package pool

import (
	"sync"
	"testing"
)

func TestPortAllocator_AllocateRelease(t *testing.T) {
	pa := NewPortAllocator(8500, 8502)
	p1, err := pa.Allocate()
	if err != nil {
		t.Fatal(err)
	}
	p2, err := pa.Allocate()
	if err != nil {
		t.Fatal(err)
	}
	p3, err := pa.Allocate()
	if err != nil {
		t.Fatal(err)
	}

	// All three ports should be distinct
	if p1 == p2 || p2 == p3 || p1 == p3 {
		t.Fatalf("expected distinct ports: %d, %d, %d", p1, p2, p3)
	}

	// Exhausted
	_, err = pa.Allocate()
	if err == nil {
		t.Fatal("expected error when exhausted")
	}

	// Release and re-allocate
	pa.Release(p2)
	p4, err := pa.Allocate()
	if err != nil {
		t.Fatal(err)
	}
	if p4 != p2 {
		t.Fatalf("expected released port %d, got %d", p2, p4)
	}
}

func TestPortAllocator_Concurrent(t *testing.T) {
	pa := NewPortAllocator(8500, 8599)
	var wg sync.WaitGroup
	allocated := make(chan int, 100)

	for i := 0; i < 100; i++ {
		wg.Add(1)
		go func() {
			defer wg.Done()
			p, err := pa.Allocate()
			if err != nil {
				return
			}
			allocated <- p
		}()
	}
	wg.Wait()
	close(allocated)

	seen := make(map[int]bool)
	for p := range allocated {
		if seen[p] {
			t.Fatalf("duplicate port %d", p)
		}
		seen[p] = true
	}
	if len(seen) != 100 {
		t.Fatalf("expected 100 ports, got %d", len(seen))
	}
}