module Searchkick
  class Query
    extend Forwardable

    attr_reader :klass, :term, :options
    attr_accessor :body

    def_delegators :execute, :map, :each, :any?, :empty?, :size, :length, :slice, :[], :to_ary,
      :records, :results, :suggestions, :each_with_hit, :with_details, :aggregations, :aggs,
      :took, :error, :model_name, :entry_name, :total_count, :total_entries,
      :current_page, :per_page, :limit_value, :padding, :total_pages, :num_pages,
      :offset_value, :offset, :previous_page, :prev_page, :next_page, :first_page?, :last_page?,
      :out_of_range?, :hits, :response, :to_a, :first

    def initialize(klass, term = "*", **options)
      unknown_keywords = options.keys - [:aggs, :body, :body_options, :boost,
        :boost_by, :boost_by_distance, :boost_where, :conversions, :debug, :emoji, :execute, :explain,
        :fields, :highlight, :includes, :index_name, :indices_boost, :limit, :load,
        :match, :misspellings, :offset, :operator, :order, :padding, :page, :per_page, :profile,
        :request_params, :routing, :select, :similar, :smart_aggs, :suggest, :track, :type, :where]
      raise ArgumentError, "unknown keywords: #{unknown_keywords.join(", ")}" if unknown_keywords.any?

      term = term.to_s

      if options[:emoji]
        term = EmojiParser.parse_unicode(term) { |e| " #{e.name} " }.strip
      end

      @klass = klass
      @term = term
      @options = options
      @match_suffix = options[:match] || searchkick_options[:match] || "analyzed"

      # prevent Ruby warnings
      @type = nil
      @routing = nil
      @misspellings = false
      @misspellings_below = nil
      @highlighted_fields = nil

      prepare
    end

    def searchkick_index
      klass ? klass.searchkick_index : nil
    end

    def searchkick_options
      klass ? klass.searchkick_options : {}
    end

    def searchkick_klass
      klass ? klass.searchkick_klass : nil
    end

    def params
      index =
        if options[:index_name]
          Array(options[:index_name]).map { |v| v.respond_to?(:searchkick_index) ? v.searchkick_index.name : v }.join(",")
        elsif searchkick_index
          searchkick_index.name
        else
          "_all"
        end

      params = {
        index: index,
        body: body
      }
      params[:type] = @type if @type
      params[:routing] = @routing if @routing
      params.merge!(options[:request_params]) if options[:request_params]
      params
    end

    def execute
      @execute ||= begin
        begin
          response = execute_search
          if @misspellings_below && response["hits"]["total"] < @misspellings_below
            prepare
            response = execute_search
          end
        rescue => e # TODO rescue type
          handle_error(e)
        end
        handle_response(response)
      end
    end

    def to_curl
      query = params
      type = query[:type]
      index = query[:index].is_a?(Array) ? query[:index].join(",") : query[:index]

      # no easy way to tell which host the client will use
      host = Searchkick.client.transport.hosts.first
      credentials = host[:user] || host[:password] ? "#{host[:user]}:#{host[:password]}@" : nil
      "curl #{host[:protocol]}://#{credentials}#{host[:host]}:#{host[:port]}/#{CGI.escape(index)}#{type ? "/#{type.map { |t| CGI.escape(t) }.join(',')}" : ''}/_search?pretty -d '#{query[:body].to_json}'"
    end

    def handle_response(response)
      opts = {
        page: @page,
        per_page: @per_page,
        padding: @padding,
        load: @load,
        includes: options[:includes],
        json: !@json.nil?,
        match_suffix: @match_suffix,
        highlighted_fields: @highlighted_fields || [],
        misspellings: @misspellings
      }

      if options[:debug]
        require "pp"

        puts "Searchkick Version: #{Searchkick::VERSION}"
        puts "Elasticsearch Version: #{Searchkick.server_version}"
        puts

