package server

import (
	"context"
	"os"
	"path/filepath"
	"syscall"
	"testing"
	"time"
)

func TestQueueEnqueueNextMarkDone(t *testing.T) {
	q, err := NewQueue("")
	if err != nil {
		t.Fatalf("new queue: %v", err)
	}

	req := VideoRequest{URL: "https://example.com/watch?v=1", OutDir: "/tmp/videos", MetadataOnly: false}
	id, err := q.Enqueue(req)
	if err != nil {
		t.Fatalf("enqueue: %v", err)
	}

	ctx, cancel := context.WithTimeout(context.Background(), time.Second)
	defer cancel()

	item, err := q.Next(ctx)
	if err != nil {
		t.Fatalf("next: %v", err)
	}

	if item.ID != id {
		t.Fatalf("expected id %s, got %s", id, item.ID)
	}

	if item.Request.URL != req.URL {
		t.Fatalf("unexpected url: %s", item.Request.URL)
	}

	if err := q.MarkDone(item.ID); err != nil {
		t.Fatalf("mark done: %v", err)
	}

	select {
	case <-time.After(20 * time.Millisecond):
	default:
	}
}

func TestQueuePersistence(t *testing.T) {
	tmpDir := t.TempDir()
	queuePath := filepath.Join(tmpDir, "queue.json")

	q, err := NewQueue(queuePath)
	if err != nil {
		t.Fatalf("new queue: %v", err)
	}

	req := VideoRequest{URL: "https://example.com/watch?v=2", OutDir: "/data", MetadataOnly: true}
	id, err := q.Enqueue(req)
	if err != nil {
		t.Fatalf("enqueue: %v", err)
	}

	if _, err := os.Stat(queuePath); err != nil {
		t.Fatalf("queue file missing: %v", err)
	}

	q2, err := NewQueue(queuePath)
	if err != nil {
		t.Fatalf("reload queue: %v", err)
	}

	ctx, cancel := context.WithTimeout(context.Background(), time.Second)
	defer cancel()

	item, err := q2.Next(ctx)
	if err != nil {
		t.Fatalf("next: %v", err)
	}

	if item.ID != id {
		t.Fatalf("expected persisted id %s, got %s", id, item.ID)
	}

	if err := q2.MarkDone(item.ID); err != nil {
		t.Fatalf("mark done: %v", err)
	}

	if _, err := os.Stat(queuePath); !os.IsNotExist(err) {
		t.Fatalf("expected queue file removed after draining, got %v", err)
	}
}

func TestWriteFileAtomicFallback(t *testing.T) {
	// Simulate EBUSY by replacing os.Rename temporarily.
	origRename := osRename
	origWriteFile := osWriteFile
	defer func() {
		osRename = origRename
		osWriteFile = origWriteFile
	}()

	tmpDir := t.TempDir()
	path := filepath.Join(tmpDir, "queue.json")
	odyssey := filepath.Join(tmpDir, "queue.json.tmp")

	osWriteFile = func(name string, data []byte, perm os.FileMode) error {
		if name == path {
			if err := os.WriteFile(name, data, perm); err != nil {
				return err
			}
			return nil
		}
		return os.WriteFile(name, data, perm)
	}

	osRename = func(oldpath, newpath string) error {
		return syscall.EBUSY
	}

	if err := writeFileAtomic(path, []byte("{}")); err != nil {
		t.Fatalf("writeFileAtomic: %v", err)
	}

	data, err := os.ReadFile(path)
	if err != nil {
		t.Fatalf("read path: %v", err)
	}

	if string(data) != "{}" {
		t.Fatalf("expected file contents '{}', got %q", data)
	}

	if _, err := os.Stat(odyssey); !os.IsNotExist(err) {
		t.Fatalf("expected tmp removed, got %v", err)
	}
}