use crate::{
    div, Action, AnyView, AnyWindowHandle, AppCell, AppContext, AsyncAppContext,
    BackgroundExecutor, Bounds, ClipboardItem, Context, Element, Entity, EventEmitter,
    ForegroundExecutor, InputEvent, KeyDownEvent, Keystroke, Model, ModelContext, Pixels, Platform,
    PlatformWindow, Point, Render, Result, Size, Task, TestDispatcher, TestPlatform, TestWindow,
    TestWindowHandlers, TextSystem, View, ViewContext, VisualContext, WindowBounds, WindowContext,
    WindowHandle, WindowOptions,
};
use anyhow::{anyhow, bail};
use futures::{Stream, StreamExt};
use std::{future::Future, mem, ops::Deref, rc::Rc, sync::Arc, time::Duration};

#[derive(Clone)]
pub struct TestAppContext {
    pub app: Rc<AppCell>,
    pub background_executor: BackgroundExecutor,
    pub foreground_executor: ForegroundExecutor,
    pub dispatcher: TestDispatcher,
    pub test_platform: Rc<TestPlatform>,
    text_system: Arc<TextSystem>,
}

impl Context for TestAppContext {
    type Result<T> = T;

    fn new_model<T: 'static>(
        &mut self,
        build_model: impl FnOnce(&mut ModelContext<'_, T>) -> T,
    ) -> Self::Result<Model<T>>
    where
        T: 'static,
    {
        let mut app = self.app.borrow_mut();
        app.new_model(build_model)
    }

    fn update_model<T: 'static, R>(
        &mut self,
        handle: &Model<T>,
        update: impl FnOnce(&mut T, &mut ModelContext<'_, T>) -> R,
    ) -> Self::Result<R> {
        let mut app = self.app.borrow_mut();
        app.update_model(handle, update)
    }

    fn update_window<T, F>(&mut self, window: AnyWindowHandle, f: F) -> Result<T>
    where
        F: FnOnce(AnyView, &mut WindowContext<'_>) -> T,
    {
        let mut lock = self.app.borrow_mut();
        lock.update_window(window, f)
    }

    fn read_model<T, R>(
        &self,
        handle: &Model<T>,
        read: impl FnOnce(&T, &AppContext) -> R,
    ) -> Self::Result<R>
    where
        T: 'static,
    {
        let app = self.app.borrow();
        app.read_model(handle, read)
    }

    fn read_window<T, R>(
        &self,
        window: &WindowHandle<T>,
        read: impl FnOnce(View<T>, &AppContext) -> R,
    ) -> Result<R>
    where
        T: 'static,
    {
        let app = self.app.borrow();
        app.read_window(window, read)
    }
}

impl TestAppContext {
    pub fn new(dispatcher: TestDispatcher) -> Self {
        let arc_dispatcher = Arc::new(dispatcher.clone());
        let background_executor = BackgroundExecutor::new(arc_dispatcher.clone());
        let foreground_executor = ForegroundExecutor::new(arc_dispatcher);
        let platform = TestPlatform::new(background_executor.clone(), foreground_executor.clone());
        let asset_source = Arc::new(());
        let http_client = util::http::FakeHttpClient::with_404_response();
        let text_system = Arc::new(TextSystem::new(platform.text_system()));

        Self {
            app: AppContext::new(platform.clone(), asset_source, http_client),
            background_executor,
            foreground_executor,
            dispatcher: dispatcher.clone(),
            test_platform: platform,
            text_system,
        }
    }

    pub fn new_app(&self) -> TestAppContext {
        Self::new(self.dispatcher.clone())
    }

    pub fn quit(&self) {
        self.app.borrow_mut().shutdown();
    }

    pub fn refresh(&mut self) -> Result<()> {
        let mut app = self.app.borrow_mut();
        app.refresh();
        Ok(())
    }

    pub fn executor(&self) -> BackgroundExecutor {
        self.background_executor.clone()
    }

    pub fn foreground_executor(&self) -> &ForegroundExecutor {
        &self.foreground_executor
    }

    pub fn update<R>(&self, f: impl FnOnce(&mut AppContext) -> R) -> R {
        let mut cx = self.app.borrow_mut();
        cx.update(f)
    }

    pub fn read<R>(&self, f: impl FnOnce(&AppContext) -> R) -> R {
        let cx = self.app.borrow();
        f(&*cx)
    }

