export const WEB_PUSH_LIMITS = Object.freeze({
  decodedHintBytes: 3 * 1024,
  hintFutureSkewMs: 5 * 60 * 1_000,
  hintMaxLifetimeMs: 24 * 60 * 60 * 1_000,
  handlerDeadlineMs: 10_000,
  fenceOperationDeadlineMs: 2_000,
  nativeOperationDeadlineMs: 30_000,
  backendOperationDeadlineMs: 15_000,
  notificationCleanupCount: 64,
  notificationCleanupDeadlineMs: 2_000,
  clientHandoffCount: 32,
} as const);

export const WEB_PUSH_PROTOCOLS = Object.freeze({
  control: "PUSH_CONTROL_V1",
  hint: "WEB_PUSH_HINT_V1",
  click: "NOTIFICATION_CLICK_DATA_V1",
  registration: "WEB_PUSH_REGISTRATION_V1",
  reconciliation: "WEB_PUSH_RECONCILIATION_V1",
  revoke: "WEB_PUSH_REVOKE_V1",
  clickHandoff: "WEB_PUSH_CLICK_HANDOFF_V1",
  reconcileRequired: "WEB_PUSH_RECONCILE_REQUIRED_V1",
} as const);

/**
 * Product IDs stay opaque to the mechanism. The selected composition must
 * provide a closed registry that resolves these syntactically validated IDs.
 */
export type NotificationTypeId = string;
export type NotificationRouteIntentId = string;

export type PushAuthoritySnapshot = Readonly<{
  fenceGeneration: string;
  sessionBindingEpoch: string;
  releaseEpoch: string;
}>;

export type PushControlAssociationV1 =
  | Readonly<{ state: "UNASSOCIATED" }>
  | Readonly<{
      state: "ACTIVE" | "REVOKED";
      associationEpoch: string;
    }>;

/**
 * One origin-scoped durable authority record shared by the window and worker.
 * It intentionally contains no account identifier or native subscription
 * material. `updatedAt` is diagnostic metadata, never an ordering authority.
 */
export type PushControlV1 = Readonly<{
  protocol: typeof WEB_PUSH_PROTOCOLS.control;
  fenceGeneration: string;
  sessionBindingEpoch: string;
  releaseEpoch: string;
  updatedAt: string;
  association: PushControlAssociationV1;
}>;

export type WebPushHintV1 = Readonly<{
  protocol: typeof WEB_PUSH_PROTOCOLS.hint;
  notificationType: NotificationTypeId;
  notificationId: string;
  associationEpoch: string;
  releaseEpoch: string;
  issuedAt: string;
  expiresAt: string;
  routeIntent: NotificationRouteIntentId;
}>;

export type NotificationClickDataV1 = Readonly<{
  protocol: typeof WEB_PUSH_PROTOCOLS.click;
  notificationId: string;
  routeIntent: NotificationRouteIntentId;
  associationEpoch: string;
  releaseEpoch: string;
  expiresAt: string;
}>;

export type WebPushReadinessState =
  | "PUSH_READY"
  | "PUSH_PERMISSION_REQUIRED"
  | "PUSH_DENIED"
  | "PUSH_UNSUPPORTED"
  | "PUSH_UNAVAILABLE";

export type WebPushUnavailableReason =
  | "ABORTED"
  | "BACKEND_ASSOCIATION_MISSING"
  | "BACKEND_REVOKE_AMBIGUOUS"
  | "BUSY"
  | "CLOSED"
  | "LOCAL_FENCE_UNSAFE"
  | "NATIVE_UNSUBSCRIBE_AMBIGUOUS"
  | "NATIVE_SUBSCRIPTION_MISSING"
  | "PERMISSION_DISMISSED"
  | "REGISTRATION_NOT_ACTIVE"
  | "REVOKED"
  | "SESSION_AUTHORITY_CHANGED"
  | "SUBSCRIPTION_KEY_MISMATCH"
  | "WORKER_UNAVAILABLE";

export type WebPushReadiness = Readonly<{
  state: WebPushReadinessState;
  reason?: WebPushUnavailableReason;
}>;

