package attach

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

	"gocloud.dev/blob"
	"gocloud.dev/gcerrors"
	"gorm.io/gorm"
)

// Owner is implemented by models that own system_files rows. MorphName
// must return the PHP class string so cutover-copied attachment_type
// values keep matching.
type Owner interface {
	MorphName() string
}

// File is Winter's system_files row. AttachmentID is a string because
// Winter stores the morph FK as a string, never an integer.
type File struct {
	ID             uint    `gorm:"column:id;primaryKey"`
	DiskName       string  `gorm:"column:disk_name"`
	FileName       string  `gorm:"column:file_name"`
	FileSize       int64   `gorm:"column:file_size"`
	ContentType    string  `gorm:"column:content_type"`
	Title          *string `gorm:"column:title"`
	Description    *string `gorm:"column:description"`
	Field          string  `gorm:"column:field"`
	AttachmentID   string  `gorm:"column:attachment_id"`
	AttachmentType string  `gorm:"column:attachment_type"`
	// Pointer so GORM can distinguish unset (nil → DEFAULT TRUE) from
	// explicit false. A non-pointer bool with default:true cannot persist
	// false because false is the zero value GORM replaces with the default.
	IsPublic  *bool     `gorm:"column:is_public;not null;default:true"`
	SortOrder int       `gorm:"column:sort_order"`
	Metadata  *string   `gorm:"column:metadata"`
	CreatedAt time.Time `gorm:"column:created_at"`
	UpdatedAt time.Time `gorm:"column:updated_at"`
}

func (File) TableName() string { return "system_files" }

// Public reports Winter's is_public flag. A nil pointer is treated as true,
// matching the SQL DEFAULT TRUE and File::create() behaviour.
func (f File) Public() bool {
	if f.IsPublic == nil {
		return true
	}
	return *f.IsPublic
}

var all []any

// Register appends models so schema tooling can see File without a plugin registry.
func Register(models ...any) {
	all = append(all, models...)
}

// All returns every model registered in this package.
func All() []any {
	return all
}

func init() {
	Register(&File{})
}

func blobKeysFor(f File) []string {
	part := PartitionDirectory(f.DiskName)
	return []string{
		part + f.DiskName,
		part + fmt.Sprintf("thumb_%d_", f.ID),
	}
}

// DeleteForOwner removes system_files rows for owner inside tx.
//
// Two-phase contract (GORM has no post-commit hook):
//  1. Inside tx this function SELECTs disk_name values, DELETEs the rows,
//     and invokes afterCommit with the blob keys so the caller can record
//     them. afterCommit must not delete blobs — a rollback cannot restore
//     bytes.
//  2. After the top-level Unscoped().Delete(...) returns without error
//     (the transaction has committed), the caller passes those keys to
//     DeleteKeys to remove originals and thumbs from the bucket.
//
// Soft-deleting an owner must not call this helper: rows and blobs stay.
func DeleteForOwner(tx *gorm.DB, owner Owner, ownerID string, afterCommit func(blobKeys []string) error) error {
	if tx == nil {
		return fmt.Errorf("attach: delete tx is nil")
	}
	if owner == nil {
		return fmt.Errorf("attach: delete owner is nil")
	}
	morph := owner.MorphName()
	var files []File
	if err := tx.Where("attachment_type = ? AND attachment_id = ?", morph, ownerID).Find(&files).Error; err != nil {
		return err
	}
	var keys []string
	for _, f := range files {
		keys = append(keys, blobKeysFor(f)...)
	}
	if err := tx.Where("attachment_type = ? AND attachment_id = ?", morph, ownerID).Delete(&File{}).Error; err != nil {
		return err
	}
	if afterCommit != nil {
		return afterCommit(keys)
	}
	return nil
}

// DeleteKeys removes blob objects after a committed force-delete.
// Keys that end in '_' are treated as List prefixes (thumb_<id>_).
func DeleteKeys(ctx context.Context, bucket *blob.Bucket, keys []string) error {
	if bucket == nil {
		return fmt.Errorf("attach: bucket is nil")
	}
	for _, key := range keys {
		if strings.HasSuffix(key, "_") || strings.HasSuffix(key, "/") {
			iter := bucket.List(&blob.ListOptions{Prefix: key})
			for {
				obj, err := iter.Next(ctx)
				if err == io.EOF {
					break
				}
				if err != nil {
					return fmt.Errorf("attach: list %q: %w", key, err)
				}
				if err := deleteKey(ctx, bucket, obj.Key); err != nil {
					return err
				}
			}
			continue
		}
		if err := deleteKey(ctx, bucket, key); err != nil {
			return err
		}
	}
	return nil
}

func deleteKey(ctx context.Context, bucket *blob.Bucket, key string) error {
	err := bucket.Delete(ctx, key)
	if err == nil || gcerrors.Code(err) == gcerrors.NotFound {
		return nil
	}
	return fmt.Errorf("attach: delete %q: %w", key, err)
}