import { assertConfig } from "./schema.js";
import { DEFAULT_ANALYTICS_RETENTION_DAYS, defaultRosterConfig } from "./defaults.js";
import type { UltraConfig } from "../types.js";

export function migrateConfig(value: unknown): UltraConfig {
  if (!value || typeof value !== "object" || Array.isArray(value)) { assertConfig(value); throw new Error("Unreachable config migration state"); }
  const migrated = structuredClone(value) as Record<string, unknown>;
  const telemetry = migrated.telemetry;
  if (telemetry && typeof telemetry === "object" && !Array.isArray(telemetry)) {
    const settings = telemetry as Record<string, unknown>;
    delete settings.enabled;
    delete settings.weeklyExportRequiresApproval;
    settings.analyticsRetentionDays ??= DEFAULT_ANALYTICS_RETENTION_DAYS;
  }
  const writer = migrated.boundedWriter;
  if (writer && typeof writer === "object" && !Array.isArray(writer)) delete (writer as Record<string, unknown>).maxParallel;
  const deep = migrated.deep;
  if (deep && typeof deep === "object" && !Array.isArray(deep)) delete (deep as Record<string, unknown>).maxParallel;
  // warRoom.maxMembers never did anything: every reader took min(3, it) and the round always built
  // the same three members. Dropped rather than left looking like a fleet-size control.
  const warRoom = migrated.warRoom;
  if (warRoom && typeof warRoom === "object" && !Array.isArray(warRoom)) {
    const room = warRoom as Record<string, unknown>;
    delete room.maxMembers;
    room.maxSpecialists ??= 2;
  }
  // Configs written before the roster became declarable carry the profile's built-in list
  // implicitly. Backfilling it is lossless: the old schema admitted nothing else.
  if (migrated.models === undefined && (migrated.profile === "private" || migrated.profile === "free")) migrated.models = defaultRosterConfig(migrated.profile);
  assertConfig(migrated);
  return migrated;
}