ok that is pretty nice

cmd/clitest/main.go

@@ -7,7 +7,6 @@ import (
 	"log"
 	"net/http"
 	"os"
-	"path"
 	"slices"
 	"sort"
 	"strings"
@@ -50,43 +49,85 @@ func main() {
 		like = append(like, ledger.LikeAfter(*likeAfter))
 
 		foo := func(w http.ResponseWriter, r *http.Request) {
-			switch path.Dir(r.URL.Path) {
-			case "/bal":
-				register := deltas.Like(like...).Register()
-				nameCurrencyDateValue := map[string]map[ledger.Currency]map[string]float64{}
-				dates := []string{}
-				for date, balances := range register {
-					dates = append(dates, date)
-					for name, balance := range balances {
-						for currency, value := range balance {
-							if _, ok := nameCurrencyDateValue[name]; !ok {
-								nameCurrencyDateValue[name] = make(map[ledger.Currency]map[string]float64)
-							}
-							if _, ok := nameCurrencyDateValue[name][currency]; !ok {
-								nameCurrencyDateValue[name][currency] = make(map[string]float64)
-							}
-							nameCurrencyDateValue[name][currency][date] += value
+			foolike := make(ledger.Likes, 0)
+			for _, v := range r.URL.Query()["likeName"] {
+				foolike = append(foolike, ledger.LikeName(v))
+			}
+			for _, v := range r.URL.Query()["likeAfter"] {
+				foolike = append(foolike, ledger.LikeAfter(v))
+			}
+			for _, v := range r.URL.Query()["likeBefore"] {
+				foolike = append(foolike, ledger.LikeBefore(v))
+			}
+			if len(foolike) == 0 {
+				foolike = like
+			}
+
+			register := deltas.Like(foolike...).Register()
+			nameCurrencyDateValue := map[string]map[ledger.Currency]map[string]float64{}
+			dates := []string{}
+			for date, balances := range register {
+				dates = append(dates, date)
+				for name, balance := range balances {
+					for currency, value := range balance {
+						if _, ok := nameCurrencyDateValue[name]; !ok {
+							nameCurrencyDateValue[name] = make(map[ledger.Currency]map[string]float64)
 						}
+						if _, ok := nameCurrencyDateValue[name][currency]; !ok {
+							nameCurrencyDateValue[name][currency] = make(map[string]float64)
+						}
+						nameCurrencyDateValue[name][currency][date] += value
 					}
 				}
-				slices.Sort(dates)
+			}
+			slices.Sort(dates)
 
-				line := charts.NewLine()
-				line.AddXAxis(dates)
+			line := charts.NewLine()
+			line.AddXAxis(dates)
+
+			switch r.URL.Path {
+			default:
+				http.NotFound(w, r)
+				return
+			case "/bal":
 				for name, currencyDateValue := range nameCurrencyDateValue {
 					for currency, dateValue := range currencyDateValue {
 						series := make([]int, len(dates))
-						for i, date := range dates {
-							series[i] = int(dateValue[date])
+						for i := range dates {
+							var lastValue float64
+							for j := range dates[:i+1] {
+								if newLastValue, ok := dateValue[dates[j]]; ok {
+									lastValue = newLastValue
+								}
+							}
+							series[i] = int(lastValue)
 						}
 						key := fmt.Sprintf("%s (%s)", name, currency)
 						line.AddYAxis(key, series)
 					}
 				}
-				if err := line.Render(w); err != nil {
-					panic(err)
-				}
 			case "/reg":
+				for name, currencyDateValue := range nameCurrencyDateValue {
+					for currency, dateValue := range currencyDateValue {
+						series := make([]int, len(dates))
+						for i := range dates {
+							var prevValue float64
+							var lastValue float64
+							for j := range dates[:i+1] {
+								if newLastValue, ok := dateValue[dates[j]]; ok {
+									prevValue = lastValue
+									lastValue = newLastValue
+								}
+							}
+							series[i] = int(lastValue - prevValue)
+						}
+						key := fmt.Sprintf("%s (%s)", name, currency)
+						line.AddYAxis(key, series)
+					}
+				}
+			}
+			if err := line.Render(w); err != nil {
+				panic(err)
 			}
 		}