/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

use flow::Flow;
use flow_ref::{self, FlowRef};
use std::collections::{LinkedList, linked_list};

// This needs to be reworked now that we have dynamically-sized types in Rust.
// Until then, it's just a wrapper around LinkedList.

pub struct FlowList {
    flows: LinkedList<FlowRef>,
}

pub struct FlowListIterator<'a> {
    it: linked_list::Iter<'a, FlowRef>,
}

pub struct MutFlowListIterator<'a> {
    it: linked_list::IterMut<'a, FlowRef>,
}

impl FlowList {
    /// Add an element last in the list
    ///
    /// O(1)
    pub fn push_back(&mut self, new_tail: FlowRef) {
        self.flows.push_back(new_tail);
    }

    /// Add an element first in the list
    ///
    /// O(1)
    pub fn push_front(&mut self, new_head: FlowRef) {
        self.flows.push_front(new_head);
    }

    pub fn pop_front(&mut self) -> Option<FlowRef> {
        self.flows.pop_front()
    }

    /// Create an empty list
    #[inline]
    pub fn new() -> FlowList {
        FlowList {
            flows: LinkedList::new(),
        }
    }

    /// Provide a forward iterator
    #[inline]
    pub fn iter(&self) -> FlowListIterator {
        FlowListIterator {
            it: self.flows.iter(),
        }
    }

    /// Provide a forward iterator with mutable references
    #[inline]
    pub fn iter_mut(&mut self) -> MutFlowListIterator {
        MutFlowListIterator {
            it: self.flows.iter_mut(),
        }
    }

    /// O(1)
    #[inline]
    pub fn is_empty(&self) -> bool {
        self.flows.is_empty()
    }

    /// O(1)
    #[inline]
    pub fn len(&self) -> usize {
        self.flows.len()
    }

    #[inline]
    pub fn split_off(&mut self, i: usize) -> Self {
        FlowList {
            flows: self.flows.split_off(i)
        }
    }
}

impl<'a> Iterator for FlowListIterator<'a> {
    type Item = &'a Flow;
    #[inline]
    fn next(&mut self) -> Option<&'a Flow> {
        self.it.next().map(|x| &**x)
    }

    #[inline]
    fn size_hint(&self) -> (usize, Option<usize>) {
        self.it.size_hint()
    }
}

impl<'a> Iterator for MutFlowListIterator<'a> {
    type Item = &'a mut Flow;
    #[inline]
    fn next(&mut self) -> Option<&'a mut Flow> {
        self.it.next().map(flow_ref::deref_mut)
    }

    #[inline]
    fn size_hint(&self) -> (usize, Option<usize>) {
        self.it.size_hint()
    }
}