use super::Axis;
use crate::{
    Autoscroll, Bias, Editor, EditorMode, NextScreen, NextScrollCursorCenterTopBottom,
    ScrollAnchor, ScrollCursorBottom, ScrollCursorCenter, ScrollCursorCenterTopBottom,
    ScrollCursorTop, SCROLL_CENTER_TOP_BOTTOM_DEBOUNCE_TIMEOUT,
};
use gpui::{Context, Point, Window};

impl Editor {
    pub fn next_screen(&mut self, _: &NextScreen, window: &mut Window, cx: &mut Context<Editor>) {
        if self.take_rename(true, window, cx).is_some() {
            return;
        }

        if self.mouse_context_menu.is_some() {
            return;
        }

        if matches!(self.mode, EditorMode::SingleLine { .. }) {
            cx.propagate();
            return;
        }
        self.request_autoscroll(Autoscroll::Next, cx);
    }

    pub fn scroll(
        &mut self,
        scroll_position: Point<f32>,
        axis: Option<Axis>,
        window: &mut Window,
        cx: &mut Context<Self>,
    ) {
        self.scroll_manager.update_ongoing_scroll(axis);
        self.set_scroll_position(scroll_position, window, cx);
    }

    pub fn scroll_cursor_center_top_bottom(
        &mut self,
        _: &ScrollCursorCenterTopBottom,
        window: &mut Window,
        cx: &mut Context<Self>,
    ) {
        let snapshot = self.snapshot(window, cx).display_snapshot;
        let visible_rows = if let Some(visible_rows) = self.visible_line_count() {
            visible_rows as u32
        } else {
            return;
        };

        let scroll_margin_rows = self.vertical_scroll_margin() as u32;
        let mut new_screen_top = self.selections.newest_display(cx).head();
        *new_screen_top.column_mut() = 0;
        match self.next_scroll_position {
            NextScrollCursorCenterTopBottom::Center => {
                *new_screen_top.row_mut() = new_screen_top.row().0.saturating_sub(visible_rows / 2);
            }
            NextScrollCursorCenterTopBottom::Top => {
                *new_screen_top.row_mut() =
                    new_screen_top.row().0.saturating_sub(scroll_margin_rows);
            }
            NextScrollCursorCenterTopBottom::Bottom => {
                *new_screen_top.row_mut() = new_screen_top
                    .row()
                    .0
                    .saturating_sub(visible_rows.saturating_sub(scroll_margin_rows));
            }
        }
        self.set_scroll_anchor(
            ScrollAnchor {
                anchor: snapshot
                    .buffer_snapshot
                    .anchor_before(new_screen_top.to_offset(&snapshot, Bias::Left)),
                offset: Default::default(),
            },
            window,
            cx,
        );

        self.next_scroll_position = self.next_scroll_position.next();
        self._scroll_cursor_center_top_bottom_task = cx.spawn(async move |editor, cx| {
            cx.background_executor()
                .timer(SCROLL_CENTER_TOP_BOTTOM_DEBOUNCE_TIMEOUT)
                .await;
            editor
                .update(cx, |editor, _| {
                    editor.next_scroll_position = NextScrollCursorCenterTopBottom::default();
                })
                .ok();
        });
    }

    pub fn scroll_cursor_top(
        &mut self,
        _: &ScrollCursorTop,
        window: &mut Window,
        cx: &mut Context<Editor>,
    ) {
        let snapshot = self.snapshot(window, cx).display_snapshot;
        let scroll_margin_rows = self.vertical_scroll_margin() as u32;

        let mut new_screen_top = self.selections.newest_display(cx).head();
        *new_screen_top.row_mut() = new_screen_top.row().0.saturating_sub(scroll_margin_rows);
        *new_screen_top.column_mut() = 0;
        let new_screen_top = new_screen_top.to_offset(&snapshot, Bias::Left);
        let new_anchor = snapshot.buffer_snapshot.anchor_before(new_screen_top);

        self.set_scroll_anchor(
            ScrollAnchor {
                anchor: new_anchor,
                offset: Default::default(),
            },
            window,
            cx,
        )
    }

    pub fn scroll_cursor_center(
        &mut self,
        _: &ScrollCursorCenter,
        window: &mut Window,
        cx: &mut Context<Editor>,
    ) {
        let snapshot = self.snapshot(window, cx).display_snapshot;
        let visible_rows = if let Some(visible_rows) = self.visible_line_count() {
            visible_rows as u32
        } else {
            return;
        };

        let mut new_screen_top = self.selections.newest_display(cx).head();
        *new_screen_top.row_mut() = new_screen_top.row().0.saturating_sub(visible_rows / 2);
        *new_screen_top.column_mut() = 0;
        let new_screen_top = new_screen_top.to_offset(&snapshot, Bias::Left);
        let new_anchor = snapshot.buffer_snapshot.anchor_before(new_screen_top);

        self.set_scroll_anchor(
            ScrollAnchor {
                anchor: new_anchor,
                offset: Default::default(),
            },
            window,
            cx,
        )
    }

    pub fn scroll_cursor_bottom(
        &mut self,
        _: &ScrollCursorBottom,
        window: &mut Window,
        cx: &mut Context<Editor>,
    ) {
        let snapshot = self.snapshot(window, cx).display_snapshot;
        let scroll_margin_rows = self.vertical_scroll_margin() as u32;
        let visible_rows = if let Some(visible_rows) = self.visible_line_count() {
            visible_rows as u32
        } else {
            return;
        };

        let mut new_screen_top = self.selections.newest_display(cx).head();
        *new_screen_top.row_mut() = new_screen_top
            .row()
            .0
            .saturating_sub(visible_rows.saturating_sub(scroll_margin_rows));
        *new_screen_top.column_mut() = 0;
        let new_screen_top = new_screen_top.to_offset(&snapshot, Bias::Left);
        let new_anchor = snapshot.buffer_snapshot.anchor_before(new_screen_top);

        self.set_scroll_anchor(
            ScrollAnchor {
                anchor: new_anchor,
                offset: Default::default(),
            },
            window,
            cx,
        )
    }
}
