//! The described things that are not fields, tables or frames.
//!
//! A meter, a token, a control, a figure. `makeover-tui` has had these since its
//! own `widget` module and this crate has not, which is the gap that showed up
//! the moment anything tried to draw a whole `quasi_router::Screen` in egui:
//! the screen walk had a renderer for the containers and nothing for four of the
//! nodes inside them, so the drawing would have landed in the consumer, one copy
//! per app. That is the divergence this suite exists to end, so it lands here.
//!
//! # What "in egui" changes, and what it does not
//!
//! The semantics are `makeover-tui`'s, deliberately: a meter is a bar and a
//! reading, a badge is round and a chip is square, a control names its key where
//! the description gave one, and a figure puts the movement on the value rather
//! than on the caption. Those are description-level readings and they do not get
//! a second opinion per host.
//!
//! What differs is forced by the target rather than chosen. A terminal spends a
//! whole cell on a character and returns a `Line` for the caller to place; egui
//! paints an arbitrary rect and answers a [`Response`], so every function here
//! draws into the `Ui` it is given and hands back what the user did to it. That
//! is also why nothing here takes a `focused` flag the way `makeover-tui`'s
//! `act` does: egui owns focus, which is the rule the crate header states.

use egui::{Align, Layout, Response, RichText, Sense, Ui, Vec2};
use makeover_layout::{Act, Figure, Meter, State, Token, Tone};

use crate::Palette;

/// The sizes a widget cannot derive from the description.
///
/// Every number a caller might reasonably want different, in one place, on the
/// footing [`FrameStyle`](crate::FrameStyle) and [`FieldStyle`](crate::FieldStyle)
/// already establish: this crate owns no sizes.
#[derive(Debug, Clone, Copy, PartialEq)]
pub struct WidgetStyle {
    /// How tall a meter's bar is drawn.
    pub meter_height: f32,
    /// How wide a meter's bar runs, or `None` to take the width on offer.
    ///
    /// `None` is the honest default in immediate mode: a bar in a side panel and
    /// a bar in a wide pane are the same description, and the available width is
    /// the only thing either of them knows.
    pub meter_width: Option<f32>,
    /// The corner radius on a meter's trough and on a token.
    pub radius: u8,
    /// Inside a token, around its label.
    pub token_padding: Vec2,
    /// Between a figure's value and its caption.
    pub figure_gap: f32,
    /// How much larger a figure's value is drawn than the body text.
    ///
    /// A multiplier rather than a size, so a figure scales with whatever text
    /// style the app has set rather than pinning a point size this crate has no
    /// business choosing.
    pub figure_scale: f32,
}

impl Default for WidgetStyle {
    /// Bars at 6pt taking the width on offer, and a figure at double text size.
    fn default() -> Self {
        Self {
            meter_height: 6.0,
            meter_width: None,
            radius: 3,
            token_padding: Vec2::new(6.0, 2.0),
            figure_gap: 2.0,
            figure_scale: 2.0,
        }
    }
}

/// A proportion as a bar and a reading.
///
/// The reading is built here from the two numbers and the noun, for the reason
/// `makeover-tui` states: [`Meter::label`] carries the noun alone, so each
/// renderer picks its own sentence order rather than the description picking one
/// for all of them.
///
/// **A bar that has run over is drawn full and reads over.** `done` may exceed
/// `total` and that is the case worth drawing, per `Meter`'s own docs: the fill
/// is clamped because a rect cannot be longer than itself, and the reading is
/// not, because "9/6" is the fact the user needs. Clamping both would hide the
/// overrun entirely, which is the bug goingson's `is_over_estimate` flag exists
/// to recover from on the other side.
///
/// A zero `total` is no set rather than a complete one, so it draws empty.
pub fn meter(ui: &mut Ui, meter: &Meter<'_>, palette: &Palette, style: &WidgetStyle) -> Response {
    let width = style
        .meter_width
        .unwrap_or_else(|| ui.available_width().max(1.0));
    ui.horizontal(|ui| {
        let (rect, response) =
            ui.allocate_exact_size(Vec2::new(width, style.meter_height), Sense::hover());
        // The trough is the sunken surface rather than a tint of the tone: a
        // bar is a thing set into the page with something in it, which is what
        // `Fill::Sunken` means, and tinting the empty half would read as a
        // second, paler proportion.
        ui.painter().rect_filled(rect, style.radius, palette.sunken);
        let share = if meter.total == 0 {
            0.0
        } else {
            (f64::from(meter.done) / f64::from(meter.total)).min(1.0)
        };
        #[expect(
            clippy::cast_possible_truncation,
            reason = "a share is 0..=1 and the product is a width in points"
        )]
        let filled = (f64::from(rect.width()) * share) as f32;
        if filled > 0.0 {
            let mut fill = rect;
            fill.set_width(filled);
            ui.painter()
                .rect_filled(fill, style.radius, palette.tone(meter.tone));
        }
        let reading = match meter.label {
            Some(label) => format!("{}/{} {label}", meter.done, meter.total),
            None => format!("{}/{}", meter.done, meter.total),
        };
        ui.label(RichText::new(reading).color(palette.content_muted));
        response
    })
    .inner
}

