/**
 * eventDefinitionRegistrar
 * 宣言的イベント定義の登録処理を共通化する
 */

/** 受信payloadハンドラをバイバリアントに扱うための型 */
type BivariantPayloadHandler<TPayload> = {
  bivarianceHack: (payload: TPayload) => void | Promise<void>;
}["bivarianceHack"];

/** 検証付きイベント定義 */
export type GuardedEventDefinition<TEvent extends string, TPayload> = {
  event: TEvent;
  validator: (value: unknown) => value is TPayload;
  orchestrate: BivariantPayloadHandler<TPayload>;
};

/** 自前検証イベント定義 */
export type SelfValidatedEventDefinition<TEvent extends string, TPayload> = {
  event: TEvent;
  validator: (value: unknown) => value is TPayload;
  orchestrate: BivariantPayloadHandler<TPayload>;
};

/** 検証不要イベント定義 */
export type UnguardedEventDefinition<TEvent extends string> = {
  event: TEvent;
  orchestrate: () => void | Promise<void>;
};

/** 汎用イベント定義 */
export type EventDefinition<TEvent extends string, TPayload> = {
  event: TEvent;
  orchestrate: (payload: TPayload) => void | Promise<void>;
};

/** 検証付きイベント定義を登録する */
export const registerGuardedEvent = <TEvent extends string, TPayload>(
  subscribe: (event: TEvent, callback: (payload: unknown) => void) => void,
  createGuard: (
    event: TEvent,
    validator: (value: unknown) => value is TPayload,
  ) => (payload: unknown) => payload is TPayload,
  definition: GuardedEventDefinition<TEvent, TPayload>,
): void => {
  const guard = createGuard(definition.event, definition.validator);
  subscribe(definition.event, (payload) => {
    if (!guard(payload)) {
      return;
    }

    void definition.orchestrate(payload);
  });
};

/** 自前検証イベント定義を登録する */
export const registerSelfValidatedEvent = <TEvent extends string, TPayload>(
  subscribe: (event: TEvent, callback: (payload: unknown) => void) => void,
  definition: SelfValidatedEventDefinition<TEvent, TPayload>,
): void => {
  subscribe(definition.event, (payload) => {
    if (!definition.validator(payload)) {
      return;
    }

    void definition.orchestrate(payload);
  });
};

/** 検証不要イベント定義を登録する */
export const registerUnguardedEvent = <TEvent extends string>(
  subscribe: (event: TEvent, callback: () => void) => void,
  definition: UnguardedEventDefinition<TEvent>,
): void => {
  subscribe(definition.event, () => {
    void definition.orchestrate();
  });
};

/** 汎用イベント定義を登録する */
export const registerEvent = <TEvent extends string, TPayload>(
  subscribe: (event: TEvent, callback: (payload: TPayload) => void) => void,
  definition: EventDefinition<TEvent, TPayload>,
): void => {
  subscribe(definition.event, (payload) => {
    void definition.orchestrate(payload);
  });
};