/* ═══════════════════════════════════════════════════════════════
   PUBLIC HREFS

   One place that turns a record into a URL. The API deliberately
   never sends paths — it sends `{ kind, id }` and, for an
   organization, the `org_kind` that decides which of the three
   routes a slug belongs to. Deciding that in each component is how
   /regions/x and /chapters/x end up both existing for the same
   record, and how the history timeline ended up emitting /event/:id
   while the router only knew /retreats/:id.

   timelineRefs.ts now delegates here rather than keeping its own
   table, so there is one answer to "where does an event live" and
   changing it is changing EVENT_BASE below.

   navConfig.js stays the source of truth for the *nav*: these are
   record routes, which never appear in it.

   ── On missing ids ──
   Every builder takes an id the caller believed it had. When it
   doesn't, the old behaviour was to interpolate the string
   "undefined" into a path, render a link to it, mount a page and
   fetch /api/organizations/undefined — four steps between the
   mistake and any sign of it, none of which name the component
   that made it.

   Now the id is checked here. In dev that's a console.error with a
   stack trace pointing at the caller; in production the path still
   comes out, because a broken link beats a crashed page, and
   useResource refuses to fetch it.
   ═══════════════════════════════════════════════════════════════ */

export type OrgKind = 'national' | 'region' | 'chapter' | 'partner'
export type RefKind = 'event' | 'organization' | 'team' | 'award' | 'person'

/* A region, a chapter and a partner read as different things to a
   visitor even though they are one table, so they get one route
   each. 'national' is NGU itself — one record, no listing to sit
   under, so it falls through to the generic path. */
const ORG_BASE: Record<string, string> = {
  region: '/regions',
  chapter: '/chapters',
  partner: '/partners',
  national: '/organizations',
}

/** Canonical base for an event page.
 *
 *  /events/:id, not /retreats/:id. The listing page is called
 *  Retreats because that's what NGU calls the gatherings it hosts,
 *  but the records are `events`, the API route is /api/events, and
 *  plenty of them — partner events, conferences — aren't retreats
 *  at all. Naming the record route after one page's editorial
 *  framing would have been wrong the first time a non-retreat got
 *  its own page.
 *
 *  Nothing redirects from /retreats/:id, because nothing ever
 *  linked there. */
export const EVENT_BASE = '/events'

const DEV = Boolean((import.meta as any)?.env?.DEV)

/* Router params arrive as strings, so an id that has already been
   through a template literal shows up as the literal word. Those
   are as broken as a genuine null. */
const BAD = new Set(['', 'undefined', 'null', 'NaN'])

export const isBadId = (id: unknown): boolean =>
  id == null || BAD.has(String(id))

function checkId(id: unknown, what: string): string {
  if (!isBadId(id)) return String(id)

  if (DEV) {
    // console.error rather than warn: this is always a bug, and the
    // stack is the whole point — it names the component that passed
    // nothing.
    console.error(
      `hrefs: ${what}() was given ${JSON.stringify(id)}. ` +
        `The link it returns will 404. Caller:`,
      new Error('hrefs: missing id').stack,
    )
  }

  return 'undefined'
}

/**
 * The API path for one record, or null when the id isn't usable.
 *
 * The mirror image of the builders below: they make the URL a
 * visitor sees, this makes the URL the client fetches, and both
 * have to agree about what counts as an id.
 *
 * It lives here rather than next to the hook that calls it because
 * it is a path, and paths are this file's job — and because a
 * component that interpolates a missing route param produces the
 * literal string "undefined", which the server cannot tell apart
 * from a slug somebody genuinely typed. It answers 404 either way,
 * and the log fills with GET /api/organizations/undefined with
 * nothing to say where it came from.
 *
 * Returning null costs a round trip and turns a mystery 404 into
 * the not-found page, which is what a visitor should see anyway.
 */
export function detailPath(base: string, id?: string | null): string | null {
  return isBadId(id) ? null : `${base}/${encodeURIComponent(String(id))}`
}

export const eventHref = (id?: string | null) =>
  `${EVENT_BASE}/${checkId(id, 'eventHref')}`

export const teamHref = (id?: string | null) => `/teams/${checkId(id, 'teamHref')}`

export const awardHref = (id?: string | null) => `/awards/${checkId(id, 'awardHref')}`

export const personHref = (id?: string | null) => `/people/${checkId(id, 'personHref')}`

export function orgHref(id?: string | null, kind?: string | null): string {
  return `${ORG_BASE[kind ?? ''] ?? '/organizations'}/${checkId(id, 'orgHref')}`
}

/* For anything holding a polymorphic reference — timeline entries,
   content blocks — where the kind arrives as data rather than being
   known at the call site.

   Returns null for a kind with no page AND for a reference with no
   id, so the caller renders plain text instead of a dead link.
   This is the one the timeline wants: an entry whose ref didn't
   resolve should read as text, not as a link to nowhere. */
export function refHref(
  kind: string | null | undefined,
  id: string | null | undefined,
  orgKind?: string | null,
): string | null {
  if (!kind || isBadId(id)) return null
  switch (kind) {
    case 'event':
      return eventHref(id)
    case 'organization':
      return orgHref(id, orgKind)
    case 'team':
      return teamHref(id)
    case 'award':
      return awardHref(id)
    case 'person':
      return personHref(id)
    default:
      return null
  }
}

/* What to call the kind in a breadcrumb or a back link. */
export const ORG_KIND_LABEL: Record<string, string> = {
  national: 'Next Generation of Unity',
  region: 'Region',
  chapter: 'Chapter',
  partner: 'Partner organization',
}

/* Where "back" goes from a record page. A chapter belongs to
   /community, a retreat to /retreats. */
export function orgListHref(kind?: string | null): { to: string; label: string } {
  switch (kind) {
    case 'region':
      return { to: '/community#local', label: 'All regions' }
    case 'chapter':
      return { to: '/community#local', label: 'All chapters' }
    case 'partner':
      return { to: '/community#partners', label: 'All partner organizations' }
    default:
      return { to: '/community', label: 'Community' }
  }
}