package shared

import (
	"fmt"
	"strings"
	"time"

	"galaxy/user/internal/domain/common"

	"golang.org/x/text/language"
)

// NormalizeString trims surrounding Unicode whitespace from value.
func NormalizeString(value string) string {
	return strings.TrimSpace(value)
}

// ParseEmail trims value and validates it as one exact normalized e-mail
// subject used by the auth-facing contract.
func ParseEmail(value string) (common.Email, error) {
	email := common.Email(NormalizeString(value))
	if err := email.Validate(); err != nil {
		return "", InvalidRequest(err.Error())
	}

	return email, nil
}

// ParseUserID trims value and validates it as one stable user identifier.
func ParseUserID(value string) (common.UserID, error) {
	userID := common.UserID(NormalizeString(value))
	if err := userID.Validate(); err != nil {
		return "", InvalidRequest(err.Error())
	}

	return userID, nil
}

// ParseRaceName trims value and validates it as one exact stored race name.
func ParseRaceName(value string) (common.RaceName, error) {
	raceName := common.RaceName(NormalizeString(value))
	if err := raceName.Validate(); err != nil {
		return "", InvalidRequest(err.Error())
	}

	return raceName, nil
}

// ParseReasonCode trims value and validates it as one machine-readable reason
// code.
func ParseReasonCode(value string) (common.ReasonCode, error) {
	reasonCode := common.ReasonCode(NormalizeString(value))
	if err := reasonCode.Validate(); err != nil {
		return "", InvalidRequest(err.Error())
	}

	return reasonCode, nil
}

// ParseLanguageTag trims value and validates it against the current Stage 03
// boundary and BCP 47 semantics, returning the canonical tag form.
func ParseLanguageTag(value string) (common.LanguageTag, error) {
	languageTag := common.LanguageTag(NormalizeString(value))
	if err := languageTag.Validate(); err != nil {
		return "", InvalidRequest(err.Error())
	}

	parsedTag, err := language.Parse(languageTag.String())
	if err != nil {
		return "", InvalidRequest("language tag must be a valid BCP 47 language tag")
	}

	canonicalTag := common.LanguageTag(parsedTag.String())
	if err := canonicalTag.Validate(); err != nil {
		return "", InvalidRequest(err.Error())
	}

	return canonicalTag, nil
}

// ParseTimeZoneName trims value and validates it against the current Stage 03
// boundary and IANA time-zone semantics.
func ParseTimeZoneName(value string) (common.TimeZoneName, error) {
	timeZoneName := common.TimeZoneName(NormalizeString(value))
	if err := timeZoneName.Validate(); err != nil {
		return "", InvalidRequest(err.Error())
	}
	if _, err := time.LoadLocation(timeZoneName.String()); err != nil {
		return "", InvalidRequest("time zone name must be a valid IANA time zone name")
	}

	return timeZoneName, nil
}

// ParseRegistrationPreferredLanguage trims value, validates it as one create-
// only BCP 47 registration language tag, and returns the canonical tag form.
func ParseRegistrationPreferredLanguage(value string) (common.LanguageTag, error) {
	languageTag, err := ParseLanguageTag(value)
	if err != nil {
		return "", reframeFieldError("registration_context.preferred_language", "language tag", err)
	}

	return languageTag, nil
}

// ParseRegistrationTimeZoneName trims value and validates it as one create-
// only IANA registration time-zone name.
func ParseRegistrationTimeZoneName(value string) (common.TimeZoneName, error) {
	timeZoneName, err := ParseTimeZoneName(value)
	if err != nil {
		return "", reframeFieldError("registration_context.time_zone", "time zone name", err)
	}

	return timeZoneName, nil
}

func reframeFieldError(fieldName string, valueName string, err error) error {
	if err == nil {
		return nil
	}

	message := err.Error()
	prefix := valueName + " "
	if strings.HasPrefix(message, prefix) {
		message = fieldName + " " + strings.TrimPrefix(message, prefix)
	} else {
		message = fmt.Sprintf("%s: %s", fieldName, message)
	}

	return InvalidRequest(message)
}