// Typed client for the anonymous FAQ API. It wraps an injected fetcher, so
// the Nuxt composable decides the base URL and headers and `node --test` can
// drive it with a stub.

import type { Faq, FaqEnvelope, FaqItem } from './types.ts'

/** Issues one GET for `path` (e.g. "/faqs/shipping") with `query`, resolving the parsed JSON. */
export type FaqFetcher = (path: string, query?: Record<string, string>) => Promise<unknown>

/** True for a fetch error that carries HTTP status 404 (ofetch, h3 or plain). */
export function isNotFound(err: unknown): boolean {
  if (!err || typeof err !== 'object') return false
  const e = err as { status?: unknown; statusCode?: unknown; response?: { status?: unknown } }
  return e.status === 404 || e.statusCode === 404 || e.response?.status === 404
}

/** The API path of a FAQ: /faqs/<slug>, the slug URL-encoded. */
export function faqPath(slug: string): string {
  return `/faqs/${encodeURIComponent(slug)}`
}

/** Items with a string question and answer; anything else is dropped. */
export function faqItems(content: unknown): FaqItem[] {
  if (!Array.isArray(content)) return []
  return content.filter(
    (item): item is FaqItem =>
      !!item && typeof item === 'object' && typeof (item as FaqItem).question === 'string' && typeof (item as FaqItem).answer === 'string',
  )
}

export interface FaqClient {
  /** The FAQ with `slug`, or null when the API answers 404 (unknown, inactive or locale not enabled). */
  getFaq(slug: string, locale?: string): Promise<Faq | null>
}

export function createFaqClient(fetcher: FaqFetcher): FaqClient {
  return {
    async getFaq(slug, locale) {
      const query = locale ? { locale } : undefined
      let res: FaqEnvelope
      try {
        res = (await (query ? fetcher(faqPath(slug), query) : fetcher(faqPath(slug)))) as FaqEnvelope
      } catch (err) {
        if (isNotFound(err)) return null
        throw err
      }
      const faq = res?.data
      if (!faq || typeof faq !== 'object') return null
      return { ...faq, description: typeof faq.description === 'string' ? faq.description : null, content: faqItems(faq.content) }
    },
  }
}