/* Copyright 2026 Marimo. All rights reserved. */

import { NoKernelConnectedError } from "@/utils/errors";
import { Logger } from "@/utils/Logger";
import { Objects } from "@/utils/objects";
import { memoizeLastValue } from "@/utils/once";
import { waitForKernelToBeInstantiated } from "../kernel/state";
import type { RuntimeManager } from "../runtime/runtime";
import { store } from "../state/jotai";
import { WebSocketState } from "../websocket/types";
import { connectionAtom, waitForConnectionOpen } from "./connection";
import type { EditRequests, RunRequests } from "./types";

type AllRequests = EditRequests & RunRequests;

// We have various requests that act differently when called and not connected to a Kernel:
//
// - throwError: Throws NoKernelConnectedError, caught by requests-toasting.tsx
//   and shown as a toast with a "Connect" button. Use for operations that
//   shouldn't silently fail but also shouldn't auto-start the kernel.
//
// - dropRequest: Silently returns undefined. Only for requests where failure is
//   expected and doesn't matter (e.g., background polling).
//
// - startConnection: Initializes the runtime and waits for connection before
//   executing. Use for user-initiated actions that should "just work" and
//   kick off the kernel if needed (e.g., clicking Run).
//
// - startConnectionWithoutKernel: Initializes the runtime and waits for an open
//   connection. Use for session-scoped server requests that do not need an
//   instantiated kernel.
//
// - waitForConnectionOpen: Waits for an existing connection but won't start one.
//   Use for operations that depend on a running kernel but shouldn't be the
//   trigger to start it (e.g., saving, interrupting).
//
// - serverOnly: Calls the HTTP delegate directly without touching the kernel.
//   Use for requests served by the marimo server itself, which resolve without
//   a session (e.g., fetching environment diagnostics).

type Action =
  | "throwError"
  | "dropRequest"
  | "startConnection"
  | "startConnectionWithoutKernel"
  | "waitForConnectionOpen"
  | "serverOnly";

const ACTIONS: Record<keyof AllRequests, Action> = {
  // These will start a connection if not already connected and then wait until the connection is open
  sendComponentValues: "startConnection",
  sendModelValue: "startConnection",
  sendInstantiate: "startConnectionWithoutKernel",
  sendRun: "startConnection",
  sendDeleteCell: "startConnection",
  sendRunScratchpad: "startConnection",
  saveAppConfig: "startConnection",
  saveCellConfig: "startConnection",
  discoverDataSources: "startConnection",

  // Export operations start a connection
  exportAsHTML: "startConnection",
  exportAsIPYNB: "startConnection",
  exportAsMarkdown: "startConnection",
  exportAsScript: "startConnection",
  exportAsPDF: "startConnection",
  readCode: "startConnection",
  sendCopy: "throwError",

  // Throw errors for operations that are not supported offline
  sendFormat: "throwError",
  sendRestart: "throwError",

  // These wait until the connection is open, but don't start a connection
  sendSave: "waitForConnectionOpen",
  invokeAiTool: "waitForConnectionOpen",
  sendFunctionRequest: "waitForConnectionOpen",

  // Session-based operations that wait for connection
  sendRename: "waitForConnectionOpen",
  autoExportAsHTML: "waitForConnectionOpen",
  autoExportAsMarkdown: "waitForConnectionOpen",
  autoExportAsIPYNB: "waitForConnectionOpen",
  updateCellOutputs: "waitForConnectionOpen",

  // Sidebar operations that wait for connection
  listSecretKeys: "throwError",
  writeSecret: "throwError",
  clearCache: "throwError",
  getCacheInfo: "throwError",

  // Operations that throw errors (sessionless but not supported offline)
  saveUserConfig: "throwError",
  sendShutdown: "throwError",
  getPackageList: "throwError",
  getSandbox: "serverOnly",
  updateManifest: "serverOnly",
  syncSandbox: "serverOnly",
  getDependencyTree: "throwError",
  addPackage: "throwError",
  removePackage: "throwError",

