SteemPostFinder

steem_post_finder.rb

require 'radiator'

class SteemPostFinder
  # the max results we can return for a single API query
  BATCH_SIZE = 100

  def initialize(tag_name)
    @tag_name = tag_name
  end

  # find posts for a tag in a datetime range
  def posts_in_time_range(start_date, end_date)
    start_date = start_date.is_a?(String) ? DateTime.parse(start_date) : start_date
    end_date = end_date.is_a?(String) ? DateTime.parse(end_date) : end_date
    posts = []

    # this is the equivalent of a do-while loop in other languages
    loop do
      # find author / permlink info if last_post exists
      last_post = posts.last
      last_author = last_post.try(:author)
      last_permlink = last_post.try(:permlink)

      # concats the posts array results to the existing posts array
      posts << get_posts_by_created(last_author, last_permlink)

      # makes the array 1-dimensional and removes duplicates and empty elements
      posts = posts.flatten.compact.uniq

      # exit the do-while loop under the following circumstances:
      # 1. no posts are found in the response, or
      # 2. the posts returned the same list of posts as the previous response
      # 3. the last post was created before the start date

      should_break = posts.blank? || posts.last == last_post || DateTime.parse(disc.last.try(:created)) < start_date
      break if should_break
    end

    # reject all posts out of time range
    posts.reject! do |post|
      created = DateTime.parse(d.created)
      created < start_date || created > end_date
    end

    posts
  end

  # gets posts from Steem API
  def get_posts_by_created(author="", permlink="")
    params = {tag: @tag_name, limit: BATCH_SIZE}
    params.merge!({
      start_author: author,
      start_permlink: permlink
    }) unless author.blank? || permlink.blank?

    # get posts from the Steem API
    response = api.get_discussions_by_created(params)
    return [] if response.blank?

    # format response results has indifferent access array of hashes
    response['result'].map(&:with_indifferent_access)
  end

  def get_post(author, permlink)
    params = { tag: @tag_name, limit: 1, start_author: author, start_permlink: permlink }
    response = api.get_discussions_by_created(params)
    response.blank? ? [] : response['result'].try(:first).try(:with_indifferent_access)
  end

  private

  def api
    @api ||= Radiator::Api.new
  end
end