my beancount importers

converter_base.rb

module Converter
  class BaseConverter
    def initialize input_file, **options
      @input_file = input_file
      @options = options
    end

    def write output_file, force: false
      if output_file.exist? && !force
        puts "  NOT overwriting #{output_file}. remove dest file and rerun or specify 'force' flag"
      else
        Pathname.new(output_file).write convert
        puts "  written to #{output_file}."
      end
    end

    private def read
      # see https://qiita.com/kentakozuka/items/d874a572ddf6cc34213f
      NKF.nkf '-w -g', Pathname.new(@input_file).binread
    end

    protected def convert
      throw 'override me'
    end

  end
end

converter_wechatpay.rb

require_relative 'converter_base'

module Converter

  class WechatPay < BaseConverter
    def convert
      raw_rows.map {|row|
        p case row['交易类型']
          when /^微信红包/
            convert_red_packet row
          when '商户消费', /-退款$/, /扫二维码付款/
            convert_transaction_row row
          when '转账'
            convert_transfer_row row
          else
            throw row
          end
      }.flatten.join("\n")
    end

    def convert_red_packet hash
      date = hash['交易时间'].split[0]
      rmb_amount = hash['金额(元)'][1..-1] # to strip '¥'
      another_account_symbol = if hash['收/支'] == '收入' then '-' else '+' end

      if hash['交易类型'] === '微信红包' && hash['收/支'] === '收入'
        another_account = 'Income:Other'
      elsif hash['交易类型'] === '微信红包-退款' && hash['收/支'] === '收入'
        another_account = 'Expenses:Other'
      elsif hash['收/支'] === '支出'
        another_account = 'Expenses:Other'
      else
        throw "cannot figure out redpacket action: #{hash}"
      end
      [
        "#{date} * #{'微信红包'.to_json} #{hash['交易对方'].to_json}",
        "  #{another_account} #{another_account_symbol}#{rmb_amount}RMB ",
        "  #{@options[:account]}",
        '',
      ]
    end

    def convert_transaction_row hash
      date = hash['交易时间'].split[0]

      recipient = hash['交易对方']
      remark = hash['商品']
      another_account = 'Expenses:TODO'
      rmb_amount = hash['金额(元)'][1..-1] # to strip '¥'
      another_account_symbol = if hash['收/支'] == '收入' then '-' else '+' end

      [
        "#{date.tr('/', '-')} * #{recipient.to_json} #{remark.to_json}",
        "  #{another_account} #{another_account_symbol}#{rmb_amount}RMB",
        "  #{@options[:account]}",
        '',
      ]
    end

    def convert_transfer_row hash
      date = hash['交易时间'].split[0]
      recipient = hash['交易对方']
      remark = hash['商品']
      rmb_amount = hash['金额(元)'][1..-1] # to strip '¥'
      if hash['收/支'] == '收入'
        another_account_symbol = '-'
        another_account = 'Income:TODO'
      else
        another_account_symbol = '+'
        another_account = 'Expenses:TODO'
      end

      [
        "#{date.tr('/', '-')} * #{recipient.to_json} #{remark.to_json}",
        "  #{another_account} #{another_account_symbol}#{rmb_amount}RMB",
        "  #{@options[:account]}",
        '',
      ]
    end

    def raw_rows
      rows = (CSV.parse read)
      if rows[15][0] == '----------------------微信支付账单明细列表--------------------'
        rows[17..-1].reverse.map{|r| Hash[ rows[16].zip r ]}
      else
        throw "cannot recognize start of bills. got #{rows[15][0]}"
      end
    end
  end
end

main.rb

#!/usr/bin/env ruby

require 'pathname'
require 'nkf'
require 'csv'
require 'json'
require_relative 'converter_wechatpay'

REPO_ROOT      = Pathname.new(__FILE__).join('..', '..')
RAW_ROOT       = REPO_ROOT.join('book', 'raw')
GENERATED_ROOT = REPO_ROOT.join('book', 'generated')

def main
  RAW_ROOT.children.sort_by(&
    to_s).each do |input_file|
    output_file = GENERATED_ROOT.join "#{input_file.basename}.beancount"

    puts "converting #{input_file} to #{output_file}"

    case input_file.basename.to_s
    when /wechat-1-.*\.csv$/i
      Converter::WechatPay.new(input_file, account: 'Assets:Wechat:Main')
        .write(output_file)
    else
      puts "unmatched file: #{input_file}"
      fail "no idea what to do"
    end
  end
end

main