FIrebase Rules

rules.json

{

"rules":{
	// Normal users will have access to only "users"
	"users":{
		    	"$user_id":{
				        // grants access to the owner of this user account
				        // whose uid must exactly match the key ($user_id)
				        ".write":"$user_id === auth.uid",
				        ".read":"$user_id === auth.uid"
			    			}
    
	        	},

        // Moderators will have "read" access to "mods". You can add individual moderator's UID in this node
        "mods"	:{
		            ".write":false,
		            ".read":"root.child('mods').child(auth.uid).exists()"
	        	},
        //Store user details with their email ID as node.
        //For this create another node with email IDs stored in their respective UID
         	"usersWithEmail":{
        		 "$email_id": {
            				".write": "root.child('authEmails').child(auth.uid).val().replace('.', '_').replace('@', '_') == $email_id && auth !== null",
             				".read": "auth !== null"
            				}
        		},

        	"authEmails":{
        		"$user_id":{
                			// grants access to the owner of this user account
                			// whose uid must exactly match the key ($user_id)
               			".write":"$user_id === auth.uid",
                			".read":"$user_id === auth.uid"
            			}
    		},
          
    	}
 }