Marketplace - Search by rate & tags - Controller - Crystal

product_controller.cr

require "cache"

class ProductController < ApplicationController

  getter filter_by_tags : Bool?

  def index
    # NO TAGS -> CACHE
    if !filter_by_tags? && !filter_by_rate?
      # CACHE
      cache_response
    else
      # OTHERWISE APPEND CLAUSE TO QUERY
      extra_clause = ""
      extra_clause += rate_where_clause if filter_by_rate?
      extra_clause += " GROUP BY products.id "
      extra_clause += tags_having_clause if filter_by_tags?
      extra_clause += " LIMIT 100"

      products = ProductQuery.all(extra_clause)

      render_json({
        data: products
        })
    end
  end

    def filter_by_rate?
      params["rate[]"]?
    end

    def filter_by_tags?
      return @filter_by_tags unless @filter_by_tags.nil?
      @filter_by_tags ||= TagKinds.values
              .map{ |tag| tag.to_s.downcase }
              .any?{ |tag| params["#{tag}[]"]? }
    end

    def rate_where_clause
      min, max = params.fetch_all("rate[]")
      return "" unless min =~ /\A[\d\.]+\Z/
      return "" unless max =~ /\A[\d\.]+\Z/
      %{ WHERE rates.amount BETWEEN #{min.to_f} AND #{max.to_f}}
    end

    def tags_having_clause
      havings = [] of String
      TagKinds.values.map{|tag|tag.to_s.downcase}.each do |tag|
        if params["#{tag}[]"]?
          tags = params.fetch_all("#{tag}[]")
          if tags.size > 0 && tags.all?{|tag|tag =~ /\A[\d\.]+\Z/}
            havings.push %{ARRAY_AGG(taggables.tag_id) && ARRAY[#{tags.join(',')}]::bigint[]}
          end
        end
      end
      if havings.size > 0
        " HAVING #{havings.join(" AND ")}"
      else
        ""
      end
    end

    def cache_response
      cache = Cache::RedisStore(String, String).new(expires_in: 15.minutes)
      products = cache.fetch("products#index-limit-100") do
        ProductQuery.all("GROUP BY products.id LIMIT 100").to_json
      end

      context.response.content_type = "application/json"
      "{data: #{products}}"
    end
  end