/// A badge or a chip.
///
/// Round for a badge, square for a chip, which is `makeover-tui`'s reading and
/// `makeover-webview`'s before it. The shape carries the difference because
/// colour is already spent on the tone.
///
/// **A chip answers a click and a badge does not**, which is
/// [`Token::interactive`] and is the whole difference between the members. The
/// `Response` comes back either way, so a caller that presses a badge is
/// pressing something this function said was not interactive; the sense is what
/// makes egui agree.
///
/// `latched` is a chip that is switched on, and it fills rather than outlines. A
/// terminal has to collide latched with focus because it has one spare axis for
/// two facts; egui does not, so it does not.
///
/// A chip's removable half is not drawn, on `makeover-tui`'s reasoning: a second
/// control inside a token is a question for whoever owns the interaction rather
/// than for a drawing.
pub fn token(
    ui: &mut Ui,
    label: &str,
    kind: Token,
    tone: Tone,
    latched: bool,
    palette: &Palette,
    style: &WidgetStyle,
) -> Response {
    let painted = palette.tone(tone);
    let radius = match kind {
        // Round enough to read as a pill whatever the height turns out to be.
        Token::Badge => u8::MAX,
        Token::Chip { .. } => style.radius,
    };
    let sense = if kind.interactive() {
        Sense::click()
    } else {
        Sense::hover()
    };

    // Laid out before the rect is allocated, because a token is exactly as wide
    // as what it says plus its padding: there is no box to fit text into here,
    // the way a table cell has one.
    let ink = if latched { palette.page } else { painted };
    let galley = ui.painter().layout_no_wrap(
        label.to_owned(),
        egui::TextStyle::Body.resolve(ui.style()),
        ink,
    );
    let size = galley.size() + style.token_padding * 2.0;
    let (rect, response) = ui.allocate_exact_size(size, sense);

    if latched {
        ui.painter().rect_filled(rect, radius, painted);
    } else {
        ui.painter().rect_stroke(
            rect,
            radius,
            egui::Stroke::new(1.0, painted),
            egui::StrokeKind::Inside,
        );
    }
    ui.painter()
        .galley(rect.center() - galley.size() / 2.0, galley, ink);
    response
}

/// A control.
///
/// The key the description named is drawn beside the label where there is one,
/// which is [`Act::key`] finally being read by a second renderer: it was written
/// for a terminal, and a desktop app has keys too.
///
/// **A disabled control is drawn and does not answer**, through
/// [`State::suppresses_interaction`] rather than a second reading of what
/// disabled means, and it takes [`Palette::content_muted`] because that is the
/// intent `State::Disabled` resolves to. egui is told through `add_enabled`, so
/// its own focus walk skips it: a control that is drawn and not reachable is
/// exactly what `disabled` means on every host, and here the host already has
/// the machinery.
pub fn act(ui: &mut Ui, act: &Act<'_>, palette: &Palette, _style: &WidgetStyle) -> Response {
    let disabled = act.state.is_some_and(State::suppresses_interaction);
    let label = match act.key {
        Some(key) => format!("{}  ({key})", act.label),
        None => act.label.to_owned(),
    };
    let colour = if disabled {
        palette.content_muted
    } else {
        palette.tone(act.tone)
    };
    ui.add_enabled(
        !disabled,
        egui::Button::new(RichText::new(label).color(colour)),
    )
}

/// A figure: the value, then what it counts under it.
///
/// The tone lands on the value and its change rather than on the caption, which
/// is what [`Figure::tone`] means: the figure is an ordinary fact and it is the
/// movement that reads as good or bad. `makeover-tui` says the same thing with a
/// bold span; here it is a larger one, because egui can size text and a terminal
/// cannot.
pub fn figure(
    ui: &mut Ui,
    figure: &Figure<'_>,
    palette: &Palette,
    style: &WidgetStyle,
) -> Response {
    ui.with_layout(Layout::top_down(Align::Min), |ui| {
        let value = match figure.change {
            Some(change) => format!("{} {change}", figure.value),
            None => figure.value.to_owned(),
        };
        let size = egui::TextStyle::Body.resolve(ui.style()).size * style.figure_scale;
        let shown = ui.label(
            RichText::new(value)
                .color(palette.tone(figure.tone))
                .size(size)
                .strong(),
        );
        ui.add_space(style.figure_gap);
        ui.label(RichText::new(figure.caption).color(palette.content_muted));
        shown
    })
    .inner
}

