package handlers

import (
	"context"
	"fmt"
	"io"
	"time"

	"rag/file-system/internal/common"
	"rag/file-system/internal/domain/model"
	"rag/file-system/internal/domain/repository"

	"github.com/google/uuid"
)

type UploadToFolderCommand struct {
	FolderID string
	FileName string
	Data     io.Reader
	S3Bucket string
	OwnerID  string
}

type MoveFileCommand struct {
	FileID         string
	TargetFolderID string
	OwnerID        string
}

type UploadToFolderHandler struct {
	FileMetaRepo repository.FileMetaRepository
	FolderRepo   repository.FolderRepository
	S3Repo       repository.FileRepository
}

func NewUploadToFolderHandler(
	fileMetaRepo repository.FileMetaRepository,
	folderRepo repository.FolderRepository,
	s3Repo repository.FileRepository,
) *UploadToFolderHandler {
	return &UploadToFolderHandler{
		FileMetaRepo: fileMetaRepo,
		FolderRepo:   folderRepo,
		S3Repo:       s3Repo,
	}
}

func (h *UploadToFolderHandler) Handle(ctx context.Context, cmd UploadToFolderCommand) (*model.FileMeta, error) {
	folder, err := h.FolderRepo.GetByID(ctx, cmd.FolderID)
	if err != nil {
		return nil, err
	}
	if folder == nil || folder.OwnerID != cmd.OwnerID {
		return nil, common.NewNotFoundError("目录不存在")
	}

	s3Key := uuid.New().String()

	if err := h.S3Repo.UploadFile(ctx, cmd.S3Bucket, s3Key, cmd.Data); err != nil {
		return nil, fmt.Errorf("S3 upload failed: %w", err)
	}

	now := time.Now()
	fileMeta := &model.FileMeta{
		ID:          uuid.New().String(),
		FolderID:    cmd.FolderID,
		Name:        cmd.FileName,
		S3Key:       s3Key,
		S3Bucket:    cmd.S3Bucket,
		ContentType: "application/octet-stream",
		OwnerID:     cmd.OwnerID,
		CreatedAt:   now,
		UpdatedAt:   now,
	}

	if err := h.FileMetaRepo.Create(ctx, fileMeta); err != nil {
		if delErr := h.S3Repo.DeleteFile(ctx, cmd.S3Bucket, s3Key); delErr != nil {
			common.Logger.Error("compensation failed: could not delete S3 object after PG write failure",
				"s3_key", s3Key, "error", delErr)
		}
		return nil, fmt.Errorf("failed to save file metadata: %w", err)
	}

	return fileMeta, nil
}

type MoveFileHandler struct {
	FileMetaRepo repository.FileMetaRepository
}

func NewMoveFileHandler(fileMetaRepo repository.FileMetaRepository) *MoveFileHandler {
	return &MoveFileHandler{FileMetaRepo: fileMetaRepo}
}

func (h *MoveFileHandler) Handle(ctx context.Context, cmd MoveFileCommand) (string, error) {
	if err := h.FileMetaRepo.Move(ctx, cmd.FileID, cmd.TargetFolderID, cmd.OwnerID); err != nil {
		return "", err
	}
	return "文件移动成功", nil
}