json output a go

cmd/clitest/main.go

@@ -1,8 +1,10 @@
 package main
 
 import (
+	"encoding/json"
 	"flag"
 	"fmt"
+	"os"
 	"sort"
 	"strings"
 
@@ -17,6 +19,7 @@ func main() {
 	likeLedger := flag.Bool("like-ledger", false, "limit data to these -like-* rather than zoom to these -like-*")
 	groupName := flag.String("group-name", ".*", "grouping to apply to names")
 	groupDate := flag.String("group-date", ".*", "grouping to apply to dates")
+	jsonOutput := flag.Bool("json", false, "json output")
 	flag.Parse()
 
 	if flag.NArg() < 1 {
@@ -45,6 +48,8 @@ func main() {
 		like = append(like, ledger.LikeAfter(*likeAfter))
 	}
 
+	jsonResult := []any{}
+
 	switch *foo {
 	case "reg":
 		sort.Slice(deltas, func(i, j int) bool {
@@ -53,7 +58,15 @@ func main() {
 		register := deltas.Register()
 		for i := range deltas {
 			if like.All(deltas[i]) {
-				fmt.Printf("%s (%+v)\n", deltas[i].Debug(), register[deltas[i].Date][deltas[i].Name].Debug())
+				if !*jsonOutput {
+					fmt.Printf("%s (%+v)\n", deltas[i].Debug(), register[deltas[i].Date][deltas[i].Name].Debug())
+				} else {
+					jsonResult = append(jsonResult, map[string]any{
+						"name":    deltas[i].Name,
+						"delta":   deltas[i],
+						"balance": register[deltas[i].Date][deltas[i].Name],
+					})
+				}
 			}
 		}
 	case "bal":
@@ -64,10 +77,21 @@ func main() {
 				results = append(results, fmt.Sprintf("%s %.2f", subk, subv))
 			}
 			if len(results) > 0 {
-				fmt.Printf("%s\t%s\n", k, strings.Join(results, " + "))
+				if !*jsonOutput {
+					fmt.Printf("%s\t%s\n", k, strings.Join(results, " + "))
+				} else {
+					jsonResult = append(jsonResult, map[string]any{
+						"name":    k,
+						"balance": v,
+					})
+				}
 			}
 		}
 	default:
 		panic(fmt.Errorf("not impl %q", flag.Args()[0]))
 	}
+
+	if *jsonOutput {
+		json.NewEncoder(os.Stdout).Encode(jsonResult)
+	}
 }