package service

import (
	"bytes"
	"context"
	"io"
	"testing"
	"time"

	"gcy_hpc_server/internal/model"
	"gcy_hpc_server/internal/storage"
	"gcy_hpc_server/internal/store"

	"go.uber.org/zap"
	gormlogger "gorm.io/gorm/logger"

	"gorm.io/driver/sqlite"
	"gorm.io/gorm"
)

type mockDownloadStorage struct {
	getObjectFn func(ctx context.Context, bucket, key string, opts storage.GetOptions) (io.ReadCloser, storage.ObjectInfo, error)
}

func (m *mockDownloadStorage) PutObject(_ context.Context, _ string, _ string, _ io.Reader, _ int64, _ storage.PutObjectOptions) (storage.UploadInfo, error) {
	return storage.UploadInfo{}, nil
}

func (m *mockDownloadStorage) GetObject(ctx context.Context, bucket, key string, opts storage.GetOptions) (io.ReadCloser, storage.ObjectInfo, error) {
	if m.getObjectFn != nil {
		return m.getObjectFn(ctx, bucket, key, opts)
	}
	return nil, storage.ObjectInfo{}, nil
}

func (m *mockDownloadStorage) ComposeObject(_ context.Context, _ string, _ string, _ []string) (storage.UploadInfo, error) {
	return storage.UploadInfo{}, nil
}

func (m *mockDownloadStorage) AbortMultipartUpload(_ context.Context, _ string, _ string, _ string) error {
	return nil
}

func (m *mockDownloadStorage) RemoveIncompleteUpload(_ context.Context, _ string, _ string) error {
	return nil
}

func (m *mockDownloadStorage) RemoveObject(_ context.Context, _ string, _ string, _ storage.RemoveObjectOptions) error {
	return nil
}

func (m *mockDownloadStorage) ListObjects(_ context.Context, _ string, _ string, _ bool) ([]storage.ObjectInfo, error) {
	return nil, nil
}

func (m *mockDownloadStorage) RemoveObjects(_ context.Context, _ string, _ []string, _ storage.RemoveObjectsOptions) error {
	return nil
}

func (m *mockDownloadStorage) BucketExists(_ context.Context, _ string) (bool, error) {
	return true, nil
}

func (m *mockDownloadStorage) MakeBucket(_ context.Context, _ string, _ storage.MakeBucketOptions) error {
	return nil
}

func (m *mockDownloadStorage) StatObject(_ context.Context, _ string, _ string, _ storage.StatObjectOptions) (storage.ObjectInfo, error) {
	return storage.ObjectInfo{}, nil
}

func setupDownloadService(t *testing.T) (*DownloadService, *store.FileStore, *store.BlobStore, *mockDownloadStorage) {
	t.Helper()

	db, err := gorm.Open(sqlite.Open(":memory:"), &gorm.Config{
		Logger: gormlogger.Default.LogMode(gormlogger.Silent),
	})
	if err != nil {
		t.Fatalf("open sqlite: %v", err)
	}
	if err := db.AutoMigrate(&model.File{}, &model.FileBlob{}); err != nil {
		t.Fatalf("auto migrate: %v", err)
	}

	mockStorage := &mockDownloadStorage{}
	blobStore := store.NewBlobStore(db)
	fileStore := store.NewFileStore(db)
	svc := NewDownloadService(mockStorage, blobStore, fileStore, "test-bucket", zap.NewNop())

	return svc, fileStore, blobStore, mockStorage
}

func createTestFileAndBlob(t *testing.T, fileStore *store.FileStore, blobStore *store.BlobStore) (*model.File, *model.FileBlob) {
	t.Helper()

	blob := &model.FileBlob{
		SHA256:   "abc123def456abc123def456abc123def456abc123def456abc123def456abcd",
		MinioKey: "chunks/session1/part-0",
		FileSize: 5000,
		MimeType: "application/octet-stream",
		RefCount: 1,
	}
	if err := blobStore.Create(context.Background(), blob); err != nil {
		t.Fatalf("create blob: %v", err)
	}

	file := &model.File{
		Name:       "test.dat",
		BlobSHA256: blob.SHA256,
		CreatedAt:  time.Now(),
		UpdatedAt:  time.Now(),
	}
	if err := fileStore.Create(context.Background(), file); err != nil {
		t.Fatalf("create file: %v", err)
	}

	return file, blob
}

func TestDownload_FullFile(t *testing.T) {
	svc, fileStore, blobStore, mockStorage := setupDownloadService(t)
	file, blob := createTestFileAndBlob(t, fileStore, blobStore)

	content := make([]byte, blob.FileSize)
	for i := range content {
		content[i] = byte(i % 256)
	}

