Realm Function - User Search

console.log("Starting function");

const Realm = require('realm');
const adminUser = Realm.Sync.User.adminUser('**')
const server_url = 'realm://**';

module.exports = function(changeEvent) {
    console.log('Change detected at path: ' + changeEvent.path);
    
    const changes = changeEvent.changes["UserSearch"];
    
    // no reason to do any work if there are no requests
    if (typeof changes === "undefined")
        return;
    if (changes.insertions.length === 0 && changes.modifications.length === 0)
        return;
    
    const globalUserSchema = {
      name: 'GlobalUser',
      properties: {
        email: {type: 'string', indexed: true},
        username: {type: 'string', indexed: true}
      }
    };


    let accountsRealm = new Realm({ sync: {user: adminUser, url: server_url + '/globalUsers', schema: [globalUserSchema] }});

    const searchRealm = changeEvent.realm; // workaround for GN returning new instance on every access
    const requests    = searchRealm.objects("UserSearch");
    const accounts    = accountsRealm.objects("GlobalUser");

    // Find users matching the request
    searchRealm.write(() => {
        // handle new requests
        changes.insertions.forEach((index) => {
            const obj = requests[index];
            
            if (obj.pattern !== "") {
                const matches = accounts.filtered("username CONTAINS[c] $0", obj.pattern);
                
                matches.forEach((match) => {
                    obj.users.push({ username: match.username });
                });
            }
            obj.resultPattern = obj.pattern;
        });
        
        // live update result if request is modified
        for (let index of changes.modifications) {
	        const obj = requests[index];
            
            if (obj.pattern === "") {
                searchRealm.delete(obj.users);
                console.log("Deleted all");
            }
            else {
                const matches = accounts.filtered("username CONTAINS[c] $0", obj.pattern);

                // remove users that are no longer matching
                const toDelete = [];
                if(obj.users.length > 0) {
                    obj.users.forEach((profile) => {
                        if (matches.filtered("email == $0", profile.email).length == 0) {
                            toDelete.push(profile);
                            console.log("Delete " + profile.email);
                        }    
                    });
                }
                searchRealm.delete(toDelete);
                
                // add new matches
                for (let match of matches) {
                    if (obj.users.filtered("username == $0", match.username).length === 0) {
                        console.log("Matched: " + match.username);
                        obj.users.push({username: match.username});
                    }
                }
            }
            obj.resultPattern = obj.pattern;
	    }
    });
};

// ----------------------------------------------------------------------------------------------
// NOTICE: The Developer Edition is currently limited to 3 running functions in the Beta version.
// Other limitations may apply in the final release.
// Professional and Enterprise Editions does not have any limitations.
// ----------------------------------------------------------------------------------------------