export function sanitizeString(
  input: string | null | undefined,
  maxLength: number = 1000
): string | null {
  if (input === null || input === undefined) {
    return null;
  }
  const trimmed = input.trim();
  if (trimmed.length > maxLength) {
    throw new Error(`Input exceeds maximum length of ${maxLength}`);
  }
  return trimmed;
}

export function sanitizeUrl(url: string | null | undefined): string | null {
  if (!url) {
    return null;
  }
  return url.trim();
}

export function sanitizeText(
  input: string | null | undefined,
  maxLength: number = 10000
): string | null {
  if (input === null || input === undefined) {
    return null;
  }
  const trimmed = input.trim();
  if (trimmed.length > maxLength) {
    throw new Error(`Text exceeds maximum length of ${maxLength}`);
  }
  return trimmed;
}

export function sanitizePrice(price: string | null | undefined): number | null {
  if (!price) {
    return null;
  }
  const parsed = parseFloat(price.trim());
  if (isNaN(parsed)) {
    throw new Error('Invalid price format');
  }
  if (parsed < 0) {
    throw new Error('Price cannot be negative');
  }
  return parsed;
}

export function sanitizeColor(color: string | null | undefined): string | null {
  if (!color) {
    return null;
  }
  return color.trim();
}

export function sanitizeCurrency(currency: string | null | undefined): string {
  if (!currency) {
    return 'DKK';
  }
  return currency.trim().toUpperCase();
}

export function sanitizeUsername(username: string): string {
  const trimmed = username.trim().toLowerCase();
  if (trimmed.length < 3 || trimmed.length > 50) {
    throw new Error('Username must be between 3 and 50 characters');
  }
  return trimmed;
}

export function sanitizeId(id: string | null | undefined): string {
  if (!id) {
    throw new Error('ID is required');
  }
  const trimmed = id.trim();
  if (trimmed.length === 0 || trimmed.length > 100) {
    throw new Error('Invalid ID');
  }
  return trimmed;
}

export function sanitizeToken(token: string | null | undefined): string {
  if (!token) {
    throw new Error('Token is required');
  }
  const trimmed = token.trim();
  if (trimmed.length === 0 || trimmed.length > 100) {
    throw new Error('Invalid token');
  }
  return trimmed;
}

// Zod schemas for type-safe form validation
import { z } from 'zod';
import { CURRENCIES } from '$lib/utils/currency';

export const currencySchema = z.enum(CURRENCIES);

export const itemSchema = z.object({
  title: z.string().min(1, 'Title is required').max(255),
  description: z.preprocess(val => (val === '' ? null : val), z.string().max(2000).optional().nullable()),
  link: z.preprocess(val => (val === '' ? null : val), z.string().url('Invalid URL').optional().nullable()),
  imageUrl: z.preprocess(val => (val === '' ? null : val), z.string().url('Invalid image URL').optional().nullable()),
  price: z.coerce.number().nonnegative().optional().nullable(),
  currency: currencySchema.default('DKK'),
  color: z.preprocess(val => (val === '' ? null : val), z.string().optional().nullable()),
  order: z.coerce.number().int().nonnegative().optional()
});

export const updateItemSchema = itemSchema.extend({
  itemId: z.string().min(1, 'Item ID is required')
});

export const wishlistSchema = z.object({
  title: z.string().min(1, 'Title is required').max(255),
  description: z.string().max(2000).optional().nullable(),
  color: z.string().optional().nullable(),
  theme: z.string().optional().nullable().transform((val) => val || 'none'),
  endDate: z.coerce.date().optional().nullable()
});

export const reorderSchema = z.array(
  z.object({
    id: z.string(),
    order: z.number().int().nonnegative()
  })
);

export type ItemFormData = z.infer<typeof itemSchema>;
export type UpdateItemFormData = z.infer<typeof updateItemSchema>;
export type WishlistFormData = z.infer<typeof wishlistSchema>;