import type { Card, CardType, Portal } from '@/types';
import { TEXT_LIMITS } from '@/lib/config';

// Re-export per retro-compatibilità con il codice che importa CARD_LIMITS.
export const CARD_LIMITS = TEXT_LIMITS.card;
export const PORTAL_LIMITS = TEXT_LIMITS.portal;

const VALID_CARD_TYPES: readonly CardType[] = [
  'INFO_PAGE',
  'EXTERNAL_LINK',
  'IMAGE_GALLERY',
  'SERVICE_REQUEST', // non esposto in admin né effettivamente utilizzato (vedi nota in types/index.ts)
  'BOOK',
  'FULLSCREEN_LOCK',
] as const;

const ALLOWED_URL_SCHEMES = new Set(['http:', 'https:', 'mailto:', 'tel:']);

export type ValidationError = {
  field: string;
  message: string;
  limit?: number;
  actual?: number;
};

export type ValidationResult = {
  valid: boolean;
  errors: ValidationError[];
};

function strLen(v: unknown): number {
  return typeof v === 'string' ? v.length : 0;
}

export function validateCard(card: Partial<Card>): ValidationResult {
  const errors: ValidationError[] = [];

  if (typeof card.title !== 'string' || card.title.trim().length === 0) {
    errors.push({ field: 'title', message: 'Il titolo è obbligatorio' });
  } else if (card.title.length > CARD_LIMITS.title) {
    errors.push({ field: 'title', message: 'Titolo troppo lungo', limit: CARD_LIMITS.title, actual: card.title.length });
  }

  if (card.shortDescription !== undefined && typeof card.shortDescription !== 'string') {
    errors.push({ field: 'shortDescription', message: 'Tipo non valido' });
  } else if (strLen(card.shortDescription) > CARD_LIMITS.shortDescription) {
    errors.push({ field: 'shortDescription', message: 'Descrizione breve troppo lunga', limit: CARD_LIMITS.shortDescription, actual: strLen(card.shortDescription) });
  }

  if (card.fullContent !== undefined && typeof card.fullContent !== 'string') {
    errors.push({ field: 'fullContent', message: 'Tipo non valido' });
  } else if (strLen(card.fullContent) > CARD_LIMITS.fullContent) {
    errors.push({ field: 'fullContent', message: 'Contenuto troppo lungo', limit: CARD_LIMITS.fullContent, actual: strLen(card.fullContent) });
  }

  // Le card External Link richiedono obbligatoriamente l'URL.
  if (card.cardType === 'EXTERNAL_LINK' && (typeof card.actionUrl !== 'string' || card.actionUrl.trim() === '')) {
    errors.push({ field: 'actionUrl', message: "L'URL è obbligatorio per le card External Link" });
  }

  if (card.actionUrl !== undefined && card.actionUrl !== '') {
    if (typeof card.actionUrl !== 'string') {
      errors.push({ field: 'actionUrl', message: 'Tipo non valido' });
    } else if (card.actionUrl.length > CARD_LIMITS.actionUrl) {
      errors.push({ field: 'actionUrl', message: 'URL troppo lungo', limit: CARD_LIMITS.actionUrl, actual: card.actionUrl.length });
    } else {
      try {
        const parsed = new URL(card.actionUrl);
        if (!ALLOWED_URL_SCHEMES.has(parsed.protocol)) {
          errors.push({ field: 'actionUrl', message: `Schema URL non ammesso (${parsed.protocol}). Usa http, https, mailto o tel.` });
        }
      } catch {
        errors.push({ field: 'actionUrl', message: 'URL non valido' });
      }
    }
  }

  if (card.cardType !== undefined && !VALID_CARD_TYPES.includes(card.cardType as CardType)) {
    errors.push({ field: 'cardType', message: `Tipo card non valido: ${String(card.cardType)}` });
  }

  return { valid: errors.length === 0, errors };
}

export function validatePortal(portal: Partial<Portal>): ValidationResult {
  const errors: ValidationError[] = [];

  if (portal.title !== undefined) {
    if (typeof portal.title !== 'string') {
      errors.push({ field: 'title', message: 'Tipo non valido' });
    } else if (portal.title.length > PORTAL_LIMITS.title) {
      errors.push({ field: 'title', message: 'Titolo portale troppo lungo', limit: PORTAL_LIMITS.title, actual: portal.title.length });
    }
  }

  if (portal.welcomeText !== undefined) {
    if (typeof portal.welcomeText !== 'string') {
      errors.push({ field: 'welcomeText', message: 'Tipo non valido' });
    } else if (portal.welcomeText.length > PORTAL_LIMITS.welcomeText) {
      errors.push({ field: 'welcomeText', message: 'Testo di benvenuto troppo lungo', limit: PORTAL_LIMITS.welcomeText, actual: portal.welcomeText.length });
    }
  }

  return { valid: errors.length === 0, errors };
}