/**
 * Credits one article's text costs, per language version. Mirrors the
 * agent's ``CREDITS_ARTICLE_TEXT``; the debit itself happens server-side.
 */
export const CREDITS_ARTICLE_TEXT: number = 200;

/** Credits one generated image costs. Mirrors ``CREDITS_ARTICLE_IMAGE``. */
export const CREDITS_ARTICLE_IMAGE: number = 120;

/** Credits one social post costs. Mirrors the agent's ``CREDITS_SOCIAL_POST``. */
export const CREDITS_SOCIAL_POST: number = 25;

/**
 * Credits one generated field (title, description, tags or FAQ) costs per
 * product. Mirrors the agent's ``CREDITS_PER_GENERATED_FIELD``.
 */
export const CREDITS_PER_GENERATED_FIELD: number = 10;

/**
 * Credits a content-generation run costs: every field it writes, for every
 * product, with one field's worth the least a product is billed.
 *
 * @param {number} products - Products the run writes for.
 * @param {number} fields - Fields written per product.
 * @returns {number} The credits the run debits.
 */
export const generatedFieldsCostCredits = (
  products: number,
  fields: number
): number =>
  Math.max(0, products) * Math.max(1, fields) * CREDITS_PER_GENERATED_FIELD;

/**
 * Credits one inline fix on a product costs: a single call, or the gap mode's
 * generate-and-compare pair. Mirror ``CREDITS_INLINE_SINGLE_CALL`` and
 * ``CREDITS_INLINE_GAP_MODE``.
 */
export const CREDITS_INLINE_SINGLE_CALL: number = 10;
export const CREDITS_INLINE_GAP_MODE: number = 15;

/**
 * Credits generating one piece of content costs across its language versions.
 *
 * @param {number} languageCount - Languages generated at once; anything under one reads as one.
 * @returns {number} The text cost; images are debited separately when generated.
 */
export const articleCostCredits = (languageCount: number): number =>
  CREDITS_ARTICLE_TEXT * Math.max(1, languageCount);

/**
 * Credits a knowledge-base document costs, by its length in pages of about
 * 2,000 characters. Mirror the agent's ``KB_DOC_TIER_*`` values.
 */
export const KB_DOCUMENT_TIERS: ReadonlyArray<{
  maxPages: number | null;
  credits: number;
}> = [
  { maxPages: 10, credits: 1 },
  { maxPages: 50, credits: 5 },
  { maxPages: null, credits: 15 },
];

/**
 * A credit amount as the label the buttons print, e.g. ``250 credits``.
 *
 * @param {number} credits - The amount.
 * @returns {string} The formatted label.
 */
export const formatCredits = (credits: number): string =>
  `${credits.toLocaleString('en-US')} ${credits === 1 ? 'credit' : 'credits'}`;

/**
 * Credits a regeneration costs: what writing the row costs in the first
 * place, so a social post is priced as a post and anything else as an article.
 *
 * @param {string | undefined} contentType - The row's content type.
 * @returns {number} The credits one regeneration debits.
 */
export const regenerateCostCredits = (
  contentType: string | undefined
): number =>
  contentType === 'social' ? CREDITS_SOCIAL_POST : CREDITS_ARTICLE_TEXT;

/**
 * The knowledge base's price, said once beside the button that processes the
 * files, since every document is billed by its own length.
 *
 * @returns {string} The sentence, e.g. ``Each document costs 1 credit up to 10 pages, …``.
 */
export const kbDocumentCostNote = (): string => {
  const [small, medium, large] = KB_DOCUMENT_TIERS;

  return `Each document costs ${formatCredits(small.credits)} up to ${
    small.maxPages
  } pages, ${formatCredits(medium.credits)} up to ${
    medium.maxPages
  } pages and ${formatCredits(large.credits)} beyond.`;
};