path: root/client/js/radio_emulator.js

// Radio Station Emulator
//
// Kaotisk Hund - 2024
//
// @license magnet:?xt=urn:btih:0b31508aeb0634b347b8270c7bee4d411b5d4109&dn=agpl-3.0.txt AGPL v3.0
//
// A simple co-mechanism to pretend playing a live radio as it would happen for
// a radio station that mostly plays prerecoded shows.
//
// Client side implementation
// Let's remind here the structures we are waiting for:
// 1. Hash
// 2. 0
// 3. audio/ogg file
// 4. application/json file
//
// 1. Hash
// Can be an SHA512sum or SHA256sum, we don't do checks, we only ask the hash
// accompanied by what do we think it is.
//
// 2. 0
// When nothing exists on the radio station we are visiting.
//
// 3. audio/ogg file
// An audio file to play.
//
// 4. application/json file
// Could be one of the following:
//   - list
//   - show_info
//
var debugMode = true;
const apiURL = "http://z.kaotisk-hund.com:8010/";
const version = "v0";
const listRequest = `${apiURL}${version}/list`
const jsonRequest = `${apiURL}${version}/application/json/`
const audioRequest = `${apiURL}${version}/audio/ogg/`

const documentTitle = "Radio Station Emulator";
const separator = " :: ";

var audioElement = document.querySelector('audio');

var placeholders = {
    currentTime: document.querySelector('.current-time'),
    listStarted: document.querySelector('.started-on'),
    currentShowHash : document.querySelector('.current-show-hash'),
    listHash : document.querySelector('.list-hash'),
    artist: document.querySelector('.artist'),
    title: document.querySelector('.title'),
    radioPlayer: document.querySelector('.radio-player'),
    youAreHere : document.querySelector('.you-are-here'),
    playProgress: document.querySelector('.play-progress'),
    startsOn: document.querySelector('.starts-on'),
    showDuration: document.querySelectorAll('.show-duration'),
    relativeTime: document.querySelector('.relative-time'),
    listeningAt: document.querySelector('.listening-at'),
    dlProgress: document.querySelector('.dl-progress'),
    minTimesPlayed: document.querySelector('.min-played'),
    maxTimesPlayed: document.querySelector('.max-played'),
    listDuration: document.querySelector('.list-duration'),
    previouslyPlayed: document.querySelector('.previously-played'),
    showInfo: document.querySelector('.show-info'),
    listInfo: document.querySelector('.list-info'),
    dt: document.querySelector('.d-t'),
    deltaTime: document.querySelector('.delta-time'),
    timeOfVisit: document.querySelector('.time-of-visit')
}

var values = {
    delta_time: 0,
    min_times_played: 0,
    maxTimesPlayed: 0,
    Dt: 0,
    now_on_sequence: 0,
    seconds_here: 0,
    current_time: 0
}

function debugLog(message)
{
    if ( debugMode ) console.log(message);
}

function setTitleSyncing(){
    document.title = "🔃Syncing" + separator + documentTitle;
}

function setTitleMessage(message){
    document.title = message + separator + documentTitle;
}

function updateComponentsAfterIncreaseSeconds()
{
    placeholders.youAreHere.innerText = values.seconds_here;
    placeholders.playProgress.value = values.current_time + values.seconds_here;
    placeholders.relativeTime.innerText = values.current_time + values.seconds_here;
    placeholders.listeningAt.innerText = Math.floor(audioElement.currentTime);
}

function increaseSeconds()
{
    values.seconds_here = values.seconds_here + 1;
    updateComponentsAfterIncreaseSeconds();
    return values.seconds_here;
}
function getSecondsHere()
{
    return values.seconds_here;
}

setInterval(increaseSeconds, 1000);


function FetchJSON( url, callback, params )
{
    setTitleSyncing();
    const request = new XMLHttpRequest();
    request.addEventListener("load", ()=>{
        var json = JSON.parse(request.response);
        if(request.status !== 404){
            callback(json, params);
        } else {
            debugLog(`ERROR ${request.status} while loading ${url}`);
        }
    });
    request.addEventListener("error", ()=>{
        debugLog("An error occured. While loading: "+url+" for "+callback+".");
    });
    request.addEventListener("abort", ()=>{
        debugLog("Request aborted: "+url+" for "+callback+".");
    });
    request.open("GET", url);
    request.send();
}

function FetchAudio(url, callback)
{
    const request = new XMLHttpRequest();
    request.responseType = 'blob';
    request.addEventListener("load", ()=>{
        if(request.status === 200){
            debugLog("Got it... trying!")
            placeholders.dlProgress.value = 100;
            audioElement.src = URL.createObjectURL(request.response);
            callback();
            // audioElement.play();
            debugLog("Tried... did it work?");
        } else {
            debugLog(`ERROR ${request.status} while loading ${url}`);
        }
    });
    request.addEventListener("progress", (event)=>{
        if (event.lengthComputable)
        {
            debugLog(`Fetching: ${event.total}`);
            placeholders.dlProgress.value = (event.loaded/event.total)*100;
        }
    });
    request.addEventListener("error", ()=>{
        debugLog("An error occured. While loading: "+url);
    });
    request.addEventListener("abort", ()=>{
        debugLog("Request aborted: "+url);
    });
    request.open("GET", url);
    request.send();
}

