package model

import (
	"encoding/base32"
	"fmt"
	"io"

	"github.com/google/uuid"
)

// Crockford's low-ambiguity base32 alphabet
var base32Encoding = base32.
	NewEncoding("0123456789ABCDEFGHJKMNPQRSTVWXYZ").
	WithPadding(base32.NoPadding)

type ID struct {
	uuid uuid.UUID
}

// Creates a new resource ID.
func NewID() ID {
	uuid, err := uuid.NewV7()
	if err != nil {
		panic(err)
	}
	return ID{
		uuid: uuid,
	}
}

// Returns the UUID representation of this ID.
func (id *ID) UUID() uuid.UUID {
	return id.uuid
}

// Returns the string representation of this ID.
func (id *ID) String() string {
	return base32Encoding.EncodeToString(id.uuid[:])
}

func (id ID) MarshalGQL(w io.Writer) {
	w.Write([]byte(fmt.Sprintf(`"%s"`, id.String())))
}

func (id *ID) UnmarshalGQL(v interface{}) error {
	switch v := v.(type) {
	case string:
		bytes, err := base32Encoding.DecodeString(v)
		if err != nil {
			return err
		}
		id.uuid, err = uuid.FromBytes(bytes)
		if err != nil {
			return err
		}
		return nil
	default:
		return fmt.Errorf("%T is not a valid ID", v)
	}
}

// database/sql.Scanner
func (id *ID) Scan(src any) error {
	var uuid uuid.UUID
	err := uuid.Scan(src)
	if err != nil {
		return err
	}
	id.uuid = uuid
	return nil
}