use gpui::{
    Entity, Modifiers, ParentElement as _, Render, Styled as _, TestAppContext, VisualTestContext,
    Window, div, point, px,
};
use gpui_native_core::input::{Input, InputState, InputStateEvent};
use gpui_native_theme::Theme;
use std::cell::RefCell;
use std::rc::Rc;

struct Harness {
    state: Entity<InputState>,
    disabled: bool,
}

impl Render for Harness {
    fn render(
        &mut self,
        _window: &mut Window,
        _cx: &mut gpui::Context<Self>,
    ) -> impl gpui::IntoElement {
        div().size_full().child(
            Input::new("test-input", self.state.clone())
                .placeholder("Placeholder")
                .disabled(self.disabled),
        )
    }
}

fn input_window(
    initial: &str,
    disabled: bool,
) -> (TestAppContext, Entity<InputState>, VisualTestContext) {
    let mut cx = TestAppContext::single();
    cx.update(Theme::init);
    let state = cx.update(|cx| InputState::new_with_text(initial, cx));
    let state_for_window = state.clone();
    let window = cx.add_window(move |_, _| Harness {
        state: state_for_window,
        disabled,
    });
    let mut visual = VisualTestContext::from_window(window.into(), &cx);
    visual.update(|window, cx| {
        window.draw(cx).clear(cx);
    });
    (cx, state, visual)
}

fn value(cx: &TestAppContext, state: &Entity<InputState>) -> String {
    cx.update(|cx| state.read(cx).value().to_string())
}

fn focus(visual: &mut VisualTestContext, state: &Entity<InputState>) {
    // Programmatic focus: a click would move the caret to the click point.
    visual.update(|window, cx| {
        let handle = state.read(cx).focus_handle();
        window.focus(&handle, cx);
    });
}

#[test]
fn typing_inserts_at_the_caret() {
    let (cx, state, mut visual) = input_window("", false);
    focus(&mut visual, &state);
    visual.simulate_keystrokes("h e l l o");
    assert_eq!(value(&cx, &state), "hello");
    visual.simulate_keystrokes("space w o r l d");
    assert_eq!(value(&cx, &state), "hello world");
}

#[test]
fn arrow_left_moves_the_caret_and_typing_splits_the_text() {
    let (cx, state, mut visual) = input_window("ab", false);
    focus(&mut visual, &state);
    visual.simulate_keystrokes("left");
    visual.simulate_keystrokes("x");
    assert_eq!(value(&cx, &state), "axb");
}

#[test]
fn backspace_deletes_before_the_caret_and_delete_after() {
    let (cx, state, mut visual) = input_window("abc", false);
    focus(&mut visual, &state);
    visual.simulate_keystrokes("backspace");
    assert_eq!(value(&cx, &state), "ab");
    // The caret sits between 'a' and 'b'; forward delete removes 'b'.
    visual.simulate_keystrokes("left");
    visual.simulate_keystrokes("delete");
    assert_eq!(value(&cx, &state), "a");
}

#[test]
fn alt_arrow_moves_by_words() {
    let (cx, state, mut visual) = input_window("hello world", false);
    focus(&mut visual, &state);
    visual.simulate_keystrokes("alt-left");
    visual.simulate_keystrokes("x");
    assert_eq!(value(&cx, &state), "hello xworld");
    visual.simulate_keystrokes("alt-left alt-left");
    visual.simulate_keystrokes("shift-right shift-right");
    visual.simulate_keystrokes("z");
    assert_eq!(value(&cx, &state), "zllo xworld");
}

#[test]
fn select_all_then_type_replaces_the_value() {
    let (cx, state, mut visual) = input_window("abcd", false);
    focus(&mut visual, &state);
    visual.simulate_keystrokes("cmd-a");
    visual.simulate_keystrokes("z");
    assert_eq!(value(&cx, &state), "z");
}

#[test]
fn shift_arrow_selects_and_backspace_removes_the_selection() {
    let (cx, state, mut visual) = input_window("ab", false);
    focus(&mut visual, &state);
    // Caret starts at the end; selecting left twice covers "ab".
    visual.simulate_keystrokes("shift-left shift-left");
    visual.simulate_keystrokes("backspace");
    assert_eq!(value(&cx, &state), "");
}

#[test]
fn disabled_input_ignores_typing_and_clicks() {
    // No programmatic focus: a disabled field must not take focus, so the
    // key events fall to nothing and the input handler is never registered.
    let (cx, state, mut visual) = input_window("", true);
    visual.simulate_click(point(px(20.), px(14.)), Modifiers::default());
    visual.simulate_keystrokes("h");
    assert_eq!(value(&cx, &state), "");
}

