MetroBank UK to FreeAgent CSV format converter

metro_bank_csv_converter.rb

require "csv"

class MetroBankCsvConverter
  def initialize(lines)
    lines =lines.split("\n")
    lines.shift(3)
    lines = lines.join("\n")
    @raw_csv = CSV.parse(lines, headers: headers)
  end

  def headers
    ["date","type","reference","currency","money_out","money_in","balance"]
  end

  def to_freeagent_csv(start_date=nil, end_date=nil)
    CSV.generate do |csv|
      transactions.each do |t|
        if t.within(start_date, end_date)
          csv << [t.date_string, t.amount, t.long_description]
        end
      end
    end
  end

  def columns
    @raw_csv.headers
  end

  def transaction_count
    transactions.count
  end

  def transactions
    transactions = []

    current_transaction = nil

    @raw_csv.each do |row|
      if row["date"].length > 0
        current_transaction = Transaction.new(row)
        transactions <<  current_transaction
      else
        current_transaction << Detail.new(row)
      end
    end

    transactions
  end

  module CsvRowWrapper
    def initialize(row)
      @row = row
    end

    def method_missing(meth, *args, &block)
      if @row.headers.include?(meth.to_s)
        @row[meth.to_s]
      else
        super
      end
    end
  end


  class Transaction
    include CsvRowWrapper
    extend Forwardable
    def_delegator :@details, :<<

    def initialize(row)
      super row
      @details = Details.new
    end

    def within(start_date, end_date)
      return true if start_date.nil? && end_date.nil?
      start_date, end_date = Date.parse(start_date), Date.parse(end_date)

      outside_range = false
      if start_date && start_date > date
        outside_range = true
      end

      if end_date && end_date < date
        outside_range = true
      end

      !outside_range
    end

    def long_description
      [type, reference, details].join(" | ")
    end

    def details
      @details.to_s
    end

    def date
      Date.parse(@row["date"])
    end

    def date_string
      date.strftime("%d/%m/%Y")
    end

    def amount
      money_in - money_out
    end

    def money_in
      to_money("money_in")
    end

    def money_out
      to_money("money_out")
    end

    def balance
      to_money("balance")
    end

    private

    def to_money(column)
      @row[column].gsub(/\,/,"").to_f
    end
  end

  class Details < Array
    def to_s
      map(&:to_s).join(" | ")
    end
  end

  class Detail
    include CsvRowWrapper

    def to_s
      reference
    end
  end
end

spec.rb

require "byebug"
require "./converter"

describe MetroBankCsvConverter do
  let(:converter) { MetroBankCsvConverter.new lines }
  let(:lines) { <<-EOF.gsub(/^\s+/, "") 
    "Transaction Search Results"
    "","","","","",""
    "Date","Transaction Type","Reference","Currency","Money Out","Money In","Balance"
    "03 DEC 2014","Outward Faster Payment","1234567","GBP","1,000,000.00","0.00","121,472,236.98"
    "","","Something something","","","",""
    "","","More silliness","","","",""
    "","","Hopefully we handle a comma, even when it's inside a string","","","",""
    "01 DEC 2014","Card Purchase","ABCDEFG","GBP","134.34","0.00","122,472,236.98"
    "","","01/12/14 01:17:02","","","",""
    "","","LINODE.COM","","","",""
    "","","855-4546633","","","",""
    "","","USD 86.84@1.54690142","","","",""
  EOF
  }

  it do
    expect(converter.columns).to eq ["date","type","reference","currency","money_out","money_in","balance"]
    expect(converter.transaction_count).to eq 2
    expect(converter.transactions[0].date_string).to eq "03/12/2014"
  end

  it do
    transaction = converter.transactions[1]

    expect(transaction.date).to        eq Date.parse("2014/12/01")
    expect(transaction.date_string).to eq "01/12/2014"
    expect(transaction.type).to        eq "Card Purchase"
    expect(transaction.reference).to   eq "ABCDEFG"
    expect(transaction.currency).to    eq "GBP"
    expect(transaction.amount).to      eq -134.34
    expect(transaction.money_out).to   eq 134.34
    expect(transaction.money_in).to    eq 0.00
    expect(transaction.balance).to     eq 122_472_236.98

    expect(transaction.details).to eq [
      "01/12/14 01:17:02",
      "LINODE.COM",
      "855-4546633",
      "USD 86.84@1.54690142"
    ].join(" | ")

    expect(converter.transactions[0].details).to eq "Something something | More silliness | Hopefully we handle a comma, even when it's inside a string"
  end

  it "Transaction#long_description" do
    long_description = converter.transactions[0].long_description

    expect(long_description).to eq "Outward Faster Payment | 1234567 | Something something | More silliness | Hopefully we handle a comma, even when it's inside a string"
  end

  describe "#to_freeagent_csv" do
    it "returns all transactions with no args" do
      csv = converter.to_freeagent_csv
      expect(csv).to eq <<-CSV.gsub(/^\s+/,"")
        03/12/2014,-1000000.0,"Outward Faster Payment | 1234567 | Something something | More silliness | Hopefully we handle a comma, even when it's inside a string"
        01/12/2014,-134.34,Card Purchase | ABCDEFG | 01/12/14 01:17:02 | LINODE.COM | 855-4546633 | USD 86.84@1.54690142
      CSV
    end

    it "accepts an inclusive date range" do
      csv = converter.to_freeagent_csv("2014/12/01", "2014/12/01")

      expect(csv).to eq <<-CSV.gsub(/^\s+/,"")
        01/12/2014,-134.34,Card Purchase | ABCDEFG | 01/12/14 01:17:02 | LINODE.COM | 855-4546633 | USD 86.84@1.54690142
      CSV

      csv = converter.to_freeagent_csv("2014/12/03", "2014/12/03")
      expect(csv).to eq <<-CSV.gsub(/^\s+/,"")
        03/12/2014,-1000000.0,"Outward Faster Payment | 1234567 | Something something | More silliness | Hopefully we handle a comma, even when it's inside a string"
      CSV

      csv = converter.to_freeagent_csv("2014/12/01", "2014/12/03")
      expect(csv).to eq <<-CSV.gsub(/^\s+/,"")
        03/12/2014,-1000000.0,"Outward Faster Payment | 1234567 | Something something | More silliness | Hopefully we handle a comma, even when it's inside a string"
        01/12/2014,-134.34,Card Purchase | ABCDEFG | 01/12/14 01:17:02 | LINODE.COM | 855-4546633 | USD 86.84@1.54690142
      CSV
    end
  end
end