export type WebPushOperation =
  | "CONTROL_OPEN"
  | "CONTROL_READ"
  | "CONTROL_PREPARE"
  | "CONTROL_ACTIVATE"
  | "CONTROL_REVOKE"
  | "CONTROL_PURGE"
  | "PERMISSION_REQUEST"
  | "SUBSCRIPTION_INSPECT"
  | "SUBSCRIPTION_CREATE"
  | "SUBSCRIPTION_RECONCILE"
  | "SUBSCRIPTION_REVOKE"
  | "PUSH_DECODE"
  | "PUSH_HANDLE"
  | "NOTIFICATION_SHOW"
  | "NOTIFICATION_CLICK"
  | "NOTIFICATION_CLEANUP";

export type WebPushFailureCode =
  | "ABORTED"
  | "ASSOCIATION_MISMATCH"
  | "BLOCKED"
  | "CONTRACT_REJECTED"
  | "CONTROL_CORRUPT"
  | "DEADLINE_EXCEEDED"
  | "DECLARATIVE_PUSH_FORBIDDEN"
  | "EXPIRED"
  | "INVALID_INPUT"
  | "LIMIT_EXCEEDED"
  | "NATIVE_FAILURE"
  | "PERMISSION_DENIED"
  | "PROVIDER_UNAVAILABLE"
  | "RELEASE_MISMATCH"
  | "STALE_AUTHORITY"
  | "STALE_REVISION"
  | "TOMBSTONE_CONFLICT"
  | "UNSUPPORTED";

export type WebPushFailure = Readonly<{
  code: WebPushFailureCode;
  operation: WebPushOperation;
  retryable: boolean;
}>;

export type WebPushResult<Value> =
  | Readonly<{ ok: true; value: Value }>
  | Readonly<{ ok: false; error: WebPushFailure }>;

export type WebPushObservationEvent =
  | "web_push_permission_finished"
  | "web_push_registration_finished"
  | "web_push_subscription_rotated"
  | "web_push_hint_processed"
  | "web_push_notification_finished"
  | "web_push_click_dispatched"
  | "web_push_association_revoked";

/**
 * WP-06. Bounded fan-out is a deliberate policy, but reporting a truncated pass
 * as plain success hid the fact that only part of the set was handled.
 */
export type WebPushCountBucket =
  | "0"
  | "1_8"
  | "9_32"
  | "33_64"
  | "GT_64";

export function webPushCountBucket(count: number): WebPushCountBucket {
  if (!Number.isFinite(count) || count <= 0) return "0";
  if (count <= 8) return "1_8";
  if (count <= 32) return "9_32";
  if (count <= 64) return "33_64";
  return "GT_64";
}

/**
 * WP-07. Certainty of a user-visible native effect. It is evidence only and
 * never authorizes a retry.
 */
export type WebPushNativeEffectCertainty =
  | "CONFIRMED"
  | "NOT_APPLIED"
  | "MAYBE_APPLIED";

export type WebPushObservation = Readonly<{
  event: WebPushObservationEvent;
  outcome: "SUCCEEDED" | "FAILED" | "DEGRADED";
  reason?: WebPushFailureCode | WebPushUnavailableReason;
  countBucket?: WebPushCountBucket;
  truncated?: boolean;
  nativeEffect?: WebPushNativeEffectCertainty;
}>;

export interface WebPushObserver {
  record(observation: WebPushObservation): void;
}

export function webPushSuccess<Value>(
  value: Value,
): WebPushResult<Value> {
  return Object.freeze({ ok: true, value });
}

export function webPushFailure(
  code: WebPushFailureCode,
  operation: WebPushOperation,
  retryable = false,
): WebPushResult<never> {
  return Object.freeze({
    ok: false,
    error: Object.freeze({ code, operation, retryable }),
  });
}

export function samePushAuthority(
  left: PushAuthoritySnapshot,
  right: PushAuthoritySnapshot,
): boolean {
  return (
    left.fenceGeneration === right.fenceGeneration &&
    left.sessionBindingEpoch === right.sessionBindingEpoch &&
    left.releaseEpoch === right.releaseEpoch
  );
}