[IMPROVEMENT] Improve health check to verify Taskwarrior availability. (#438)

* feat: make health check fail when task binary is missing

* updating the PR applying the check for the version

---------

Co-authored-by: GAURAV KARMAKAR <gaurav.k@graeon.ai>

Author: gaurav02081

backend/controllers/healthcheck.go

@@ -3,18 +3,49 @@ package controllers
 import (
 	"encoding/json"
 	"net/http"
+	"os/exec"
+	"regexp"
+	"strconv"
 )
 
 func HealthCheckHandler(w http.ResponseWriter, r *http.Request) {
+	// if it get any other request other than get then it will show error
 	if r.Method != http.MethodGet {
 		http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
 		return
 	}
+	// Default state is healthy
+	status := "healthy"
+	statusCode := http.StatusOK
+
+	// checks the taskwarrior version and if the command fails will give 503 (dependency missing)
+	cmd := exec.Command("task", "--version")
+	output, err := cmd.Output()
+	if err != nil {
+		status = "unhealthy: taskwarrior not found or failed to execute"
+		statusCode = http.StatusServiceUnavailable
+	} else {
+		re := regexp.MustCompile(`(\d+)\.(\d+)`)
+		matches := re.FindStringSubmatch(string(output))
+
+		if len(matches) < 3 {
+			status = "unhealthy: unable to determine taskwarrior version"
+			statusCode = http.StatusServiceUnavailable
+		} else {
+			// check the taskwarrior version (major version should be >= 3 )
+			major, _ := strconv.Atoi(matches[1])
+
+			if major < 3 {
+				status = "unhealthy: unsupported taskwarrior version (>= 3.0 required)"
+				statusCode = http.StatusServiceUnavailable
+			}
+		}
+	}
 
 	w.Header().Set("Content-Type", "application/json")
-	w.WriteHeader(http.StatusOK)
+	w.WriteHeader(statusCode)
 	json.NewEncoder(w).Encode(map[string]string{
-		"status":  "healthy",
+		"status":  status,
 		"service": "ccsync-backend",
 	})
 }