/**
 * Copyright (c) Microsoft Corporation. All rights reserved.
 * Licensed under the MIT License.
 */
import { MemoryScope } from './memoryScope'
import { ExceptionHelper } from '@microsoft/agents-activity'
import { Errors } from '../../errorHelper'
import { ScopePath } from '../scopePath'
import { DialogContext } from '../../dialogContext'

/**
 * @private
 */
const TURN_STATE = 'turn'

/**
 * A memory scope that provides access to the turn's state.
 * This scope is used to store and retrieve information specific to the current turn.
 */
export class TurnMemoryScope extends MemoryScope {
  /**
   * Initializes a new instance of the TurnMemoryScope class.
   */
  constructor () {
    super(ScopePath.turn, true)
  }

  /**
   * Gets the backing memory for this scope.
   *
   * @param dialogContext - The DialogContext object for this turn.
   * @returns The memory for the scope.
   */
  getMemory (dialogContext: DialogContext): object {
    let memory = dialogContext.context.turnState.get(TURN_STATE)
    if (typeof memory !== 'object') {
      memory = {}
      dialogContext.context.turnState.set(TURN_STATE, memory)
    }

    return memory
  }

  /**
   * Changes the backing object for the memory scope.
   *
   * @param dialogContext - The DialogContext object for this turn.
   * @param memory - Memory object to set for the scope.
   */
  setMemory (dialogContext: DialogContext, memory: object): void {
    if (memory === undefined) {
      throw ExceptionHelper.generateException(
        Error,
        Errors.UndefinedMemoryObject,
        undefined,
        { scopeName: 'TurnMemoryScope' }
      )
    }

    dialogContext.context.turnState.set(TURN_STATE, memory)
  }
}