equity command

Fixes #29

Author: howeyc

ledger/cmd/print.go

@@ -57,6 +57,10 @@ func cliTransactions() ([]*ledger.Transaction, error) {
 		return nil, parseError
 	}
 
+	sort.Slice(generalLedger, func(i, j int) bool {
+		return generalLedger[i].Date.Before(generalLedger[j].Date)
+	})
+
 	timeStartIndex, timeEndIndex := 0, 0
 	for idx := 0; idx < len(generalLedger); idx++ {
 		if generalLedger[idx].Date.After(parsedStartDate) {

ledger/cmd/printEquity.go

@@ -0,0 +1,67 @@
+package cmd
+
+import (
+	"log"
+	"math/big"
+	"sort"
+	"time"
+
+	"github.com/howeyc/ledger"
+	"github.com/spf13/cobra"
+)
+
+// equityCmd represents the equity command
+var equityCmd = &cobra.Command{
+	Use:   "equity",
+	Short: "Print account equity as transaction",
+	Run: func(cmd *cobra.Command, args []string) {
+		generalLedger, err := cliTransactions()
+		if err != nil {
+			log.Fatalln(err)
+		}
+
+		var trans ledger.Transaction
+		trans.Payee = "Opening Balances"
+		trans.Date = time.Now()
+		if len(generalLedger) > 0 {
+			trans.Date = generalLedger[len(generalLedger)-1].Date
+		}
+
+		balances := make(map[string]*big.Rat)
+		for _, trans := range generalLedger {
+			for _, accChange := range trans.AccountChanges {
+				if ratNum, ok := balances[accChange.Name]; !ok {
+					balances[accChange.Name] = new(big.Rat).Set(accChange.Balance)
+				} else {
+					ratNum.Add(ratNum, accChange.Balance)
+				}
+			}
+		}
+
+		ratZero := big.NewRat(0, 1)
+		for name, bal := range balances {
+			if bal.Cmp(ratZero) != 0 {
+				trans.AccountChanges = append(trans.AccountChanges, ledger.Account{
+					Name:    name,
+					Balance: bal,
+				})
+			}
+		}
+
+		sort.Slice(trans.AccountChanges, func(i, j int) bool {
+			return trans.AccountChanges[i].Name < trans.AccountChanges[j].Name
+		})
+
+		PrintTransaction(&trans, 80)
+	},
+}
+
+func init() {
+	rootCmd.AddCommand(equityCmd)
+
+	var startDate, endDate time.Time
+	startDate = time.Date(1970, 1, 1, 0, 0, 0, 0, time.Local)
+	endDate = time.Now().Add(time.Hour * 24)
+	equityCmd.Flags().StringVarP(&startString, "begin-date", "b", startDate.Format(transactionDateFormat), "Begin date of transaction processing.")
+	equityCmd.Flags().StringVarP(&endString, "end-date", "e", endDate.Format(transactionDateFormat), "End date of transaction processing.")
+}