        puts "Model Searchkick Options"
        pp searchkick_options
        puts

        puts "Search Options"
        pp options
        puts

        if searchkick_index
          puts "Model Search Data"
          begin
            pp klass.first(3).map { |r| {index: searchkick_index.record_data(r).merge(data: searchkick_index.send(:search_data, r))}}
          rescue => e
            puts "#{e.class.name}: #{e.message}"
          end
          puts

          puts "Elasticsearch Mapping"
          puts JSON.pretty_generate(searchkick_index.mapping)
          puts

          puts "Elasticsearch Settings"
          puts JSON.pretty_generate(searchkick_index.settings)
          puts
        end

        puts "Elasticsearch Query"
        puts to_curl
        puts

        puts "Elasticsearch Results"
        puts JSON.pretty_generate(response)
      end

      # set execute for multi search
      @execute = Searchkick::Results.new(searchkick_klass, response, opts)
    end

    private

    def handle_error(e)
      status_code = e.message[1..3].to_i
      if status_code == 404
        raise MissingIndexError, "Index missing - run #{reindex_command}"
      elsif status_code == 500 && (
        e.message.include?("IllegalArgumentException[minimumSimilarity >= 1]") ||
        e.message.include?("No query registered for [multi_match]") ||
        e.message.include?("[match] query does not support [cutoff_frequency]") ||
        e.message.include?("No query registered for [function_score]")
      )

        raise UnsupportedVersionError, "This version of Searchkick requires Elasticsearch 2 or greater"
      elsif status_code == 400
        if (
          e.message.include?("bool query does not support [filter]") ||
          e.message.include?("[bool] filter does not support [filter]")
        )

          raise UnsupportedVersionError, "This version of Searchkick requires Elasticsearch 2 or greater"
        elsif e.message.include?("[multi_match] analyzer [searchkick_search] not found")
          raise InvalidQueryError, "Bad mapping - run #{reindex_command}"
        else
          raise InvalidQueryError, e.message
        end
      else
        raise e
      end
    end

    def reindex_command
      searchkick_klass ? "#{searchkick_klass.name}.reindex" : "reindex"
    end

    def execute_search
      Searchkick.client.search(params)
    end

    def prepare
      boost_fields, fields = set_fields

      operator = options[:operator] || "and"

      # pagination
      page = [options[:page].to_i, 1].max
      per_page = (options[:limit] || options[:per_page] || 1_000).to_i
      padding = [options[:padding].to_i, 0].max
      offset = options[:offset] || (page - 1) * per_page + padding

      # model and eager loading
      load = options[:load].nil? ? true : options[:load]

      conversions_fields = Array(options[:conversions] || searchkick_options[:conversions]).map(&:to_s)

      all = term == "*"

      @json = options[:body]
      if @json
        payload = @json
      else
        if options[:similar]
          payload = {
            more_like_this: {
              fields: fields,
              like_text: term,
              min_doc_freq: 1,
              min_term_freq: 1,
              analyzer: "searchkick_search2"
            }
          }
        elsif all
          payload = {
            match_all: {}
          }
        else
          queries = []

          misspellings =
            if options.key?(:misspellings)
              options[:misspellings]
            else
              true
            end

          if misspellings.is_a?(Hash) && misspellings[:below] && !@misspellings_below
            @misspellings_below = misspellings[:below].to_i
            misspellings = false
          end

          if misspellings != false
            edit_distance = (misspellings.is_a?(Hash) && (misspellings[:edit_distance] || misspellings[:distance])) || 1
            transpositions =
              if misspellings.is_a?(Hash) && misspellings.key?(:transpositions)
                {fuzzy_transpositions: misspellings[:transpositions]}
              else
                {fuzzy_transpositions: true}
              end
            prefix_length = (misspellings.is_a?(Hash) && misspellings[:prefix_length]) || 0
            default_max_expansions = @misspellings_below ? 20 : 3
            max_expansions = (misspellings.is_a?(Hash) && misspellings[:max_expansions]) || default_max_expansions
            @misspellings = true
          else
            @misspellings = false
          end

          fields.each do |field|
            qs = []

