module Searchkick
  module IndexOptions
    def index_options
      options = @options
      language = options[:language]
      language = language.call if language.respond_to?(:call)
      index_type = options[:_type]
      index_type = index_type.call if index_type.respond_to?(:call)

      if options[:mappings] && !options[:merge_mappings]
        settings = options[:settings] || {}
        mappings = options[:mappings]
      else
        below60 = Searchkick.server_below?("6.0.0")
        below62 = Searchkick.server_below?("6.2.0")

        default_type = "text"
        default_analyzer = :searchkick_index
        keyword_mapping = {type: "keyword"}

        all = options.key?(:_all) ? options[:_all] : false
        index_true_value = true
        index_false_value = false

        keyword_mapping[:ignore_above] = options[:ignore_above] || 30000

        settings = {
          analysis: {
            analyzer: {
              searchkick_keyword: {
                type: "custom",
                tokenizer: "keyword",
                filter: ["lowercase"] + (options[:stem_conversions] ? ["searchkick_stemmer"] : [])
              },
              default_analyzer => {
                type: "custom",
                # character filters -> tokenizer -> token filters
                # https://www.elastic.co/guide/en/elasticsearch/guide/current/analysis-intro.html
                char_filter: ["ampersand"],
                tokenizer: "standard",
                # synonym should come last, after stemming and shingle
                # shingle must come before searchkick_stemmer
                filter: ["standard", "lowercase", "asciifolding", "searchkick_index_shingle", "searchkick_stemmer"]
              },
              searchkick_search: {
                type: "custom",
                char_filter: ["ampersand"],
                tokenizer: "standard",
                filter: ["standard", "lowercase", "asciifolding", "searchkick_search_shingle", "searchkick_stemmer"]
              },
              searchkick_search2: {
                type: "custom",
                char_filter: ["ampersand"],
                tokenizer: "standard",
                filter: ["standard", "lowercase", "asciifolding", "searchkick_stemmer"]
              },
              # https://github.com/leschenko/elasticsearch_autocomplete/blob/master/lib/elasticsearch_autocomplete/analyzers.rb
              searchkick_autocomplete_search: {
                type: "custom",
                tokenizer: "keyword",
                filter: ["lowercase", "asciifolding"]
              },
              searchkick_word_search: {
                type: "custom",
                tokenizer: "standard",
                filter: ["lowercase", "asciifolding"]
              },
              searchkick_suggest_index: {
                type: "custom",
                tokenizer: "standard",
                filter: ["lowercase", "asciifolding", "searchkick_suggest_shingle"]
              },
              searchkick_text_start_index: {
                type: "custom",
                tokenizer: "keyword",
                filter: ["lowercase", "asciifolding", "searchkick_edge_ngram"]
              },
              searchkick_text_middle_index: {
                type: "custom",
                tokenizer: "keyword",
                filter: ["lowercase", "asciifolding", "searchkick_ngram"]
              },
              searchkick_text_end_index: {
                type: "custom",
                tokenizer: "keyword",
                filter: ["lowercase", "asciifolding", "reverse", "searchkick_edge_ngram", "reverse"]
              },
              searchkick_word_start_index: {
                type: "custom",
                tokenizer: "standard",
                filter: ["lowercase", "asciifolding", "searchkick_edge_ngram"]
              },
              searchkick_word_middle_index: {
                type: "custom",
                tokenizer: "standard",
                filter: ["lowercase", "asciifolding", "searchkick_ngram"]
              },
              searchkick_word_end_index: {
                type: "custom",
                tokenizer: "standard",
                filter: ["lowercase", "asciifolding", "reverse", "searchkick_edge_ngram", "reverse"]
              }
            },
            filter: {
              searchkick_index_shingle: {
                type: "shingle",
                token_separator: ""
              },
              # lucky find http://web.archiveorange.com/archive/v/AAfXfQ17f57FcRINsof7
              searchkick_search_shingle: {
                type: "shingle",
                token_separator: "",
                output_unigrams: false,
                output_unigrams_if_no_shingles: true
              },
              searchkick_suggest_shingle: {
                type: "shingle",
                max_shingle_size: 5
              },
              searchkick_edge_ngram: {
                type: "edgeNGram",
                min_gram: 1,
                max_gram: 50
              },
              searchkick_ngram: {
                type: "nGram",
                min_gram: 1,
                max_gram: 50
              },
              searchkick_stemmer: {
                # use stemmer if language is lowercase, snowball otherwise
                type: language == language.to_s.downcase ? "stemmer" : "snowball",
                language: language || "English"
              }
            },
            char_filter: {
              # https://www.elastic.co/guide/en/elasticsearch/guide/current/custom-analyzers.html
              # &_to_and
              ampersand: {
                type: "mapping",
                mappings: ["&=> and "]
              }
            }
          }
        }