  // Folder and file operations throw errors
  getFileRoots: "startConnection",
  sendListFiles: "startConnection",
  sendSearchFiles: "startConnection",
  sendCreateFileOrFolder: "throwError",
  sendDeleteFileOrFolder: "throwError",
  sendCopyFileOrFolder: "throwError",
  sendRenameFileOrFolder: "throwError",
  sendUpdateFile: "throwError",
  sendFileDetails: "throwError",
  openFile: "throwError",

  // Served by the marimo server without a kernel session
  getEnvironmentInfo: "serverOnly",
  getExportAvailability: "serverOnly",

  // Session-scoped server operations
  installExportRequirements: "startConnectionWithoutKernel",

  // Home operations throw errors
  getRecentFiles: "startConnection",
  getWorkspaceFiles: "startConnection",
  getRunningNotebooks: "startConnection",
  shutdownSession: "startConnection",
  openTutorial: "startConnection",
  getUsageStats: "waitForConnectionOpen",

  // These wait for connection
  sendStdin: "waitForConnectionOpen",
  sendInterrupt: "waitForConnectionOpen",
  sendPdb: "waitForConnectionOpen",
  sendSetBreakpoints: "waitForConnectionOpen",
  sendInstallMissingPackages: "waitForConnectionOpen",
  readSnippets: "waitForConnectionOpen",
  previewDatasetColumn: "waitForConnectionOpen",
  previewSQLTable: "waitForConnectionOpen",
  previewSQLTableList: "waitForConnectionOpen",
  previewSQLSchemaList: "waitForConnectionOpen",
  previewDataSourceConnection: "waitForConnectionOpen",
  validateSQL: "waitForConnectionOpen",
  listStorageEntries: "waitForConnectionOpen",
  downloadStorage: "waitForConnectionOpen",

  // Sync operations that wait for connection
  sendDocumentTransaction: "waitForConnectionOpen",
  sendCodeCompletionRequest: "waitForConnectionOpen",
};

/**
 * Create a lazy requests client.
 * On any request, we will initialize the runtime manager (if not already initialized)
 * and handle it based on the action type defined in ACTIONS.
 */
export function createLazyRequests(
  delegate: AllRequests,
  getRuntimeManager: () => RuntimeManager,
): AllRequests {
  // Memoize the init call, just once per runtime manager
  const initOnce = memoizeLastValue(async (runtimeManager: RuntimeManager) => {
    store.set(connectionAtom, { state: WebSocketState.CONNECTING });
    await runtimeManager.init();
  });

  // oxlint-disable-next-line typescript/no-explicit-any
  function wrapRequest<T extends (...args: any[]) => Promise<any>>(
    request: T,
    key: keyof AllRequests,
  ): T {
    const action = ACTIONS[key];

    const wrapped = (async (...args) => {
      const runtimeManager = getRuntimeManager();

      if (!runtimeManager.isLazy) {
        return request(...args);
      }

      switch (action) {
        case "serverOnly":
          // Served by the marimo server itself; no kernel required
          return request(...args);

        case "dropRequest":
          Logger.debug(
            `Dropping request: ${key}, since not connected to a kernel.`,
          );
          // Silently drop the request
          return;

        case "throwError":
          throw new NoKernelConnectedError();

        case "waitForConnectionOpen":
          // Wait for connection but don't start it
          await waitForConnectionOpen();
          await waitForKernelToBeInstantiated();
          return request(...args);

        case "startConnectionWithoutKernel":
        case "startConnection":
          // Start connection and wait for it to be open
          await initOnce(runtimeManager);
          await waitForConnectionOpen();
          if (action === "startConnection") {
            await waitForKernelToBeInstantiated();
          }
          return request(...args);

        default:
          // This should never happen if ACTIONS is complete
          throw new Error(`Unknown action for "${key}"`);
      }
    }) as T;
    return wrapped;
  }

  return Objects.mapValues(delegate, (value, key) => {
    return wrapRequest(value, key);
  }) as AllRequests;
}

export const visibleForTesting = {
  ACTIONS,
};