import std/endians
import std/locks
import std/logging
import std/math
import std/monotimes
import std/os
import std/strformat
import std/tables
import std/times
import std/streams

import ./core

const NBUFFERS = 32
# it seems that some alsa hardware has a problem with smaller buffers than 512
when defined(linux):
  const BUFFERSAMPLECOUNT = 512
else:
  const BUFFERSAMPLECOUNT = 256

when defined(windows):
  include ./platform/windows/audio
when defined(linux):
  include ./platform/linux/audio

# TODO: this should probably be in the load-code-stuff
# proc LoadSound*(mixer: var Mixer, name: string, resource: string) =
# assert not (name in mixer.sounds)
# mixer.sounds[name] = LoadAudio(resource)

proc addSound*(name: string, sound: SoundData) =
  if name in engine().mixer.sounds:
    warn "sound with name '", name, "' was already loaded, overwriting"
  engine().mixer.sounds[name] = sound

proc addTrack*(name: string, level: AudioLevel = 1'f) =
  if name in engine().mixer.tracks:
    warn "track with name '", name, "' was already loaded, overwriting"
  engine().mixer.lock.withLock:
    engine().mixer.tracks[name] = Track(level: level)

proc play*(
    soundName: string,
    track = "",
    stopOtherSounds = false,
    loop = false,
    levelLeft, levelRight: AudioLevel,
): uint64 =
  assert track in engine().mixer.tracks, &"Track '{track}' does not exists"
  assert soundName in engine().mixer.sounds, soundName & " not loaded"
  engine().mixer.lock.withLock:
    if stopOtherSounds:
      engine().mixer.tracks[track].playing.clear()
    engine().mixer.tracks[track].playing[engine().mixer.playbackCounter] = Playback(
      sound: engine().mixer.sounds[soundName],
      position: 0,
      loop: loop,
      levelLeft: levelLeft,
      levelRight: levelRight,
      paused: false,
    )
  result = engine().mixer.playbackCounter
  inc engine().mixer.playbackCounter

proc play*(
    soundName: string,
    track = "",
    stopOtherSounds = false,
    loop = false,
    level: AudioLevel = 1'f,
): uint64 =
  play(
    soundName = soundName,
    track = track,
    stopOtherSounds = stopOtherSounds,
    loop = loop,
    levelLeft = level,
    levelRight = level,
  )

proc stop*() =
  engine().mixer.lock.withLock:
    for track in engine().mixer.tracks.mvalues:
      track.playing.clear()

proc getLevel*(): AudioLevel =
  engine().mixer.level

proc getLevel*(track: string): AudioLevel =
  engine().mixer.tracks[track].level

proc getLevel*(playbackId: uint64): (AudioLevel, AudioLevel) =
  for track in engine().mixer.tracks.mvalues:
    if playbackId in track.playing:
      return (track.playing[playbackId].levelLeft, track.playing[playbackId].levelRight)

proc setLevel*(level: AudioLevel) =
  engine().mixer.level = level

proc setLevel*(track: string, level: AudioLevel) =
  engine().mixer.lock.withLock:
    engine().mixer.tracks[track].level = level

proc setLevel*(playbackId: uint64, levelLeft, levelRight: AudioLevel) =
  engine().mixer.lock.withLock:
    for track in engine().mixer.tracks.mvalues:
      if playbackId in track.playing:
        track.playing[playbackId].levelLeft = levelLeft
        track.playing[playbackId].levelRight = levelRight

proc setLevel*(playbackId: uint64, level: AudioLevel) =
  setLevel(playbackId, level, level)

proc stop*(track: string) =
  assert track in engine().mixer.tracks
  engine().mixer.lock.withLock:
    engine().mixer.tracks[track].playing.clear()

proc stop*(playbackId: uint64) =
  engine().mixer.lock.withLock:
    for track in engine().mixer.tracks.mvalues:
      if playbackId in track.playing:
        track.playing.del(playbackId)
        break

proc pause*(value: bool) =
  engine().mixer.lock.withLock:
    for track in engine().mixer.tracks.mvalues:
      for playback in track.playing.mvalues:
        playback.paused = value

proc pause*(track: string, value: bool) =
  engine().mixer.lock.withLock:
    for playback in engine().mixer.tracks[track].playing.mvalues:
      playback.paused = value

proc pause*(playbackId: uint64, value: bool) =
  engine().mixer.lock.withLock:
    for track in engine().mixer.tracks.mvalues:
      if playbackId in track.playing:
        track.playing[playbackId].paused = value

proc pause*() =
  pause(true)

proc pause*(track: string) =
  pause(track, true)

