asciimike/Chat.rules

## Chat.rules
function isChatMessage(message) {
    return message.size() == 4
        && message.username is string
        && message.userId is string
        && message.createdAt is timestamp
        && message.messageText is string
        && message.messageText.size() <= 160;
}

function isUser(user) {
    return user.size() == 1
        && (user.role == 'editor' || user.role == 'reader');
}

function isAdminUser(user) {
    return user.size() == 1
        && user.role == 'admin';
}

service cloud.firestore {
  match /databases/{database}/documents {
    match /rooms/{roomId} {
        function getRoleForUser(userId) {
            return get(/databases/$(database)/documents/rooms/$(roomId)/users/$(userId)).data.role;
        }
        function roomExists(roomId) {
            return exists(/databases/$(database)/documents/rooms/$(roomId));
        }
        match /messages/{messageId} {
            allow create: if isChatMessage(request.resource.data)
                          && request.resource.data.userId == request.auth.uid
                          && getRoleForUser(request.auth.uid) == 'editor';
            allow get, list: if getRoleForUser(request.auth.uid) in ['editor', 'reader'];
        }
        match /users/{userId} {
            allow create: if (!roomExists(roomId)
                              && isAdminUser(request.resource.data)
                              && request.auth.uid == userId)
                          || (getRoleForUser(request.auth.uid) == 'admin'
                              && isUser(request.resource.data)
                              && request.auth.uid != userId);
        }
    }
  }
}

## index.html
<html>
    <head>
        <title>Firebase Pro Series Chat App</title>
        <script src="https://www.gstatic.com/firebasejs/4.9.0/firebase.js"></script>
        <script src="https://www.gstatic.com/firebasejs/4.9.0/firebase-firestore.js"></script>
        <script type='text/javascript' src='https://ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.min.js'></script>
    </head>

    <body>
        <div id="stream">
            <h1>Pro Chat</h1>
            <input type="text" id="usernameInput" placeholder="Provide a username"/>
            <input type="text" id="msgInput" placeholder="Add message"/>
            <button type="submit" id="submit">Submit</button>
            </br>
            </br>
            <div id="msg-box"></div>
        </div>

        <script>
        // STEP 0: Configure Firebase
        // TODO: Replace with your own config
        var config = {
            apiKey: ...,
            authDomain: ...,
            databaseURL: ...,
            projectId: ...,
            storageBucket: ...,
            messagingSenderId: ...
        };
        firebase.initializeApp(config);

        //STEP 1: Create references
        var firestore = firebase.firestore();
        var auth = firebase.auth();
        var uid;

        // STEP 2: Log a user in
        auth.signInAnonymously().then(user => {
            uid = user.uid;
            console.log(uid);

            // STEP 3: Listen for new messages
            firestore.collection('rooms')
                     .doc('public')
                     .collection('messages')
                     .orderBy('createdAt')
                     .onSnapshot(docs => {
                        $('#msg-box').empty();
                         docs.forEach(function (doc) {
                             var message = doc.data();
                             $('#msg-box').append($("<div class='msg-text'>").text(message.username).append('<br/>').append($('<span/>').text(message.messageText))).append('<br/>');
                         });
                     }, error => {
                         alert(error);
                     });
        });

        //STEP 2: Store messages in Cloud Firestore
        $('#submit').on('click', function () {
            if (uid !== null) {
                var username = $('#usernameInput').val();
                var message = $('#msgInput').val();
                firestore.collection('rooms')
                        .doc('public')
                        .collection('messages')
                        .add({
                            'username': username,
                            'userId': uid,
                            'createdAt': new Date(),
                            'messageText': message
                        }).catch(error => {
                            alert(error);
                        });
                $('#msgInput').val('');
            } else {
                alert('You must log in to post!');
            }
        });
        </script>
    </body>
</html>

## Message.json
{
  "username": "Mike McDonald",
  "userId": "7199732f-ec7a-46bd-8949-71cd323a21fd",
  "createdAt": "2018-01-29T01:23:45Z",
  "messageText": "Hello, World!"
}

