import { pageNumberOf } from "@/lib/model/locus"
import type { FacsimileConfig } from "@/lib/schemas/model"

/**
 * Facsimile asset resolution (§4). The catalog stores **relative** keys; the
 * delivery base is a runtime env (`VITE_FACSIMILE_BASE`) so one catalog serves
 * both dev (the `public/facsimile/` copy) and prod (the R2 public base).
 */

export type ImagesConfig = Extract<FacsimileConfig, { kind: "images" }>
export type PdfConfig = Extract<FacsimileConfig, { kind: "pdf" }>

export function facsimileBase(): string {
  const base = import.meta.env.VITE_FACSIMILE_BASE ?? "/facsimile/"
  return base.endsWith("/") ? base : `${base}/`
}

/** Husserl: the page image for an anchor, or null if that page isn't mapped. */
export function imageUrlFor(config: ImagesConfig, anchorId: string | null): string | null {
  if (!anchorId) return null
  const key = config.pages[anchorId]
  return key ? facsimileBase() + key : null
}

/** Heidegger: the source PDF URL (rendered client-side via pdf.js). */
export function pdfUrlFor(config: PdfConfig): string {
  return facsimileBase() + config.pdfKey
}

/** Heidegger: 1-based PDF page for an anchor (print page + delta), or null. */
export function pdfPageFor(config: PdfConfig, anchorId: string | null): number | null {
  if (!anchorId) return null
  const n = pageNumberOf(anchorId)
  return n === null ? null : n + config.pageDelta
}