#[cfg(test)]
mod tests {
    use super::*;

    fn palette() -> Palette {
        use egui::Color32;
        Palette {
            page: Color32::from_rgb(1, 1, 1),
            raised: Color32::from_rgb(2, 2, 2),
            overlay: Color32::from_rgb(3, 3, 3),
            well: Color32::from_rgb(4, 4, 4),
            sunken: Color32::from_rgb(5, 5, 5),
            bevel_light: Color32::from_rgb(6, 6, 6),
            bevel_dark: Color32::from_rgb(7, 7, 7),
            elevation: Color32::from_black_alpha(40),
            content: Color32::from_rgb(20, 20, 20),
            content_muted: Color32::from_rgb(21, 21, 21),
            action: Color32::from_rgb(22, 22, 22),
            danger: Color32::from_rgb(23, 23, 23),
            success: Color32::from_rgb(24, 24, 24),
            warning: Color32::from_rgb(25, 25, 25),
            info: Color32::from_rgb(26, 26, 26),
        }
    }

    #[test]
    fn every_tone_resolves_and_no_two_share_a_colour() {
        // The reason the three status intents arrived together: a resolver
        // missing one has to invent a colour for it.
        let p = palette();
        let all = [
            p.tone(Tone::Neutral),
            p.tone(Tone::Info),
            p.tone(Tone::Success),
            p.tone(Tone::Warning),
            p.tone(Tone::Danger),
        ];
        for (i, a) in all.iter().enumerate() {
            for b in &all[i + 1..] {
                assert_ne!(a, b, "two tones resolved to one colour");
            }
        }
        assert_eq!(p.tone(Tone::Neutral), p.content, "neutral is ordinary text");
    }

    #[test]
    fn a_meter_draws_and_an_overrun_does_not_panic() {
        // `done` may exceed `total`, which is the case Meter's own docs call
        // the one worth drawing. The fill clamps; the reading does not.
        let p = palette();
        let style = WidgetStyle::default();
        egui::__run_test_ui(|ui| {
            meter(ui, &Meter::new(3, 6), &p, &style);
            meter(ui, &Meter::new(9, 6), &p, &style);
            // No set, rather than a complete one.
            meter(ui, &Meter::new(0, 0), &p, &style);
            // The overflow `makeover-layout` pins on its own side.
            meter(ui, &Meter::new(u32::MAX, u32::MAX), &p, &style);
        });
    }

    #[test]
    fn a_chip_answers_a_click_and_a_badge_does_not() {
        // `Token::interactive` is the whole difference between the members, and
        // the sense is what makes egui agree with it.
        let p = palette();
        let style = WidgetStyle::default();
        egui::__run_test_ui(|ui| {
            let badge = token(ui, "beta", Token::Badge, Tone::Info, false, &p, &style);
            assert!(!badge.sense.senses_click(), "a badge answers no click");

            let chip = token(
                ui,
                "drums",
                Token::Chip { removable: false },
                Tone::Neutral,
                false,
                &p,
                &style,
            );
            assert!(chip.sense.senses_click(), "a chip answers a click");
        });
    }

    #[test]
    fn a_disabled_control_is_drawn_and_does_not_answer() {
        // Present, visible, and not answering. Through
        // `State::suppresses_interaction` rather than a second reading here.
        let p = palette();
        let style = WidgetStyle::default();
        egui::__run_test_ui(|ui| {
            let live = act(ui, &Act::new("Save"), &p, &style);
            assert!(live.enabled());

            let gone = act(ui, &Act::new("Save").state(State::Disabled), &p, &style);
            assert!(!gone.enabled(), "a disabled control still answers");
        });
    }

    #[test]
    fn a_control_shows_the_key_the_description_named() {
        // `Act::key` was written for a terminal before there was one. A desktop
        // app has keys too, so this is its second reader.
        let p = palette();
        let style = WidgetStyle::default();
        egui::__run_test_ui(|ui| {
            act(ui, &Act::new("New").key("n"), &p, &style);
            act(ui, &Act::new("New"), &p, &style);
        });
    }

    #[test]
    fn a_figure_draws_its_movement_beside_its_value() {
        let p = palette();
        let style = WidgetStyle::default();
        egui::__run_test_ui(|ui| {
            figure(ui, &Figure::new("17", "Current streak"), &p, &style);
            figure(
                ui,
                &Figure::new("17", "Current streak")
                    .change("+3")
                    .tone(Tone::Success),
                &p,
                &style,
            );
        });
    }
}