proc pause*(playbackId: uint64) =
  pause(playbackId, true)

proc unpause*() =
  pause(false)

proc unpause*(track: string) =
  pause(track, false)

proc unpause*(playbackId: uint64) =
  pause(playbackId, false)

proc fadeTo*(track: string, level: AudioLevel, time: float) =
  engine().mixer.tracks[track].targetLevel = level
  engine().mixer.tracks[track].fadeTime = time
  engine().mixer.tracks[track].fadeStep =
    level.float - engine().mixer.tracks[track].level.float / time

proc isPlaying*(): bool =
  engine().mixer.lock.withLock:
    for track in engine().mixer.tracks.mvalues:
      for playback in track.playing.values:
        if not playback.paused:
          return true
  return false

proc isPlaying*(track: string): bool =
  engine().mixer.lock.withLock:
    if engine().mixer.tracks.contains(track):
      for playback in engine().mixer.tracks[track].playing.values:
        if not playback.paused:
          return true
    return false

func applyLevel(sample: Sample, levelLeft, levelRight: AudioLevel): Sample =
  [int16(float(sample[0]) * levelLeft), int16(float(sample[1]) * levelRight)]

func clip(value: int32): int16 =
  int16(max(min(int32(high(int16)), value), int32(low(int16))))

# used for combining sounds
func mix(a, b: Sample): Sample =
  [clip(int32(a[0]) + int32(b[0])), clip(int32(a[1]) + int32(b[1]))]

proc updateSoundBuffer*(mixer: var Mixer) =
  let t = getMonoTime()

  let dt = (t - mixer.lastUpdate).inNanoseconds.float64 / 1_000_000_000'f64
  mixer.lastUpdate = t

  # update fadings
  mixer.lock.withLock:
    for track in mixer.tracks.mvalues:
      if track.fadeTime > 0:
        track.fadeTime -= dt
        track.level = (track.level.float64 + track.fadeStep.float64 * dt).clamp(
          AudioLevel.low, AudioLevel.high
        )
        if track.fadeTime <= 0:
          track.level = track.targetLevel
  # mix
  var hasData = false
  for i in 0 ..< mixer.buffers[mixer.currentBuffer].len:
    var mixedSample = [0'i16, 0'i16]
    mixer.lock.withLock:
      for track in mixer.tracks.mvalues:
        var stoppedSounds: seq[uint64]
        for (id, playback) in track.playing.mpairs:
          if playback.paused:
            continue
          let sample = applyLevel(
            playback.sound[playback.position],
            mixer.level * track.level * playback.levelLeft,
            mixer.level * track.level * playback.levelRight,
          )
          mixedSample = mix(mixedSample, sample)
          hasData = true
          inc playback.position
          if playback.position >= playback.sound.len:
            if playback.loop:
              playback.position = 0
            else:
              stoppedSounds.add id
        for id in stoppedSounds:
          track.playing.del(id)
      mixer.buffers[mixer.currentBuffer][i] = mixedSample
  # send data to sound device
  if hasData:
    mixer.device.WriteSoundData(mixer.currentBuffer)
    mixer.currentBuffer = (mixer.currentBuffer + 1) mod mixer.buffers.len

# DSP functions
# TODO: finish implementation, one day

#[
#
proc lowPassFilter(data: var SoundData, cutoff: int) =
  let alpha = float(cutoff) / AUDIO_SAMPLE_RATE
  var value = data[0]
  for i in 0 ..< data.len:
    value[0] += int16(alpha * float(data[i][0] - value[0]))
    value[1] += int16(alpha * float(data[i][1] - value[1]))
    data[i] = value

  proc downsample(data: var SoundData, n: int) =
    let newLen = (data.len - 1) div n + 1
    for i in 0 ..< newLen:
      data[i] = data[i * n]
    data.setLen(newLen)

  proc upsample(data: var SoundData, m: int) =
    data.setLen(data.len * m)
    var i = data.len - 1
    while i < 0:
      if i mod m == 0:
        data[i] = data[i div m]
      else:
        data[i] = [0, 0]
      i.dec

    proc slowdown(data: var SoundData, m, n: int) =
      data.upsample(m)
      # TODO
      # data.lowPassFilter(m)
      data.downsample(n)

