package merrors

import (
	"fmt"
	"strings"
)

// InvalidArgumentClassified returns an invalid-argument error with a stable
// machine reason and structured field names for transport adapters.
func InvalidArgumentClassified(reason, msg string, argumentNames ...string) error {
	return classifiedError{
		base:          ErrInvalidArg,
		msg:           invalidArgumentMessage(msg, argumentNames...),
		reason:        strings.TrimSpace(reason),
		argumentNames: normalizeArgumentNames(argumentNames),
	}
}

func invalidArgumentMessage(msg string, argumentNames ...string) string {
	normalizedNames := normalizeArgumentNames(argumentNames)
	names := make([]string, 0, len(normalizedNames))
	for _, name := range normalizedNames {
		names = append(names, fmt.Sprintf("%q", name))
	}
	if len(names) == 0 {
		return msg
	}

	prefix := "broken argument"
	if len(names) > 1 {
		prefix = "broken arguments"
	}
	return fmt.Sprintf("%s %s: %s", prefix, strings.Join(names, ", "), msg)
}

func normalizeArgumentNames(argumentNames []string) []string {
	names := make([]string, 0, len(argumentNames))
	for _, name := range argumentNames {
		if name = strings.TrimSpace(name); name != "" {
			names = append(names, name)
		}
	}
	return names
}