const _ = require('underscore');
const MailspringStore = require('mailspring-store').default;
const {
  Actions,
  AccountStore,
  ThreadCountsStore,
  WorkspaceStore,
  OutboxStore,
  FocusedPerspectiveStore,
  CategoryStore,
} = require('mailspring-exports');

const SidebarSection = require('./sidebar-section');
const SidebarActions = require('./sidebar-actions');
const AccountCommands = require('./account-commands');

const Sections = {
  Standard: 'Standard',
  User: 'User',
};

class SidebarStore extends MailspringStore {
  constructor() {
    super();

    if (AppEnv.savedState.sidebarKeysCollapsed == null) {
      AppEnv.savedState.sidebarKeysCollapsed = {};
    }

    this._sections = {};
    this._sections[Sections.Standard] = {};
    this._sections[Sections.User] = [];
    this._registerCommands();
    this._registerMenuItems();
    this._registerListeners();
    this._updateSections();
  }

  accounts() {
    return AccountStore.accounts();
  }

  sidebarAccountIds() {
    return FocusedPerspectiveStore.sidebarAccountIds();
  }

  standardSection() {
    return this._sections[Sections.Standard];
  }

  userSections() {
    return this._sections[Sections.User];
  }

  _registerListeners() {
    this.listenTo(Actions.setCollapsedSidebarItem, this._onSetCollapsedByName);
    this.listenTo(SidebarActions.setKeyCollapsed, this._onSetCollapsedByKey);
    this.listenTo(AccountStore, this._onAccountsChanged);
    this.listenTo(FocusedPerspectiveStore, this._onFocusedPerspectiveChanged);
    this.listenTo(WorkspaceStore, this._updateSections);
    this.listenTo(OutboxStore, this._updateSections);
    this.listenTo(ThreadCountsStore, this._updateSections);
    this.listenTo(CategoryStore, this._updateSections);

    this.configSubscription = AppEnv.config.onDidChange(
      'core.workspace.showUnreadForAllCategories',
      this._updateSections
    );
  }

  _onSetCollapsedByKey = (itemKey, collapsed) => {
    const currentValue = AppEnv.savedState.sidebarKeysCollapsed[itemKey];
    if (currentValue !== collapsed) {
      AppEnv.savedState.sidebarKeysCollapsed[itemKey] = collapsed;
      this._updateSections();
    }
  };

  _onSetCollapsedByName = (itemName, collapsed) => {
    let item = _.findWhere(this.standardSection().items, { name: itemName });
    if (!item) {
      for (let section of this.userSections()) {
        item = _.findWhere(section.items, { name: itemName });
        if (item) {
          break;
        }
      }
    }
    if (!item) {
      return;
    }
    this._onSetCollapsedByKey(item.id, collapsed);
  };

  _registerCommands = accounts => {
    if (accounts == null) {
      accounts = AccountStore.accounts();
    }
    AccountCommands.registerCommands(accounts);
  };

  _registerMenuItems = accounts => {
    if (accounts == null) {
      accounts = AccountStore.accounts();
    }
    AccountCommands.registerMenuItems(accounts, FocusedPerspectiveStore.sidebarAccountIds());
  };

  // TODO Refactor this
  // Listen to changes on the account store only for when the account label
  // or order changes. When accounts or added or removed, those changes will
  // come in through the FocusedPerspectiveStore
  _onAccountsChanged = () => {
    this._updateSections();
  };

  // TODO Refactor this
  // The FocusedPerspectiveStore tells this store the accounts that should be
  // displayed in the sidebar (i.e. unified inbox vs single account) and will
  // trigger whenever an account is added or removed, as well as when a
  // perspective is focused.
  // However, when udpating the SidebarSections, we also depend on the actual
  // accounts in the AccountStore. The problem is that the FocusedPerspectiveStore
  // triggers before the AccountStore is actually updated, so we need to wait for
  // the AccountStore to get updated (via `defer`) before updateing our sidebar
  // sections
  _onFocusedPerspectiveChanged = () => {
    _.defer(() => {
      this._registerCommands();
      this._registerMenuItems();
      this._updateSections();
    });
  };

  _updateSections = () => {
    const accounts = FocusedPerspectiveStore.sidebarAccountIds()
      .map(id => AccountStore.accountForId(id))
      .filter(a => !!a);

    if (accounts.length === 0) {
      return;
    }
    const multiAccount = accounts.length > 1;

    this._sections[Sections.Standard] = SidebarSection.standardSectionForAccounts(accounts);
    this._sections[Sections.User] = accounts.map(function(acc) {
      const opts = {};
      if (multiAccount) {
        opts.title = acc.label;
        opts.collapsible = true;
      }
      return SidebarSection.forUserCategories(acc, opts);
    });
    this.trigger();
  };
}

module.exports = new SidebarStore();