    pub fn add_window<F, V>(&mut self, build_window: F) -> WindowHandle<V>
    where
        F: FnOnce(&mut ViewContext<V>) -> V,
        V: 'static + Render,
    {
        let mut cx = self.app.borrow_mut();
        cx.open_window(WindowOptions::default(), |cx| cx.new_view(build_window))
    }

    pub fn add_empty_window(&mut self) -> AnyWindowHandle {
        let mut cx = self.app.borrow_mut();
        cx.open_window(WindowOptions::default(), |cx| cx.new_view(|_| EmptyView {}))
            .any_handle
    }

    pub fn add_window_view<F, V>(&mut self, build_window: F) -> (View<V>, &mut VisualTestContext)
    where
        F: FnOnce(&mut ViewContext<V>) -> V,
        V: 'static + Render,
    {
        let mut cx = self.app.borrow_mut();
        let window = cx.open_window(WindowOptions::default(), |cx| cx.new_view(build_window));
        drop(cx);
        let view = window.root_view(self).unwrap();
        let cx = Box::new(VisualTestContext::from_window(*window.deref(), self));
        // it might be nice to try and cleanup these at the end of each test.
        (view, Box::leak(cx))
    }

    pub fn text_system(&self) -> &Arc<TextSystem> {
        &self.text_system
    }

    pub fn write_to_clipboard(&self, item: ClipboardItem) {
        self.test_platform.write_to_clipboard(item)
    }

    pub fn read_from_clipboard(&self) -> Option<ClipboardItem> {
        self.test_platform.read_from_clipboard()
    }

    pub fn simulate_new_path_selection(
        &self,
        select_path: impl FnOnce(&std::path::Path) -> Option<std::path::PathBuf>,
    ) {
        self.test_platform.simulate_new_path_selection(select_path);
    }

    pub fn simulate_prompt_answer(&self, button_ix: usize) {
        self.test_platform.simulate_prompt_answer(button_ix);
    }

    pub fn has_pending_prompt(&self) -> bool {
        self.test_platform.has_pending_prompt()
    }

    pub fn simulate_window_resize(&self, window_handle: AnyWindowHandle, size: Size<Pixels>) {
        let (mut handlers, scale_factor) = self
            .app
            .borrow_mut()
            .update_window(window_handle, |_, cx| {
                let platform_window = cx.window.platform_window.as_test().unwrap();
                let scale_factor = platform_window.scale_factor();
                match &mut platform_window.bounds {
                    WindowBounds::Fullscreen | WindowBounds::Maximized => {
                        platform_window.bounds = WindowBounds::Fixed(Bounds {
                            origin: Point::default(),
                            size: size.map(|pixels| f64::from(pixels).into()),
                        });
                    }
                    WindowBounds::Fixed(bounds) => {
                        bounds.size = size.map(|pixels| f64::from(pixels).into());
                    }
                }

                (
                    mem::take(&mut platform_window.handlers.lock().resize),
                    scale_factor,
                )
            })
            .unwrap();

        for handler in &mut handlers {
            handler(size, scale_factor);
        }

        self.app
            .borrow_mut()
            .update_window(window_handle, |_, cx| {
                let platform_window = cx.window.platform_window.as_test().unwrap();
                platform_window.handlers.lock().resize = handlers;
            })
            .unwrap();
    }

    pub fn spawn<Fut, R>(&self, f: impl FnOnce(AsyncAppContext) -> Fut) -> Task<R>
    where
        Fut: Future<Output = R> + 'static,
        R: 'static,
    {
        self.foreground_executor.spawn(f(self.to_async()))
    }

    pub fn has_global<G: 'static>(&self) -> bool {
        let app = self.app.borrow();
        app.has_global::<G>()
    }

    pub fn read_global<G: 'static, R>(&self, read: impl FnOnce(&G, &AppContext) -> R) -> R {
        let app = self.app.borrow();
        read(app.global(), &app)
    }

    pub fn try_read_global<G: 'static, R>(
        &self,
        read: impl FnOnce(&G, &AppContext) -> R,
    ) -> Option<R> {
        let lock = self.app.borrow();
        Some(read(lock.try_global()?, &lock))
    }

    pub fn set_global<G: 'static>(&mut self, global: G) {
        let mut lock = self.app.borrow_mut();
        lock.set_global(global);
    }

    pub fn update_global<G: 'static, R>(
        &mut self,
        update: impl FnOnce(&mut G, &mut AppContext) -> R,
    ) -> R {
        let mut lock = self.app.borrow_mut();
        lock.update_global(update)
    }

