module ReportParsers
  class Form13Parser < BaseParser
    SHEET_NAME = 'Отчет об изменениях капитала'
    FORM_CODE = '1.3'

    def call
      return {} unless sheet_exists?(SHEET_NAME)

      sheet = spreadsheet.sheet(SHEET_NAME)
      build_payloads(sheet)
    end

    private

    def build_payloads(sheet)
      header_row = find_section1_header_row(sheet)
      return {} unless header_row

      report_year = extract_report_year(sheet)
      return {} unless report_year

      name_col  = find_name_column(sheet, header_row)
      code_col  = find_code_column(sheet, header_row)
      total_col = find_total_column(sheet, header_row)
      return {} unless code_col && total_col

      end_row = section1_end_row(sheet, header_row)
      payloads_by_year = {}

      (header_row + 2).upto(end_row) do |row|
        line_code = read_cell(sheet, row, code_col).to_s.strip.presence
        next unless line_code&.match?(/\A3[123]\d{2}\z/)

        row_year = year_from_code(line_code, report_year)
        next unless row_year

        name_cell = read_cell(sheet, row, name_col).to_s.strip
        name_cell = read_cell(sheet, row, 1).to_s.strip if name_cell.blank?
        value = read_cell(sheet, row, total_col)

        payloads_by_year[row_year] ||= { form_code: FORM_CODE, sheet_name: SHEET_NAME, rows: [] }
        payloads_by_year[row_year][:rows] << {
          line_name: normalize_line_name(name_cell),
          line_code: line_code,
          value: value
        }
      end

      payloads_by_year
    end

    def year_from_code(code, report_year)
      case code[1]
      when '1' then report_year - 2
      when '2' then report_year - 1
      when '3' then report_year
      end
    end

    def extract_report_year(sheet)
      1.upto([sheet.last_row, 10].min) do |row|
        1.upto(sheet.last_column) do |col|
          m = sheet.cell(row, col).to_s.match(/\bза\s+(20\d{2})\s*г/i)
          return m[1].to_i if m
        end
      end
      year = yearly_file&.year.to_i
      year.positive? ? year : nil
    end

    def find_section1_header_row(sheet)
      1.upto(sheet.last_row) do |row|
        cells = 1.upto(sheet.last_column).map { |col| normalize_label(sheet.cell(row, col)) }
        next unless cells.any? { |c| c.include?('наименование показателя') }
        next unless cells.any? { |c| c.include?('код строки') || c == 'код' }

        return row
      end
      nil
    end

    def find_name_column(sheet, header_row)
      1.upto(sheet.last_column) do |col|
        return col if normalize_label(sheet.cell(header_row, col)).include?('наименование показателя')
      end
      1
    end

    def find_code_column(sheet, header_row)
      1.upto(sheet.last_column) do |col|
        text = normalize_label(sheet.cell(header_row, col))
        return col if text.include?('код строки') || text == 'код'
      end
      nil
    end

    def find_total_column(sheet, header_row)
      result = nil
      [header_row, header_row + 1].each do |row|
        1.upto(sheet.last_column) do |col|
          result = col if normalize_label(sheet.cell(row, col)) == 'итого'
        end
        return result if result
      end
      nil
    end

    def section1_end_row(sheet, from_row)
      (from_row + 1).upto(sheet.last_row) do |row|
        return row - 1 if normalize_label(sheet.cell(row, 1)).match?(/\A2\.\s*корректировки/i)
      end
      sheet.last_row
    end
  end
end