package domain

import (
	"errors"
	"regexp"
	"time"

	"github.com/google/uuid"
)

// Branding is one event's visual customisation. All fields are optional —
// a brand-new event renders with the GuestGuard defaults until the host
// fills any of these in. Tier 2 Block D.
type Branding struct {
	EventID         uuid.UUID `json:"event_id"`
	PrimaryColor    *string   `json:"primary_color,omitempty"`
	AccentColor     *string   `json:"accent_color,omitempty"`
	LogoURL         *string   `json:"logo_url,omitempty"`
	CoverImageURL   *string   `json:"cover_image_url,omitempty"`
	FontFamily      *string   `json:"font_family,omitempty"`
	GreetingMessage *string   `json:"greeting_message,omitempty"`
	UpdatedAt       time.Time `json:"updated_at"`
}

// AllowedFonts is the curated picker list the host can choose from. Locking
// it down keeps render times sane (no hot-loading arbitrary @font-face
// files) and avoids smuggling untrusted CSS into our emails.
var AllowedFonts = []string{
	"Inter",
	"Playfair Display",
	"Cormorant Garamond",
	"Lora",
	"DM Sans",
	"Manrope",
}

// IsAllowedFont reports whether `f` is in the curated set. Empty string is
// fine — the RSVP page falls back to its default.
func IsAllowedFont(f string) bool {
	if f == "" {
		return true
	}
	for _, a := range AllowedFonts {
		if f == a {
			return true
		}
	}
	return false
}

// hexColorRe matches #abc, #abcd, #aabbcc, #aabbccdd (alpha optional).
// Lowercase + uppercase OK. Length checked because Go regexp + Postgres
// don't agree on Unicode digits and we want plain ASCII here.
var hexColorRe = regexp.MustCompile(`^#([0-9A-Fa-f]{3,8})$`)

// IsValidHexColor accepts the three common hex shorthand forms. Empty is OK
// (clears the column).
func IsValidHexColor(c string) bool {
	if c == "" {
		return true
	}
	if !hexColorRe.MatchString(c) {
		return false
	}
	n := len(c) - 1
	return n == 3 || n == 4 || n == 6 || n == 8
}

var (
	ErrBrandingNotFound = errors.New("branding not found")
	ErrInvalidColor     = errors.New("color must be a hex value (e.g. #22c55e)")
	ErrUnknownFont      = errors.New("font is not in the allowlist")
)