package domain

import "time"

// Theme represents the UI theme preference.
type Theme string

const (
	ThemeLight  Theme = "light"
	ThemeDark   Theme = "dark"
	ThemeSystem Theme = "system"
)

// validThemes is the set of allowed theme values.
var validThemes = map[Theme]bool{
	ThemeLight:  true,
	ThemeDark:   true,
	ThemeSystem: true,
}

// DigestFrequency represents the email digest frequency preference.
type DigestFrequency string

const (
	DigestNone   DigestFrequency = "none"
	DigestDaily  DigestFrequency = "daily"
	DigestWeekly DigestFrequency = "weekly"
)

// validDigests is the set of allowed digest frequency values.
var validDigests = map[DigestFrequency]bool{
	DigestNone:   true,
	DigestDaily:  true,
	DigestWeekly: true,
}

// validLanguages is the set of allowed BCP-47 language tags.
var validLanguages = map[string]bool{
	"en": true,
	"fr": true,
	"es": true,
	"de": true,
	"ja": true,
}

// NotificationPreferences holds notification-related preferences.
type NotificationPreferences struct {
	Email  bool
	Push   bool
	Digest DigestFrequency
}

// UserPreferences represents a user's preference settings.
type UserPreferences struct {
	UserID        string
	Theme         Theme
	Language      string
	Notifications NotificationPreferences
	UpdatedAt     time.Time
}

// DefaultPreferences returns the default preferences for a given user ID.
func DefaultPreferences(userID string) *UserPreferences {
	return &UserPreferences{
		UserID:   userID,
		Theme:    ThemeSystem,
		Language: "en",
		Notifications: NotificationPreferences{
			Email:  true,
			Push:   true,
			Digest: DigestWeekly,
		},
	}
}

// Validate checks that all preference values are valid.
// Returns a domain error if any value is invalid.
func (p *UserPreferences) Validate() error {
	if !validThemes[p.Theme] {
		return ErrInvalidTheme
	}
	if !validLanguages[p.Language] {
		return ErrInvalidLanguage
	}
	if !validDigests[p.Notifications.Digest] {
		return ErrInvalidDigest
	}
	return nil
}