/**
 * Copyright 2018 Google Inc. All Rights Reserved.
 *
 * 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 {AppOptions, AppHandler, ServiceBaseApp, attach} from '../../assistant';
import {JsonObject} from '../../common';
import * as common from '../../common';
import {Headers, BuiltinFrameworkMetadata} from '../../framework';
import * as Api from './api/v1';
import {google} from 'googleapis';

const encoding = 'utf8';
const homegraphWrapperDeprecationNotice = method =>
  `SmartHomeApp.${method} Home Graph wrapper method is deprecated. Use Google APIs Node.js Client for Home Graph: https://www.npmjs.com/package/@googleapis/homegraph`;

/**
 * @public
 * @deprecated Home Graph credentials are deprecated.
 * Use Google APIs Node.js Client for Home Graph:
 * https://www.npmjs.com/package/@googleapis/homegraph
 */
export interface SmartHomeJwt {
  type: 'service_account';
  project_id: string;
  private_key_id: string;
  private_key: string;
  client_email: string;
  client_id: string;
  auth_uri: string;
  token_uri: string;
  auth_provider_x509_cert_url: string;
  client_x509_cert_url: string;
}

/** @public */
export interface SmartHomeOptions extends AppOptions {
  /**
   * An API key to use the home graph API. See
   * https://console.cloud.google.com/apis/api/homegraph.googleapis.com/overview
   * to learn more.
   * @public
   * @deprecated Home Graph credentials are deprecated.
   * Use Google APIs Node.js Client for Home Graph:
   * https://www.npmjs.com/package/@googleapis/homegraph
   */
  key?: string;

  /**
   * A JWT (JSON Web Token) that is able to access the home graph API.
   * This is used for report state. See https://jwt.io/. A JWT can be
   * created through the Google Cloud Console: https://console.cloud.google.com/apis/credentials
   * @public
   * @deprecated Home Graph credentials are deprecated.
   * Use Google APIs Node.js Client for Home Graph:
   * https://www.npmjs.com/package/@googleapis/homegraph
   */
  jwt?: SmartHomeJwt;
}

/** @public */
export interface SmartHomeHandler<
  TRequest extends Api.SmartHomeV1Request,
  TResponse extends Api.SmartHomeV1Response
> {
  (body: TRequest, headers: Headers, framework: BuiltinFrameworkMetadata):
    | TResponse
    | Promise<TResponse>;
}

/** @hidden */
export interface SmartHomeHandlers {
  [intent: string]: SmartHomeHandler<
    Api.SmartHomeV1Request,
    Api.SmartHomeV1Response
  >;
}

/** @public */
export interface SmartHomeApp extends ServiceBaseApp {
  /** @hidden */
  _intents: SmartHomeHandlers;

  /** @hidden */
  _intent(
    intent: Api.SmartHomeV1Intents,
    handler: SmartHomeHandler<Api.SmartHomeV1Request, Api.SmartHomeV1Response>
  ): this;

  /**
   * Defines a function that will run when a SYNC request is received.
   *
   * @example
   * ```javascript
   *
   * const app = smarthome();
   * app.onSync((body, headers) => {
   *   return {
   *     requestId: 'ff36...',
   *     payload: {
   *       ...
   *     }
   *   }
   * })
   * ```
   *
   * @param handler The function that will run for a SYNC request. It should
   *   return a valid response or a Promise that resolves to valid response.
   *
   * @public
   */
  onSync(
    handler: SmartHomeHandler<
      Api.SmartHomeV1SyncRequest,
      Api.SmartHomeV1SyncResponse
    >
  ): this;

  /**
   * Defines a function that will run when a QUERY request is received.
   *
   * @example
   * ```javascript
   *
   * const app = smarthome();
   * app.onQuery((body, headers) => {
   *   return {
   *     requestId: 'ff36...',
   *     payload: {
   *       ...
   *     }
   *   }
   * })
   * ```
   *
   * @param handler The function that will run for a QUERY request. It should
   *   return a valid response or a Promise that resolves to valid response.
   *
   * @public
   */
  onQuery(
    handler: SmartHomeHandler<
      Api.SmartHomeV1QueryRequest,
      Api.SmartHomeV1QueryResponse
    >
  ): this;