            factor = boost_fields[field] || 1
            shared_options = {
              query: term,
              boost: 10 * factor
            }

            match_type =
              if field.end_with?(".phrase")
                field = field.sub(/\.phrase\z/, ".analyzed")
                :match_phrase
              else
                :match
              end

            shared_options[:operator] = operator if match_type == :match

            if field == "_all" || field.end_with?(".analyzed")
              shared_options[:cutoff_frequency] = 0.001 unless operator == "and" || misspellings == false
              qs.concat [
                shared_options.merge(analyzer: "searchkick_search"),
                shared_options.merge(analyzer: "searchkick_search2")
              ]
            elsif field.end_with?(".exact")
              f = field.split(".")[0..-2].join(".")
              queries << {match: {f => shared_options.merge(analyzer: "keyword")}}
            else
              analyzer = field =~ /\.word_(start|middle|end)\z/ ? "searchkick_word_search" : "searchkick_autocomplete_search"
              qs << shared_options.merge(analyzer: analyzer)
            end

            if misspellings != false && match_type == :match
              qs.concat qs.map { |q| q.except(:cutoff_frequency).merge(fuzziness: edit_distance, prefix_length: prefix_length, max_expansions: max_expansions, boost: factor).merge(transpositions) }
            end

            # boost exact matches more
            if field =~ /\.word_(start|middle|end)\z/ && searchkick_options[:word] != false
              queries << {
                bool: {
                  must: {
                    bool: {
                      should: qs.map { |q| {match_type => {field => q}} }
                    }
                  },
                  should: {match_type => {field.sub(/\.word_(start|middle|end)\z/, ".analyzed") => qs.first}}
                }
              }
            else
              queries.concat(qs.map { |q| {match_type => {field => q}} })
            end
          end

          payload = {
            dis_max: {
              queries: queries
            }
          }

          if conversions_fields.present? && options[:conversions] != false
            shoulds = []
            conversions_fields.each do |conversions_field|
              # wrap payload in a bool query
              script_score = {field_value_factor: {field: "#{conversions_field}.count"}}

              shoulds << {
                nested: {
                  path: conversions_field,
                  score_mode: "sum",
                  query: {
                    function_score: {
                      boost_mode: "replace",
                      query: {
                        match: {
                          "#{conversions_field}.query" => term
                        }
                      }
                    }.merge(script_score)
                  }
                }
              }
            end
            payload = {
              bool: {
                must: payload,
                should: shoulds
              }
            }
          end
        end

        custom_filters = []
        multiply_filters = []

        set_boost_by(multiply_filters, custom_filters)
        set_boost_where(custom_filters)
        set_boost_by_distance(custom_filters) if options[:boost_by_distance]

        if custom_filters.any?
          payload = {
            function_score: {
              functions: custom_filters,
              query: payload,
              score_mode: "sum"
            }
          }
        end

        if multiply_filters.any?
          payload = {
            function_score: {
              functions: multiply_filters,
              query: payload,
              score_mode: "multiply"
            }
          }
        end

        payload = {
          query: payload,
          size: per_page,
          from: offset
        }
        payload[:explain] = options[:explain] if options[:explain]
        payload[:profile] = options[:profile] if options[:profile]

        # order
        set_order(payload) if options[:order]

        # indices_boost
        set_boost_by_indices(payload)

        # filters
        filters = where_filters(options[:where])
        set_filters(payload, filters) if filters.any?

        # aggregations
        set_aggregations(payload) if options[:aggs]

        # suggestions
        set_suggestions(payload) if options[:suggest]

        # highlight
        set_highlights(payload, fields) if options[:highlight]

        # timeout shortly after client times out
        payload[:timeout] ||= "#{Searchkick.search_timeout + 1}s"

        # An empty array will cause only the _id and _type for each hit to be returned
        # doc for :select - http://www.elasticsearch.org/guide/reference/api/search/fields/
        # doc for :select_v2 - https://www.elastic.co/guide/en/elasticsearch/reference/current/search-request-source-filtering.html
        if options[:select]
          if options[:select] == []
            # intuitively [] makes sense to return no fields, but ES by default returns all fields
            payload[:_source] = false
          else
            payload[:_source] = options[:select]
          end
        elsif load
          payload[:_source] = false
        end

        if options[:type] || (klass != searchkick_klass && searchkick_index)
          @type = [options[:type] || klass].flatten.map { |v| searchkick_index.klass_document_type(v) }
        end

