From 6c4f67e3dad98c216379e171a19f980fe92c1502 Mon Sep 17 00:00:00 2001
From: Josh Holtrop <jholtrop@gmail.com>
Date: Sun, 4 Aug 2013 19:05:11 -0400
Subject: [PATCH] add Value class; keep track of account balances over time

---
 lib/gnucash.rb             |  1 +
 lib/gnucash/account.rb     |  9 +++++++++
 lib/gnucash/transaction.rb |  7 +------
 lib/gnucash/value.rb       | 30 ++++++++++++++++++++++++++++++
 4 files changed, 41 insertions(+), 6 deletions(-)
 create mode 100644 lib/gnucash/value.rb

diff --git a/lib/gnucash.rb b/lib/gnucash.rb
index c14cd88..a1d5287 100644
--- a/lib/gnucash.rb
+++ b/lib/gnucash.rb
@@ -1,6 +1,7 @@
 require "gnucash/account"
 require "gnucash/book"
 require "gnucash/transaction"
+require "gnucash/value"
 require "gnucash/version"
 
 module Gnucash
diff --git a/lib/gnucash/account.rb b/lib/gnucash/account.rb
index f8d7bcd..578bf92 100644
--- a/lib/gnucash/account.rb
+++ b/lib/gnucash/account.rb
@@ -38,6 +38,15 @@ module Gnucash
       @transactions.sort! do |a, b|
         a[:txn].date <=> b[:txn].date
       end
+      balance = Value.new(0)
+      @balances = @transactions.map do |txn_hash|
+        balance += txn_hash[:value]
+        [txn_hash[:txn].date, balance]
+      end
+    end
+
+    def current_balance
+      @balances.last[1] rescue Value.new(0)
     end
   end
 end
diff --git a/lib/gnucash/transaction.rb b/lib/gnucash/transaction.rb
index 275ee00..92ca16a 100644
--- a/lib/gnucash/transaction.rb
+++ b/lib/gnucash/transaction.rb
@@ -10,13 +10,8 @@ module Gnucash
       @id = node.xpath('trn:id').text
       @date = node.xpath('trn:date-posted/ts:date').text.split(' ').first
       @splits = node.xpath('trn:splits/trn:split').map do |split_node|
-        value_str = split_node.xpath('split:value').text
-        value_parts = value_str.split('/')
-        unless value_parts.size == 2 and value_parts[1] == '100'
-          raise "Unexpected value format: #{value_str.inspect}"
-        end
+        value = Value.new(split_node.xpath('split:value').text)
         account_id = split_node.xpath('split:account').text
-        value = value_parts.first.to_i
         account = @book.find_account_by_id(account_id)
         unless account
           raise "Could not find account with ID #{account_id} for transaction #{@id}"
diff --git a/lib/gnucash/value.rb b/lib/gnucash/value.rb
new file mode 100644
index 0000000..9c8e7a6
--- /dev/null
+++ b/lib/gnucash/value.rb
@@ -0,0 +1,30 @@
+module Gnucash
+  class Value
+    attr_accessor :val
+    def initialize(val)
+      if val.is_a?(String)
+        if val =~ /^(-?\d+)\/100$/
+          @val = $1.to_i
+        else
+          raise "Unexpected value string: #{val.inspect}"
+        end
+      elsif val.is_a?(Fixnum)
+        @val = val
+      else
+        raise "Unexpected value type: #{val.class}"
+      end
+    end
+
+    def +(other)
+      Value.new(@val + other.val)
+    end
+
+    def -(other)
+      Value.new(@val - other.val)
+    end
+
+    def to_s
+      (@val / 100.0).round(2).to_s
+    end
+  end
+end