// Vendor modules
import * as actionTypes from "@nteract/actions";
import { JSONObject } from "@nteract/commutable";
import {
  HelpLink,
  KernelStatus,
  makeHelpLinkRecord,
  makeKernelInfoRecord,
  makeKernelNotStartedRecord,
  makeKernelsRecord,
  makeLocalKernelRecord,
  makeRemoteKernelRecord
} from "@nteract/types";
import { List, Map } from "immutable";
import { Action, Reducer } from "redux";
import { combineReducers } from "redux-immutable";

const byRef = (state = Map(), action: Action): Map<unknown, unknown> => {
  let typedAction;
  switch (action.type) {
    case actionTypes.SET_LANGUAGE_INFO:
      // TODO: Should the kernel hold language info?
      return state;
    case actionTypes.KILL_KERNEL_SUCCESSFUL:
      typedAction = action as actionTypes.KillKernelSuccessful;
      return state.setIn(
        [typedAction.payload.kernelRef, "status"],
        KernelStatus.Killed
      );
    case actionTypes.KILL_KERNEL_FAILED:
      typedAction = action as actionTypes.KillKernelFailed;
      return state.setIn(
        [typedAction.payload.kernelRef, "status"],
        KernelStatus.Error
      );
    case actionTypes.RESTART_KERNEL:
      typedAction = action as actionTypes.RestartKernel;
      return state.setIn(
        [typedAction.payload.kernelRef, "status"],
        KernelStatus.Restarting
      );
    case actionTypes.LAUNCH_KERNEL:
      typedAction = action as actionTypes.LaunchKernelAction;
      return state.set(
        typedAction.payload.kernelRef,
        makeKernelNotStartedRecord({
          status: KernelStatus.Starting,
          kernelSpecName: typedAction.payload.kernelSpec.name
        })
      );
    case actionTypes.LAUNCH_KERNEL_BY_NAME:
      typedAction = action as actionTypes.LaunchKernelByNameAction;
      return state.set(
        typedAction.payload.kernelRef,
        makeKernelNotStartedRecord({
          status: KernelStatus.Starting,
          kernelSpecName: typedAction.payload.kernelSpecName
        })
      );
    case actionTypes.CHANGE_KERNEL_BY_NAME:
      typedAction = action as actionTypes.ChangeKernelByName;
      return state.setIn(
        [typedAction.payload.oldKernelRef, "status"],
        "changing"
      );
    case actionTypes.SET_KERNEL_INFO:
      typedAction = action as actionTypes.SetKernelInfo;
      let codemirrorMode = typedAction.payload.info.codemirrorMode;
      // If the codemirror mode isn't set, fallback on the language name
      if (!codemirrorMode) {
        codemirrorMode = typedAction.payload.info.languageName;
      }
      switch (typeof codemirrorMode) {
        case "string":
          // already set as we want it
          break;
        case "object":
          codemirrorMode = Map(codemirrorMode as JSONObject);
          break;
        default:
          // any other case results in falling back to language name
          codemirrorMode = typedAction.payload.info.languageName;
      }

      const helpLinks = typedAction.payload.info.helpLinks
        ? List(
          (typedAction.payload.info.helpLinks as HelpLink[]).map(
            makeHelpLinkRecord
          )
        )
        : List();

      return state.setIn(
        [typedAction.payload.kernelRef, "info"],
        makeKernelInfoRecord(typedAction.payload.info).merge({
          helpLinks,
          codemirrorMode
        })
      );
    case actionTypes.SET_EXECUTION_STATE:
      typedAction = action as actionTypes.SetExecutionStateAction;
      return state.setIn(
        [typedAction.payload.kernelRef, "status"],
        typedAction.payload.kernelStatus
      );
    case actionTypes.LAUNCH_KERNEL_SUCCESSFUL:
      typedAction = action as actionTypes.NewKernelAction;
      switch (typedAction.payload.kernel.type) {
        case "zeromq":
          return state.set(
            typedAction.payload.kernelRef,
            makeLocalKernelRecord(typedAction.payload.kernel)
          );
        case "websocket":
          return state.set(
            typedAction.payload.kernelRef,
            makeRemoteKernelRecord(typedAction.payload.kernel)
          );
        default:
          throw new Error(
            `Unrecognized kernel type in kernel ${typedAction.payload.kernel}.`
          );
      }
    case actionTypes.DISPOSE_KERNEL: {
      typedAction = action as actionTypes.DisposeKernel;
      return state.delete(typedAction.payload.kernelRef);
    }
    default:
      return state;
  }
};

export const kernels: Reducer<
  {
    byRef: Map<unknown, unknown>;
  },
  Action<any>
> = combineReducers({ byRef }, makeKernelsRecord as any);