        # routing
        @routing = options[:routing] if options[:routing]
      end

      # merge more body options
      payload = payload.deep_merge(options[:body_options]) if options[:body_options]

      @body = payload
      @page = page
      @per_page = per_page
      @padding = padding
      @load = load
    end

    def set_fields
      boost_fields = {}
      fields = options[:fields] || searchkick_options[:searchable]
      fields =
        if fields
          fields.map do |value|
            k, v = value.is_a?(Hash) ? value.to_a.first : [value, options[:match] || searchkick_options[:match] || :word]
            k2, boost = k.to_s.split("^", 2)
            field = "#{k2}.#{v == :word ? 'analyzed' : v}"
            boost_fields[field] = boost.to_f if boost
            field
          end
        else
          ["_all"]
        end
      [boost_fields, fields]
    end

    def set_boost_by_distance(custom_filters)
      boost_by_distance = options[:boost_by_distance] || {}

      # legacy format
      if boost_by_distance[:field]
        boost_by_distance = {boost_by_distance[:field] => boost_by_distance.except(:field)}
      end

      boost_by_distance.each do |field, attributes|
        attributes = {function: :gauss, scale: "5mi"}.merge(attributes)
        unless attributes[:origin]
          raise ArgumentError, "boost_by_distance requires :origin"
        end
        function_params = attributes.select { |k, _| [:origin, :scale, :offset, :decay].include?(k) }
        function_params[:origin] = location_value(function_params[:origin])
        custom_filters << {
          attributes[:function] => {
            field => function_params
          }
        }
      end
    end

    def set_boost_by(multiply_filters, custom_filters)
      boost_by = options[:boost_by] || {}
      if boost_by.is_a?(Array)
        boost_by = Hash[boost_by.map { |f| [f, {factor: 1}] }]
      elsif boost_by.is_a?(Hash)
        multiply_by, boost_by = boost_by.partition { |_, v| v[:boost_mode] == "multiply" }.map { |i| Hash[i] }
      end
      boost_by[options[:boost]] = {factor: 1} if options[:boost]

      custom_filters.concat boost_filters(boost_by, log: true)
      multiply_filters.concat boost_filters(multiply_by || {})
    end

    def set_boost_where(custom_filters)
      boost_where = options[:boost_where] || {}
      boost_where.each do |field, value|
        if value.is_a?(Array) && value.first.is_a?(Hash)
          value.each do |value_factor|
            custom_filters << custom_filter(field, value_factor[:value], value_factor[:factor])
          end
        elsif value.is_a?(Hash)
          custom_filters << custom_filter(field, value[:value], value[:factor])
        else
          factor = 1000
          custom_filters << custom_filter(field, value, factor)
        end
      end
    end

    def set_boost_by_indices(payload)
      return unless options[:indices_boost]

      indices_boost = options[:indices_boost].each_with_object({}) do |(key, boost), memo|
        index = key.respond_to?(:searchkick_index) ? key.searchkick_index.name : key
        # try to use index explicitly instead of alias: https://github.com/elasticsearch/elasticsearch/issues/4756
        index_by_alias = Searchkick.client.indices.get_alias(index: index).keys.first
        memo[index_by_alias || index] = boost
      end

      payload[:indices_boost] = indices_boost
    end

    def set_suggestions(payload)
      suggest_fields = (searchkick_options[:suggest] || []).map(&:to_s)

