local url = "wss://kc.is.being.pet/ws" 

local screen = peripheral.wrap("monitor_1")
local speakers = {
  l = peripheral.wrap("speaker_1"),
  r = peripheral.wrap("speaker_0"),
}

local ws = assert(http.websocket(url))

local function parse_u16(data)
  local v =  table.remove(data, 1)
  v = bit.bor(v, bit.blshift(table.remove(data, 1), 8))
  return v, data
end

local metadata_pkt = ws.receive()
metadata_pkt = { string.byte(metadata_pkt, 1, #metadata_pkt) }
local framerate = table.remove(metadata_pkt, 1)
local n_channels = table.remove(metadata_pkt, 1)
local sample_rate, data = parse_u16(metadata_pkt)
local screen_w, data = parse_u16(data)
local screen_h, data = parse_u16(data)
local samples_per_frame = math.floor(sample_rate / framerate)

print(string.format("FPS: %d", framerate))
print(string.format("Audio: %d channels, %d Hz", n_channels, sample_rate))
print(string.format("Video: %dx%d", screen_w, screen_h))
print(string.format("S/F: %d", samples_per_frame)) 

local function decode_s8(buf)
    local buffer = {}
    for i = 1, #buf do
        local v = buf[i]
        if bit32.band(v, 0x80) then
            v = bit32.bxor(v, 0x7F) - 128
        end
        table.insert(buffer, v)
        table.insert(buffer, v)
    end
    return buffer
end

local function mkSpeakerCoro(p, b)
  return function()
    while not p.playAudio(b) do
      os.pullEvent("speaker_audio_empty")
    end
  end
end

while true do
  local video_pkt = ws.receive()
  local channels = { l = {}, r = {} }
  local offset = 1
  channels.l = decode_s8({ string.byte(video_pkt, offset, offset + samples_per_frame - 1) })
  offset = offset + samples_per_frame
  channels.r = decode_s8({ string.byte(video_pkt, offset, offset + samples_per_frame - 1) })
  offset = offset + samples_per_frame
  for y = 1, screen_h do
    local tx, bg, fg = {}, {}, {}
    for x = 1, screen_w do
      table.insert(tx, string.sub(video_pkt, offset, offset))
      local color = string.byte(video_pkt, offset + 1, offset + 1)
      table.insert(bg, string.format("%x", bit.brshift(color, 4)))
      table.insert(fg, string.format("%x", bit.band(color, 0xF)))
      offset = offset + 2
    end
    screen.setCursorPos(1, y)
    screen.blit(table.concat(tx), table.concat(bg), table.concat(fg))
  end

  for i = 1, 16 do
    local r, g, b = string.byte(video_pkt, offset, offset + 3)
    screen.setPaletteColor(bit.blshift(1, i - 1), bit.bor(bit.bor(bit.blshift(r, 16), bit.blshift(g, 8)), b))
    offset = offset + 3
  end

  parallel.waitForAll(
    mkSpeakerCoro(speakers.l, channels.l),
    mkSpeakerCoro(speakers.r, channels.r))
end