const chai = require('chai');
const expect = chai.expect;
let currentTime = 1;
function now() {
return currentTime;
}
const LOOP_MAX = 10000;
function getCurrentTrackState(playlist) {
let startPoint = playlist[0].addedAt;
let currentPoint = playlist[0].addedAt;
let loopIteration = 0;
let i = 0;
while (true) {
const track = playlist[i];
loopIteration++;
if (loopIteration > LOOP_MAX) {
throw new Error(`Max iterations reached: ${currentPoint}`);
}
if (track.addedAt <= currentPoint) {
currentPoint += track.length;
if (currentPoint > now()) {
return {
currentTrack: track,
currentTrackOffset: now() - (currentPoint - track.length),
nextTrack: playlist[(i + 1) % playlist.length]
}
} else {
i = (i + 1) % playlist.length;
}
} else {
// Reset i to 0 (-1 + 1 for the end of the loop)
i = 0;
}
}
}
/*
For playlist a: 1, b: 2
c: 1 was added at time 5
Correctly played
11111111
012345678901234567
ab ab cab cab c...
c
Currently played
11111111
012345678901234567
ab abbcab cab...
c
ab cab <-- what the calculation is thinking when it adds c and
recalculates what should be playing
*/
const playlist1 = [{
addedAt: 1,
uri: "a",
length: 1
}, {
addedAt: 1,
uri: "b",
length: 2
}, {
addedAt: 5,
uri: "c",
length: 1
}];
currentTime = 6;
var results = getCurrentTrackState(playlist1);
expect(results.currentTrack.uri).to.equal("b");
expect(results.nextTrack.uri).to.equal("c");
expect(results.currentTrackOffset).to.equal(1);
1;
const playlist2 = [{
addedAt: 1,
uri: "a",
length: 1
}];
currentTime = 6;
var results = getCurrentTrackState(playlist2);
expect(results.currentTrack.uri).to.equal("a");
expect(results.nextTrack.uri).to.equal("a");
expect(results.currentTrackOffset).to.equal(0);
1;
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