module Csv
  class SalesLogCsvService
    def initialize(user:, export_type:, year:)
      @user = user
      @export_type = export_type
      @year = year
      @attributes = sales_log_attributes
    end

    def prepare_csv(logs)
      CSV.generate(headers: true) do |csv|
        csv << formatted_attribute_headers

        logs.find_each do |log|
          csv << @attributes.map { |attribute| value(attribute, log) }
        end
      end
    end

  private

    CUSTOM_CALL_CHAINS = {
      day: {
        labels: %i[saledate day],
        codes: %i[saledate day],
      },
      month: {
        labels: %i[saledate month],
        codes: %i[saledate month],
      },
      year: {
        labels: %i[saledate year],
        codes: %i[saledate year],
      },
      is_dpo: {
        labels: %i[assigned_to is_dpo],
        codes: %i[assigned_to is_dpo],
      },
      assigned_to: {
        labels: %i[assigned_to email],
        codes: %i[assigned_to email],
      },
      created_by: {
        labels: %i[created_by email],
        codes: %i[created_by email],
      },
      owning_organisation_name: {
        labels: %i[owning_organisation name],
        codes: %i[owning_organisation name],
      },
      managing_organisation_name: {
        labels: %i[managing_organisation name],
        codes: %i[managing_organisation name],
      },
      creation_method: {
        labels: %i[creation_method],
        codes: %i[creation_method_before_type_cast],
      },
      mscharge_value_check: {
        labels: %i[monthly_charges_value_check],
        codes: %i[monthly_charges_value_check],
      },
    }.freeze

    PERSON_DETAILS = {}.tap { |hash|
      hash["age1"] = { "refused_code" => "-9", "refused_label" => "Not known", "age_known_field" => "age1_known" }
      (2..6).each do |i|
        hash["age#{i}"] = { "refused_code" => "-9", "refused_label" => "Not known", "details_known_field" => "details_known_#{i}", "age_known_field" => "age#{i}_known" }
        hash["sex#{i}"] = { "refused_code" => "R", "refused_label" => "Prefers not to say", "details_known_field" => "details_known_#{i}" }
        hash["relat#{i}"] = { "refused_code" => "R", "refused_label" => "Prefers not to say", "details_known_field" => "details_known_#{i}" }
        hash["ecstat#{i}"] = { "refused_code" => "10", "refused_label" => "Prefers not to say", "details_known_field" => "details_known_#{i}" }
      end
    }.freeze

    FIELDS_ALWAYS_EXPORTED_AS_CODES = %w[
      la
      prevloc
    ].freeze

    FIELDS_ALWAYS_EXPORTED_AS_LABELS = {
      "la_label" => "la",
      "prevloc_label" => "prevloc",
    }.freeze

    SYSTEM_DATE_FIELDS = %w[
      created_at
      updated_at
    ].freeze

    ORDERED_ADDRESS_FIELDS = %w[uprn address_line1 address_line2 town_or_city county postcode_full is_la_inferred la_label la uprn_selection address_search_value_check address_line1_input postcode_full_input address_line1_as_entered address_line2_as_entered town_or_city_as_entered county_as_entered postcode_full_as_entered la_as_entered].freeze

    SUPPORT_ONLY_ATTRIBUTES = %w[address_line1_as_entered address_line2_as_entered town_or_city_as_entered county_as_entered postcode_full_as_entered la_as_entered created_by value_value_check mscharge_value_check].freeze

    SUPPORT_ATTRIBUTE_NAME_MAPPINGS = {
      "duplicate_set_id" => "DUPLICATESET",
      "bulk_upload_id" => "BULKUPLOADID",
      "created_at" => "CREATEDDATE",
      "updated_at" => "UPLOADDATE",
      "old_form_id" => "FORM",
      "collection_start_year" => "COLLECTIONYEAR",
      "creation_method" => "CREATIONMETHOD",
      "is_dpo" => "DATAPROTECT",
      "created_by" => "CREATEDBY",
      "owning_organisation_name" => "OWNINGORGNAME",
      "managing_organisation_name" => "MANINGORGNAME",
      "assigned_to" => "USERNAME",
      "ownershipsch" => "OWNERSHIP",
      "companybuy" => "COMPANY",
      "buylivein" => "LIVEINBUYER",
      "jointpur" => "JOINT",
      "address_line1" => "ADDRESS1",
      "address_line2" => "ADDRESS2",
      "town_or_city" => "TOWNCITY",
      "postcode_full" => "POSTCODE",
      "is_la_inferred" => "ISLAINFERRED",
      "la_label" => "LANAME",
      "uprn_selection" => "UPRNSELECTED",
      "address_line1_input" => "ADDRESS1INPUT",
      "postcode_full_input" => "POSTCODEINPUT",
      "address_line1_as_entered" => "BULKADDRESS1",
      "address_line2_as_entered" => "BULKADDRESS2",
      "town_or_city_as_entered" => "BULKTOWNCITY",
      "county_as_entered" => "BULKCOUNTY",
      "postcode_full_as_entered" => "BULKPOSTCODE",
      "la_as_entered" => "BULKLA",
      "ethnic_group" => "ETHNICGROUP1",
      "nationality_all" => "NATIONALITYALL1",
      "buy1livein" => "LIVEINBUYER1",
      "ethnic_group2" => "ETHNICGROUP2",
      "ethnicbuy2" => "ETHNIC2",
      "nationality_all_buyer2" => "NATIONALITYALL2",
      "buy2livein" => "LIVEINBUYER2",
      "hholdcount" => "HHTYPE",
      "previous_la_known" => "PREVIOUSLAKNOWN",
      "prevloc_label" => "PREVLOCNAME",
      "prevtenbuy2" => "PREVTEN2",
      "income1nk" => "INC1NK",
      "income2nk" => "INC2NK",
      "staircasesale" => "STAIRCASETOSALE",
      "soctenant" => "SOCTEN",
      "mortlen" => "MORTLEN1",
      "has_mscharge" => "HASMSCHARGE",
      "nationalbuy2" => "NATIONAL2",
      "uprn_confirmed" => "UPRNCONFIRMED",
    }.freeze

    def formatted_attribute_headers
      return @attributes unless @user.support?

