package storage_migrate

import (
	"context"
	"crypto/md5"
	"encoding/hex"
	"fmt"
	"io"
	"os"
	"path"
	"path/filepath"
	"strings"
	"time"

	"quyun/v2/app/commands"
	"quyun/v2/database"
	"quyun/v2/database/models"
	"quyun/v2/providers/postgres"
	"quyun/v2/providers/storage"

	"github.com/spf13/cobra"
	"go.ipao.vip/atom"
	"go.ipao.vip/atom/container"
	"go.uber.org/dig"
	"gorm.io/gorm"
)

func defaultProviders() container.Providers {
	return commands.Default(container.Providers{
		postgres.DefaultProvider(),
		storage.DefaultProvider(),
		database.DefaultProvider(),
	}...)
}

func Command() atom.Option {
	return atom.Command(
		atom.Name("storage-migrate"),
		atom.Short("migrate media assets to md5 object keys"),
		atom.Arguments(func(cmd *cobra.Command) {
			cmd.Flags().Bool("dry-run", false, "preview changes without writing")
			cmd.Flags().Int("batch", 200, "batch size per scan")
		}),
		atom.RunE(Serve),
		atom.Providers(defaultProviders()),
		atom.Example("storage-migrate --dry-run"),
	)
}

type Service struct {
	dig.In

	DB      *gorm.DB
	Storage *storage.Storage
}

func Serve(cmd *cobra.Command, args []string) error {
	return container.Container.Invoke(func(ctx context.Context, svc Service) error {
		models.SetDefault(svc.DB)

		dryRun, _ := cmd.Flags().GetBool("dry-run")
		batchSize, _ := cmd.Flags().GetInt("batch")
		if batchSize <= 0 {
			batchSize = 200
		}

		localPath := svc.Storage.Config.LocalPath
		if localPath == "" {
			localPath = "./storage"
		}

		fmt.Printf("storage migrate: dry-run=%v batch=%d local-path=%s\n", dryRun, batchSize, localPath)

		tenantCache := make(map[int64]*models.Tenant)
		offset := 0
		for {
			tbl, q := models.MediaAssetQuery.QueryContext(ctx)
			list, err := q.Order(tbl.ID.Asc()).Offset(offset).Limit(batchSize).Find()
			if err != nil {
				return err
			}
			if len(list) == 0 {
				break
			}

			for _, asset := range list {
				// 仅处理本地存储且有实际文件路径的资源。
				if strings.ToLower(asset.Provider) != "local" {
					continue
				}
				if asset.ObjectKey == "" {
					continue
				}
				if strings.HasPrefix(asset.ObjectKey, "http://") || strings.HasPrefix(asset.ObjectKey, "https://") {
					continue
				}

				srcPath := asset.ObjectKey
				if !filepath.IsAbs(srcPath) {
					srcPath = filepath.Join(localPath, filepath.FromSlash(srcPath))
				}

				hash, size, err := fileMD5(srcPath)
				if err != nil {
					fmt.Printf("skip asset=%d err=%v\n", asset.ID, err)
					continue
				}

				filename := asset.Meta.Data().Filename
				if filename == "" {
					filename = path.Base(asset.ObjectKey)
				}

				var tenant *models.Tenant
				if asset.TenantID > 0 {
					if cached, ok := tenantCache[asset.TenantID]; ok {
						tenant = cached
					} else if t, err := models.TenantQuery.WithContext(ctx).Where(models.TenantQuery.ID.Eq(asset.TenantID)).First(); err == nil {
						tenantCache[asset.TenantID] = t
						tenant = t
					}
				}

				newKey := buildObjectKey(tenant, hash, filename)
				dstPath := filepath.Join(localPath, filepath.FromSlash(newKey))
				if asset.ObjectKey == newKey && asset.Hash == hash {
					continue
				}

				if !dryRun {
					if asset.ObjectKey != newKey {
						if err := os.MkdirAll(filepath.Dir(dstPath), 0o755); err != nil {
							return err
						}
						if _, err := os.Stat(dstPath); err == nil {
							if srcPath != dstPath {
								_ = os.Remove(srcPath)
							}
						} else if err := os.Rename(srcPath, dstPath); err != nil {
							return err
						}
					}

					_, err := models.MediaAssetQuery.WithContext(ctx).
						Where(models.MediaAssetQuery.ID.Eq(asset.ID)).
						UpdateSimple(
							models.MediaAssetQuery.ObjectKey.Value(newKey),
							models.MediaAssetQuery.Hash.Value(hash),
							models.MediaAssetQuery.UpdatedAt.Value(time.Now()),
						)
					if err != nil {
						return err
					}
				}

				fmt.Printf("migrated asset=%d key=%s hash=%s size=%d\n", asset.ID, newKey, hash, size)
			}

			offset += len(list)
		}

		return nil
	})
}

func buildObjectKey(tenant *models.Tenant, hash, filename string) string {
	// 按租户维度组织对象路径：quyun/<tenant_uuid>/<md5>.<ext>
	tenantUUID := "public"
	if tenant != nil && tenant.UUID.String() != "" {
		tenantUUID = tenant.UUID.String()
	}
	ext := strings.ToLower(filepath.Ext(filename))
	return path.Join("quyun", tenantUUID, hash+ext)
}

func fileMD5(filename string) (string, int64, error) {
	f, err := os.Open(filename)
	if err != nil {
		return "", 0, err
	}
	defer f.Close()

	h := md5.New()
	size, err := io.Copy(h, f)
	if err != nil {
		return "", size, err
	}
	return hex.EncodeToString(h.Sum(nil)), size, nil
}