feat: validate user availability

app/internal/handlers/volunteer_schedual.go

@@ -2,10 +2,33 @@ package handlers
 
 import (
 	"fmt"
-	"net/http"
+	"time"
+
+	"github.com/patel-mann/poll-system/app/internal/models"
 )
 
-func VolunteerSchedualHandler(w *http.ResponseWriter, r http.Request) {
+func ValidatedFreeTime(parsedDate time.Time, assignTime time.Time, userID int) (bool)  {
+    var startTime, endTime time.Time
 
-	fmt.Print("Not Implementated Yet!!!")
+		dateOnly := parsedDate.Format("2006-01-02")
+
+    err := models.DB.QueryRow(
+        `SELECT start_time, end_time
+         FROM availability
+         WHERE user_id = $1 AND day = $2`,
+        userID, dateOnly,
+    ).Scan(&startTime, &endTime)
+
+    if err != nil {
+        fmt.Printf("Database query failed: %v\n", err)
+				return false
+    }
+
+		if assignTime.After(startTime) && assignTime.Before(endTime) {
+			return true
+		}else{
+			return false
+		}
+
+	return false
 }