import KeymapRepository, { KeymapRepositoryImpl }
  from '../repositories/KeymapRepository';
import SettingRepository, { SettingRepositoryImpl }
  from '../repositories/SettingRepository';
import AddonEnabledRepository, { AddonEnabledRepositoryImpl }
  from '../repositories/AddonEnabledRepository';

import * as operations from '../../shared/operations';
import { Keymaps } from '../../shared/Settings';
import * as keyUtils from '../../shared/utils/keys';

type KeymapEntityMap = Map<keyUtils.Key[], operations.Operation>;

const reservedKeymaps: Keymaps = {
  '<Esc>': { type: operations.CANCEL },
  '<C-[>': { type: operations.CANCEL },
};

const mapStartsWith = (
  mapping: keyUtils.Key[],
  keys: keyUtils.Key[],
): boolean => {
  if (mapping.length < keys.length) {
    return false;
  }
  for (let i = 0; i < keys.length; ++i) {
    if (!keyUtils.equals(mapping[i], keys[i])) {
      return false;
    }
  }
  return true;
};

export default class KeymapUseCase {
  private repository: KeymapRepository;

  private settingRepository: SettingRepository;

  private addonEnabledRepository: AddonEnabledRepository;

  constructor({
    repository = new KeymapRepositoryImpl(),
    settingRepository = new SettingRepositoryImpl(),
    addonEnabledRepository = new AddonEnabledRepositoryImpl(),
  } = {}) {
    this.repository = repository;
    this.settingRepository = settingRepository;
    this.addonEnabledRepository = addonEnabledRepository;
  }

  nextOp(key: keyUtils.Key): operations.Operation | null {
    let keys = this.repository.enqueueKey(key);

    let keymaps = this.keymapEntityMap();
    let matched = Array.from(keymaps.keys()).filter(
      (mapping: keyUtils.Key[]) => {
        return mapStartsWith(mapping, keys);
      });
    if (!this.addonEnabledRepository.get()) {
      // available keymaps are only ADDON_ENABLE and ADDON_TOGGLE_ENABLED if
      // the addon disabled
      matched = matched.filter((keymap) => {
        let type = (keymaps.get(keymap) as operations.Operation).type;
        return type === operations.ADDON_ENABLE ||
          type === operations.ADDON_TOGGLE_ENABLED;
      });
    }
    if (matched.length === 0) {
      // No operations to match with inputs
      this.repository.clear();
      return null;
    } else if (matched.length > 1 ||
      matched.length === 1 && keys.length < matched[0].length) {
      // More than one operations are matched
      return null;
    }
    // Exactly one operation is matched
    let operation = keymaps.get(matched[0]) as operations.Operation;
    this.repository.clear();
    return operation;
  }

  clear(): void {
    this.repository.clear();
  }

  private keymapEntityMap(): KeymapEntityMap {
    let keymaps = {
      ...this.settingRepository.get().keymaps,
      ...reservedKeymaps,
    };
    let entries = Object.entries(keymaps).map((entry) => {
      return [
        keyUtils.fromMapKeys(entry[0]),
        entry[1],
      ];
    }) as [keyUtils.Key[], operations.Operation][];
    return new Map<keyUtils.Key[], operations.Operation>(entries);
  }
}