#[test]
fn set_value_replaces_the_buffer() {
    let (cx, state, mut visual) = input_window("", false);
    visual.update(|window, cx| {
        state.update(cx, |state, cx| state.set_value("preset", window, cx));
    });
    assert_eq!(value(&cx, &state), "preset");
}

/// Subscribes to `state`'s events, recording each variant into a sink that
/// lives for the rest of the test. The returned `Subscription` must stay
/// bound for the same lifetime — dropping it unsubscribes.
fn record_events(
    cx: &mut TestAppContext,
    state: &Entity<InputState>,
) -> (Rc<RefCell<Vec<InputStateEvent>>>, gpui::Subscription) {
    let sink = Rc::new(RefCell::new(Vec::new()));
    let sink_for_sub = sink.clone();
    let subscription = cx.update(|cx| {
        cx.subscribe(state, move |_, event, _| {
            sink_for_sub.borrow_mut().push(event.clone());
        })
    });
    // Subscriptions activate through a deferred effect.
    cx.run_until_parked();
    (sink, subscription)
}

fn count(sink: &Rc<RefCell<Vec<InputStateEvent>>>, event: &InputStateEvent) -> usize {
    sink.borrow().iter().filter(|e| e == &event).count()
}

#[test]
fn text_changed_emits_for_edits_but_not_for_caret_moves() {
    let (mut cx, state, mut visual) = input_window("", false);
    let (sink, _subscription) = record_events(&mut cx, &state);
    focus(&mut visual, &state);

    visual.simulate_keystrokes("a space b");
    assert_eq!(count(&sink, &InputStateEvent::TextChanged), 3);

    // Caret movement repaints but is not a text change.
    visual.simulate_keystrokes("left");
    assert_eq!(count(&sink, &InputStateEvent::TextChanged), 3);
}

#[test]
fn set_value_no_op_does_not_emit_changed() {
    let (mut cx, state, mut visual) = input_window("same", false);
    let (sink, _subscription) = record_events(&mut cx, &state);

    visual.update(|window, cx| {
        state.update(cx, |state, cx| state.set_value("same", window, cx));
    });
    visual.run_until_parked();
    assert_eq!(count(&sink, &InputStateEvent::TextChanged), 0);

    visual.update(|window, cx| {
        state.update(cx, |state, cx| state.set_value("other", window, cx));
    });
    visual.run_until_parked();
    assert_eq!(count(&sink, &InputStateEvent::TextChanged), 1);
}

#[test]
fn set_value_silent_updates_without_emitting() {
    let (mut cx, state, mut visual) = input_window("same", false);
    let (sink, _subscription) = record_events(&mut cx, &state);

    visual.update(|window, cx| {
        state.update(cx, |state, cx| state.set_value_silent("other", window, cx));
    });
    visual.run_until_parked();
    assert_eq!(value(&cx, &state), "other");
    assert_eq!(count(&sink, &InputStateEvent::TextChanged), 0);
}

#[test]
fn focus_and_blur_emit_events() {
    let (mut cx, state, mut visual) = input_window("", false);
    let (sink, _subscription) = record_events(&mut cx, &state);

    focus(&mut visual, &state);
    visual.update(|window, cx| {
        window.draw(cx).clear(cx);
    });
    visual.run_until_parked();
    assert_eq!(count(&sink, &InputStateEvent::Focused), 1);

    visual.update(|window, cx| window.blur(cx));
    visual.update(|window, cx| {
        window.draw(cx).clear(cx);
    });
    visual.run_until_parked();
    assert_eq!(count(&sink, &InputStateEvent::Blurred), 1);
}

#[test]
fn pasted_newlines_become_spaces() {
    let (cx, state, mut visual) = input_window("", false);
    focus(&mut visual, &state);
    cx.update(|cx| {
        cx.write_to_clipboard(gpui::ClipboardItem::new_string("a\nb\rc".to_string()));
    });
    visual.simulate_keystrokes("cmd-v");
    // `\r` is dropped and `\n` becomes a space, matching the sanitizer.
    assert_eq!(value(&cx, &state), "a bc");
}

#[test]
fn set_value_sanitizes_newlines() {
    let (cx, state, mut visual) = input_window("", false);
    visual.update(|window, cx| {
        state.update(cx, |state, cx| state.set_value("a\nb", window, cx));
    });
    assert_eq!(value(&cx, &state), "a b");
}

#[test]
fn enter_emits_submitted() {
    let (mut cx, state, mut visual) = input_window("draft", false);
    let (sink, _subscription) = record_events(&mut cx, &state);
    focus(&mut visual, &state);
    visual.update(|window, cx| {
        window.draw(cx).clear(cx);
    });

    visual.simulate_keystrokes("enter");
    assert_eq!(count(&sink, &InputStateEvent::Submitted), 1);
    // The content is left in place for the subscriber to read or clear.
    assert_eq!(value(&cx, &state), "draft");
}