import { httpError } from '../../shared/http/httpError.mjs';

export function normalizeArticle(input) {
  if (!input || typeof input !== 'object' || Array.isArray(input)) {
    throw httpError(400, 'Article payload must be an object');
  }

  const article = {
    ...input,
    slug: readRequiredString(input, 'slug'),
    title: readRequiredString(input, 'title'),
    date: readRequiredString(input, 'date'),
    author: readRequiredString(input, 'author'),
    categories: normalizeCategories(input.categories),
    cover: readRequiredString(input, 'cover'),
    excerpt: readRequiredString(input, 'excerpt'),
    contentHtml: readRequiredString(input, 'contentHtml', { preserveWhitespace: true }),
    readingMinutes: normalizeReadingMinutes(input.readingMinutes),
  };

  if (/[/?#]/.test(article.slug)) {
    throw httpError(400, 'Slug must not contain "/", "?" or "#"');
  }

  if (Number.isNaN(new Date(article.date).getTime())) {
    throw httpError(400, 'Date must be a valid date string');
  }

  return article;
}

export function assertUniqueSlug(articles, slug, exceptSlug) {
  const duplicate = articles.find((article) => article.slug === slug && article.slug !== exceptSlug);

  if (duplicate) {
    throw httpError(409, `Slug "${slug}" is already used`);
  }
}

function readRequiredString(input, key, options = {}) {
  const value = input[key];

  if (typeof value !== 'string') {
    throw httpError(400, `"${key}" must be a string`);
  }

  const normalized = options.preserveWhitespace ? value : value.trim();
  if (!normalized) {
    throw httpError(400, `"${key}" is required`);
  }

  return normalized;
}

function normalizeCategories(value) {
  const categories = Array.isArray(value)
    ? value
    : String(value || '')
        .split(',')
        .map((category) => category.trim());

  const normalized = categories.filter(Boolean);
  if (normalized.length === 0) {
    throw httpError(400, 'At least one category is required');
  }

  return [...new Set(normalized)];
}

function normalizeReadingMinutes(value) {
  const minutes = Number(value);

  if (!Number.isInteger(minutes) || minutes < 1) {
    throw httpError(400, '"readingMinutes" must be a positive integer');
  }

  return minutes;
}