use editor::scroll::autoscroll::Autoscroll;
use gpui::ViewContext;
use language::{Bias, Point};
use workspace::Workspace;

use crate::{normal::ChangeCase, state::Mode, Vim};

pub fn change_case(_: &mut Workspace, _: &ChangeCase, cx: &mut ViewContext<Workspace>) {
    Vim::update(cx, |vim, cx| {
        let count = vim.pop_number_operator(cx).unwrap_or(1) as u32;
        vim.update_active_editor(cx, |editor, cx| {
            let mut ranges = Vec::new();
            let mut cursor_positions = Vec::new();
            let snapshot = editor.buffer().read(cx).snapshot(cx);
            for selection in editor.selections.all::<Point>(cx) {
                match vim.state.mode {
                    Mode::Visual { line: true } => {
                        let start = Point::new(selection.start.row, 0);
                        let end =
                            Point::new(selection.end.row, snapshot.line_len(selection.end.row));
                        ranges.push(start..end);
                        cursor_positions.push(start..start);
                    }
                    Mode::Visual { line: false } => {
                        ranges.push(selection.start..selection.end);
                        cursor_positions.push(selection.start..selection.start);
                    }
                    Mode::Insert | Mode::Normal => {
                        let start = selection.start;
                        let mut end = start;
                        for _ in 0..count {
                            end = snapshot.clip_point(end + Point::new(0, 1), Bias::Right);
                        }
                        ranges.push(start..end);

                        if end.column == snapshot.line_len(end.row) {
                            end = snapshot.clip_point(end - Point::new(0, 1), Bias::Left);
                        }
                        cursor_positions.push(end..end)
                    }
                }
            }
            editor.transact(cx, |editor, cx| {
                for range in ranges.into_iter().rev() {
                    let snapshot = editor.buffer().read(cx).snapshot(cx);
                    editor.buffer().update(cx, |buffer, cx| {
                        let text = snapshot
                            .text_for_range(range.start..range.end)
                            .flat_map(|s| s.chars())
                            .flat_map(|c| {
                                if c.is_lowercase() {
                                    c.to_uppercase().collect::<Vec<char>>()
                                } else {
                                    c.to_lowercase().collect::<Vec<char>>()
                                }
                            })
                            .collect::<String>();

                        buffer.edit([(range, text)], None, cx)
                    })
                }
                editor.change_selections(Some(Autoscroll::fit()), cx, |s| {
                    s.select_ranges(cursor_positions)
                })
            });
        });
        vim.switch_mode(Mode::Normal, true, cx)
    })
}
#[cfg(test)]
mod test {
    use crate::{state::Mode, test::NeovimBackedTestContext};

    #[gpui::test]
    async fn test_change_case(cx: &mut gpui::TestAppContext) {
        let mut cx = NeovimBackedTestContext::new(cx).await;
        cx.set_shared_state("ˇabC\n").await;
        cx.simulate_shared_keystrokes(["~"]).await;
        cx.assert_shared_state("AˇbC\n").await;
        cx.simulate_shared_keystrokes(["2", "~"]).await;
        cx.assert_shared_state("ABˇc\n").await;

        // works in visual mode
        cx.set_shared_state("a😀C«dÉ1*fˇ»\n").await;
        cx.simulate_shared_keystrokes(["~"]).await;
        cx.assert_shared_state("a😀CˇDé1*F\n").await;

        // works with multibyte characters
        cx.simulate_shared_keystrokes(["~"]).await;
        cx.set_shared_state("aˇC😀é1*F\n").await;
        cx.simulate_shared_keystrokes(["4", "~"]).await;
        cx.assert_shared_state("ac😀É1ˇ*F\n").await;

        // works with line selections
        cx.set_shared_state("abˇC\n").await;
        cx.simulate_shared_keystrokes(["shift-v", "~"]).await;
        cx.assert_shared_state("ˇABc\n").await;

        // works with multiple cursors (zed only)
        cx.set_state("aˇßcdˇe\n", Mode::Normal);
        cx.simulate_keystroke("~");
        cx.assert_state("aSSˇcdˇE\n", Mode::Normal);
    }
}