edamame 0.1.4

//! About edamame popover: bean art, rotating acronym tagline, installed version, author credit,
//! and three buttons.
//!
//! It deliberately reports **no** release information of its own: it used to fetch the latest
//! release on first open, which made merely opening the page a network request and put a second
//! surface in the business of rendering release state.  `modal::UpdateModal`, which the button
//! stacks on top, is the one display site for that.
//!
//! The tagline rotation is *derived* from `opened_at.elapsed()` at render time rather than mutated
//! by a tick; [`Modal::next_deadline`] tells the run loop when to wake and redraw.

use std::any::Any;
use std::time::{Duration, Instant};

use crossterm::event::KeyEvent;
use ratatui::layout::Rect;
use ratatui::Frame;

use super::chrome::{body_columns, ModalChrome};
use super::types::{Modal, ModalKind, ModalOutcome, ModalRenderCtx};
use crate::app::update_check;
use crate::app::App;
use crate::ui::{about, ModalButton, ModalResponse};

const INSTALLED_VERSION: &str = env!("CARGO_PKG_VERSION");

/// How long each acronym expansion stays up before rotating.
const TAGLINE_INTERVAL: Duration = Duration::from_secs(4);

/// Indices into `buttons`, named so the order and the `resolve` arms can't drift apart.  Every
/// button has a name: the old catch-all `ButtonPressed(_)` arm meant a fourth would have silently
/// opened GitHub.
const RELEASE_NOTES_BUTTON: usize = 0;
const CHECK_UPDATES_BUTTON: usize = 1;
const VIEW_ON_GITHUB_BUTTON: usize = 2;

pub struct AboutModal {
    chrome: ModalChrome,
    buttons: Vec<ModalButton>,
    opened_at: Instant,
    /// Offset into [`about::TAGLINES`] so the page doesn't open on the
    /// same expansion every time.
    tagline_start: usize,
}

impl AboutModal {
    pub(crate) fn new() -> Self {
        // Vary the opening tagline without a rand dependency: sub-second wall-clock nanos are
        // effectively uniform across user-initiated opens.
        let tagline_start = std::time::SystemTime::now()
            .duration_since(std::time::UNIX_EPOCH)
            .map(|d| d.subsec_nanos() as usize % about::TAGLINES.len())
            .unwrap_or(0);
        Self {
            chrome: ModalChrome::new(ModalKind::Normal, true),
            buttons: vec![
                // First: it sits under the installed-version row it describes, and unlike the
                // other two it answers from the binary itself.
                ModalButton::new("Release notes"),
                ModalButton::new("Check for updates"),
                ModalButton::new("View on GitHub"),
            ],
            opened_at: Instant::now(),
            tagline_start,
        }
    }

    fn tagline_index(&self) -> usize {
        let flips = self.opened_at.elapsed().as_secs() / TAGLINE_INTERVAL.as_secs();
        self.tagline_start + flips as usize
    }

    /// Map a response to an outcome, shared by the key and click paths.  Every button keeps the
    /// page open, so the user returns to it from the browser or the stacked modal.
    fn resolve(&mut self, response: ModalResponse) -> ModalOutcome {
        match response {
            ModalResponse::Continue => ModalOutcome::Continue,
            ModalResponse::Cancelled => ModalOutcome::Close,
            ModalResponse::ButtonPressed(RELEASE_NOTES_BUTTON) => {
                ModalOutcome::ContinueAnd(Box::new(|app| app.open_post_upgrade_modal()))
            }
            ModalResponse::ButtonPressed(CHECK_UPDATES_BUTTON) => {
                ModalOutcome::ContinueAnd(Box::new(|app| app.open_update_modal()))
            }
            ModalResponse::ButtonPressed(VIEW_ON_GITHUB_BUTTON) => {
                ModalOutcome::ContinueAnd(Box::new(|app| {
                    app.spawn_open_worker(update_check::GITHUB_URL.to_owned());
                }))
            }
            // A stray index acts on nothing rather than falling into whichever arm is last.
            ModalResponse::ButtonPressed(_) => ModalOutcome::Continue,
        }
    }
}

impl Modal for AboutModal {
    fn render(&mut self, frame: &mut Frame<'_>, area: Rect, ctx: &ModalRenderCtx<'_>) {
        let body = about::body_lines(
            ctx.theme,
            self.tagline_index(),
            INSTALLED_VERSION,
            body_columns(area),
        );
        self.chrome
            .render(frame, area, ctx, "About edamame", &body, &self.buttons);
    }

    fn handle_key(
        &mut self,
        key: KeyEvent,
        _app: &mut App,
        _doc_height: usize,
        _doc_width: usize,
    ) -> ModalOutcome {
        let response = self.chrome.on_key(&key, self.buttons.len());
        self.resolve(response)
    }

    fn handle_wheel(&mut self, delta: i32) {
        self.chrome.on_wheel(delta);
    }

    fn handle_click(&mut self, col: u16, row: u16, _app: &mut App) -> ModalOutcome {
        let response = self.chrome.on_click(col, row);
        self.resolve(response)
    }