        case language
        when "chinese"
          settings[:analysis][:analyzer].merge!(
            default_analyzer => {
              type: "ik_smart"
            },
            searchkick_search: {
              type: "ik_smart"
            },
            searchkick_search2: {
              type: "ik_max_word"
            }
          )

          settings[:analysis][:filter].delete(:searchkick_stemmer)
        when "japanese"
          settings[:analysis][:analyzer].merge!(
            default_analyzer => {
              type: "kuromoji"
            },
            searchkick_search: {
              type: "kuromoji"
            },
            searchkick_search2: {
              type: "kuromoji"
            }
          )
        when "korean"
          settings[:analysis][:analyzer].merge!(
            default_analyzer => {
              type: "openkoreantext-analyzer"
            },
            searchkick_search: {
              type: "openkoreantext-analyzer"
            },
            searchkick_search2: {
              type: "openkoreantext-analyzer"
            }
          )
        when "vietnamese"
          settings[:analysis][:analyzer].merge!(
            default_analyzer => {
              type: "vi_analyzer"
            },
            searchkick_search: {
              type: "vi_analyzer"
            },
            searchkick_search2: {
              type: "vi_analyzer"
            }
          )
        when "polish", "ukrainian", "smartcn"
          settings[:analysis][:analyzer].merge!(
            default_analyzer => {
              type: language
            },
            searchkick_search: {
              type: language
            },
            searchkick_search2: {
              type: language
            }
          )
        end

        if Searchkick.env == "test"
          settings[:number_of_shards] = 1
          settings[:number_of_replicas] = 0
        end

        if options[:similarity]
          settings[:similarity] = {default: {type: options[:similarity]}}
        end

        unless below62
          settings[:index] = {
            max_ngram_diff: 49,
            max_shingle_diff: 4
          }
        end

        settings.deep_merge!(options[:settings] || {})

        # synonyms
        synonyms = options[:synonyms] || []

        synonyms = synonyms.call if synonyms.respond_to?(:call)

        if synonyms.any?
          settings[:analysis][:filter][:searchkick_synonym] = {
            type: "synonym",
            # only remove a single space from synonyms so three-word synonyms will fail noisily instead of silently
            synonyms: synonyms.select { |s| s.size > 1 }.map { |s| s.is_a?(Array) ? s.map { |s2| s2.sub(/\s+/, "") }.join(",") : s }.map(&:downcase)
          }
          # choosing a place for the synonym filter when stemming is not easy
          # https://groups.google.com/forum/#!topic/elasticsearch/p7qcQlgHdB8
          # TODO use a snowball stemmer on synonyms when creating the token filter

          # http://elasticsearch-users.115913.n3.nabble.com/synonym-multi-words-search-td4030811.html
          # I find the following approach effective if you are doing multi-word synonyms (synonym phrases):
          # - Only apply the synonym expansion at index time
          # - Don't have the synonym filter applied search
          # - Use directional synonyms where appropriate. You want to make sure that you're not injecting terms that are too general.
          settings[:analysis][:analyzer][default_analyzer][:filter].insert(4, "searchkick_synonym") if below60
          settings[:analysis][:analyzer][default_analyzer][:filter] << "searchkick_synonym"

          %w(word_start word_middle word_end).each do |type|
            settings[:analysis][:analyzer]["searchkick_#{type}_index".to_sym][:filter].insert(2, "searchkick_synonym")
          end
        end

        if options[:wordnet]
          settings[:analysis][:filter][:searchkick_wordnet] = {
            type: "synonym",
            format: "wordnet",
            synonyms_path: Searchkick.wordnet_path
          }

          settings[:analysis][:analyzer][default_analyzer][:filter].insert(4, "searchkick_wordnet")
          settings[:analysis][:analyzer][default_analyzer][:filter] << "searchkick_wordnet"

