feat: fire scheduled workflow runs from the housekeeping leader

server/internal/api/workflows.go

@@ -13,7 +13,9 @@ import (
 	"gitea.hostxtra.co.uk/mrhid6/vantage/server/internal/auth"
 	"gitea.hostxtra.co.uk/mrhid6/vantage/server/internal/models"
 	"gitea.hostxtra.co.uk/mrhid6/vantage/server/internal/services"
+	"gitea.hostxtra.co.uk/mrhid6/vantage/server/internal/workflowsched"
 	"github.com/gin-gonic/gin"
+	"go.mongodb.org/mongo-driver/v2/mongo"
 )
 
 func registerWorkflowRoutes(g *gin.RouterGroup) {
@@ -34,6 +36,8 @@ func registerWorkflowRoutes(g *gin.RouterGroup) {
 	g.DELETE("/workflows/:id", deleteWorkflow)
 	g.POST("/workflows/:id/run", runWorkflow)
 	g.GET("/workflows/:id/runs", listWorkflowRuns)
+	g.PUT("/workflows/:id/schedule", putWorkflowSchedule)
+	g.GET("/workflows/:id/schedule/preview", previewWorkflowSchedule)
 
 	g.GET("/runs/:runId", getRun)
 	g.POST("/runs/:runId/cancel", cancelRun)
@@ -386,3 +390,51 @@ func cancelRun(c *gin.Context) {
 	services.LogEvent(auth.InstanceID(c), "workflow.run_cancelled", actorFromCtx(c), "", c.Param("runId"), "run cancelled")
 	c.JSON(http.StatusOK, gin.H{"cancelled": true})
 }
+
+func putWorkflowSchedule(c *gin.Context) {
+	var body models.Schedule
+	if err := c.ShouldBindJSON(&body); err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "invalid body"})
+		return
+	}
+
+	instanceID := auth.InstanceID(c)
+	next, err := services.SetSchedule(instanceID, c.Param("id"), &body)
+	if err != nil {
+		if errors.Is(err, workflowsched.ErrBadSchedule) {
+			c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
+			return
+		}
+		if errors.Is(err, mongo.ErrNoDocuments) {
+			c.JSON(http.StatusNotFound, gin.H{"error": "workflow not found"})
+			return
+		}
+		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
+		return
+	}
+
+	services.LogEvent(instanceID, "workflow.schedule_updated", actorFromCtx(c), "", c.Param("id"),
+		fmt.Sprintf("schedule %q %s enabled=%v", body.Cron, body.TZ, body.Enabled))
+	c.JSON(http.StatusOK, gin.H{"schedule": body, "next_run_at": next})
+}
+
+// previewWorkflowSchedule exists so the browser and the scheduler agree on
+// what a cron string means. A client-side cron parser that disagrees with the
+// server by one field is a bug found in production, at night.
+func previewWorkflowSchedule(c *gin.Context) {
+	expr := c.Query("cron")
+	tz := c.Query("tz")
+
+	occurrences := make([]time.Time, 0, 3)
+	from := time.Now()
+	for i := 0; i < 3; i++ {
+		next, err := workflowsched.NextOccurrence(expr, tz, from)
+		if err != nil {
+			c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
+			return
+		}
+		occurrences = append(occurrences, next)
+		from = next
+	}
+	c.JSON(http.StatusOK, gin.H{"occurrences": occurrences})
+}