// Copyright (C) 2019 The Android Open Source Project
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

import {binaryDecode, binaryEncode} from '../base/string_utils';
import {TRACE_SUFFIX} from '../common/constants';

import {
  ConsumerPortResponse,
  hasProperty,
  isReadBuffersResponse,
  Typed,
} from './consumer_port_types';
import {Consumer, RpcConsumerPort} from './record_controller_interfaces';

export interface ChromeExtensionError extends Typed {
  error: string;
}

export interface ChromeExtensionStatus extends Typed {
  status: string;
}

export interface GetCategoriesResponse extends Typed {
  categories: string[];
}

export type ChromeExtensionMessage = ChromeExtensionError|ChromeExtensionStatus|
    ConsumerPortResponse|GetCategoriesResponse;

export function isChromeExtensionError(obj: Typed):
    obj is ChromeExtensionError {
  return obj.type === 'ChromeExtensionError';
}

export function isChromeExtensionStatus(obj: Typed):
    obj is ChromeExtensionStatus {
  return obj.type === 'ChromeExtensionStatus';
}

function isObject(obj: unknown): obj is object {
  return typeof obj === 'object' && obj !== null;
}

export function isGetCategoriesResponse(obj: unknown):
    obj is GetCategoriesResponse {
  if (!(isObject(obj) && hasProperty(obj, 'type') &&
        obj.type === 'GetCategoriesResponse')) {
    return false;
  }

  return hasProperty(obj, 'categories') && Array.isArray(obj.categories);
}

// This class acts as a proxy from the record controller (running in a worker),
// to the frontend. This is needed because we can't directly talk with the
// extension from a web-worker, so we use a MessagePort to communicate with the
// frontend, that will consecutively forward it to the extension.

// Rationale for the binaryEncode / binaryDecode calls below:
// Messages to/from extensions need to be JSON serializable. ArrayBuffers are
// not supported. For this reason here we use binaryEncode/Decode.
// See https://developer.chrome.com/extensions/messaging#simple

export class ChromeExtensionConsumerPort extends RpcConsumerPort {
  private extensionPort: MessagePort;

  constructor(extensionPort: MessagePort, consumer: Consumer) {
    super(consumer);
    this.extensionPort = extensionPort;
    this.extensionPort.onmessage = this.onExtensionMessage.bind(this);
  }

  onExtensionMessage(message: {data: ChromeExtensionMessage}) {
    if (isChromeExtensionError(message.data)) {
      this.sendErrorMessage(message.data.error);
      return;
    }
    if (isChromeExtensionStatus(message.data)) {
      this.sendStatus(message.data.status);
      return;
    }

    // In this else branch message.data will be a ConsumerPortResponse.
    if (isReadBuffersResponse(message.data) && message.data.slices) {
      const slice = message.data.slices[0].data as unknown as string;
      message.data.slices[0].data = binaryDecode(slice);
    }
    this.sendMessage(message.data);
  }

  handleCommand(method: string, requestData: Uint8Array): void {
    const reqEncoded = binaryEncode(requestData);
    this.extensionPort.postMessage({method, requestData: reqEncoded});
  }

  getRecordedTraceSuffix(): string {
    return `${TRACE_SUFFIX}.gz`;
  }
}