function genericCallback(json, params)
{
    debugLog('genericCallback');
    debugLog(json);
    debugLog(params);
}

var calledLoadShowCallback = 0;

function stopHereAndReflect()
{
    return 0;
}

function updateComponentsAfterLoadShowCallback(json, listItem)
{
    setTitleMessage ( "▶️ " + json.artist + " - " + json.title );
    placeholders.currentShowHash.innerText = listItem.hash;
    placeholders.artist.innerText = json.artist;
    placeholders.title.innerText = json.title;
    placeholders.showDuration.forEach((element)=>{element.innerText = Math.floor(listItem.duration/1000)});
    placeholders.startsOn.innerText = listItem.starts_on;
    placeholders.playProgress.max = Math.floor(listItem.duration/1000);
    placeholders.showInfo.innerText = JSON.stringify(json, null, 2);
    placeholders.currentTime.innerText = values.current_time;
}

function loadShowCallback(json, params)
{
    const [ list, now_on_sequence, listItem, hash_of_list ] = params;
    debugLog('loadShowCallback');
    debugLog(json);
    debugLog(listItem);
    //debugLog(params);
    audioElement.load();
    FetchAudio(`${audioRequest}${json.hash}`, sync_radio);
    audioElement.type = json.mimetype;
    values.current_time = Math.floor((values.now_on_sequence/1000)); // - listItem.starts_on)/1000);
    updateComponentsAfterLoadShowCallback(json, listItem);
    audioElement.addEventListener('ended', function(){
        values.current_time = 0;
        values.seconds_here = 0;
        placeholders.currentTime.value = 0;
        FetchJSON(`${listRequest}`, hashCallback, [ new Date().getTime() ]);
    });
}

function slowIncreaseVolume()
{
    if (audioElement.volume < 0.91)
    {
        audioElement.volume += 0.05;
    }
    else
    {
        audioElement.volume = 1;
    }
}

function preciseIncreaseVolume(value)
{
    if ( value <= 1 ) audioElement.volume = value;
}

function fadeInAudio()
{
    var timeSpan = 1000;
    var timeStep = 100;
    for ( var i = 0; i <= 90; i++ )
    {
        timeSpan = timeSpan + timeStep;
        var newVolume = Math.sin(i*(Math.PI/180));
        setTimeout( preciseIncreaseVolume(newVolume), timeSpan);
    }
}

function sync_radio()
{
    var new_now = values.current_time + getSecondsHere();
    debugLog("Trying to sync @ "+ values.current_time + " + " + getSecondsHere() + " = " + new_now);
    audioElement.currentTime = new_now;
    audioElement.play();
    audioElement.muted = false;
    audioElement.volume = 0;
    fadeInAudio();
    return new_now;
}

function syncOnDOMfromListCallback(now, hash_of_list, json)
{
    placeholders.timeOfVisit.innerText = now;
    placeholders.listStarted.innerText = json.started_on;
    placeholders.listDuration.innerText = json.duration;
    placeholders.listHash.innerText = hash_of_list;
    placeholders.deltaTime.innerText = values.delta_time;
    placeholders.minTimesPlayed.innerText = values.min_times_played;
    placeholders.maxTimesPlayed.innerText = values.max_times_to_be_played;
    placeholders.dt.innerText = values.Dt;
    placeholders.currentTime.innerText = values.now_on_sequence;
    placeholders.listInfo.innerText = JSON.stringify(json, null, 2);
}

function appendPreviouslyPlayedShows(listItem){
    if ( document.querySelector(`#s-${listItem.hash}`) === null )
    {
        var tmp = document.createElement('pre');
        tmp.id = `s-${listItem.hash}`;
        tmp.innerText = JSON.stringify(listItem, null, 2);
        placeholders.previouslyPlayed.append(tmp);
    }
}

function listCallback(json, params)
{
    debugLog('listCallback');
    debugLog(json);
    debugLog(params);
    var [ now, hash_of_list ] = params;
    values.delta_time = now - json.started_on;
    values.min_times_played = Math.floor( values.delta_time / json.duration );
    values.max_times_to_be_played = values.delta_time / json.duration;
    values.Dt = values.max_times_to_be_played - values.min_times_played;
    values.now_on_sequence = values.Dt * json.duration;
    syncOnDOMfromListCallback(now, hash_of_list, json);
    debugLog(`now_on_sequence: ${values.now_on_sequence}, Dt: ${values.Dt}`)
    debugLog(json.list.map((item, index)=>({index, value: item})).sort((a,b)=>{return b.value.index - a.value.index}));
    if ( json.list.length === 1 )
    {
        FetchJSON(`${jsonRequest}${json.list[0].hash}`, loadShowCallback, [json, values.now_on_sequence, json.list[0], hash_of_list]);
    }
    else
    {
        for ( var i = 0; i < json.list.length - 1; i++)
        {
            if( i !== 0 ) appendPreviouslyPlayedShows(json.list[i-1<