      # intersection
      if options[:fields]
        suggest_fields &= options[:fields].map { |v| (v.is_a?(Hash) ? v.keys.first : v).to_s.split("^", 2).first }
      end

      if suggest_fields.any?
        payload[:suggest] = {text: term}
        suggest_fields.each do |field|
          payload[:suggest][field] = {
            phrase: {
              field: "#{field}.suggest"
            }
          }
        end
      end
    end

    def set_highlights(payload, fields)
      payload[:highlight] = {
        fields: Hash[fields.map { |f| [f, {}] }]
      }

      if options[:highlight].is_a?(Hash)
        if (tag = options[:highlight][:tag])
          payload[:highlight][:pre_tags] = [tag]
          payload[:highlight][:post_tags] = [tag.to_s.gsub(/\A<(\w+).+/, "</\\1>")]
        end

        if (fragment_size = options[:highlight][:fragment_size])
          payload[:highlight][:fragment_size] = fragment_size
        end
        if (encoder = options[:highlight][:encoder])
          payload[:highlight][:encoder] = encoder
        end

        highlight_fields = options[:highlight][:fields]
        if highlight_fields
          payload[:highlight][:fields] = {}

          highlight_fields.each do |name, opts|
            payload[:highlight][:fields]["#{name}.#{@match_suffix}"] = opts || {}
          end
        end
      end

      @highlighted_fields = payload[:highlight][:fields].keys
    end

    def set_aggregations(payload)
      aggs = options[:aggs]
      payload[:aggs] = {}

      aggs = Hash[aggs.map { |f| [f, {}] }] if aggs.is_a?(Array) # convert to more advanced syntax

      aggs.each do |field, agg_options|
        size = agg_options[:limit] ? agg_options[:limit] : 1_000
        shared_agg_options = agg_options.slice(:order, :min_doc_count)

        if agg_options[:ranges]
          payload[:aggs][field] = {
            range: {
              field: agg_options[:field] || field,
              ranges: agg_options[:ranges]
            }.merge(shared_agg_options)
          }
        elsif agg_options[:date_ranges]
          payload[:aggs][field] = {
            date_range: {
              field: agg_options[:field] || field,
              ranges: agg_options[:date_ranges]
            }.merge(shared_agg_options)
          }
        elsif histogram = agg_options[:date_histogram]
          interval = histogram[:interval]
          payload[:aggs][field] = {
            date_histogram: {
              field: histogram[:field],
              interval: interval
            }
          }
        else
          payload[:aggs][field] = {
            terms: {
              field: agg_options[:field] || field,
              size: size
            }.merge(shared_agg_options)
          }
        end

        where = {}
        where = (options[:where] || {}).reject { |k| k == field } unless options[:smart_aggs] == false
        agg_filters = where_filters(where.merge(agg_options[:where] || {}))
        if agg_filters.any?
          payload[:aggs][field] = {
            filter: {
              bool: {
                must: agg_filters
              }
            },
            aggs: {
              field => payload[:aggs][field]
            }
          }
        end
      end
    end

    def set_filters(payload, filters)
      if options[:aggs]
        payload[:post_filter] = {
          bool: {
            filter: filters
          }
        }
      else
        # more efficient query if no aggs
        payload[:query] = {
          bool: {
            must: payload[:query],
            filter: filters
          }
        }
      end
    end

    # TODO id transformation for arrays
    def set_order(payload)
      order = options[:order].is_a?(Enumerable) ? options[:order] : {options[:order] => :asc}
      id_field = below50? ? :_id : :_uid
      payload[:sort] = order.is_a?(Array) ? order : Hash[order.map { |k, v| [k.to_s == "id" ? id_field : k, v] }]
    end

    def where_filters(where)
      filters = []
      (where || {}).each do |field, value|
        field = :_id if field.to_s == "id"

        if field == :or
          value.each do |or_clause|
            filters << {bool: {should: or_clause.map { |or_statement| {bool: {filter: where_filters(or_statement)}} }}}
          end
        elsif field == :_or
          filters << {bool: {should: value.map { |or_statement| {bool: {filter: where_filters(or_statement)}} }}}
        elsif field == :_not
          filters << {bool: {must_not: where_filters(value)}}
        elsif field == :_and
          filters << {bool: {must: value.map { |or_statement| {bool: {filter: where_filters(or_statement)}} }}}
        else
          # expand ranges
          if value.is_a?(Range)
            value = {gte: value.first, (value.exclude_end? ? :lt : :lte) => value.last}
          end

