package dbx

import (
	"database/sql/driver"
	"fmt"
	"io"

	"github.com/segmentio/ksuid"
)

// BinaryKSUID wraps segmentio/ksuid for binary-column storage (BINARY(20), BYTEA).
// SQL Scan/Value use the raw 20-byte encoding. GraphQL transit uses a string
// scalar (base62 KSUID).
type BinaryKSUID struct {
	ksuid.KSUID
}

// NewBinaryKSUID generates a new BinaryKSUID.
func NewBinaryKSUID() BinaryKSUID {
	return BinaryKSUID{KSUID: ksuid.New()}
}

// ParseBinaryKSUID parses a BinaryKSUID from its raw 20-byte form.
func ParseBinaryKSUID(b []byte) (BinaryKSUID, error) {
	id, err := ksuid.FromBytes(b)
	if err != nil {
		return BinaryKSUID{}, err
	}
	return BinaryKSUID{KSUID: id}, nil
}

// AsStringKSUID returns a StringKSUID view of the same identifier.
func (b BinaryKSUID) AsStringKSUID() StringKSUID {
	return StringKSUID{KSUID: b.KSUID}
}

// Scan implements sql.Scanner for binary-backed KSUID columns.
func (b *BinaryKSUID) Scan(src any) error {
	switch v := src.(type) {
	case nil:
		*b = BinaryKSUID{}
		return nil
	case []byte:
		if len(v) == ksuidStringLength {
			return fmt.Errorf("BinaryKSUID.Scan: string-encoded KSUID (%d bytes); use StringKSUID", len(v))
		}
		id, err := ksuid.FromBytes(v)
		if err != nil {
			return fmt.Errorf("BinaryKSUID.Scan: %w", err)
		}
		*b = BinaryKSUID{KSUID: id}
		return nil
	case string:
		return fmt.Errorf("BinaryKSUID.Scan: string value %q; use StringKSUID or store raw bytes", v)
	default:
		return fmt.Errorf("BinaryKSUID.Scan: unable to scan type %T", v)
	}
}

// Value implements driver.Valuer for binary-backed KSUID columns.
func (b BinaryKSUID) Value() (driver.Value, error) {
	if b.IsNil() {
		return nil, nil
	}
	return b.Bytes(), nil
}

// UnmarshalGQL implements the graphql.Unmarshaler interface.
func (b *BinaryKSUID) UnmarshalGQL(value any) error {
	return unmarshalKSUIDFromGQL(value, b.UnmarshalText)
}

// MarshalGQL implements the graphql.Marshaler interface.
func (b BinaryKSUID) MarshalGQL(w io.Writer) {
	marshalKSUIDToGQL(w, b.KSUID)
}