package corebin

import (
	"os"
	"path/filepath"
	"sync"
	"sync/atomic"
	"testing"
	"time"
)

func TestResolveTrustsCacheWithoutStat(t *testing.T) {
	Invalidate()
	dir := t.TempDir()
	path := filepath.Join(dir, "core")
	if err := os.WriteFile(path, []byte("x"), 0o755); err != nil {
		t.Fatal(err)
	}
	key := CacheKey(dir, "naive")
	calls := 0
	fn := func() (string, error) {
		calls++
		return path, nil
	}
	if p, err := Resolve(key, fn); err != nil || p != path || calls != 1 {
		t.Fatalf("first: %q %v calls=%d", p, err, calls)
	}
	_ = os.Remove(path) // missing on disk — cache still trusted until Invalidate
	if p, err := Resolve(key, fn); err != nil || p != path || calls != 1 {
		t.Fatalf("cached without Stat: %q %v calls=%d", p, err, calls)
	}
	Invalidate()
	if _, err := Resolve(key, fn); err == nil && calls != 2 {
		// fn returns deleted path; Resolve still succeeds
	}
	if calls != 2 {
		t.Fatalf("after Invalidate expected refresh, calls=%d", calls)
	}
}

func TestResolveSingleflight(t *testing.T) {
	Invalidate()
	key := CacheKey(t.TempDir(), "naive")
	var calls atomic.Int32
	var started sync.WaitGroup
	started.Add(1)
	fn := func() (string, error) {
		calls.Add(1)
		started.Wait()
		time.Sleep(20 * time.Millisecond)
		return "embedded-test-core", nil
	}
	var wg sync.WaitGroup
	for i := 0; i < 8; i++ {
		wg.Add(1)
		go func() {
			defer wg.Done()
			if _, err := Resolve(key, fn); err != nil {
				t.Errorf("resolve: %v", err)
			}
		}()
	}
	time.Sleep(10 * time.Millisecond)
	started.Done()
	wg.Wait()
	if calls.Load() != 1 {
		t.Fatalf("expected 1 cold resolve, got %d", calls.Load())
	}
}

func TestVirtualEmbeddedAWG(t *testing.T) {
	Invalidate()
	key := CacheKey("/bin", "awg")
	calls := 0
	p, err := Resolve(key, func() (string, error) {
		calls++
		return "embedded-amneziawg-go", nil
	})
	if err != nil || p != "embedded-amneziawg-go" || calls != 1 {
		t.Fatalf("%q %v calls=%d", p, err, calls)
	}
	if !VirtualPath(p) {
		t.Fatal("expected virtual")
	}
	p2, err := Resolve(key, func() (string, error) {
		calls++
		return "embedded-amneziawg-go", nil
	})
	if err != nil || p2 != p || calls != 1 {
		t.Fatalf("second: %q calls=%d", p2, calls)
	}
}