// Copyright 2015, 2016 Parity Technologies (UK) Ltd.
// This file is part of Parity.

// Parity is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// Parity is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with Parity.  If not, see <http://www.gnu.org/licenses/>.

import * as abis from './abi';

export default class Registry {
  constructor (api) {
    this._api = api;

    this._contracts = {};
    this._pendingContracts = {};

    this._instance = null;
    this._fetching = false;
    this._queue = [];

    this.getInstance();
  }

  getInstance () {
    if (this._instance) {
      return Promise.resolve(this._instance);
    }

    if (this._fetching) {
      return new Promise((resolve) => {
        this._queue.push({ resolve });
      });
    }

    this._fetching = true;

    return this._api.parity
      .registryAddress()
      .then((address) => {
        this._fetching = false;
        this._instance = this._api.newContract(abis.registry, address).instance;

        this._queue.forEach((queued) => {
          queued.resolve(this._instance);
        });

        this._queue = [];

        return this._instance;
      });
  }

  getContract (_name) {
    const name = _name.toLowerCase();

    if (this._contracts[name]) {
      return Promise.resolve(this._contracts[name]);
    }

    if (this._pendingContracts[name]) {
      return this._pendingContracts[name];
    }

    const promise = this
      .lookupAddress(name)
      .then((address) => {
        this._contracts[name] = this._api.newContract(abis[name], address);
        delete this._pendingContracts[name];
        return this._contracts[name];
      });

    this._pendingContracts[name] = promise;

    return promise;
  }

  getContractInstance (_name) {
    return this
      .getContract(_name)
      .then((contract) => contract.instance);
  }

  lookupAddress (_name) {
    const name = _name.toLowerCase();
    const sha3 = this._api.util.sha3(name);

    return this.getInstance().then((instance) => {
      return instance.getAddress.call({}, [sha3, 'A']);
    })
    .then((address) => {
      console.log('[lookupAddress]', `(${sha3}) ${name}: ${address}`);
      return address;
    });
  }
}