    pub fn to_async(&self) -> AsyncAppContext {
        AsyncAppContext {
            app: Rc::downgrade(&self.app),
            background_executor: self.background_executor.clone(),
            foreground_executor: self.foreground_executor.clone(),
        }
    }

    pub fn dispatch_action<A>(&mut self, window: AnyWindowHandle, action: A)
    where
        A: Action,
    {
        window
            .update(self, |_, cx| cx.dispatch_action(action.boxed_clone()))
            .unwrap();

        self.background_executor.run_until_parked()
    }

    /// simulate_keystrokes takes a space-separated list of keys to type.
    /// cx.simulate_keystrokes("cmd-shift-p b k s p enter")
    /// will run backspace on the current editor through the command palette.
    pub fn simulate_keystrokes(&mut self, window: AnyWindowHandle, keystrokes: &str) {
        for keystroke in keystrokes
            .split(" ")
            .map(Keystroke::parse)
            .map(Result::unwrap)
        {
            self.dispatch_keystroke(window, keystroke.into(), false);
        }

        self.background_executor.run_until_parked()
    }

    /// simulate_input takes a string of text to type.
    /// cx.simulate_input("abc")
    /// will type abc into your current editor.
    pub fn simulate_input(&mut self, window: AnyWindowHandle, input: &str) {
        for keystroke in input.split("").map(Keystroke::parse).map(Result::unwrap) {
            self.dispatch_keystroke(window, keystroke.into(), false);
        }

        self.background_executor.run_until_parked()
    }

    pub fn dispatch_keystroke(
        &mut self,
        window: AnyWindowHandle,
        keystroke: Keystroke,
        is_held: bool,
    ) {
        let keystroke2 = keystroke.clone();
        let handled = window
            .update(self, |_, cx| {
                cx.dispatch_event(InputEvent::KeyDown(KeyDownEvent { keystroke, is_held }))
            })
            .is_ok_and(|handled| handled);
        if handled {
            return;
        }

        let input_handler = self.update_test_window(window, |window| window.input_handler.clone());
        let Some(input_handler) = input_handler else {
            panic!(
                "dispatch_keystroke {:?} failed to dispatch action or input",
                &keystroke2
            );
        };
        let text = keystroke2.ime_key.unwrap_or(keystroke2.key);
        input_handler.lock().replace_text_in_range(None, &text);
    }

    pub fn update_test_window<R>(
        &mut self,
        window: AnyWindowHandle,
        f: impl FnOnce(&mut TestWindow) -> R,
    ) -> R {
        window
            .update(self, |_, cx| {
                f(cx.window
                    .platform_window
                    .as_any_mut()
                    .downcast_mut::<TestWindow>()
                    .unwrap())
            })
            .unwrap()
    }

    pub fn notifications<T: 'static>(&mut self, entity: &impl Entity<T>) -> impl Stream<Item = ()> {
        let (tx, rx) = futures::channel::mpsc::unbounded();
        self.update(|cx| {
            cx.observe(entity, {
                let tx = tx.clone();
                move |_, _| {
                    let _ = tx.unbounded_send(());
                }
            })
            .detach();
            cx.observe_release(entity, move |_, _| tx.close_channel())
                .detach()
        });
        rx
    }

    pub fn events<Evt, T: 'static + EventEmitter<Evt>>(
        &mut self,
        entity: &Model<T>,
    ) -> futures::channel::mpsc::UnboundedReceiver<Evt>
    where
        Evt: 'static + Clone,
    {
        let (tx, rx) = futures::channel::mpsc::unbounded();
        entity
            .update(self, |_, cx: &mut ModelContext<T>| {
                cx.subscribe(entity, move |_model, _handle, event, _cx| {
                    let _ = tx.unbounded_send(event.clone());
                })
            })
            .detach();
        rx
    }

    pub async fn condition<T: 'static>(
        &mut self,
        model: &Model<T>,
        mut predicate: impl FnMut(&mut T, &mut ModelContext<T>) -> bool,
    ) {
        let timer = self.executor().timer(Duration::from_secs(3));
        let mut notifications = self.notifications(model);

        use futures::FutureExt as _;
        use smol::future::FutureExt as _;

        async {
            loop {
                if model.update(self, &mut predicate) {
                    return Ok(());
                }

                if notifications.next().await.is_none() {
                    bail!("model dropped")
                }
            }
        }
        .race(timer.map(|_| Err(anyhow!("condition timed out"))))
        .await
        .unwrap();
    }
}

impl<T: Send> Model<T> {
    pub fn next_event<Evt>(&self, cx: &mut TestAppContext) -> Evt
    where
        Evt: Send + Clone + 'static,
        T: EventEmitter<Evt>,
    {
        let (tx, mut rx) = futures::channel::mpsc::unbounded();
        let _subscription = self.update(cx, |_, cx| {
            cx.subscribe(self, move |_, _, event, _| {
                tx.unbounded_send(event.clone()).ok();
            })
        });

