gistfile1.txt

class DiscussionMessagesController < ApplicationController
  def create
    opponent_id = params[:discussion_message][:opponent_id]

    @discussion = find_sample_discussion opponent_id

    unless @discussion
      @discussion = Discussion.create()
      @discussion.discussion_users.new(user_id: opponent_id)
      @discussion.discussion_users.new(user_id: current_user.id)
      @discussion.save
    end

    @discussion_message = DiscussionMessage.new discussion_message_params
    @discussion_message.discussion_id = @discussion.id
    
    if @discussion_message.save
      render json: { }, status: :ok
    else
      render json: @discussion_message.errors, status: :unprocessable_entity
    end
  end

  private

  def find_sample_discussion opponent_id
    current_user.discussion_users.each do |user|
      if DiscussionUser.find_by_user_id_and_discussion_id(opponent_id, user.discussion.id).present?
        return user.discussion
      end
    end
    nil
  end

  def discussion_message_params
    params.require(:discussion_message).permit(:text, :discussion_id, :user_id)
  end
end