/**
 * 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 * as Api from './api/v2'
import { JsonObject } from '../../common'
import { Conversation, ConversationBaseOptions, ConversationOptionsInit } from './conversation'

/** @public */
export interface ActionsSdkConversationOptions<
  TConvData,
  TUserStorage
> extends ConversationBaseOptions<TConvData, TUserStorage> {
  /** @public */
  body?: Api.GoogleActionsV2AppRequest
}

const serializeData = <TConvData>(data: TConvData) =>
  JSON.stringify({ data })

const deserializeData = <TConvData>(
  body: Api.GoogleActionsV2AppRequest, defaultData?: TConvData,
) => {
  const { conversation = {} } = body
  const { conversationToken } = conversation
  const data: TConvData = conversationToken ?
    JSON.parse(conversationToken).data : Object.assign({}, defaultData)
  return data
}

/** @public */
export class ActionsSdkConversation<
  TConvData = JsonObject,
  TUserStorage = JsonObject
> extends Conversation<TUserStorage> {
  /** @public */
  body: Api.GoogleActionsV2AppRequest

  /**
   * Get the current Actions SDK intent.
   *
   * @example
   * ```javascript
   *
   * app.intent('actions.intent.MAIN', conv => {
   *   const intent = conv.intent // will be 'actions.intent.MAIN'
   * })
   * ```
   *
   * @public
   */
  intent: string

  /**
   * The session data in JSON format.
   * Stored using conversationToken.
   *
   * @example
   * ```javascript
   *
   * app.intent('actions.intent.MAIN', conv => {
   *   conv.data.someProperty = 'someValue'
   * })
   * ```
   *
   * @public
   */
  data: TConvData

  /** @hidden */
  _init: ConversationOptionsInit<TConvData, TUserStorage>

  /** @public */
  constructor(options: ActionsSdkConversationOptions<TConvData, TUserStorage> = {}) {
    const { body = {} } = options
    super({
      request: body,
      headers: options.headers,
      init: options.init,
      ordersv3: options.ordersv3,
    })

    this.body = body

    const { inputs = [] } = body
    const [firstInput = {}] = inputs

    const { intent = '' } = firstInput

    this.intent = intent

    this.data = deserializeData<TConvData>(this.body, this._init.data)
  }

  /** @public */
  serialize(): Api.GoogleActionsV2AppResponse {
    if (this._raw) {
      return this._raw
    }
    const {
      richResponse,
      expectUserResponse,
      userStorage,
      expectedIntent,
      noInputPrompts,
      speechBiasingHints,
    } = this.response()
    const inputPrompt: Api.GoogleActionsV2InputPrompt = {
      noInputPrompts,
    }
    if (richResponse.items!.length) {
      inputPrompt.richInitialPrompt = richResponse
    }
    const possibleIntents: Api.GoogleActionsV2ExpectedIntent[] = [expectedIntent || {
      intent: 'actions.intent.TEXT',
    }]
    const expectedInput: Api.GoogleActionsV2ExpectedInput = {
      possibleIntents,
      speechBiasingHints,
    }
    if (inputPrompt.richInitialPrompt || inputPrompt.noInputPrompts) {
      expectedInput.inputPrompt = inputPrompt
    }
    const response: Api.GoogleActionsV2AppResponse = {
      expectUserResponse,
    }
    if (expectUserResponse) {
      response.expectedInputs = [expectedInput]
    } else {
      response.finalResponse = { richResponse }
    }
    const convDataDefault = deserializeData<TConvData>({}, this._init.data)
    const convDataDefaultSerialized = serializeData(convDataDefault)
    const convDataDefaulted = deserializeData<TConvData>(this.body, this._init.data)
    const convDataIn = serializeData(convDataDefaulted)
    const convDataOut = serializeData(this.data)
    if (convDataOut !== convDataDefaultSerialized || convDataOut !== convDataIn) {
      response.conversationToken = convDataOut
    }
    if (userStorage) {
      response.userStorage = userStorage
    }
    return response
  }
}