fn_registry/apps/dag_engine/handlers_dags.go

package main

import (
	"context"
	"encoding/json"
	"net/http"
)

func handleListDags(executor *Executor) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		dags, err := executor.ListDAGs()
		if err != nil {
			writeError(w, http.StatusInternalServerError, err.Error())
			return
		}
		writeJSON(w, http.StatusOK, dags)
	}
}

func handleGetDag(executor *Executor) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		name := r.PathValue("name")
		info, dag, validation, err := executor.GetDAG(name)
		if err != nil {
			writeError(w, http.StatusNotFound, err.Error())
			return
		}

		// Get recent runs.
		runs, _, _ := executor.store.ListRuns(dag.Name, 10, 0)

		resp := map[string]interface{}{
			"info":       info,
			"dag":        dag,
			"validation": validation,
			"runs":       runs,
		}
		writeJSON(w, http.StatusOK, resp)
	}
}

func handleRunDag(executor *Executor) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		name := r.PathValue("name")
		info, _, _, err := executor.GetDAG(name)
		if err != nil {
			writeError(w, http.StatusNotFound, err.Error())
			return
		}

		// Execute asynchronously.
		go func() {
			ctx := context.Background()
			executor.ExecuteDAG(ctx, info.FilePath, "api")
		}()

		// Return run acknowledgment.
		writeJSON(w, http.StatusAccepted, map[string]string{
			"status":  "accepted",
			"dag":     name,
			"message": "DAG execution started",
		})
	}
}

// --- JSON helpers ---

func writeJSON(w http.ResponseWriter, status int, data interface{}) {
	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(status)
	json.NewEncoder(w).Encode(data)
}

func writeError(w http.ResponseWriter, status int, msg string) {
	writeJSON(w, status, map[string]string{"error": msg})
}