//! Publication-and-visit-bound input for a mounted diagnostic list.
//!
//! Keep this wrapper at the same widget-tree position, inside the list's outer
//! scroller. Pass `None` with an empty child while hidden/removed; unmounting the
//! wrapper loses its ability to consume an outstanding release. Every change to
//! row identity/order/action must have a fresh publication Id. Pass the pair
//! (publication generation, drawer visit): a new visit resets armed controls even
//! if Hide and Show coalesce without an intermediate hidden Tree. The child tree
//! resets when either component changes, clearing button presses and row focus;
//! the outer scroller and editor trees are not reset.
//!
//! Capturing stops Iced event bubbling and later consumers that respect capture.
//! It cannot undo an earlier sibling's event handling. This is a row-list guard,
//! not a root event filter or a guard for actions in child overlays. Diagnostic
//! messages still need publication/snapshot and drawer-visit validation at dispatch.
use iced::advanced::{Clipboard, Layout, Shell, Widget, layout, overlay, renderer, widget};
use iced::{Element, Event, Length, Rectangle, Size, Vector, mouse, touch};
use oa_core::Id;

pub struct Guard<'a, Message, Theme = iced::Theme, Renderer = iced::Renderer> {
    identity: Option<(Id, Id)>,
    content: Element<'a, Message, Theme, Renderer>,
}

impl<'a, Message, Theme, Renderer> Guard<'a, Message, Theme, Renderer> {
    pub fn new(
        identity: Option<(Id, Id)>,
        content: impl Into<Element<'a, Message, Theme, Renderer>>,
    ) -> Self {
        Self {
            identity,
            content: content.into(),
        }
    }
}

#[derive(Clone, Copy, Debug, PartialEq, Eq)]
enum Pointer {
    Mouse,
    Touch(touch::Finger),
}
impl Pointer {
    fn press(event: &Event) -> Option<Self> {
        match event {
            Event::Mouse(mouse::Event::ButtonPressed(mouse::Button::Left)) => Some(Self::Mouse),
            Event::Touch(touch::Event::FingerPressed { id, .. }) => Some(Self::Touch(*id)),
            _ => None,
        }
    }
    fn release(event: &Event) -> Option<Self> {
        match event {
            Event::Mouse(mouse::Event::ButtonReleased(mouse::Button::Left)) => Some(Self::Mouse),
            Event::Touch(
                touch::Event::FingerLifted { id, .. } | touch::Event::FingerLost { id, .. },
            ) => Some(Self::Touch(*id)),
            _ => None,
        }
    }
}

struct State {
    identity: Option<(Id, Id)>,
    pressed: Option<Pointer>,
    swallowed: Vec<Pointer>,
}
impl State {
    fn quarantine(&mut self, pointer: Pointer) {
        if !self.swallowed.contains(&pointer) {
            self.swallowed.push(pointer);
        }
    }
    fn forget(&mut self, pointer: Pointer) -> bool {
        let found = self.swallowed.contains(&pointer);
        self.swallowed.retain(|item| *item != pointer);
        found
    }
}

