require "csv"

class BulkUpload::Sales::Year2022::CsvParser
  MAX_COLUMNS = 126
  FORM_YEAR = 2022

  attr_reader :path

  def initialize(path:)
    @path = path
  end

  def row_offset
    with_headers? ? 5 : 0
  end

  def col_offset
    with_headers? ? 1 : 0
  end

  def cols
    @cols ||= ("A".."DV").to_a
  end

  def row_parsers
    @row_parsers ||= body_rows.map do |row|
      stripped_row = row[col_offset..]
      headers = ("field_1".."field_125").to_a
      hash = Hash[headers.zip(stripped_row)]

      BulkUpload::Sales::Year2022::RowParser.new(hash)
    end
  end

  def body_rows
    rows[row_offset..]
  end

  def rows
    @rows ||= CSV.parse(normalised_string, row_sep:)
  end

  def column_for_field(field)
    cols[headers.find_index(field) + col_offset]
  end

  def wrong_template_for_year?
    !(first_record_sale_date >= form.start_date && first_record_sale_date <= form.end_date)
  end

private

  def form
    @form ||= FormHandler.instance.sales_form_for_start_year(FORM_YEAR)
  end

  def first_record_sale_date
    @first_record_sale_date ||= row_parsers.first.saledate || Date.new
  end

  def headers
    @headers ||= ("field_1".."field_125").to_a
  end

  def with_headers?
    rows.map { |r| r[0] }.any? { |cell| cell&.match?(/field number/i) }
  end

  def row_sep
    "\n"
  end

  def normalised_string
    return @normalised_string if @normalised_string

    @normalised_string = File.read(path, encoding: "bom|utf-8")
    @normalised_string.gsub!("\r\n", "\n")
    @normalised_string.scrub!("")
    @normalised_string.tr!("\r", "\n")

    @normalised_string
  end
end