          value = {in: value} if value.is_a?(Array)

          if value.is_a?(Hash)
            value.each do |op, op_value|
              case op
              when :within, :bottom_right
                # do nothing
              when :near
                filters << {
                  geo_distance: {
                    field => location_value(op_value),
                    distance: value[:within] || "50mi"
                  }
                }
              when :geo_polygon
                filters << {
                  geo_polygon: {
                    field => op_value
                  }
                }
              when :geo_shape
                shape = op_value.except(:relation)
                shape[:coordinates] = coordinate_array(shape[:coordinates]) if shape[:coordinates]
                filters << {
                  geo_shape: {
                    field => {
                      relation: op_value[:relation] || "intersects",
                      shape: shape
                    }
                  }
                }
              when :top_left
                filters << {
                  geo_bounding_box: {
                    field => {
                      top_left: location_value(op_value),
                      bottom_right: location_value(value[:bottom_right])
                    }
                  }
                }
              when :regexp # support for regexp queries without using a regexp ruby object
                filters << {regexp: {field => {value: op_value}}}
              when :not # not equal
                filters << {bool: {must_not: term_filters(field, op_value)}}
              when :all
                op_value.each do |val|
                  filters << term_filters(field, val)
                end
              when :in
                filters << term_filters(field, op_value)
              else
                range_query =
                  case op
                  when :gt
                    {from: op_value, include_lower: false}
                  when :gte
                    {from: op_value, include_lower: true}
                  when :lt
                    {to: op_value, include_upper: false}
                  when :lte
                    {to: op_value, include_upper: true}
                  else
                    raise "Unknown where operator: #{op.inspect}"
                  end
                # issue 132
                if (existing = filters.find { |f| f[:range] && f[:range][field] })
                  existing[:range][field].merge!(range_query)
                else
                  filters << {range: {field => range_query}}
                end
              end
            end
          else
            filters << term_filters(field, value)
          end
        end
      end
      filters
    end

    def term_filters(field, value)
      if value.is_a?(Array) # in query
        if value.any?(&:nil?)
          {bool: {should: [term_filters(field, nil), term_filters(field, value.compact)]}}
        else
          {in: {field => value}}
        end
      elsif value.nil?
        {bool: {must_not: {exists: {field: field}}}}
      elsif value.is_a?(Regexp)
        {regexp: {field => {value: value.source}}}
      else
        {term: {field => value}}
      end
    end

    def custom_filter(field, value, factor)
      if below50?
        {
          filter: {
            bool: {
              must: where_filters(field => value)
            }
          },
          boost_factor: factor
        }
      else
        {
          filter: where_filters(field => value),
          weight: factor
        }
      end
    end

    def boost_filters(boost_by, options = {})
      boost_by.map do |field, value|
        log = value.key?(:log) ? value[:log] : options[:log]
        value[:factor] ||= 1
        script_score = {
          field_value_factor: {
            field: field,
            factor: value[:factor].to_f,
            modifier: log ? "ln2p" : nil
          }
        }

        {
          filter: {
            exists: {
              field: field
            }
          }
        }.merge(script_score)
      end
    end

    # Recursively descend through nesting of arrays until we reach either a lat/lon object or an array of numbers,
    # eventually returning the same structure with all values transformed to [lon, lat].
    #
    def coordinate_array(value)
      if value.is_a?(Hash)
        [value[:lon], value[:lat]]
      elsif value.is_a?(Array) and !value[0].is_a?(Numeric)
        value.map { |a| coordinate_array(a) }
      else
        value
      end
    end

    def location_value(value)
      if value.is_a?(Array)
        value.map(&:to_f).reverse
      else
        value
      end
    end

    def below50?
      Searchkick.server_below?("5.0.0-alpha1")
    end
  end
end