use editor::{
    combine_syntax_and_fuzzy_match_highlights, display_map::ToDisplayPoint, Anchor, AnchorRangeExt,
    Autoscroll, DisplayPoint, Editor, ToPoint,
};
use fuzzy::StringMatch;
use gpui::{
    actions, elements::*, geometry::vector::Vector2F, AnyViewHandle, AppContext, Entity,
    MouseState, MutableAppContext, RenderContext, Task, View, ViewContext, ViewHandle,
};
use language::Outline;
use ordered_float::OrderedFloat;
use picker::{Picker, PickerDelegate};
use settings::Settings;
use std::cmp::{self, Reverse};
use workspace::Workspace;

actions!(outline, [Toggle]);

pub fn init(cx: &mut MutableAppContext) {
    cx.add_action(OutlineView::toggle);
    Picker::<OutlineView>::init(cx);
}

struct OutlineView {
    picker: ViewHandle<Picker<Self>>,
    active_editor: ViewHandle<Editor>,
    outline: Outline<Anchor>,
    selected_match_index: usize,
    prev_scroll_position: Option<Vector2F>,
    matches: Vec<StringMatch>,
    last_query: String,
}

pub enum Event {
    Dismissed,
}

impl Entity for OutlineView {
    type Event = Event;

    fn release(&mut self, cx: &mut MutableAppContext) {
        self.restore_active_editor(cx);
    }
}

impl View for OutlineView {
    fn ui_name() -> &'static str {
        "OutlineView"
    }

    fn render(&mut self, cx: &mut RenderContext<Self>) -> ElementBox {
        ChildView::new(self.picker.clone(), cx).boxed()
    }

    fn focus_in(&mut self, _: AnyViewHandle, cx: &mut ViewContext<Self>) {
        if cx.is_self_focused() {
            cx.focus(&self.picker);
        }
    }
}

impl OutlineView {
    fn new(
        outline: Outline<Anchor>,
        editor: ViewHandle<Editor>,
        cx: &mut ViewContext<Self>,
    ) -> Self {
        let handle = cx.weak_handle();
        Self {
            picker: cx.add_view(|cx| Picker::new(handle, cx).with_max_size(800., 1200.)),
            last_query: Default::default(),
            matches: Default::default(),
            selected_match_index: 0,
            prev_scroll_position: Some(editor.update(cx, |editor, cx| editor.scroll_position(cx))),
            active_editor: editor,
            outline,
        }
    }

    fn toggle(workspace: &mut Workspace, _: &Toggle, cx: &mut ViewContext<Workspace>) {
        if let Some(editor) = workspace
            .active_item(cx)
            .and_then(|item| item.downcast::<Editor>())
        {
            let buffer = editor
                .read(cx)
                .buffer()
                .read(cx)
                .snapshot(cx)
                .outline(Some(cx.global::<Settings>().theme.editor.syntax.as_ref()));
            if let Some(outline) = buffer {
                workspace.toggle_modal(cx, |_, cx| {
                    let view = cx.add_view(|cx| OutlineView::new(outline, editor, cx));
                    cx.subscribe(&view, Self::on_event).detach();
                    view
                });
            }
        }
    }

    fn restore_active_editor(&mut self, cx: &mut MutableAppContext) {
        self.active_editor.update(cx, |editor, cx| {
            editor.highlight_rows(None);
            if let Some(scroll_position) = self.prev_scroll_position {
                editor.set_scroll_position(scroll_position, cx);
            }
        })
    }

    fn set_selected_index(&mut self, ix: usize, navigate: bool, cx: &mut ViewContext<Self>) {
        self.selected_match_index = ix;
        if navigate && !self.matches.is_empty() {
            let selected_match = &self.matches[self.selected_match_index];
            let outline_item = &self.outline.items[selected_match.candidate_id];
            self.active_editor.update(cx, |active_editor, cx| {
                let snapshot = active_editor.snapshot(cx).display_snapshot;
                let buffer_snapshot = &snapshot.buffer_snapshot;
                let start = outline_item.range.start.to_point(buffer_snapshot);
                let end = outline_item.range.end.to_point(buffer_snapshot);
                let display_rows = start.to_display_point(&snapshot).row()
                    ..end.to_display_point(&snapshot).row() + 1;
                active_editor.highlight_rows(Some(display_rows));
                active_editor.request_autoscroll(Autoscroll::Center, cx);
            });
        }
        cx.notify();
    }

