#!/usr/bin/env ruby

require "csv"
require "time"

def payee(r)
  case r["Type"]
  when "Payment"
   r["Amount (total)"][0] == "-" ? r["To"] : r["From"]
  when "Charge"
    r["Amount (total)"][0] == "-" ? r["From"] : r["To"]
  when "Standard Transfer"
    r["Destination"]
  else
  end
end

def date(r)
  Time.parse(r["Datetime"]).to_date.iso8601
end

infile = ARGV.first || "venmo_statement.csv"
outfile = File.basename(infile, File.extname(infile)) + "_ynab4.csv"

lines = File.read(infile).lines
lines.shift until lines.first.include?("ID,")

CSV.open(outfile, "wb") do |out|
  out << %w[Date Payee Memo Amount]

  CSV.parse(lines.join, headers: true) do |r|
    next unless r["ID"]

    if r["Funding Source"] && r["Funding Source"] != "Venmo balance"
      out << [date(r), r["Funding Source"], nil, r["Amount (total)"].gsub(/\A-/, "+")]
    end

    out << [
      date(r),
      payee(r),
      r["Note"],
      r["Amount (total)"]
    ]
  end
end