/**
 * Celilo Module Contract Registry
 *
 * Maps contract version strings to their canonical hook signatures. The
 * manifest's `celilo_contract` field selects which contract applies; the
 * registry is the single source of truth for what each version promises.
 *
 * To mint a new contract version: add a new file (e.g. `./v2.ts`), import its
 * contract object here, and register it in `CONTRACTS`. Old contracts stay
 * registered indefinitely so legacy modules continue to validate.
 */

import { V1_CONTRACT } from './v1';
import type { ContractHookSignature, ContractHooks } from './v1';

export type { ContractHooks, ContractHookSignature };

/**
 * Look up a hook signature by an UNTRUSTED name.
 *
 * `ContractHooks` is keyed by `HookName` (celilo#821), which is what makes a
 * missing or unknown entry a compile error. The executor's `hookName` is a
 * plain `string` on purpose — it comes from a module manifest, and deciding
 * whether it names a real hook is precisely what the caller is asking. This
 * helper is the one place that crossing is expressed, so every other use of
 * `ContractHooks` stays exact.
 *
 * Returns `undefined` for a name the contract does not define; the caller
 * turns that into "Hook 'x' is not part of celilo_contract 1.0".
 */
export function contractHookSignature(
  hooks: ContractHooks,
  name: string,
): ContractHookSignature | undefined {
  return (hooks as Record<string, ContractHookSignature | undefined>)[name];
}

/**
 * The shape of a registered contract.
 */
export interface Contract {
  /** Semver-style version string (e.g. "1.0"). */
  version: string;
  /** Canonical hook signatures for this version. */
  hooks: ContractHooks;
}

/**
 * Registry of every contract version Celilo knows about.
 * The keys are the strings users write in `celilo_contract`.
 *
 * When minting a new version, also add its string literal to
 * `SUPPORTED_CONTRACT_VERSIONS` below so Zod's enum picks it up.
 */
export const CONTRACTS: Record<string, Contract> = {
  '1.0': V1_CONTRACT,
};

/**
 * Const tuple of supported contract version strings, used to drive the Zod
 * enum that validates the manifest's `celilo_contract` field.
 */
export const SUPPORTED_CONTRACT_VERSIONS = ['1.0'] as const;
export type SupportedContractVersion = (typeof SUPPORTED_CONTRACT_VERSIONS)[number];

/**
 * Look up a contract by version string.
 *
 * @returns The contract, or `undefined` if the version is not registered.
 */
export function resolveContract(version: string): Contract | undefined {
  return CONTRACTS[version];
}

/**
 * List of all registered contract version strings, used for error messages
 * and for validating the `celilo_contract` field's enum.
 */
export function supportedContractVersions(): string[] {
  return Object.keys(CONTRACTS);
}