    fn on_event(
        workspace: &mut Workspace,
        _: ViewHandle<Self>,
        event: &Event,
        cx: &mut ViewContext<Workspace>,
    ) {
        match event {
            Event::Dismissed => workspace.dismiss_modal(cx),
        }
    }
}

impl PickerDelegate for OutlineView {
    fn match_count(&self) -> usize {
        self.matches.len()
    }

    fn selected_index(&self) -> usize {
        self.selected_match_index
    }

    fn set_selected_index(&mut self, ix: usize, cx: &mut ViewContext<Self>) {
        self.set_selected_index(ix, true, cx);
    }

    fn center_selection_after_match_updates(&self) -> bool {
        true
    }

    fn update_matches(&mut self, query: String, cx: &mut ViewContext<Self>) -> Task<()> {
        let selected_index;
        if query.is_empty() {
            self.restore_active_editor(cx);
            self.matches = self
                .outline
                .items
                .iter()
                .enumerate()
                .map(|(index, _)| StringMatch {
                    candidate_id: index,
                    score: Default::default(),
                    positions: Default::default(),
                    string: Default::default(),
                })
                .collect();

            let editor = self.active_editor.read(cx);
            let cursor_offset = editor.selections.newest::<usize>(cx).head();
            let buffer = editor.buffer().read(cx).snapshot(cx);
            selected_index = self
                .outline
                .items
                .iter()
                .enumerate()
                .map(|(ix, item)| {
                    let range = item.range.to_offset(&buffer);
                    let distance_to_closest_endpoint = cmp::min(
                        (range.start as isize - cursor_offset as isize).abs(),
                        (range.end as isize - cursor_offset as isize).abs(),
                    );
                    let depth = if range.contains(&cursor_offset) {
                        Some(item.depth)
                    } else {
                        None
                    };
                    (ix, depth, distance_to_closest_endpoint)
                })
                .max_by_key(|(_, depth, distance)| (*depth, Reverse(*distance)))
                .map(|(ix, _, _)| ix)
                .unwrap_or(0);
        } else {
            self.matches = smol::block_on(self.outline.search(&query, cx.background().clone()));
            selected_index = self
                .matches
                .iter()
                .enumerate()
                .max_by_key(|(_, m)| OrderedFloat(m.score))
                .map(|(ix, _)| ix)
                .unwrap_or(0);
        }
        self.last_query = query;
        self.set_selected_index(selected_index, !self.last_query.is_empty(), cx);
        Task::ready(())
    }

    fn confirm(&mut self, cx: &mut ViewContext<Self>) {
        self.prev_scroll_position.take();
        self.active_editor.update(cx, |active_editor, cx| {
            if let Some(rows) = active_editor.highlighted_rows() {
                let snapshot = active_editor.snapshot(cx).display_snapshot;
                let position = DisplayPoint::new(rows.start, 0).to_point(&snapshot);
                active_editor.change_selections(Some(Autoscroll::Center), cx, |s| {
                    s.select_ranges([position..position])
                });
            }
        });
        cx.emit(Event::Dismissed);
    }

    fn dismiss(&mut self, cx: &mut ViewContext<Self>) {
        self.restore_active_editor(cx);
        cx.emit(Event::Dismissed);
    }

    fn render_match(
        &self,
        ix: usize,
        mouse_state: &mut MouseState,
        selected: bool,
        cx: &AppContext,
    ) -> ElementBox {
        let settings = cx.global::<Settings>();
        let string_match = &self.matches[ix];
        let style = settings.theme.picker.item.style_for(mouse_state, selected);
        let outline_item = &self.outline.items[string_match.candidate_id];

        Text::new(outline_item.text.clone(), style.label.text.clone())
            .with_soft_wrap(false)
            .with_highlights(combine_syntax_and_fuzzy_match_highlights(
                &outline_item.text,
                style.label.text.clone().into(),
                outline_item.highlight_ranges.iter().cloned(),
                &string_match.positions,
            ))
            .contained()
            .with_padding_left(20. * outline_item.depth as f32)
            .contained()
            .with_style(style.container)
            .boxed()
    }
}