import * as actions from "../actions";
import Completions from "../Completions";
import CompletionType from "../../shared/CompletionType";

export interface State {
  mode: string;
  messageText: string;
  consoleText: string;
  completionTypes: CompletionType[];
  completionSource: string;
  completions: Completions;
  select: number;
  viewIndex: number;
}

const defaultState = {
  mode: "",
  messageText: "",
  consoleText: "",
  completionTypes: [],
  completionSource: "",
  completions: [],
  select: -1,
  viewIndex: 0,
};

const nextSelection = (state: State): number => {
  if (state.completions.length === 0) {
    return -1;
  }
  if (state.select < 0) {
    return 0;
  }

  const length = state.completions
    .map((g) => g.items.length)
    .reduce((x, y) => x + y);
  if (state.select + 1 < length) {
    return state.select + 1;
  }
  return -1;
};

const prevSelection = (state: State): number => {
  const length = state.completions
    .map((g) => g.items.length)
    .reduce((x, y) => x + y);
  if (state.select < 0) {
    return length - 1;
  }
  return state.select - 1;
};

const nextConsoleText = (completions: any[], select: number, defaults: any) => {
  if (select < 0) {
    return defaults;
  }
  const items = completions
    .map((g) => g.items)
    .reduce((g1, g2) => g1.concat(g2));
  return items[select].content;
};

// eslint-disable-next-line max-lines-per-function
export default function reducer(
  state: State = defaultState,
  action: actions.ConsoleAction
): State {
  switch (action.type) {
    case actions.CONSOLE_HIDE:
      return { ...state, mode: "" };
    case actions.CONSOLE_SHOW_COMMAND:
      return {
        ...state,
        mode: "command",
        consoleText: action.text,
        completionTypes: action.completionTypes,
        completions: [],
      };
    case actions.CONSOLE_SHOW_FIND:
      return { ...state, mode: "find", consoleText: "", completions: [] };
    case actions.CONSOLE_SHOW_ERROR:
      return { ...state, mode: "error", messageText: action.text };
    case actions.CONSOLE_SHOW_INFO:
      return { ...state, mode: "info", messageText: action.text };
    case actions.CONSOLE_HIDE_COMMAND:
      return {
        ...state,
        mode:
          state.mode === "command" || state.mode === "find" ? "" : state.mode,
      };
    case actions.CONSOLE_SET_CONSOLE_TEXT:
      return { ...state, consoleText: action.consoleText };
    case actions.CONSOLE_SET_COMPLETIONS:
      return {
        ...state,
        completions: action.completions,
        completionSource: action.completionSource,
        select: -1,
      };
    case actions.CONSOLE_COMPLETION_NEXT: {
      const select = nextSelection(state);
      return {
        ...state,
        select: select,
        consoleText: nextConsoleText(
          state.completions,
          select,
          state.completionSource
        ),
      };
    }
    case actions.CONSOLE_COMPLETION_PREV: {
      const select = prevSelection(state);
      return {
        ...state,
        select: select,
        consoleText: nextConsoleText(
          state.completions,
          select,
          state.completionSource
        ),
      };
    }
    default:
      return state;
  }
}