	mockStorage.getObjectFn = func(_ context.Context, _, _ string, opts storage.GetOptions) (io.ReadCloser, storage.ObjectInfo, error) {
		if opts.Start == nil || opts.End == nil {
			t.Fatal("expected Start and End to be set")
		}
		if *opts.Start != 0 {
			t.Fatalf("expected start=0, got %d", *opts.Start)
		}
		if *opts.End != blob.FileSize-1 {
			t.Fatalf("expected end=%d, got %d", blob.FileSize-1, *opts.End)
		}
		return io.NopCloser(bytes.NewReader(content)), storage.ObjectInfo{Size: blob.FileSize}, nil
	}

	reader, gotFile, gotBlob, start, end, err := svc.Download(context.Background(), file.ID, "")
	if err != nil {
		t.Fatalf("Download: %v", err)
	}
	defer reader.Close()

	if gotFile.ID != file.ID {
		t.Fatalf("expected file ID %d, got %d", file.ID, gotFile.ID)
	}
	if gotBlob.SHA256 != blob.SHA256 {
		t.Fatalf("expected blob SHA256 %s, got %s", blob.SHA256, gotBlob.SHA256)
	}
	if start != 0 {
		t.Fatalf("expected start=0, got %d", start)
	}
	if end != blob.FileSize-1 {
		t.Fatalf("expected end=%d, got %d", blob.FileSize-1, end)
	}

	read, _ := io.ReadAll(reader)
	if int64(len(read)) != blob.FileSize {
		t.Fatalf("expected %d bytes, got %d", blob.FileSize, len(read))
	}
}

func TestDownload_WithRange(t *testing.T) {
	svc, fileStore, blobStore, mockStorage := setupDownloadService(t)
	file, _ := createTestFileAndBlob(t, fileStore, blobStore)

	content := make([]byte, 1024)
	for i := range content {
		content[i] = byte(i % 256)
	}

	mockStorage.getObjectFn = func(_ context.Context, _, _ string, opts storage.GetOptions) (io.ReadCloser, storage.ObjectInfo, error) {
		if opts.Start == nil || opts.End == nil {
			t.Fatal("expected Start and End to be set")
		}
		if *opts.Start != 0 {
			t.Fatalf("expected start=0, got %d", *opts.Start)
		}
		if *opts.End != 1023 {
			t.Fatalf("expected end=1023, got %d", *opts.End)
		}
		return io.NopCloser(bytes.NewReader(content[:1024])), storage.ObjectInfo{Size: 1024}, nil
	}

	reader, _, _, start, end, err := svc.Download(context.Background(), file.ID, "bytes=0-1023")
	if err != nil {
		t.Fatalf("Download: %v", err)
	}
	defer reader.Close()

	if start != 0 {
		t.Fatalf("expected start=0, got %d", start)
	}
	if end != 1023 {
		t.Fatalf("expected end=1023, got %d", end)
	}

	read, _ := io.ReadAll(reader)
	if len(read) != 1024 {
		t.Fatalf("expected 1024 bytes, got %d", len(read))
	}
}

func TestDownload_FileNotFound(t *testing.T) {
	svc, _, _, _ := setupDownloadService(t)

	_, _, _, _, _, err := svc.Download(context.Background(), 99999, "")
	if err == nil {
		t.Fatal("expected error for missing file")
	}
	if err.Error() != "file not found" {
		t.Fatalf("unexpected error: %v", err)
	}
}

func TestDownload_BlobNotFound(t *testing.T) {
	svc, fileStore, _, _ := setupDownloadService(t)

	file := &model.File{
		Name:       "orphan.dat",
		BlobSHA256: "nonexistent_hash_0000000000000000000000000000000000000000",
		CreatedAt:  time.Now(),
		UpdatedAt:  time.Now(),
	}
	if err := fileStore.Create(context.Background(), file); err != nil {
		t.Fatalf("create file: %v", err)
	}

	_, _, _, _, _, err := svc.Download(context.Background(), file.ID, "")
	if err == nil {
		t.Fatal("expected error for missing blob")
	}
	if err.Error() != "blob not found" {
		t.Fatalf("unexpected error: %v", err)
	}
}

func TestGetFileMetadata(t *testing.T) {
	svc, fileStore, blobStore, _ := setupDownloadService(t)
	file, _ := createTestFileAndBlob(t, fileStore, blobStore)

	gotFile, gotBlob, err := svc.GetFileMetadata(context.Background(), file.ID)
	if err != nil {
		t.Fatalf("GetFileMetadata: %v", err)
	}

	if gotFile.ID != file.ID {
		t.Fatalf("expected file ID %d, got %d", file.ID, gotFile.ID)
	}
	if gotBlob.FileSize != 5000 {
		t.Fatalf("expected file size 5000, got %d", gotBlob.FileSize)
	}
	if gotBlob.MimeType != "application/octet-stream" {
		t.Fatalf("expected mime type application/octet-stream, got %s", gotBlob.MimeType)
	}
}