package gtq

import (
	"runtime"
	"sync"
	"testing"
	"time"
)

var testQ = NewQueue()

func testAdd(n int) {
	for i := 0; i < n; i++ {
		testQ.Add(func() {
			time.Sleep(1)
		})
	}
}

func testRemove(wg *sync.WaitGroup, removed chan int) {
	defer wg.Done()
	var i int
	for testQ.Remove() != nil {
		i++
	}
	removed <- i
}

func TestParallelQueueAdd(t *testing.T) {
	max := runtime.GOMAXPROCS(0)
	var wg sync.WaitGroup
	for n := 0; n < max; n++ {
		wg.Add(1)
		go func() {
			defer wg.Done()
			testAdd(1000000)
		}()
	}
	wg.Wait()
	t.Log("Queue size is", testQ.Length())
	targetSize := max * 1000000
	if testQ.Length() != targetSize {
		t.Error("Queue size should be", targetSize)
	}
}

func TestParallelQueueRemove(t *testing.T) {
	target := testQ.Length()
	var wg sync.WaitGroup
	max := runtime.GOMAXPROCS(0)
	removed := make(chan int, max)
	for n := 0; n < max; n++ {
		wg.Add(1)
		go testRemove(&wg, removed)
	}
	wg.Wait()
	close(removed)
	var total int
	for count := range removed {
		total += count
	}
	if total != target {
		t.Error("removed", total, "but expected", target)
	}
	t.Log("removed", total)
}

func BenchmarkParallelQueue(b *testing.B) {
	testQ = NewQueue()
	b.ResetTimer()
	max := runtime.GOMAXPROCS(0)
	var wg1, wg2 sync.WaitGroup
	removed := make(chan int, max)
	for i := 0; i < max; i++ {
		wg1.Add(1)
		wg2.Add(1)
		go func() {
			testAdd(b.N / (max * 2))
			wg1.Done()
		}()
		go func() {
			testRemove(&wg2, removed)
		}()
	}
	wg1.Wait()
	wg2.Wait()
}