added crons web apis and ui listing

tools/cron/cron.go

@@ -21,8 +21,8 @@ type Cron struct {
 	timezone   *time.Location
 	ticker     *time.Ticker
 	startTimer *time.Timer
-	jobs       []*Job
 	tickerDone chan bool
+	jobs       []*Job
 	interval   time.Duration
 	mux        sync.RWMutex
 }

tools/cron/job.go

@@ -1,5 +1,7 @@
 package cron
 
+import "encoding/json"
+
 // Job defines a single registered cron job.
 type Job struct {
 	fn       func()
@@ -12,8 +14,8 @@ func (j *Job) Id() string {
 	return j.id
 }
 
-// Expr returns the plain cron job schedule expression.
-func (j *Job) Expr() string {
+// Expression returns the plain cron job schedule expression.
+func (j *Job) Expression() string {
 	return j.schedule.rawExpr
 }
 
@@ -23,3 +25,17 @@ func (j *Job) Run() {
 		j.fn()
 	}
 }
+
+// MarshalJSON implements [json.Marshaler] and export the current
+// jobs data into valid JSON.
+func (j Job) MarshalJSON() ([]byte, error) {
+	plain := struct {
+		Id         string `json:"id"`
+		Expression string `json:"expression"`
+	}{
+		Id:         j.Id(),
+		Expression: j.Expression(),
+	}
+
+	return json.Marshal(plain)
+}

tools/cron/job_test.go

@@ -1,6 +1,9 @@
 package cron
 
-import "testing"
+import (
+	"encoding/json"
+	"testing"
+)
 
 func TestJobId(t *testing.T) {
 	expected := "test"
@@ -22,8 +25,8 @@ func TestJobExpr(t *testing.T) {
 
 	j := Job{schedule: s}
 
-	if j.Expr() != expected {
-		t.Fatalf("Expected job with cron expression %q, got %q", expected, j.Expr())
+	if j.Expression() != expected {
+		t.Fatalf("Expected job with cron expression %q, got %q", expected, j.Expression())
 	}
 }
 
@@ -47,3 +50,22 @@ func TestJobRun(t *testing.T) {
 		t.Fatalf("Expected calls %q, got %q", expected, calls)
 	}
 }
+
+func TestJobMarshalJSON(t *testing.T) {
+	s, err := NewSchedule("1 2 3 4 5")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	j := Job{id: "test_id", schedule: s}
+
+	raw, err := json.Marshal(j)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	expected := `{"id":"test_id","expression":"1 2 3 4 5"}`
+	if str := string(raw); str != expected {
+		t.Fatalf("Expected\n%s\ngot\n%s", expected, str)
+	}
+}