package dbx

import (
	"fmt"
	"io"
	"strconv"
)

// Uint64Marshaler wraps a uint64 for GraphQL JSON output as a string scalar.
type Uint64Marshaler uint64

// MarshalGQL writes the uint64 as a JSON string for gqlgen compatibility.
func (u Uint64Marshaler) MarshalGQL(w io.Writer) {
	fmt.Fprintf(w, "\"%d\"", uint64(u))
}

// MarshalUint64 marshals a uint64 as a JSON string to avoid JavaScript
// precision loss for integers larger than 2^53-1.
func MarshalUint64(i uint64) Uint64Marshaler {
	return Uint64Marshaler(i)
}

// UnmarshalUint64 unmarshals a uint64 from a JSON string or number.
func UnmarshalUint64(v any) (uint64, error) {
	switch value := v.(type) {
	case string:
		if value == "" {
			return 0, nil
		}
		n, err := strconv.ParseUint(value, 10, 64)
		if err != nil {
			return 0, fmt.Errorf("invalid uint64 string: %w", err)
		}
		return n, nil
	case int:
		if value < 0 {
			return 0, fmt.Errorf("invalid negative uint64: %d", value)
		}
		return uint64(value), nil
	case int64:
		if value < 0 {
			return 0, fmt.Errorf("invalid negative uint64: %d", value)
		}
		return uint64(value), nil
	case float64:
		if value < 0 || value != float64(uint64(value)) {
			return 0, fmt.Errorf("invalid uint64 number: %v", value)
		}
		return uint64(value), nil
	case uint64:
		return value, nil
	default:
		return 0, fmt.Errorf("invalid uint64 type: %T", v)
	}
}