  /**
   * Defines a function that will run when an EXECUTE request is received.
   *
   * @example
   * ```javascript
   *
   * const app = smarthome();
   * app.onExecute((body, headers) => {
   *   return {
   *     requestId: 'ff36...',
   *     payload: {
   *       ...
   *     }
   *   }
   * })
   * ```
   * @param handler The function that will run for an EXECUTE request. It should
   *   return a valid response or a Promise that resolves to valid response.
   *
   * @public
   */
  onExecute(
    handler: SmartHomeHandler<
      Api.SmartHomeV1ExecuteRequest,
      Api.SmartHomeV1ExecuteResponse
    >
  ): this;

  /**
   * Defines a function that will run when a DISCONNECT request is received.
   *
   * @example
   * ```javascript
   *
   * const app = smarthome();
   * app.onDisconnect((body, headers) => {
   *   // User unlinked their account, stop reporting state for user
   *   return {}
   * })
   * ```
   * @param handler The function that will run for an EXECUTE request. It should
   *   return a valid response or a Promise that resolves to valid response.
   *
   * @public
   */
  onDisconnect(
    handler: SmartHomeHandler<
      Api.SmartHomeV1DisconnectRequest,
      Api.SmartHomeV1DisconnectResponse
    >
  ): this;

  /**
   * Sends a request to the home graph to send a new SYNC request. This should
   * be called when a device is added or removed for a given user id.
   *
   * When calling this function, an API key needs to be provided as an option
   * in the constructor. See https://developers.google.com/actions/smarthome/create-app#request-sync
   * to learn more.
   *
   * @example
   * ```javascript
   *
   * const app = smarthome({
   *   key: "123ABC"
   * });
   *
   * const addNewDevice = () => {
   *   app.requestSync('user-123')
   *     .then((res) => {
   *       // Request sync was successful
   *     })
   *     .catch((res) => {
   *       // Request sync failed
   *     })
   * }
   *
   * // When request sync is called, a SYNC
   * // intent will be received soon after.
   * app.onSync(body => {
   *   // ...
   * })
   * ```
   *
   * @param agentUserId The user identifier.
   *
   * @public
   * @deprecated Home Graph wrapper methods are deprecated.
   * Use Google APIs Node.js Client for Home Graph:
   * https://www.npmjs.com/package/@googleapis/homegraph
   */
  requestSync(agentUserId: string): Promise<string>;

  /**
   * Reports the current state of a device or set of devices to the home graph.
   * This may be done if the state of the device was changed locally, like a
   * light turning on through a light switch.
   *
   * When calling this function, a JWT (JSON Web Token) needs to be provided
   * as an option in the constructor.
   *
   * @example
   * ```javascript
   * const app = smarthome({
   *   jwt: require('./jwt.json');
   * });
   *
   * const reportState = () => {
   *   app.reportState({
   *     requestId: '123ABC',
   *     agentUserId: 'user-123',
   *     payload: {
   *       devices: {
   *         states: {
   *           "light-123": {
   *             on: true
   *           }
   *         }
   *       }
   *     }
   *   })
   *   .then((res) => {
   *     // Report state was successful
   *   })
   *   .catch((res) => {
   *     // Report state failed
   *   })
   * };
   * ```
   *
   * @param reportedState A payload containing a device or set of devices with their states
   *
   * @public
   * @deprecated Home Graph wrapper methods are deprecated.
   * Use Google APIs Node.js Client for Home Graph:
   * https://www.npmjs.com/package/@googleapis/homegraph
   */
  reportState(
    reportedState: Api.SmartHomeV1ReportStateRequest
  ): Promise<string>;

  /**
   * @public
   * @deprecated Home Graph credentials are deprecated.
   * Use Google APIs Node.js Client for Home Graph:
   * https://www.npmjs.com/package/@googleapis/homegraph
   */
  key?: string;

  /**
   * @public
   * @deprecated Home Graph credentials are deprecated.
   * Use Google APIs Node.js Client for Home Graph:
   * https://www.npmjs.com/package/@googleapis/homegraph
   */
  jwt?: SmartHomeJwt;
}

