import {
  GearApi,
  Hex,
  MessageEnqueued,
  ProgramChanged,
  UserMessageSent,
} from "https://gear-js.deno.dev/api/index.ts";
import { UnsubscribePromise } from "https://deno.land/x/polkadot/api/types/index.ts";

export function waitForInit(
  api: GearApi,
  programId: string
): Promise<UnsubscribePromise> {
  let messageId: Hex;
  return new Promise((resolve, reject) => {
    const unsub = api.query.system.events((events) => {
      events.forEach(({ event }) => {
        switch (event.method) {
          case "MessageEnqueued":
            const meEvent = event as MessageEnqueued;
            if (
              meEvent.data.destination.eq(programId) &&
              meEvent.data.entry.isInit
            ) {
              messageId = meEvent.data.id.toHex();
            }
            break;
          case "UserMessageSent":
            const {
              data: {
                message: { source, reply, payload },
              },
            } = event as UserMessageSent;
            if (
              source.eq(programId) &&
              reply.isSome &&
              reply.unwrap()[0].eq(messageId) &&
              reply.unwrap()[1].eq(1)
            ) {
              reject(payload.toHuman());
            }
            break;
          case "ProgramChanged":
            const pcEvent = event as ProgramChanged;
            if (pcEvent.data.id.eq(programId) && pcEvent.data.change.isActive) {
              resolve(unsub);
            }
            break;
        }
      });
    });
  });
}