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

let channels = {}
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']
}

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

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

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

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

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

document.addEventListener('DOMContentLoaded', () => {
    /**
     * Process the received data from the server.
     * @param data The received message
     */
    function processMessage(data) {
        // TODO Implement chat protocol
        switch (data['type']) {
            case 'fetch_channels':
                setChannels(data['channels'])
                break
            case 'send_message':
                receiveMessage(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()
})