import { DomainError } from "./domain-error.ts";

export type RelayPlacementRouteRecord = {
  tenant_id: string;
  tenant_status: string;
  home_region: string;
  relay_node_id: string | null;
  generation: number;
  placement_state: string;
  authorization_revision: number;
  internal_endpoint_ref?: string | null;
  relay_node_status?: string | null;
};

export type RelayRouteResolution = {
  relay_node_id: string;
  placement_generation: number;
  home_region: string;
  local: boolean;
  endpoint_ref?: string;
};

export function isWritableRelayPlacement(
  placementState: string | null | undefined,
  relayNodeStatus: string | null | undefined,
): boolean {
  return ["active", "draining"].includes(placementState ?? "") && relayNodeStatus === "active";
}

export function resolveRelayPlacementRoute(
  placement: RelayPlacementRouteRecord,
  currentNodeId: string,
): RelayRouteResolution {
  if (!placement.relay_node_id || !["active", "draining"].includes(placement.placement_state)) {
    throw new DomainError("service_provisioning", "租户 Relay 正在准备", 503, true, 5);
  }
  if (placement.relay_node_status !== "active") {
    throw new DomainError("region_unavailable", "目标 Relay 节点当前不可用", 503, true, 5);
  }
  const local = placement.relay_node_id === currentNodeId;
  const endpointRef = placement.internal_endpoint_ref?.trim() ?? "";
  if (!local && !/^[A-Za-z0-9][A-Za-z0-9._:-]{0,127}$/u.test(endpointRef)) {
    throw new DomainError("route_unavailable", "目标 Relay 内部路由不可用", 503, true, 5);
  }
  return {
    relay_node_id: placement.relay_node_id,
    placement_generation: placement.generation,
    home_region: placement.home_region,
    local,
    ...(local ? {} : { endpoint_ref: endpointRef }),
  };
}