      @attributes.map do |attribute|
        SUPPORT_ATTRIBUTE_NAME_MAPPINGS[attribute] || attribute.upcase
      end
    end

    def sales_log_attributes
      ordered_questions = FormHandler.instance.ordered_questions_for_year(@year, "sales")
      ordered_questions.reject! { |q| q.id.match?(/((?<!la)_known)|(_check)|(_asked)|nationality_all_group|nationality_all_buyer2_group/) }
      attributes = insert_derived_and_related_attributes(ordered_questions)
      order_address_fields_for_support(attributes)
      final_attributes = non_question_fields + attributes
      @user.support? ? final_attributes : final_attributes - SUPPORT_ONLY_ATTRIBUTES
    end

    def insert_derived_and_related_attributes(ordered_questions)
      ordered_questions.flat_map do |question|
        if question.type == "checkbox"
          question.answer_options.keys
        elsif attribute_mappings.key? question.id
          attribute_mappings[question.id]
        else
          question.id
        end
      end
    end

    def attribute_mappings
      mappings = {
        "saledate" => %w[day month year],
        "exdate" => %w[exday exmonth exyear],
        "hodate" => %w[hoday homonth hoyear],
        "ppostcode_full" => %w[ppostc1 ppostc2],
        "la" => %w[la la_label],
        "prevloc" => %w[prevloc prevloc_label],
        "assigned_to_id" => %w[created_by assigned_to],
        "owning_organisation_id" => %w[owning_organisation_name],
        "managing_organisation_id" => %w[managing_organisation_name],
        "value" => %w[value value_value_check],
        "mscharge" => %w[mscharge mscharge_value_check],
      }
      unless @user.support? && @year >= 2024
        mappings["postcode_full"] = %w[pcode1 pcode2]
      end
      mappings
    end

    def order_address_fields_for_support(attributes)
      if @user.support? && @year >= 2024
        first_address_field_index = attributes.find_index { |q| all_address_fields.include?(q) }
        if first_address_field_index
          attributes.reject! { |q| all_address_fields.include?(q) }
          attributes.insert(first_address_field_index, *ORDERED_ADDRESS_FIELDS)
        end
      end
    end

    def non_question_fields
      case @year
      when 2022
        %w[id status created_at updated_at old_form_id collection_start_year creation_method is_dpo]
      when 2023
        %w[id status duplicate_set_id created_at updated_at old_form_id collection_start_year creation_method is_dpo]
      when 2024
        %w[id status duplicate_set_id created_at updated_at collection_start_year creation_method bulk_upload_id is_dpo]
      else
        %w[id status duplicate_set_id created_at updated_at collection_start_year creation_method bulk_upload_id is_dpo]
      end
    end

    def all_address_fields
      ORDERED_ADDRESS_FIELDS + %w[uprn_confirmed]
    end

    def value(attribute, log)
      if CUSTOM_CALL_CHAINS.key? attribute.to_sym
        call_chain = CUSTOM_CALL_CHAINS[attribute.to_sym][@export_type.to_sym]
        call_chain.reduce(log) { |object, next_call| object&.public_send(next_call) }
      elsif FIELDS_ALWAYS_EXPORTED_AS_CODES.include? attribute
        log.send(attribute)
      elsif FIELDS_ALWAYS_EXPORTED_AS_LABELS.key? attribute
        attribute = FIELDS_ALWAYS_EXPORTED_AS_LABELS[attribute]
        value = log.send(attribute)
        get_label(value, attribute, log)
      elsif SYSTEM_DATE_FIELDS.include? attribute
        log.public_send(attribute)&.iso8601
      elsif PERSON_DETAILS.key?(attribute) && (person_details_not_known?(log, attribute) || age_not_known?(log, attribute))
        case @export_type
        when "codes"
          PERSON_DETAILS.find { |key, _value| key == attribute }[1]["refused_code"]
        when "labels"
          PERSON_DETAILS.find { |key, _value| key == attribute }[1]["refused_label"]
        end
      else
        value = log.public_send(attribute)
        case @export_type
        when "codes"
          value
        when "labels"
          answer_label = get_label(value, attribute, log)
          answer_label || label_if_boolean_value(value) || value
        end
      end
    end

    def person_details_not_known?(log, attribute)
      details_known_field = PERSON_DETAILS.find { |key, _value| key == attribute }[1]["details_known_field"]
      log[details_known_field] == 2 # 1 for lettings logs, 2 for sales logs
    end

    def age_not_known?(log, attribute)
      age_known_field = PERSON_DETAILS.find { |key, _value| key == attribute }[1]["age_known_field"]
      log[age_known_field] == 1
    end

    def get_label(value, attribute, log)
      log.form
         .get_question(attribute, log)
         &.label_from_value(value)
    end

    def label_if_boolean_value(value)
      return "Yes" if value == true
      return "No" if value == false
    end
  end
end