package biz

import (
	"context"
	"io"
	"time"

	"rag/file-system/internal/data"

	"github.com/go-kratos/kratos/v2/log"
)

// FileRepo defines the interface for S3 storage operations.
type FileRepo interface {
	UploadFile(ctx context.Context, bucket, key string, fileData io.Reader) error
	DownloadFile(ctx context.Context, bucket, key string) (io.ReadCloser, error)
	ListBuckets(ctx context.Context) ([]string, error)
	CreateBucket(ctx context.Context, name string) error
	DeleteBucket(ctx context.Context, name string) error
	ListObjectsV2(ctx context.Context, bucket, prefix string, maxKeys int32, token *string) (*data.ListFilesResult, error)
	GeneratePresignedURL(ctx context.Context, bucket, key string, expiry time.Duration) (string, error)
	GetFileContent(ctx context.Context, bucket, key string) (string, error)
	DeleteFile(ctx context.Context, bucket, key string) error
	CreateMultipartUpload(ctx context.Context, bucket, key string) (string, error)
	UploadPart(ctx context.Context, bucket, key, uploadID string, partNumber int32, fileData io.Reader) (string, error)
	CompleteMultipartUpload(ctx context.Context, bucket, key, uploadID string, parts []data.Part) (string, error)
	AbortMultipartUpload(ctx context.Context, bucket, key, uploadID string) error
}

// FileUsecase wraps FileRepo and provides file-level business operations.
type FileUsecase struct {
	repo FileRepo
	log  *log.Helper
}

// NewFileUsecase creates a new FileUsecase.
func NewFileUsecase(repo FileRepo, logger log.Logger) *FileUsecase {
	return &FileUsecase{
		repo: repo,
		log:  log.NewHelper(logger),
	}
}

// UploadFile uploads data to the specified bucket and key.
func (uc *FileUsecase) UploadFile(ctx context.Context, bucket, key string, fileData io.Reader) error {
	return uc.repo.UploadFile(ctx, bucket, key, fileData)
}

// DownloadFile downloads an object from S3.
func (uc *FileUsecase) DownloadFile(ctx context.Context, bucket, key string) (io.ReadCloser, error) {
	return uc.repo.DownloadFile(ctx, bucket, key)
}

// GetFileContent retrieves text content for preview.
func (uc *FileUsecase) GetFileContent(ctx context.Context, bucket, key string) (string, error) {
	return uc.repo.GetFileContent(ctx, bucket, key)
}

// DeleteFile removes a file from S3.
func (uc *FileUsecase) DeleteFile(ctx context.Context, bucket, key string) error {
	return uc.repo.DeleteFile(ctx, bucket, key)
}

// ListObjectsV2 lists files with pagination support.
func (uc *FileUsecase) ListObjectsV2(ctx context.Context, bucket, prefix string, maxKeys int32, token *string) (*data.ListFilesResult, error) {
	return uc.repo.ListObjectsV2(ctx, bucket, prefix, maxKeys, token)
}

// GeneratePresignedURL generates a presigned URL with custom expiry.
func (uc *FileUsecase) GeneratePresignedURL(ctx context.Context, bucket, key string, expiry time.Duration) (string, error) {
	return uc.repo.GeneratePresignedURL(ctx, bucket, key, expiry)
}

// GetPreviewURL generates a presigned URL with 24h expiry for file preview.
func (uc *FileUsecase) GetPreviewURL(ctx context.Context, bucket, key string) (string, error) {
	return uc.repo.GeneratePresignedURL(ctx, bucket, key, 24*time.Hour)
}

// CreateMultipartUpload initializes a multipart upload session.
func (uc *FileUsecase) CreateMultipartUpload(ctx context.Context, bucket, key string) (string, error) {
	return uc.repo.CreateMultipartUpload(ctx, bucket, key)
}

// UploadPart uploads a single part of a multipart upload.
func (uc *FileUsecase) UploadPart(ctx context.Context, bucket, key, uploadID string, partNumber int32, fileData io.Reader) (string, error) {
	return uc.repo.UploadPart(ctx, bucket, key, uploadID, partNumber, fileData)
}

// CompleteMultipartUpload assembles all parts to complete the upload.
func (uc *FileUsecase) CompleteMultipartUpload(ctx context.Context, bucket, key, uploadID string, parts []data.Part) (string, error) {
	return uc.repo.CompleteMultipartUpload(ctx, bucket, key, uploadID, parts)
}

// AbortMultipartUpload cancels an in-progress multipart upload.
func (uc *FileUsecase) AbortMultipartUpload(ctx context.Context, bucket, key, uploadID string) error {
	return uc.repo.AbortMultipartUpload(ctx, bucket, key, uploadID)
}