export const PROTOCOL_SCHEMA = 1 as const;
export const CONTEXT_ID = "linuxcnc-2.10.0-pre0-wasm-m1-py-c1" as const;

export type MessageKind =
  | "HELLO" | "CAPABILITIES" | "SESSION_ATTACH" | "SESSION_READY"
  | "LOAD_WORKSPACE" | "COMMAND_RESULT" | "STATE_SNAPSHOT" | "EVENT"
  | "ALARM" | "RECOVERY_STATUS" | "ERROR";

export type MessageEnvelope<TPayload = unknown> = {
  schema_version: typeof PROTOCOL_SCHEMA;
  kind: MessageKind | string;
  context_id: string;
  session_id: string;
  seq: number;
  operation_id?: string;
  simulation_tick?: number;
  payload: TPayload;
};

export type MotionSnapshot = {
  axes?: number[];
  joints?: number[];
  velocity?: number[];
  homed?: boolean[];
  limits?: number;
};

export type SimSnapshotV1 = {
  snapshot_id?: string;
  base_snapshot_id?: string;
  full?: boolean;
  simulation_tick: number;
  state_hash: string;
  task?: { state: string; mode: string; interp_state?: string; current_line?: number | null };
  motion?: MotionSnapshot;
  coordinates?: { machine?: number[]; relative?: number[]; g5x?: number; g92?: number[]; tool_offset?: number[] };
  spindle?: Array<{ enabled?: boolean; direction?: number; commanded?: number; actual?: number; at_speed?: boolean }>;
  io?: { coolant?: number; lube?: boolean; digital?: number[]; analog?: number[]; probe?: boolean };
  tool?: { current?: number; prepared?: number; pocket?: number; change_state?: string };
  overrides?: { feed?: number; rapid?: number; spindle?: number[]; adaptive?: number; feed_hold?: boolean };
  hal?: { graph_revision?: number; changed_values?: ArrayBuffer };
  alarms?: Array<{ id?: string; severity?: string; code?: string; acknowledged?: boolean }>;
  recovery?: { status?: string; last_verified_seq?: number; checkpoint_tick?: number };
};

export type Capabilities = {
  context_id?: string;
  abi?: Record<string, unknown>;
  snapshot?: Record<string, unknown>;
  commands?: string[];
  streams?: string[];
  limits?: Record<string, number>;
  exclusions?: string[];
};

export function isEnvelope(value: unknown): value is MessageEnvelope {
  if (!value || typeof value !== "object") return false;
  const candidate = value as Partial<MessageEnvelope>;
  return candidate.schema_version === PROTOCOL_SCHEMA
    && typeof candidate.kind === "string"
    && typeof candidate.context_id === "string"
    && typeof candidate.session_id === "string"
    && Number.isSafeInteger(candidate.seq)
    && "payload" in candidate;
}