/**
 * The event block: what used to be hardcoded, as data. Built from the
 * notification the same way for every kind, so a handler reads what it is
 * answering without parsing the wire payload.
 */

import { getActionDefaults } from "../scope/actions";
import type { Notification } from "../scope/index";
import { traceContextOf } from "./tracing";

export interface EventBlock {
  version: 1;
  /** `service`, `link`, `scope`, or any kind the event block names. */
  kind: string;
  action: { id: string; slug: string; type: string; mode: "tracked" | "data" };
  entity: { kind: string; id: string; nrn?: string };
  package: { slug: string; version: string };
  trace?: { trace_id: string; parent_run_id?: string };
  /** `event()` handlers: the notification's action name. */
  name?: string;
  /** `event()` handlers: the notification's source. */
  source?: string;
  /** `event()` handlers: the notification's context. */
  context?: Record<string, unknown>;
}

export function buildEvent(
  notification: Notification,
  opts: {
    kind: string;
    action: string;
    packageSlug: string;
    packageVersion: string;
  }
): EventBlock {
  const n = notification as Notification & {
    link?: { id?: unknown } | null;
    scope?: { id?: unknown };
    event?: { kind?: string } | string;
  };
  const kind = (typeof n.event === "object" && n.event?.kind) || opts.kind;
  const entityId =
    kind === "link"
      ? n.link?.id
      : kind === "scope"
      ? n.parameters?.scope_id ?? n.scope?.id
      : n.service?.id;
  const trace = traceContextOf(notification as Record<string, unknown>);
  return {
    version: 1,
    kind,
    action: {
      id: String(n.id ?? ""),
      slug: String(n.slug ?? opts.action),
      type: String(n.type ?? "custom"),
      mode: getActionDefaults(opts.action).lifecycle ? "tracked" : "data",
    },
    entity: {
      kind,
      id: entityId != null ? String(entityId) : "",
      nrn: n.entity_nrn,
    },
    package: { slug: opts.packageSlug, version: opts.packageVersion },
    ...(trace
      ? {
          trace: {
            trace_id: trace.traceId,
            ...(trace.parentRunId ? { parent_run_id: trace.parentRunId } : {}),
          },
        }
      : {}),
  };
}