chain.ts

import type {
  Chain,
  CustomConversion,
  FixedConversion,
  Layout,
} from "@wormhole-foundation/sdk-base";
import { chainToChainId, chains, toChain } from "@wormhole-foundation/sdk-base";

const chainItemBase = { binary: "uint", size: 2 } as const;

type DontExpandAllChains<C> =
  C extends typeof chains ? Chain : C extends Chain[] ? C[number] : never;

type AllowNull<T, B extends boolean> = B extends true ? T | null : T;

export const chainItem = <
  const C extends readonly Chain[] = typeof chains,
  const N extends boolean = false,
>(opts?: {
  allowedChains?: C;
  allowNull?: N;
}) =>
  ({
    ...chainItemBase,
    custom: {
      to: (val: number): AllowNull<DontExpandAllChains<C>, N> => {
        if (val === 0) {
          if (!opts?.allowNull)
            throw new Error("ChainId 0 is not valid for this protocol and action");

          return null as AllowNull<DontExpandAllChains<C>, N>;
        }

        const chain = toChain(val);
        const allowedChains = opts?.allowedChains ?? chains;
        if (!allowedChains.includes(chain))
          throw new Error(`Chain ${chain} not in allowed chains ${allowedChains}`);

        return chain as DontExpandAllChains<C>;
      },
      from: (val: AllowNull<C[number], N>): number => (val == null ? 0 : chainToChainId(val)),
    } satisfies CustomConversion<number, AllowNull<C[number], N>>,
  }) as const satisfies Layout;

export const fixedChainItem = <const C extends Chain>(chain: C) =>
  ({
    ...chainItemBase,
    custom: {
      to: chain,
      from: chainToChainId(chain),
    } satisfies FixedConversion<number, C>,
  }) as const satisfies Layout;