        // Run other tasks until the event is emitted.
        loop {
            match rx.try_next() {
                Ok(Some(event)) => return event,
                Ok(None) => panic!("model was dropped"),
                Err(_) => {
                    if !cx.executor().tick() {
                        break;
                    }
                }
            }
        }
        panic!("no event received")
    }
}

impl<V: 'static> View<V> {
    pub fn next_notification(&self, cx: &TestAppContext) -> impl Future<Output = ()> {
        use postage::prelude::{Sink as _, Stream as _};

        let (mut tx, mut rx) = postage::mpsc::channel(1);
        let mut cx = cx.app.app.borrow_mut();
        let subscription = cx.observe(self, move |_, _| {
            tx.try_send(()).ok();
        });

        let duration = if std::env::var("CI").is_ok() {
            Duration::from_secs(5)
        } else {
            Duration::from_secs(1)
        };

        async move {
            let notification = crate::util::timeout(duration, rx.recv())
                .await
                .expect("next notification timed out");
            drop(subscription);
            notification.expect("model dropped while test was waiting for its next notification")
        }
    }
}

impl<V> View<V> {
    pub fn condition<Evt>(
        &self,
        cx: &TestAppContext,
        mut predicate: impl FnMut(&V, &AppContext) -> bool,
    ) -> impl Future<Output = ()>
    where
        Evt: 'static,
        V: EventEmitter<Evt>,
    {
        use postage::prelude::{Sink as _, Stream as _};

        let (tx, mut rx) = postage::mpsc::channel(1024);
        let timeout_duration = Duration::from_millis(100); //todo!() cx.condition_duration();

        let mut cx = cx.app.borrow_mut();
        let subscriptions = (
            cx.observe(self, {
                let mut tx = tx.clone();
                move |_, _| {
                    tx.blocking_send(()).ok();
                }
            }),
            cx.subscribe(self, {
                let mut tx = tx.clone();
                move |_, _: &Evt, _| {
                    tx.blocking_send(()).ok();
                }
            }),
        );

        let cx = cx.this.upgrade().unwrap();
        let handle = self.downgrade();

        async move {
            crate::util::timeout(timeout_duration, async move {
                loop {
                    {
                        let cx = cx.borrow();
                        let cx = &*cx;
                        if predicate(
                            handle
                                .upgrade()
                                .expect("view dropped with pending condition")
                                .read(cx),
                            cx,
                        ) {
                            break;
                        }
                    }

                    // todo!(start_waiting)
                    // cx.borrow().foreground_executor().start_waiting();
                    rx.recv()
                        .await
                        .expect("view dropped with pending condition");
                    // cx.borrow().foreground_executor().finish_waiting();
                }
            })
            .await
            .expect("condition timed out");
            drop(subscriptions);
        }
    }
}

use derive_more::{Deref, DerefMut};
#[derive(Deref, DerefMut)]
pub struct VisualTestContext<'a> {
    #[deref]
    #[deref_mut]
    cx: &'a mut TestAppContext,
    window: AnyWindowHandle,
}

impl<'a> VisualTestContext<'a> {
    pub fn update<R>(&mut self, f: impl FnOnce(&mut WindowContext) -> R) -> R {
        self.cx.update_window(self.window, |_, cx| f(cx)).unwrap()
    }

    pub fn from_window(window: AnyWindowHandle, cx: &'a mut TestAppContext) -> Self {
        Self { cx, window }
    }

    pub fn run_until_parked(&self) {
        self.cx.background_executor.run_until_parked();
    }

    pub fn dispatch_action<A>(&mut self, action: A)
    where
        A: Action,
    {
        self.cx.dispatch_action(self.window, action)
    }

    pub fn window_title(&mut self) -> Option<String> {
        self.cx
            .update_window(self.window, |_, cx| {
                cx.window.platform_window.as_test().unwrap().title.clone()
            })
            .unwrap()
    }

    pub fn simulate_keystrokes(&mut self, keystrokes: &str) {
        self.cx.simulate_keystrokes(self.window, keystrokes)
    }

