let open = field_bottom(&mut h);
    assert!(
        open <= height - ime,
        "the keyboard covers the composer: its bottom is at {open}, the IME starts at {}",
        height - ime
    );
    assert!(
        (closed - open - ime).abs() < 1.0,
        "the composer moved {} for a {ime}px inset",
        closed - open
    );
}

/// A newline typed into the composer must leave the caret inside the
/// bar's own padding, not flush against its bottom edge.
///
/// Iris's phone, 2026-09-08: "when typing with the keyboard up and
/// entering enough newlines ... the text drops down close to the bottom
/// and seems to ignore the padding. If I close (and optionally reopen)
/// the keyboard it seems to fix itself." The cause was `Scroll::draw`
/// placing its child against *last* frame's content length and stopping
/// there: each newline drew the field in a box one line short of its
/// text, and since the text is centred in its box it hung half a line
/// past each end, putting the caret's line box a full padding below the
/// bar's inside edge. Nothing dirtied that subtree again, so the stale
/// placement was simply the last one drawn -- until the keyboard closed
/// and the inset rewrite forced a redraw, which is the "fixes itself"
/// half of the report. No settling frame here on purpose: the placement
/// is corrected within the frame that typed, so the first frame drawn
/// after a keystroke is already right.
#[test]
fn a_newline_leaves_the_caret_inside_the_composers_padding() {
    let (mut h, screen) = opened();
    let height = h.size().y;
    let ime = 1000.0;
    screen.composer.set_bottom_inset(&mut h.rsc, ime);
    h.frame(PHONE_FRAME_MS * 2);

    h.state.set_focus(Some(screen.composer.field));
    screen.composer.field.edit(&mut h.rsc).set_cursor_byte(0);
    // Past `composer::MAX_LINES`, so the bar is capped and scrolling
    // rather than still growing -- the state the report is about.
    for _ in 0..12 {
        screen.composer.field.edit(&mut h.rsc).insert("a\n");
        h.frame(PHONE_FRAME_MS);
    }
    let message = h
        .render
        .debug(h.rsc.widgets(), "Message")
        .find(|a| !a.primitives.is_empty())
        .expect("the composer field is drawn");
    // The caret is the last primitive `TextEdit::draw` emits.
    let caret = h
        .render
        .primitive_corners(message.primitives.last().unwrap().slot, &h.rsc);
    // The bar sits directly on the IME, so its inside edge is one
    // `FIELD_PAD_DP` above `height - ime`. Stated in pixels rather than
    // read back from the composer, which is the thing under test.
    let bar_bottom = height - ime;
    let padding = 12.0 * PHONE_SCALE;
    assert!(
        caret.bot_right.y < bar_bottom - padding / 2.0,
        "the caret is in the bar's bottom padding: it ends at {}, the bar's edge is {bar_bottom} \
         and its padding is {padding}px",
        caret.bot_right.y,
    );

    // The old assertion only guarded the last line. A viewport one line
    // shorter than the field still kept that caret above the bottom while
    // moving the first line above the bar's mask, visibly slicing it off.
    let mask = h.rsc.ui.masks[message.mask.idx()];
    let bar = h.render.primitive_corners(mask.primitive, &h.rsc);
    let visible_content_top = message
        .primitives
        .iter()
        .map(|p| h.render.primitive_corners(p.slot, &h.rsc))
        .filter(|r| r.bot_right.y > bar.top_left.y)
        .map(|r| r.top_left.y)
        .fold(f32::INFINITY, f32::min);
    assert!(
        visible_content_top > bar.top_left.y,
        "the composer's first visible line is clipped above its bar: content starts at {visible_content_top}, bar starts at {}",
        bar.top_left.y,
    );
}