selection = []
visited = []
current = 0
playing = 1

document.addEventListener('keyup', function(event) {
  if(event.keyCode == 37) { prev() } // left
  else if(event.keyCode == 39) { next() } // right
  else if(event.keyCode == 32) {
    toggle_play()
  } // space
  else if(event.keyCode == 13) { new_selection() } // enter
});

function new_selection() {
  images = Object.keys(distances)
  start = images[Math.floor(Math.random()*images.length)]
  sortable = []
  for (file in distances[start]) {
    if (visited.indexOf(file) == -1) { // not in visited
      sortable.push([file,distances[start][file]]) // objects cannot be sorted in js, use array instead
    }
  }
  n = 6
  selection = []
  sorted = sortable.sort(function(a, b) { return a[1] - b[1]; }).slice(0,n); // sort by distance, get first n elements
  sorted.forEach(function(img,index) { 
    selection.push(img[0])
    visited.push(img[0])
  }) 
  selection = selection.sort(() => Math.random() - 0.5); // shuffle
  current = 0
  update()
}

function src(id,path) { document.getElementById(id).src = path }
function onclick(id,fun) { document.getElementById(id).onclick = fun }

function hide_controls() {
  document.getElementById("prev").style.display = "none"
  document.getElementById("next").style.display = "none"
}

function show_controls() {
  document.getElementById("prev").style.display = "block"
  document.getElementById("next").style.display = "block"
}

function toggle_play() { playing == 1 ? stop() : play() }

function play() {
  playing = 1
  interval = setInterval(function () { next() }, 3000);
  document.getElementById("play-indicator").title = "Pause slideshow"
  document.getElementById("play-indicator").innerText = "\u23F8"
  hide_controls()
}

function stop() {
  playing = 0
  clearInterval(interval)
  document.getElementById("play-indicator").title = "Play slideshow"
  document.getElementById("play-indicator").innerText = "\u23F5"
  show_controls()
}

function prev() {
  current = (current-1+selection.length) % selection.length // js % cannot handle negative values
  update()
}

function next() {
  current = (current+1) % selection.length
  update()
}

function update() {
  src('image',"/pictures/"+selection[current])
}