plateforme-tfjm2/chat/static/chat.js

(async () => {
    // check notification permission
    // This is useful to alert people that they should do something
    await Notification.requestPermission()
})()

const MAX_MESSAGES = 50

let channels = {}
let messages = {}
let selected_channel_id = null

/**
 * Display a new notification with the given title and the given body.
 * @param title The title of the notification
 * @param body The body of the notification
 * @param timeout The time (in milliseconds) after that the notification automatically closes. 0 to make indefinite. Default to 5000 ms.
 * @return Notification
 */
function showNotification(title, body, timeout = 5000) {
    let notif = new Notification(title, {'body': body, 'icon': "/static/tfjm.svg"})
    if (timeout)
        setTimeout(() => notif.close(), timeout)
    return notif
}

function selectChannel(channel_id) {
    let channel = channels[channel_id]
    if (!channel) {
        console.error('Channel not found:', channel_id)
        return
    }

    selected_channel_id = channel_id

    let channelTitle = document.getElementById('channel-title')
    channelTitle.innerText = channel['name']

    let messageInput = document.getElementById('input-message')
    messageInput.disabled = !channel['write_access']

    redrawMessages()
}

function sendMessage() {
    let messageInput = document.getElementById('input-message')
    let message = messageInput.value
    messageInput.value = ''

    if (!message) {
        return
    }

    socket.send(JSON.stringify({
        'type': 'send_message',
        'channel_id': selected_channel_id,
        'content': message,
    }))
}

function setChannels(new_channels) {
    channels = {}
    for (let channel of new_channels) {
        channels[channel['id']] = channel
        if (!messages[channel['id']])
            messages[channel['id']] = new Map()

        fetchMessages(channel['id'])
    }

    if (new_channels && (!selected_channel_id || !channels[selected_channel_id]))
        selectChannel(Object.keys(channels)[0])
}

function receiveMessage(message) {
    messages[message['channel_id']].push(message)
    redrawMessages()
}

function fetchMessages(channel_id, offset = 0, limit = MAX_MESSAGES) {
    socket.send(JSON.stringify({
        'type': 'fetch_messages',
        'channel_id': channel_id,
        'offset': offset,
        'limit': limit,
    }))
}

function fetchPreviousMessages() {
    let channel_id = selected_channel_id
    let offset = messages[channel_id].size
    fetchMessages(channel_id, offset, MAX_MESSAGES)
}

function receiveFetchedMessages(data) {
    let channel_id = data['channel_id']
    let new_messages = data['messages']

    if (!messages[channel_id])
        messages[channel_id] = new Map()

    for (let message of new_messages)
        messages[channel_id].set(message['id'], message)

    // Sort messages by timestamp
    messages[channel_id] = new Map([...messages[channel_id].values()]
      .sort((a, b) => new Date(a['timestamp']) - new Date(b['timestamp']))
      .map(message => [message['id'], message]))

    redrawMessages()
}

function redrawMessages() {
    let messageList = document.getElementById('message-list')
    messageList.innerHTML = ''

    let lastMessage = null
    let lastContentDiv = null

    for (let message of messages[selected_channel_id].values()) {
        if (lastMessage && lastMessage['author'] === message['author']) {
            let lastTimestamp = new Date(lastMessage['timestamp'])
            let newTimestamp = new Date(message['timestamp'])
            if ((newTimestamp - lastTimestamp) / 1000 < 60 * 10) {
                let messageContentDiv = document.createElement('div')
                messageContentDiv.innerText = message['content']
                lastContentDiv.appendChild(messageContentDiv)
                continue
            }
        }

        let messageElement = document.createElement('li')
        messageElement.classList.add('list-group-item')
        messageList.appendChild(messageElement)

        let authorDiv = document.createElement('div')
        messageElement.appendChild(authorDiv)

        let authorSpan = document.createElement('span')
        authorSpan.classList.add('text-muted', 'fw-bold')
        authorSpan.innerText = message['author']
        authorDiv.appendChild(authorSpan)

        let dateSpan = document.createElement('span')
        dateSpan.classList.add('text-muted', 'float-end')
        dateSpan.innerText = new Date(message['timestamp']).toLocaleString()
        authorDiv.appendChild(dateSpan)

        let contentDiv = document.createElement('div')
        messageElement.appendChild(contentDiv)

        let messageContentDiv = document.createElement('div')
        messageContentDiv.innerText = message['content']
        contentDiv.appendChild(messageContentDiv)

        lastMessage = message
        lastContentDiv = contentDiv
    }

    let fetchMoreButton = document.getElementById('fetch-previous-messages')
    if (!messages[selected_channel_id] || messages[selected_channel_id].size % MAX_MESSAGES !== 0)
        fetchMoreButton.classList.add('d-none')
    else
        fetchMoreButton.classList.remove('d-none')
}

document.addEventListener('DOMContentLoaded', () => {
    /**
     * Process the received data from the server.
     * @param data The received message
     */
    function processMessage(data) {
        switch (data['type']) {
            case 'fetch_channels':
                setChannels(data['channels'])
                break
            case 'send_message':
                receiveMessage(data)
                break
            case 'fetch_messages':
                receiveFetchedMessages(data)
                break
            default:
                console.log(data)
                console.error('Unknown message type:', data['type'])
                break
        }
    }

    function setupSocket(nextDelay = 1000) {
        // Open a global websocket
        socket = new WebSocket(
            (document.location.protocol === 'https:' ? 'wss' : 'ws') + '://' + window.location.host + '/ws/chat/'
        )

        // Listen on websockets and process messages from the server
        socket.addEventListener('message', e => {
            // Parse received data as JSON
            const data = JSON.parse(e.data)

            processMessage(data)
        })

        // Manage errors
        socket.addEventListener('close', e => {
            console.error('Chat socket closed unexpectedly, restarting…')
            setTimeout(() => setupSocket(2 * nextDelay), nextDelay)
        })

        socket.addEventListener('open', e => {
            socket.send(JSON.stringify({
                'type': 'fetch_channels',
            }))
        })
    }

    setupSocket()
})