          %w(word_start word_middle word_end).each do |type|
            settings[:analysis][:analyzer]["searchkick_#{type}_index".to_sym][:filter].insert(2, "searchkick_wordnet")
          end
        end

        if options[:special_characters] == false
          settings[:analysis][:analyzer].each_value do |analyzer_settings|
            analyzer_settings[:filter].reject! { |f| f == "asciifolding" }
          end
        end

        mapping = {}

        # conversions
        Array(options[:conversions]).each do |conversions_field|
          mapping[conversions_field] = {
            type: "nested",
            properties: {
              query: {type: default_type, analyzer: "searchkick_keyword"},
              count: {type: "integer"}
            }
          }
        end

        mapping_options = Hash[
          [:suggest, :word, :text_start, :text_middle, :text_end, :word_start, :word_middle, :word_end, :highlight, :searchable, :filterable]
            .map { |type| [type, (options[type] || []).map(&:to_s)] }
        ]

        word = options[:word] != false && (!options[:match] || options[:match] == :word)

        mapping_options[:searchable].delete("_all")

        analyzed_field_options = {type: default_type, index: index_true_value, analyzer: default_analyzer}

        mapping_options.values.flatten.uniq.each do |field|
          fields = {}

          if options.key?(:filterable) && !mapping_options[:filterable].include?(field)
            fields[field] = {type: default_type, index: index_false_value}
          else
            fields[field] = keyword_mapping
          end

          if !options[:searchable] || mapping_options[:searchable].include?(field)
            if word
              fields["analyzed"] = analyzed_field_options

              if mapping_options[:highlight].include?(field)
                fields["analyzed"][:term_vector] = "with_positions_offsets"
              end
            end

            mapping_options.except(:highlight, :searchable, :filterable, :word).each do |type, f|
              if options[:match] == type || f.include?(field)
                fields[type] = {type: default_type, index: index_true_value, analyzer: "searchkick_#{type}_index"}
              end
            end
          end

          mapping[field] = fields[field].merge(fields: fields.except(field))
        end

        (options[:locations] || []).map(&:to_s).each do |field|
          mapping[field] = {
            type: "geo_point"
          }
        end

        options[:geo_shape] = options[:geo_shape].product([{}]).to_h if options[:geo_shape].is_a?(Array)
        (options[:geo_shape] || {}).each do |field, shape_options|
          mapping[field] = shape_options.merge(type: "geo_shape")
        end

        if options[:inheritance]
          mapping[:type] = keyword_mapping
        end

        routing = {}
        if options[:routing]
          routing = {required: true}
          unless options[:routing] == true
            routing[:path] = options[:routing].to_s
          end
        end

        dynamic_fields = {
          # analyzed field must be the default field for include_in_all
          # http://www.elasticsearch.org/guide/reference/mapping/multi-field-type/
          # however, we can include the not_analyzed field in _all
          # and the _all index analyzer will take care of it
          "{name}" => keyword_mapping
        }

        if below60 && all
          dynamic_fields["{name}"][:include_in_all] = !options[:searchable]
        end

        if options.key?(:filterable)
          dynamic_fields["{name}"] = {type: default_type, index: index_false_value}
        end

        unless options[:searchable]
          if options[:match] && options[:match] != :word
            dynamic_fields[options[:match]] = {type: default_type, index: index_true_value, analyzer: "searchkick_#{options[:match]}_index"}
          end

          if word
            dynamic_fields["analyzed"] = analyzed_field_options
          end
        end

        # http://www.elasticsearch.org/guide/reference/mapping/multi-field-type/
        multi_field = dynamic_fields["{name}"].merge(fields: dynamic_fields.except("{name}"))

        mappings = {
          index_type => {
            properties: mapping,
            _routing: routing,
            # https://gist.github.com/kimchy/2898285
            dynamic_templates: [
              {
                string_template: {
                  match: "*",
                  match_mapping_type: "string",
                  mapping: multi_field
                }
              }
            ]
          }
        }

        if below60
          all_enabled = all && (!options[:searchable] || options[:searchable].to_a.map(&:to_s).include?("_all"))
          mappings[index_type][:_all] = all_enabled ? analyzed_field_options : {enabled: false}
        end

        mappings = mappings.deep_merge(options[:mappings] || {})
      end

      {
        settings: settings,
        mappings: mappings
      }
    end
  end
end