package dbx

import (
	"encoding/json"
	"fmt"
	"io"
	"log/slog"

	"github.com/segmentio/ksuid"
)

// UUID is a wrapper around ksuid.KSUID that implements the
// graphql.Unmarshaler and graphql.Marshaler interfaces for use in GraphQL APIs.
// It also provides additional convenience functions such as ParseUUID and NewUUID.
type UUID struct {
	ksuid.KSUID
}

type uuidTransport struct {
	UUIDStr string `json:"uuid_str"`
}

// Generates a new, wrapped KSUID. In the strange case that random bytes can't be read, it will panic.
func NewUUID() UUID {
	return UUID{KSUID: ksuid.New()}
}

// ParseUUID parses a UUID from a string. If the string is not a valid UUID, it will return an error.
func ParseUUID(s string) (UUID, error) {
	ksuid, err := ksuid.Parse(s)
	if err != nil {
		return UUID{}, err
	}
	return UUID{KSUID: ksuid}, nil
}

// UnmarshalGQL implements the graphql.Unmarshaler interface
func (u *UUID) UnmarshalGQL(value interface{}) error {
	slog.Debug("uuid unmarshaling from gql", "val", value)
	str, ok := value.(string)
	if !ok {
		return fmt.Errorf("GraphQL failed to unmarshal UUID value: %v", value)
	}

	if err := u.UnmarshalText([]byte(str)); err != nil {
		return err
	}

	return nil
}

// MarshalGQL implements the graphql.Marshaler interface
func (u UUID) MarshalGQL(w io.Writer) {
	transport := uuidTransport{UUIDStr: u.String()}
	json, err := json.Marshal(transport)
	if err != nil {
		panic(fmt.Errorf("GraphQL failed to JSON-marshal UUID value: %s", err))
	}
	slog.Debug("uuid marshaling to gql", "uuid", u.String(), "json", string(json))
	_, err = w.Write(json)
	if err != nil {
		panic(fmt.Errorf("GraphQL failed to write UUID value: %s", string(json)))
	}
}