package wantlist

import (
	u "github.com/jbenet/go-ipfs/util"
	"sort"
	"sync"
)

type ThreadSafe struct {
	lk sync.RWMutex
	Wantlist
}

// not threadsafe
type Wantlist struct {
	set map[u.Key]*Entry
}

type Entry struct {
	// TODO consider making entries immutable so they can be shared safely and
	// slices can be copied efficiently.
	Key      u.Key
	Priority int
}

type entrySlice []*Entry

func (es entrySlice) Len() int           { return len(es) }
func (es entrySlice) Swap(i, j int)      { es[i], es[j] = es[j], es[i] }
func (es entrySlice) Less(i, j int) bool { return es[i].Priority > es[j].Priority }

func NewThreadSafe() *ThreadSafe {
	return &ThreadSafe{
		Wantlist: *New(),
	}
}

func New() *Wantlist {
	return &Wantlist{
		set: make(map[u.Key]*Entry),
	}
}

func (w *ThreadSafe) Add(k u.Key, priority int) {
	// TODO rm defer for perf
	w.lk.Lock()
	defer w.lk.Unlock()
	w.Wantlist.Add(k, priority)
}

func (w *ThreadSafe) Remove(k u.Key) {
	// TODO rm defer for perf
	w.lk.Lock()
	defer w.lk.Unlock()
	w.Wantlist.Remove(k)
}

func (w *ThreadSafe) Contains(k u.Key) bool {
	// TODO rm defer for perf
	w.lk.RLock()
	defer w.lk.RUnlock()
	return w.Wantlist.Contains(k)
}

func (w *ThreadSafe) Entries() []*Entry {
	w.lk.RLock()
	defer w.lk.RUnlock()
	return w.Wantlist.Entries()
}

func (w *ThreadSafe) SortedEntries() []*Entry {
	w.lk.RLock()
	defer w.lk.RUnlock()
	return w.Wantlist.SortedEntries()
}

func (w *Wantlist) Add(k u.Key, priority int) {
	if _, ok := w.set[k]; ok {
		return
	}
	w.set[k] = &Entry{
		Key:      k,
		Priority: priority,
	}
}

func (w *Wantlist) Remove(k u.Key) {
	delete(w.set, k)
}

func (w *Wantlist) Contains(k u.Key) bool {
	_, ok := w.set[k]
	return ok
}

func (w *Wantlist) Entries() []*Entry {
	var es entrySlice
	for _, e := range w.set {
		es = append(es, e)
	}
	return es
}

func (w *Wantlist) SortedEntries() []*Entry {
	var es entrySlice
	for _, e := range w.set {
		es = append(es, e)
	}
	sort.Sort(es)
	return es
}