package fit

import (
	"sort"
)

//First places the Item into the first Bin in which it fits.
func First(bins []Bin, capacity int64, x Item) ([]Bin, error) {
	for i, b := range bins {
		if !b.fits(x) {
			continue
		}
		bins[i].add(x)
		return bins, nil
	}
	n := newBin(capacity)
	err := n.add(x)
	if err != nil {
		return nil, err
	}
	bins = append(bins, n)
	return bins, nil
}

//Best places the Item into the fullest Bin it fits.
func Best(bins []Bin, capacity int64, x Item) ([]Bin, error) {
	sort.Sort(sort.Reverse(BinsBySize(bins)))
	for i, b := range bins {
		if !b.fits(x) {
			continue
		}
		err := bins[i].add(x)
		if err != nil {
			return nil, err
		}
		return bins, nil
	}
	n := newBin(capacity)
	n.add(x)
	bins = append(bins, n)
	return bins, nil
}

//Worst places the Item into the least full Bin in which it fits.
func Worst(bins []Bin, capacity int64, x Item) ([]Bin, error) {
	sort.Sort(BinsBySize(bins))
	for i, b := range bins {
		if !b.fits(x) {
			continue
		}
		err := bins[i].add(x)
		if err != nil {
			return nil, err
		}
		return bins, nil
	}
	n := newBin(capacity)
	n.add(x)
	bins = append(bins, n)
	return bins, nil
}

//BinSelectFunc is a strategy for placing an item into one of the bins.
//
//If required, a new bin is added with the given capacity.
type BinSelectFunc func(bins []Bin, capacity int64, item Item) ([]Bin, error)