impl<Message, Theme, Renderer: renderer::Renderer> Widget<Message, Theme, Renderer>
    for Guard<'_, Message, Theme, Renderer>
{
    fn tag(&self) -> widget::tree::Tag {
        widget::tree::Tag::of::<State>()
    }
    fn state(&self) -> widget::tree::State {
        widget::tree::State::new(State {
            identity: self.identity,
            pressed: None,
            swallowed: Vec::new(),
        })
    }
    fn children(&self) -> Vec<widget::Tree> {
        vec![widget::Tree::new(&self.content)]
    }
    fn diff(&self, tree: &mut widget::Tree) {
        let state = tree.state.downcast_mut::<State>();
        if state.identity != self.identity {
            state.identity = self.identity;
            if let Some(pointer) = state.pressed.take() {
                state.quarantine(pointer);
            }
            tree.children = self.children();
        } else {
            tree.diff_children(std::slice::from_ref(&self.content));
        }
    }
    fn size(&self) -> Size<Length> {
        self.content.as_widget().size()
    }
    fn size_hint(&self) -> Size<Length> {
        self.content.as_widget().size_hint()
    }
    fn layout(
        &mut self,
        tree: &mut widget::Tree,
        renderer: &Renderer,
        limits: &layout::Limits,
    ) -> layout::Node {
        self.content
            .as_widget_mut()
            .layout(&mut tree.children[0], renderer, limits)
    }
    fn operate(
        &mut self,
        tree: &mut widget::Tree,
        layout: Layout<'_>,
        renderer: &Renderer,
        operation: &mut dyn widget::Operation,
    ) {
        self.content
            .as_widget_mut()
            .operate(&mut tree.children[0], layout, renderer, operation);
    }
    fn update(
        &mut self,
        tree: &mut widget::Tree,
        event: &Event,
        layout: Layout<'_>,
        cursor: mouse::Cursor,
        renderer: &Renderer,
        clipboard: &mut dyn Clipboard,
        shell: &mut Shell<'_, Message>,
        viewport: &Rectangle,
    ) {
        let state = tree.state.downcast_mut::<State>();
        let release = Pointer::release(event);
        if let Some(pointer) = release {
            // Bounds may have become empty or moved. Consume the physical
            // gesture's terminal event regardless of its current position.
            if state.forget(pointer) {
                shell.capture_event();
                return;
            }
            // Iced Button has a single is_pressed bit, not a pointer identity.
            // A different finger/mouse release must not activate that button.
            if state.pressed.is_some_and(|pressed| pressed != pointer) {
                shell.capture_event();
                return;
            }
        }
        let press = Pointer::press(event);
        if let Some(pointer) = state.pressed.filter(|pointer| {
            press == Some(*pointer) || (release == Some(*pointer) && shell.is_event_captured())
        }) {
            // Recover an omitted terminal event, or cancel one intercepted by
            // an earlier consumer. An off-target mouse release / lost touch
            // clears Iced Button's pressed state without rebuilding this
            // publication's tree (which would also discard row focus).
            state.pressed = None;
            let cancel = match pointer {
                Pointer::Mouse => Event::Mouse(mouse::Event::ButtonReleased(mouse::Button::Left)),
                Pointer::Touch(id) => Event::Touch(touch::Event::FingerLost {
                    id,
                    position: iced::Point::ORIGIN,
                }),
            };
            let mut discarded = Vec::new();
            let mut cancellation = Shell::new(&mut discarded);
            self.content.as_widget_mut().update(
                &mut tree.children[0],
                &cancel,
                layout,
                mouse::Cursor::Unavailable,
                renderer,
                clipboard,
                &mut cancellation,
                viewport,
            );
            // Cancellation must not publish an action or capture the fresh
            // down. Preserve rendering requests from the state change only.
            shell.request_redraw();
            if cancellation.is_layout_invalid() {
                shell.invalidate_layout();
            }
            if cancellation.are_widgets_invalid() {
                shell.invalidate_widgets();
            }
        }
        if shell.is_event_captured() || self.identity.is_none() {
            return;
        }
        if let Some(pointer) = press {
            // A fresh down starts a new gesture even if the platform omitted a
            // previous release (for example while the window lacked focus).
            state.forget(pointer);
            if let Some(pressed) = state.pressed {
                if pressed != pointer {
                    state.quarantine(pointer);
                }
                shell.capture_event();
                return;
            }
        }
        let was_pressed = release.is_some() && release == state.pressed;
        if was_pressed {
            state.pressed = None;
        }
        self.content.as_widget_mut().update(
            &mut tree.children[0],
            event,
            layout,
            cursor,
            renderer,
            clipboard,
            shell,
            viewport,
        );
        if let Some(pointer) = press
            && shell.is_event_captured()
        {
            state.pressed = Some(pointer);
        }
        if was_pressed {
            // FingerLost cancels Iced Button state but does not itself capture.
            shell.capture_event();
        }
    }
    fn draw(
        &self,
        tree: &widget::Tree,
        renderer: &mut Renderer,
        theme: &Theme,
        style: &renderer::Style,
        layout: Layout<'_>,
        cursor: mouse::Cursor,
        viewport: &Rectangle,
    ) {
        self.content.as_widget().draw(
            &tree.children[0],
            renderer,
            theme,
            style,
            layout,
            cursor,
            viewport,
        );
    }
    fn mouse_interaction(
        &self,
        tree: &widget::Tree,
        layout: Layout<'_>,
        cursor: mouse::Cursor,
        viewport: &Rectangle,
        renderer: &Renderer,
    ) -> mouse::Interaction {
        self.content.as_widget().mouse_interaction(
            &tree.children[0],
            layout,
            cursor,
            viewport,
            renderer,
        )
    }
    fn overlay<'b>(
        &'b mut self,
        tree: &'b mut widget::Tree,
        layout: Layout<'b>,
        renderer: &Renderer,
        viewport: &Rectangle,
        translation: Vector,
    ) -> Option<overlay::Element<'b, Message, Theme, Renderer>> {
        self.content.as_widget_mut().overlay(
            &mut tree.children[0],
            layout,
            renderer,
            viewport,
            translation,
        )
    }
}

impl<'a, Message: 'a, Theme: 'a, Renderer: renderer::Renderer + 'a>
    From<Guard<'a, Message, Theme, Renderer>> for Element<'a, Message, Theme, Renderer>
{
    fn from(guard: Guard<'a, Message, Theme, Renderer>) -> Self {
        Element::new(guard)
    }
}

#[cfg(test)]
mod tests;