// MIT License
//
// Copyright (c) 2016-2017 xtaci
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.

package smux

// _itimediff returns the time difference between two uint32 values.
// The result is a signed 32-bit integer representing the difference between 'later' and 'earlier'.
func _itimediff(later, earlier uint32) int32 {
	return (int32)(later - earlier)
}

// shaperHeap is a min-heap of writeRequest.
// It orders writeRequests by class first, then by sequence number within the same class.
type shaperHeap []writeRequest

func (h shaperHeap) Len() int { return len(h) }

// Less determines the ordering of elements in the heap.
// Requests are ordered by their class first. If two requests have the same class,
// they are ordered by their sequence numbers.
func (h shaperHeap) Less(i, j int) bool {
	if h[i].class != h[j].class {
		return h[i].class < h[j].class
	}
	return _itimediff(h[j].seq, h[i].seq) > 0
}

func (h shaperHeap) Swap(i, j int)       { h[i], h[j] = h[j], h[i] }
func (h *shaperHeap) Push(x interface{}) { *h = append(*h, x.(writeRequest)) }

func (h *shaperHeap) Pop() interface{} {
	old := *h
	n := len(old)
	x := old[n-1]
	*h = old[0 : n-1]
	return x
}