    ]#

proc setupDevice(mixer: var Mixer) =
  # call this inside audio thread
  var bufferaddresses: seq[ptr SoundData]
  for i in 0 ..< NBUFFERS:
    mixer.buffers.add newSeq[Sample](BUFFERSAMPLECOUNT)
  for i in 0 ..< mixer.buffers.len:
    bufferaddresses.add (addr mixer.buffers[i])
  mixer.device = OpenSoundDevice(AUDIO_SAMPLE_RATE, bufferaddresses)

proc destroy(mixer: var Mixer) =
  mixer.lock.deinitLock()
  mixer.device.CloseSoundDevice()

proc audioWorker*(mixer: ptr Mixer) {.thread.} =
  mixer[].setupDevice()
  onThreadDestruction(
    proc() =
      mixer[].lock.withLock(mixer[].destroy())
      freeShared(mixer)
  )
  while true:
    mixer[].updateSoundBuffer()

# audio-generator helpers

proc sinewave(f: float): proc(x: float): float =
  proc ret(x: float): float =
    sin(x * 2 * Pi * f)

  result = ret

proc sineSoundData*(f: float, len: float, rate: int, amplitude = 0.5'f32): SoundData =
  let dt = 1'f / float(rate)
  var sine = sinewave(f)
  for i in 0 ..< int(float(rate) * len):
    let t = dt * float(i)
    let value = int16(sine(t) * float(high(int16)) * amplitude)
    result.add [value, value]

# loaders

type
  Encoding {.size: sizeof(uint32).} = enum
    # Unspecified = 0
    # Uint8Ulaw = 1
    # Int8 = 2
    Int16 = 3
    # Int24 = 4
    # Int32 = 5
    # Float32 = 6
    # Float64 = 7

  AuHeader = object
    magicNumber: uint32
    dataOffset: uint32
    dataSize: uint32
    encoding: Encoding
    sampleRate: uint32
    channels: uint32

proc readSample(stream: Stream, encoding: Encoding, channels: int): Sample =
  result[0] = stream.readint16()
  swapEndian16(addr result[0], addr result[0])

  if channels == 2:
    result[1] = stream.readint16()
    swapEndian16(addr result[1], addr result[1])
  else:
    result[1] = result[0]

# https://en.wikipedia.org/wiki/Au_file_format
proc readAU*(stream: Stream): SoundData =
  var header: AuHeader

  for name, value in fieldPairs(header):
    var bytes: array[4, uint8]
    stream.read(bytes)
    swap(bytes[0], bytes[3])
    swap(bytes[1], bytes[2])
    value = cast[typeof(value)](bytes)

  assert header.magicNumber == 0x2e736e64
  if header.sampleRate != AUDIO_SAMPLE_RATE:
    raise newException(
      Exception,
      &"Only support sample rate of {AUDIO_SAMPLE_RATE} Hz but got {header.sampleRate} Hz, please resample (e.g. ffmpeg -i <infile> -ar {AUDIO_SAMPLE_RATE} <outfile>)",
    )
  if not (header.channels in [1'u32, 2'u32]):
    raise newException(
      Exception,
      "Only support mono and stereo audio at the moment (1 or 2 channels), but found " &
        $header.channels,
    )

  var annotation: string
  stream.read(annotation)

  stream.setPosition(int(header.dataOffset))
  while not stream.atEnd():
    result.add stream.readSample(header.encoding, int(header.channels))

{.compile: currentSourcePath.parentDir() & "/thirdparty/stb/stb_vorbis.c".}

proc stb_vorbis_decode_memory(
  mem: pointer,
  len: cint,
  channels: ptr cint,
  sample_rate: ptr cint,
  output: ptr ptr cshort,
): cint {.importc.}

proc readVorbis*(stream: Stream): SoundData =
  var
    data = stream.readAll()
    channels: cint
    sampleRate: cint
    output: ptr cshort

  var nSamples = stb_vorbis_decode_memory(
    addr data[0], cint(data.len), addr channels, addr sampleRate, addr output
  )

  if nSamples < 0:
    raise newException(
      Exception, &"Unable to read ogg/vorbis sound file, error code: {nSamples}"
    )
  if sampleRate != AUDIO_SAMPLE_RATE:
    raise newException(
      Exception,
      &"Only support sample rate of {AUDIO_SAMPLE_RATE} Hz but got {sampleRate} Hz, please resample (e.g. ffmpeg -i <infile> -acodec libvorbis -ar {AUDIO_SAMPLE_RATE} <outfile>)",
    )

  if channels == 2:
    result.setLen(int(nSamples))
    copyMem(addr result[0], output, nSamples * sizeof(Sample))
    nativeFree(output)
  elif channels == 1:
    for i in 0 ..< nSamples:
      let value = cast[ptr UncheckedArray[int16]](output)[i]
      result.add [value, value]
    nativeFree(output)
  else:
    nativeFree(output)
    raise newException(
      Exception,
      "Only support mono and stereo audio at the moment (1 or 2 channels), but found " &
        $channels,
    )