    pub fn simulate_input(&mut self, input: &str) {
        self.cx.simulate_input(self.window, input)
    }

    pub fn simulate_activation(&mut self) {
        self.simulate_window_events(&mut |handlers| {
            handlers
                .active_status_change
                .iter_mut()
                .for_each(|f| f(true));
        })
    }

    pub fn simulate_deactivation(&mut self) {
        self.simulate_window_events(&mut |handlers| {
            handlers
                .active_status_change
                .iter_mut()
                .for_each(|f| f(false));
        })
    }

    fn simulate_window_events(&mut self, f: &mut dyn FnMut(&mut TestWindowHandlers)) {
        let handlers = self
            .cx
            .update_window(self.window, |_, cx| {
                cx.window
                    .platform_window
                    .as_test()
                    .unwrap()
                    .handlers
                    .clone()
            })
            .unwrap();
        f(&mut *handlers.lock());
    }
}

impl<'a> Context for VisualTestContext<'a> {
    type Result<T> = <TestAppContext as Context>::Result<T>;

    fn new_model<T: 'static>(
        &mut self,
        build_model: impl FnOnce(&mut ModelContext<'_, T>) -> T,
    ) -> Self::Result<Model<T>> {
        self.cx.new_model(build_model)
    }

    fn update_model<T, R>(
        &mut self,
        handle: &Model<T>,
        update: impl FnOnce(&mut T, &mut ModelContext<'_, T>) -> R,
    ) -> Self::Result<R>
    where
        T: 'static,
    {
        self.cx.update_model(handle, update)
    }

    fn read_model<T, R>(
        &self,
        handle: &Model<T>,
        read: impl FnOnce(&T, &AppContext) -> R,
    ) -> Self::Result<R>
    where
        T: 'static,
    {
        self.cx.read_model(handle, read)
    }

    fn update_window<T, F>(&mut self, window: AnyWindowHandle, f: F) -> Result<T>
    where
        F: FnOnce(AnyView, &mut WindowContext<'_>) -> T,
    {
        self.cx.update_window(window, f)
    }

    fn read_window<T, R>(
        &self,
        window: &WindowHandle<T>,
        read: impl FnOnce(View<T>, &AppContext) -> R,
    ) -> Result<R>
    where
        T: 'static,
    {
        self.cx.read_window(window, read)
    }
}

impl<'a> VisualContext for VisualTestContext<'a> {
    fn new_view<V>(
        &mut self,
        build_view: impl FnOnce(&mut ViewContext<'_, V>) -> V,
    ) -> Self::Result<View<V>>
    where
        V: 'static + Render,
    {
        self.window
            .update(self.cx, |_, cx| cx.new_view(build_view))
            .unwrap()
    }

    fn update_view<V: 'static, R>(
        &mut self,
        view: &View<V>,
        update: impl FnOnce(&mut V, &mut ViewContext<'_, V>) -> R,
    ) -> Self::Result<R> {
        self.window
            .update(self.cx, |_, cx| cx.update_view(view, update))
            .unwrap()
    }

    fn replace_root_view<V>(
        &mut self,
        build_view: impl FnOnce(&mut ViewContext<'_, V>) -> V,
    ) -> Self::Result<View<V>>
    where
        V: 'static + Render,
    {
        self.window
            .update(self.cx, |_, cx| cx.replace_root_view(build_view))
            .unwrap()
    }

    fn focus_view<V: crate::FocusableView>(&mut self, view: &View<V>) -> Self::Result<()> {
        self.window
            .update(self.cx, |_, cx| {
                view.read(cx).focus_handle(cx).clone().focus(cx)
            })
            .unwrap()
    }

    fn dismiss_view<V>(&mut self, view: &View<V>) -> Self::Result<()>
    where
        V: crate::ManagedView,
    {
        self.window
            .update(self.cx, |_, cx| {
                view.update(cx, |_, cx| cx.emit(crate::DismissEvent))
            })
            .unwrap()
    }
}

impl AnyWindowHandle {
    pub fn build_view<V: Render + 'static>(
        &self,
        cx: &mut TestAppContext,
        build_view: impl FnOnce(&mut ViewContext<'_, V>) -> V,
    ) -> View<V> {
        self.update(cx, |_, cx| cx.new_view(build_view)).unwrap()
    }
}

pub struct EmptyView {}

impl Render for EmptyView {
    fn render(&mut self, _cx: &mut crate::ViewContext<Self>) -> impl Element {
        div()
    }
}