Add bar chart to compare accounts over years

cmd/lweb/handler_barchart.go

@@ -0,0 +1,95 @@
+package main
+
+import (
+	"bytes"
+	"fmt"
+	"image/color"
+	"image/png"
+	"math"
+	"net/http"
+	"strings"
+	"time"
+
+	"github.com/howeyc/ledger/pkg/ledger"
+
+	"github.com/gorilla/mux"
+	"github.com/vdobler/chart"
+	"github.com/vdobler/chart/imgg"
+)
+
+func BarChartHandler(w http.ResponseWriter, r *http.Request) {
+	vars := mux.Vars(r)
+	accountNames := vars["accountNames"]
+	accounts := strings.Split(accountNames, ",")
+	startString := vars["startDate"]
+	endString := vars["endDate"]
+
+	ledgerFileReader := bytes.NewReader(ledgerBuffer.Bytes())
+
+	trans, terr := ledger.ParseLedger(ledgerFileReader)
+	if terr != nil {
+		http.Error(w, terr.Error(), 500)
+		return
+	}
+
+	barc := chart.BarChart{Title: "Bar Chart"}
+	barc.XRange.Label = "Fiscal Year"
+	barc.YRange.Label = "USD"
+	barc.ShowVal = 1
+
+	parsedStartDate, _ := time.Parse("2006-01-02", startString)
+	parsedEndDate, _ := time.Parse("2006-01-02", endString)
+
+	categories := []string{}
+	pointData := make(map[string][]chart.Point)
+	xIdx := 0
+	for startDate := parsedStartDate; startDate.Before(parsedEndDate); startDate = startDate.AddDate(1, 0, 0) {
+		endDate := startDate.AddDate(1, 0, 1)
+		timeStartIndex, timeEndIndex := 0, 0
+		for idx := 0; idx < len(trans); idx++ {
+			if trans[idx].Date.After(startDate) {
+				timeStartIndex = idx
+				break
+			}
+		}
+		for idx := len(trans) - 1; idx >= 0; idx-- {
+			if trans[idx].Date.Before(endDate) {
+				timeEndIndex = idx
+				break
+			}
+		}
+		ytrans := trans[timeStartIndex : timeEndIndex+1]
+
+		balances := ledger.GetBalances(ytrans, accounts)
+
+		for _, accName := range accounts {
+			for _, bal := range balances {
+				if accName == bal.Name {
+					value, _ := bal.Balance.Float64()
+					value = math.Abs(value)
+					point := chart.Point{X: float64(xIdx), Y: value}
+					if curData, found := pointData[accName]; found {
+						curData = append(curData, point)
+						pointData[accName] = curData
+					} else {
+						pointData[accName] = []chart.Point{point}
+					}
+				}
+			}
+		}
+		categories = append(categories, fmt.Sprintf("%d", startDate.Year()))
+		xIdx++
+	}
+	barc.XRange.Category = categories
+
+	for aIdx, accName := range accounts {
+		style := chart.AutoStyle(aIdx, true)
+		barc.AddData(accName, pointData[accName], style)
+	}
+
+	igr := imgg.New(1600, 900, color.RGBA{0xff, 0xff, 0xff, 0xff}, nil, nil)
+	barc.Plot(igr)
+
+	// Set type to png
+	png.Encode(w, igr.Image)
+}

cmd/lweb/main.go

@@ -42,6 +42,7 @@ func main() {
 	r.HandleFunc("/accounts", AccountsHandler).Methods("GET")
 	r.HandleFunc("/account/{accountName}", AccountHandler).Methods("GET")
 	r.HandleFunc("/piechart/{accountName}/{startDate}/{endDate}/chart.png", PieChartHandler).Methods("GET")
+	r.HandleFunc("/barchart/{accountNames}/{startDate}/{endDate}/chart.png", BarChartHandler).Methods("GET")
 	r.PathPrefix("/").Handler(http.StripPrefix("/", http.FileServer(http.Dir("webroot"))))
 
 	http.Handle("/", r)