ditto/src/schema.ts

import { z } from '@/deps.ts';

/** Validates individual items in an array, dropping any that aren't valid. */
function filteredArray<T extends z.ZodTypeAny>(schema: T) {
  return z.any().array().catch([])
    .transform((arr) => (
      arr.map((item) => {
        const parsed = schema.safeParse(item);
        return parsed.success ? parsed.data : undefined;
      }).filter((item): item is z.infer<T> => Boolean(item))
    ));
}

const jsonSchema = z.string().transform((value, ctx) => {
  try {
    return JSON.parse(value) as unknown;
  } catch (_e) {
    ctx.addIssue({ code: z.ZodIssueCode.custom, message: 'Invalid JSON' });
    return z.NEVER;
  }
});

const emojiTagSchema = z.tuple([z.literal('emoji'), z.string(), z.string().url()]);

/** https://developer.mozilla.org/en-US/docs/Glossary/Base64#the_unicode_problem */
const decode64Schema = z.string().transform((value, ctx) => {
  try {
    const binString = atob(value);
    const bytes = Uint8Array.from(binString, (m) => m.codePointAt(0)!);
    return new TextDecoder().decode(bytes);
  } catch (_e) {
    ctx.addIssue({ code: z.ZodIssueCode.custom, message: 'Invalid base64', fatal: true });
    return z.NEVER;
  }
});

const hashtagSchema = z.string().regex(/^\w{1,30}$/);

/**
 * Limits the length before trying to parse the URL.
 * https://stackoverflow.com/a/417184/8811886
 */
const safeUrlSchema = z.string().max(2048).url();

export { decode64Schema, emojiTagSchema, filteredArray, hashtagSchema, jsonSchema, safeUrlSchema };