/** @public */
export interface SmartHome {
  (options?: SmartHomeOptions): AppHandler & SmartHomeApp;
}

const makeApiCall = (
  url: string,
  data: JsonObject,
  jwt?: SmartHomeJwt
): Promise<string> => {
  const options = {
    hostname: 'homegraph.googleapis.com',
    port: 443,
    path: url,
    method: 'POST',
    headers: {},
  };

  const apiCall = (options: JsonObject) => {
    if (jwt && !options.headers.Authorization) {
      throw new Error(
        'JWT is defined but Authorization header is not defined ' +
          JSON.stringify(options)
      );
    }
    return new Promise<string>((resolve, reject) => {
      const buffers: Buffer[] = [];
      const req = common.request(options, res => {
        res.on('data', d => {
          buffers.push(typeof d === 'string' ? Buffer.from(d, encoding) : d);
        });

        res.on('end', () => {
          const apiResponse: string = Buffer.concat(buffers).toString(encoding);
          const apiResponseJson = JSON.parse(apiResponse);
          if (apiResponseJson.error && apiResponseJson.error.code >= 400) {
            // While the response ended, it contains an error.
            // In this case, this should reject the Promise.
            reject(apiResponse);
            return;
          }
          resolve(apiResponse);
        });
      });

      req.on('error', e => {
        reject(e);
      });
      // Write data to request body
      req.write(JSON.stringify(data));
      req.end();
    });
  };

  if (jwt) {
    return new Promise<JsonObject>((resolve, reject) => {
      // For testing, we do not need to actually authorize
      if (jwt.client_id === 'sample-client-id') {
        options.headers = {
          Authorization: ' Bearer 1234',
        };
        resolve(options);
        return;
      }
      // Generate JWT, then make the API call if provided
      const jwtClient = new google.auth.JWT(
        jwt.client_email,
        undefined,
        jwt.private_key,
        ['https://www.googleapis.com/auth/homegraph'],
        undefined
      );
      jwtClient.authorize((err: Error, tokens: JsonObject) => {
        if (err) {
          return reject(err);
        }
        options.headers = {
          Authorization: ` Bearer ${tokens.access_token}`,
        };
        resolve(options);
      });
    }).then(options => {
      return apiCall(options);
    });
  } else {
    return apiCall(options);
  }
};

/**
 *
 * @example
 * ```javascript
 *
 * const app = smarthome({
 *   debug: true,
 *   key: '<api-key>',
 *   jwt: require('./key.json')
 * });
 *
 * app.onSync((body, headers) => {
 *   return { ... }
 * });
 *
 * app.onQuery((body, headers) => {
 *   return { ... }
 * });
 *
 * app.onExecute((body, headers) => {
 *   return { ... }
 * });
 *
 * exports.smarthome = functions.https.onRequest(app);
 *
 * ```
 *
 * @public
 */
export const smarthome: SmartHome = (options = {}) =>
  attach<SmartHomeApp>(
    {
      _intents: {},
      _intent(this: SmartHomeApp, intent, handler) {
        this._intents[intent] = handler;
        return this;
      },
      onSync(this: SmartHomeApp, handler) {
        return this._intent('action.devices.SYNC', handler);
      },
      onQuery(this: SmartHomeApp, handler) {
        return this._intent('action.devices.QUERY', handler);
      },
      onExecute(this: SmartHomeApp, handler) {
        return this._intent('action.devices.EXECUTE', handler);
      },
      onDisconnect(this: SmartHomeApp, handler) {
        return this._intent('action.devices.DISCONNECT', handler);
      },
      async requestSync(this: SmartHomeApp, agentUserId) {
        common.warn.log(homegraphWrapperDeprecationNotice('requestSync'));
        if (this.jwt) {
          return await makeApiCall(
            '/v1/devices:requestSync',
            {
              agent_user_id: agentUserId,
            },
            this.jwt
          );
        }
        if (this.key) {
          return await makeApiCall(
            `/v1/devices:requestSync?key=${encodeURIComponent(this.key)}`,
            {
              agent_user_id: agentUserId,
            }
          );
        }
        throw new Error(
          'An API key was not specified. ' +
            'Please visit https://console.cloud.google.com/apis/api/homegraph.googleapis.com/overview'
        );
      },
      async reportState(this: SmartHomeApp, reportedState) {
        common.warn.log(homegraphWrapperDeprecationNotice('reportState'));
        if (!this.jwt) {
          throw new Error(
            'A JWT was not specified. ' +
              'Please visit https://console.cloud.google.com/apis/credentials'
          );
        }
        return await makeApiCall(
          '/v1/devices:reportStateAndNotification',
          reportedState,
          this.jwt
        );
      },
      key: options.key,
      jwt: options.jwt,
      async handler(
        this: SmartHomeApp,
        body: Api.SmartHomeV1Request,
        headers,
        metadata = {}
      ) {
        const {intent} = body.inputs[0];
        const handler = this._intents[intent];

        return {
          status: 200,
          headers: {},
          body: await handler(body, headers, metadata),
        };
      },
    },
    options
  );