    fn kind(&self) -> ModalKind {
        self.chrome.kind()
    }

    fn dismissable(&self) -> bool {
        self.chrome.dismissable()
    }

    fn next_deadline(&self) -> Option<Instant> {
        // The next boundary of a `TAGLINE_INTERVAL` grid anchored at `opened_at`.  The saturating
        // conversion keeps an absurdly long session from wrapping the deadline into the past, where
        // the run loop's `> now` filter would drop it.
        let periods = self.opened_at.elapsed().as_nanos() / TAGLINE_INTERVAL.as_nanos();
        let periods = u32::try_from(periods).unwrap_or(u32::MAX);
        Some(self.opened_at + TAGLINE_INTERVAL * periods.saturating_add(1))
    }

    fn as_any(&self) -> &dyn Any {
        self
    }

    fn as_any_mut(&mut self) -> &mut dyn Any {
        self
    }
}

#[cfg(test)]
mod tests {
    use crossterm::event::{KeyCode, KeyEvent, KeyModifiers};

    use super::*;
    use crate::app::test_utils::make_app;
    use crate::ui::MIN_PAD_H;

    fn key(code: KeyCode) -> KeyEvent {
        KeyEvent::new(code, KeyModifiers::NONE)
    }

    #[test]
    fn open_about_pushes_to_stack_once() {
        let mut app = make_app();
        app.open_about_modal();
        assert!(app.modal_stack.contains::<AboutModal>());
        app.open_about_modal();
        assert_eq!(app.modal_stack.count::<AboutModal>(), 1);
    }

    #[test]
    fn opening_about_does_not_touch_the_network() {
        // "Check for updates" is the only thing that reaches GitHub from this page.
        let mut app = make_app();
        app.open_about_modal();
        assert!(!app.release_check_in_flight);
        assert!(app.latest_release.is_none());
    }

    /// Press the button at `index` on a fresh page and run what it asked the app to do.  Focus
    /// starts on button 0, so `index` Tabs reach it.
    fn press_button(app: &mut App, index: usize) {
        let mut modal = AboutModal::new();
        for _ in 0..index {
            modal.handle_key(key(KeyCode::Tab), app, 24, 80);
        }
        let outcome = modal.handle_key(key(KeyCode::Enter), app, 24, 80);
        let ModalOutcome::ContinueAnd(action) = outcome else {
            panic!("expected the About page to stay open");
        };
        action(app);
    }

    #[test]
    fn the_check_button_stacks_the_update_modal_over_about() {
        let mut app = make_app();
        app.open_about_modal();
        press_button(&mut app, CHECK_UPDATES_BUTTON);
        assert!(app.modal_stack.contains::<crate::app::modal::UpdateModal>());
        assert!(
            app.modal_stack.contains::<AboutModal>(),
            "About stays underneath"
        );
    }

    #[test]
    fn the_release_notes_button_stacks_the_post_upgrade_modal_over_about() {
        let mut app = make_app();
        app.open_about_modal();
        press_button(&mut app, RELEASE_NOTES_BUTTON);
        assert!(app
            .modal_stack
            .contains::<crate::app::modal::PostUpgradeModal>());
        assert!(
            app.modal_stack.contains::<AboutModal>(),
            "About stays underneath"
        );
    }

    #[test]
    fn the_release_notes_button_reaches_no_network() {
        // It answers out of the binary's own changelog.
        let mut app = make_app();
        app.open_about_modal();
        press_button(&mut app, RELEASE_NOTES_BUTTON);
        assert!(!app.release_check_in_flight);
        assert!(app.latest_release.is_none());
    }

    #[test]
    fn enter_on_github_button_keeps_modal_open() {
        let mut app = make_app();
        let mut modal = AboutModal::new();
        for _ in 0..VIEW_ON_GITHUB_BUTTON {
            modal.handle_key(key(KeyCode::Tab), &mut app, 24, 80);
        }
        let outcome = modal.handle_key(key(KeyCode::Enter), &mut app, 24, 80);
        assert!(matches!(outcome, ModalOutcome::ContinueAnd(_)));
    }

    #[test]
    fn every_button_index_has_a_named_arm() {
        // The old catch-all at the end of `resolve` meant a new button silently opened GitHub.
        assert_eq!(AboutModal::new().buttons.len(), VIEW_ON_GITHUB_BUTTON + 1);
    }

    #[test]
    fn the_body_is_built_for_the_columns_the_frame_will_have() {
        // `body_columns` is the ceiling `ModalView` gives the body: the terminal less the minimum
        // padding.  The About body drops its pod against that number, so getting it wrong draws a
        // pod into a frame too narrow to hold it.
        assert_eq!(body_columns(Rect::new(0, 0, 80, 24)), 80 - 2 * MIN_PAD_H);
        // Narrower than the padding itself must not underflow.
        assert_eq!(body_columns(Rect::new(0, 0, 1, 24)), 0);
    }

    #[test]
    fn the_tagline_keeps_asking_for_a_redraw() {
        let modal = AboutModal::new();
        let now = Instant::now();
        let d = modal.next_deadline().expect("tagline deadline");
        assert!(d > now && d <= now + TAGLINE_INTERVAL);
    }

    #[test]
    fn esc_dismisses() {
        let mut app = make_app();
        let mut modal = AboutModal::new();
        let outcome = modal.handle_key(key(KeyCode::Esc), &mut app, 24, 80);
        assert!(matches!(outcome, ModalOutcome::Close));
    }
}