require "active_support/core_ext/module/delegation"

module PgSearch
  class ScopeOptions
    delegate :connection, :quoted_table_name, :sanitize_sql_array, :to => :@model

    def initialize(name, config)
      @name = name
      @config = config
      @model = config.model
      @feature_options = Hash[config.features]
    end

    def apply(scope)
      scope.select("#{quoted_table_name}.*, (#{rank}) AS pg_search_rank").where(conditions).order("pg_search_rank DESC, #{order_within_rank}").joins(joins)
    end

    private

    def conditions
      @config.features.map do |feature_name, feature_options|
        "(#{sanitize_sql_array(feature_for(feature_name).conditions)})"
      end.join(" OR ")
    end

    def order_within_rank
      @config.order_within_rank || "#{primary_key} ASC"
    end

    def primary_key
      "#{quoted_table_name}.#{connection.quote_column_name(@model.primary_key)}"
    end

    def joins
      @config.associations.map do |association|
        association.join(primary_key)
      end.join(' ')
    end

    FEATURE_CLASSES = {
      :dmetaphone => Features::DMetaphone,
      :tsearch => Features::TSearch,
      :trigram => Features::Trigram
    }

    def feature_for(feature_name)
      feature_name = feature_name.to_sym
      feature_class = FEATURE_CLASSES[feature_name]

      raise ArgumentError.new("Unknown feature: #{feature_name}") unless feature_class

      normalizer = Normalizer.new(@config)

      feature_class.new(
        @config.query,
        @feature_options[feature_name],
        @config.columns,
        @config.model,
        normalizer
      )
    end

    def rank
      (@config.ranking_sql || ":tsearch").gsub(/:(\w*)/) do
        sanitize_sql_array(feature_for($1).rank)
      end
    end
  end
end