use {
    r3vi::{
        view::{
            OuterViewPort,
            singleton::*,
            sequence::*,
        },
        buffer::{
            singleton::SingletonBuffer,
            vec::VecBuffer
        },
        projection::{
            decorate_sequence::*,
        }
    },
    crate::{
        editors::list::ListCursorMode,
        edit_tree::TreeCursor
    },
    cgmath::Vector2,
};

#[derive(Clone, Copy, Eq, PartialEq, Debug)]
pub enum TreeNavResult { Continue, Exit }

#[derive(Clone, Copy, Eq, PartialEq, Debug)]
pub enum TreeHeightOp { P, Q, Max }

#[derive(Clone, Copy, Debug)]
pub enum TreeNavCmd {
    pxev, nexd, up, dn,
    qpxev, qnexd, dup, qdn,

    dn_pxev,
    up_nexd,
    pxev_dn_qnexd
}

pub trait TreeNav {
    /* CORE
    */
    fn get_cursor(&self) -> TreeCursor {
        TreeCursor::default()
    }

    fn get_addr_view(&self) -> OuterViewPort<dyn SequenceView<Item = isize>> {
        VecBuffer::<isize>::new().get_port().to_sequence()
    }

    fn get_mode_view(&self) -> OuterViewPort<dyn SingletonView<Item = ListCursorMode>> {
        SingletonBuffer::new(ListCursorMode::Select).get_port()
    }

    fn get_cursor_warp(&self) -> TreeCursor {
        TreeCursor::default()
    }

    fn get_height(&self, _op: &TreeHeightOp) -> usize {
        0
    }

    fn goby(&mut self, _direction: Vector2<isize>) -> TreeNavResult {
        TreeNavResult::Exit
    }

    fn goto(&mut self, _new_cursor: TreeCursor) -> TreeNavResult {
        TreeNavResult::Exit
    }

    /* HULL
    */
    fn set_addr(&mut self, addr: isize) -> TreeNavResult {
        let mut c = self.get_cursor();
        c.tree_addr[0] = addr;
        self.goto(c)
    }

    fn set_leaf_mode(&mut self, new_leaf_mode: ListCursorMode) -> TreeNavResult {
        let mut c = self.get_cursor();
        c.leaf_mode = new_leaf_mode;
        self.goto(c)
    }

    fn get_leaf_mode(&mut self) -> ListCursorMode {
        self.get_cursor().leaf_mode
    }

    fn toggle_leaf_mode(&mut self) -> TreeNavResult {
        let old_mode = self.get_leaf_mode();
        self.set_leaf_mode(
            match old_mode {
                ListCursorMode::Insert => ListCursorMode::Select,
                ListCursorMode::Select => ListCursorMode::Insert
            }
        );
        TreeNavResult::Continue
    }

    fn up(&mut self) -> TreeNavResult {
        self.goby(Vector2::new(0, -1))
    }

    fn dn(&mut self) -> TreeNavResult {
        self.goby(Vector2::new(0, 1))
    }

    fn pxev(&mut self) -> TreeNavResult {
        self.goby(Vector2::new(-1, 0))
    }

    fn nexd(&mut self) -> TreeNavResult {
        self.goby(Vector2::new(1, 0))
    }

    // TODO
    fn qpxev(&mut self) -> TreeNavResult {
        let mut c = self.get_cursor();
        match c.tree_addr.len() {
            0 => {
                self.goto(TreeCursor::home())
            },
            depth => {
                if c.tree_addr[depth-1] != 0 {
                    c.tree_addr[depth-1] = 0;
                } else {
                    self.pxev();
                    c = self.get_cursor();
                    let d = c.tree_addr.len();
                    if d > 0 {
                        c.tree_addr[d-1] = 0;
                    }
                }

                self.goto(c)
            }
        }
    }

    fn qnexd(&mut self) -> TreeNavResult {
        let mut c = self.get_cursor_warp();
        match c.tree_addr.len() {
            0 => {
                TreeNavResult::Exit
            },
            depth => {
                if c.tree_addr[depth-1] != -1 {
                    c.tree_addr[depth-1] = -1;
                } else {
                    self.nexd();
                    c = self.get_cursor();
                    let d = c.tree_addr.len();
                    if d > 0 {
                        c.tree_addr[d-1] = -1;
                    }
                }

                self.goto(c)
            }
        }
    }

}