nut 0.1.1

use either::Either;

use super::{Bucket, ElemRef};

/// Contains references to retrieved bucket's item key, value and flags
#[derive(Debug)]
pub struct CursorItem<'a> {
    pub key: Option<&'a [u8]>,
    pub value: Option<&'a [u8]>,
    pub flags: u32,
}

impl<'a> CursorItem<'a> {
    pub(crate) fn new(key: Option<&'a [u8]>, value: Option<&'a [u8]>, flags: u32) -> Self {
        Self { key, value, flags }
    }

    #[inline]
    pub(crate) fn new_null(key: Option<&'a [u8]>, value: Option<&'a [u8]>) -> Self {
        CursorItem::new(key, value, 0)
    }

    /// returns true if key and value are None
    pub fn is_none(&self) -> bool {
        self.key.is_none() && self.value.is_none()
    }

    /// returns true if key or value are Some
    #[inline]
    pub fn is_some(&self) -> bool {
        !self.is_none()
    }

    #[inline]
    pub fn is_bucket(&self) -> bool {
        self.flags & Bucket::FLAG != 0
    }

    /// unwraps item into key, value and flags
    pub fn unwrap(self) -> (Option<&'a [u8]>, Option<&'a [u8]>, u32) {
        (self.key, self.value, self.flags)
    }
}

impl<'a> From<&ElemRef> for CursorItem<'a> {
    fn from(el_ref: &ElemRef) -> Self {
        if (el_ref.count() == 0) || el_ref.index >= el_ref.count() {
            return Self::new(None, None, 0);
        }
        unsafe {
            match el_ref.upgrade() {
                Either::Left(ref p) => {
                    let elem = p.leaf_page_element(el_ref.index);
                    Self::new(
                        Some(&*(elem.key() as *const [u8])),
                        Some(&*(elem.value() as *const [u8])),
                        elem.flags,
                    )
                }
                Either::Right(ref n) => {
                    let inode = &n.0.inodes.borrow()[el_ref.index];
                    Self::new(
                        Some(&*(inode.key.as_slice() as *const [u8])),
                        Some(&*(inode.value.as_slice() as *const [u8])),
                        inode.flags,
                    )
                }
            }
        }
    }
}