/**
 * Produce worker env parsing: the two settings a produce box needs that are not
 * plain pass-throughs — the lane this worker claims, and the lower-third font.
 *
 * Both are validated loudly at boot (a silently-defaulted lane would claim the
 * wrong rows; a missing font fails every compose job at encode time, far too late).
 */
import { accessSync, constants } from "node:fs";

/** `MEDIA_WORKER_LANE`: default worker claims local-or-NULL, a remote worker only remote. */
export function laneFromEnv(value: string | undefined): "local" | "remote" {
  if (value === undefined || value === "") return "local";
  if (value === "local" || value === "remote") return value;
  throw new Error(`MEDIA_WORKER_LANE must be 'local' or 'remote' (got ${JSON.stringify(value)})`);
}

/**
 * `MEDIA_PRODUCE_FONT`: absolute path to a readable .ttf. Defaults to the
 * DejaVu face present on the worker's base image; validated now (ENOENT at
 * encode time is a 15-minute-late failure for the first job that needs it).
 */
export function resolveProduceFont(value: string | undefined): string {
  const font = value ?? "/usr/share/fonts/truetype/dejavu/DejaVuSans-Bold.ttf";
  if (!font.startsWith("/")) throw new Error("MEDIA_PRODUCE_FONT must be an absolute path");
  if (!font.endsWith(".ttf")) throw new Error("MEDIA_PRODUCE_FONT must point to a .ttf");
  try {
    accessSync(font, constants.R_OK);
  } catch {
    throw new Error(`MEDIA_PRODUCE_FONT is not readable: ${font}`);
  }
  return font;
}