import { crudEventNames } from '../db/schema.ts';
import type { Connection } from '../protocol/connection.ts';
import { MESSAGE_TYPE } from '../protocol/messageTypes.ts';
import type { GenesisMessage, MockServerConfig, ResourceItem } from '../types.ts';

// GenesisResources (foundation-comms/src/resources/genesis/genesis.ts) gates
// every datasource/request-reply/commit call on this list first — an empty
// or missing RESOURCES_REQUEST_ACK.RESOURCES makes every resource silently
// "not exist" client-side, before META_REQUEST or DATA_LOGON is ever tried.
// Auto-derive it from config.queries/requestReplies/eventHandlers (same
// philosophy as db/metadata.ts's field inference) so projects don't have to
// hand-maintain a redundant list; set config.resources explicitly to override,
// or config.additionalResources to add to it.
function deriveResources(config: MockServerConfig): ResourceItem[] {
  const resources: ResourceItem[] = [];
  for (const name of Object.keys(config.queries ?? {})) {
    resources.push({ RESOURCE_NAME: name, RESOURCE_TYPE: 'DATASERVER' });
  }
  for (const name of Object.keys(config.requestReplies ?? {})) {
    resources.push({ RESOURCE_NAME: name, RESOURCE_TYPE: 'REQUEST_SERVER' });
  }
  const eventNames = new Set([
    ...Object.keys(config.eventHandlers ?? {}),
    // The generic CRUD events tables register through TableDef.events.
    ...crudEventNames(config),
    // Events served only by eventSchemas + defaultEventHandler still need to
    // be discoverable, or the client-side resource gate blocks them before
    // the commit is ever sent.
    ...Object.keys(config.eventSchemas ?? {}),
  ]);
  for (const name of eventNames) {
    resources.push({ RESOURCE_NAME: name, RESOURCE_TYPE: 'EVENT_HANDLER' });
  }
  return resources;
}

const resourceKey = (resource: ResourceItem) =>
  `${resource.RESOURCE_TYPE}:${resource.RESOURCE_NAME}`;

// The derived resources, then config.additionalResources not among them.
export function listResources(config: MockServerConfig): ResourceItem[] {
  if (config.resources) return config.resources;
  const resources = deriveResources(config);
  const listed = new Set(resources.map(resourceKey));
  for (const resource of config.additionalResources ?? []) {
    if (listed.has(resourceKey(resource))) continue;
    listed.add(resourceKey(resource));
    resources.push(resource);
  }
  return resources;
}

export function handleResourcesRequest(
  message: GenesisMessage,
  connection: Connection,
  config: MockServerConfig,
): void {
  connection.reply(message, {
    MESSAGE_TYPE: MESSAGE_TYPE.RESOURCES_REQUEST_ACK,
    RESOURCES: listResources(config),
  });
}