use std::{cell::RefCell, ops::Range, rc::Rc};

use pathfinder_geometry::rect::RectF;

use crate::{platform::InputHandler, AnyView, AppContext};

pub struct WindowInputHandler {
    pub app: Rc<RefCell<AppContext>>,
    pub window_id: usize,
}

impl WindowInputHandler {
    fn read_focused_view<T, F>(&self, f: F) -> Option<T>
    where
        F: FnOnce(&dyn AnyView, &AppContext) -> T,
    {
        // Input-related application hooks are sometimes called by the OS during
        // a call to a window-manipulation API, like prompting the user for file
        // paths. In that case, the AppContext will already be borrowed, so any
        // InputHandler methods need to fail gracefully.
        //
        // See https://github.com/zed-industries/community/issues/444
        let app = self.app.try_borrow().ok()?;

        let view_id = app.focused_view_id(self.window_id)?;
        let view = app.views.get(&(self.window_id, view_id))?;
        let result = f(view.as_ref(), &app);
        Some(result)
    }

    fn update_focused_view<T, F>(&mut self, f: F) -> Option<T>
    where
        F: FnOnce(usize, usize, &mut dyn AnyView, &mut AppContext) -> T,
    {
        let mut app = self.app.try_borrow_mut().ok()?;
        app.update(|app| {
            let view_id = app.focused_view_id(self.window_id)?;
            let mut view = app.views.remove(&(self.window_id, view_id))?;
            let result = f(self.window_id, view_id, view.as_mut(), &mut *app);
            app.views.insert((self.window_id, view_id), view);
            Some(result)
        })
    }
}

impl InputHandler for WindowInputHandler {
    fn text_for_range(&self, range: Range<usize>) -> Option<String> {
        self.read_focused_view(|view, cx| view.text_for_range(range.clone(), cx))
            .flatten()
    }

    fn selected_text_range(&self) -> Option<Range<usize>> {
        self.read_focused_view(|view, cx| view.selected_text_range(cx))
            .flatten()
    }

    fn replace_text_in_range(&mut self, range: Option<Range<usize>>, text: &str) {
        self.update_focused_view(|window_id, view_id, view, cx| {
            view.replace_text_in_range(range, text, cx, window_id, view_id);
        });
    }

    fn marked_text_range(&self) -> Option<Range<usize>> {
        self.read_focused_view(|view, cx| view.marked_text_range(cx))
            .flatten()
    }

    fn unmark_text(&mut self) {
        self.update_focused_view(|window_id, view_id, view, cx| {
            view.unmark_text(cx, window_id, view_id);
        });
    }

    fn replace_and_mark_text_in_range(
        &mut self,
        range: Option<Range<usize>>,
        new_text: &str,
        new_selected_range: Option<Range<usize>>,
    ) {
        self.update_focused_view(|window_id, view_id, view, cx| {
            view.replace_and_mark_text_in_range(
                range,
                new_text,
                new_selected_range,
                cx,
                window_id,
                view_id,
            );
        });
    }

    fn rect_for_range(&self, range_utf16: Range<usize>) -> Option<RectF> {
        let app = self.app.borrow();
        let (presenter, _) = app.presenters_and_platform_windows.get(&self.window_id)?;
        let presenter = presenter.borrow();
        presenter.rect_for_text_range(range_utf16, &app)
    }
}