## User.json
{
  "role": "editor"  // or "reader"
}
	function isChatMessage(message) {
	return message.size() == 4
	&& message.username is string
	&& message.userId is string
	&& message.createdAt is timestamp
	&& message.messageText is string
	&& message.messageText.size() <= 160;
	}

	function isUser(user) {
	return user.size() == 1
	&& (user.role == 'editor' \|\| user.role == 'reader');
	}

	function isAdminUser(user) {
	return user.size() == 1
	&& user.role == 'admin';
	}

	service cloud.firestore {
	match /databases/{database}/documents {
	match /rooms/{roomId} {
	function getRoleForUser(userId) {
	return get(/databases/$(database)/documents/rooms/$(roomId)/users/$(userId)).data.role;
	}
	function roomExists(roomId) {
	return exists(/databases/$(database)/documents/rooms/$(roomId));
	}
	match /messages/{messageId} {
	allow create: if isChatMessage(request.resource.data)
	&& request.resource.data.userId == request.auth.uid
	&& getRoleForUser(request.auth.uid) == 'editor';
	allow get, list: if getRoleForUser(request.auth.uid) in ['editor', 'reader'];
	}
	match /users/{userId} {
	allow create: if (!roomExists(roomId)
	&& isAdminUser(request.resource.data)
	&& request.auth.uid == userId)
	\|\| (getRoleForUser(request.auth.uid) == 'admin'
	&& isUser(request.resource.data)
	&& request.auth.uid != userId);
	}
	}
	}
	}
	<html>
	<head>
	<title>Firebase Pro Series Chat App</title>
	<script src="https://www.gstatic.com/firebasejs/4.9.0/firebase.js"></script>
	<script src="https://www.gstatic.com/firebasejs/4.9.0/firebase-firestore.js"></script>
	<script type='text/javascript' src='https://ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.min.js'></script>
	</head>

	<body>
	<div id="stream">
	<h1>Pro Chat</h1>
	<input type="text" id="usernameInput" placeholder="Provide a username"/>
	<input type="text" id="msgInput" placeholder="Add message"/>
	<button type="submit" id="submit">Submit</button>
	</br>
	</br>
	<div id="msg-box"></div>
	</div>

	<script>
	// STEP 0: Configure Firebase
	// TODO: Replace with your own config
	var config = {
	apiKey: ...,
	authDomain: ...,
	databaseURL: ...,
	projectId: ...,
	storageBucket: ...,
	messagingSenderId: ...
	};
	firebase.initializeApp(config);

	//STEP 1: Create references
	var firestore = firebase.firestore();
	var auth = firebase.auth();
	var uid;

	// STEP 2: Log a user in
	auth.signInAnonymously().then(user => {
	uid = user.uid;
	console.log(uid);

	// STEP 3: Listen for new messages
	firestore.collection('rooms')
	.doc('public')
	.collection('messages')
	.orderBy('createdAt')
	.onSnapshot(docs => {
	$('#msg-box').empty();
	docs.forEach(function (doc) {
	var message = doc.data();
	$('#msg-box').append($("<div class='msg-text'>").text(message.username).append('<br/>').append($('<span/>').text(message.messageText))).append('<br/>');
	});
	}, error => {
	alert(error);
	});
	});

	//STEP 2: Store messages in Cloud Firestore
	$('#submit').on('click', function () {
	if (uid !== null) {
	var username = $('#usernameInput').val();
	var message = $('#msgInput').val();
	firestore.collection('rooms')
	.doc('public')
	.collection('messages')
	.add({
	'username': username,
	'userId': uid,
	'createdAt': new Date(),
	'messageText': message
	}).catch(error => {
	alert(error);
	});
	$('#msgInput').val('');
	} else {
	alert('You must log in to post!');
	}
	});
	</script>
	</body>
	</html>
	{
	"username": "Mike McDonald",
	"userId": "7199732f-ec7a-46bd-8949-71cd323a21fd",
	"createdAt": "2018-01-29T01:23:45Z",
	"messageText": "Hello, World!"
	}