use editor::{Editor, ToPoint};
use gpui::{Subscription, View, WeakView};
use std::fmt::Write;
use text::{Point, Selection};
use ui::{
    div, Button, ButtonCommon, Clickable, FluentBuilder, IntoElement, LabelSize, ParentElement,
    Render, Tooltip, ViewContext,
};
use util::paths::FILE_ROW_COLUMN_DELIMITER;
use workspace::{item::ItemHandle, StatusItemView, Workspace};

pub struct CursorPosition {
    position: Option<Point>,
    selected_count: usize,
    workspace: WeakView<Workspace>,
    _observe_active_editor: Option<Subscription>,
}

impl CursorPosition {
    pub fn new(workspace: &Workspace) -> Self {
        Self {
            position: None,
            selected_count: 0,
            workspace: workspace.weak_handle(),
            _observe_active_editor: None,
        }
    }

    fn update_position(&mut self, editor: View<Editor>, cx: &mut ViewContext<Self>) {
        let editor = editor.read(cx);
        let buffer = editor.buffer().read(cx).snapshot(cx);

        self.selected_count = 0;
        let mut last_selection: Option<Selection<usize>> = None;
        for selection in editor.selections.all::<usize>(cx) {
            self.selected_count += selection.end - selection.start;
            if last_selection
                .as_ref()
                .map_or(true, |last_selection| selection.id > last_selection.id)
            {
                last_selection = Some(selection);
            }
        }
        self.position = last_selection.map(|s| s.head().to_point(&buffer));

        cx.notify();
    }
}

impl Render for CursorPosition {
    fn render(&mut self, cx: &mut ViewContext<Self>) -> impl IntoElement {
        div().when_some(self.position, |el, position| {
            let mut text = format!(
                "{}{FILE_ROW_COLUMN_DELIMITER}{}",
                position.row + 1,
                position.column + 1
            );
            if self.selected_count > 0 {
                write!(text, " ({} selected)", self.selected_count).unwrap();
            }

            el.child(
                Button::new("go-to-line-column", text)
                    .label_size(LabelSize::Small)
                    .on_click(cx.listener(|this, _, cx| {
                        if let Some(workspace) = this.workspace.upgrade() {
                            workspace.update(cx, |workspace, cx| {
                                if let Some(editor) = workspace
                                    .active_item(cx)
                                    .and_then(|item| item.act_as::<Editor>(cx))
                                {
                                    workspace
                                        .toggle_modal(cx, |cx| crate::GoToLine::new(editor, cx))
                                }
                            });
                        }
                    }))
                    .tooltip(|cx| Tooltip::for_action("Go to Line/Column", &crate::Toggle, cx)),
            )
        })
    }
}

impl StatusItemView for CursorPosition {
    fn set_active_pane_item(
        &mut self,
        active_pane_item: Option<&dyn ItemHandle>,
        cx: &mut ViewContext<Self>,
    ) {
        if let Some(editor) = active_pane_item.and_then(|item| item.act_as::<Editor>(cx)) {
            self._observe_active_editor = Some(cx.observe(&editor, Self::update_position));
            self.update_position(editor, cx);
        } else {
            self.position = None;
            self._observe_active_editor = None;
        }

        cx.notify();
    }
}