__precompile__(true)

module PortAudio

using SampledSignals
using RingBuffers
using Compat
using Compat: undef, fetch, @compat
using Compat.LinearAlgebra: transpose!
using Compat: stdout
using Compat.Sys: iswindows

import Base: eltype, show
import Base: close, isopen
import Base: read, read!, write, flush

export PortAudioStream


# Get binary dependencies loaded from BinDeps
include("../deps/deps.jl")
include("pa_shim.jl")
include("libportaudio.jl")

# These sizes are all in frames

# the block size is what we request from portaudio if no blocksize is given.
# The ringbuffer and pre-fill will be twice the blocksize
const DEFAULT_BLOCKSIZE=4096

# data is passed to and from the ringbuffer in chunks with this many frames
# it should be at most the ringbuffer size, and must evenly divide into the
# the underlying portaudio buffer size. E.g. if PortAudio is running with a
# 2048-frame buffer period, the chunk size can be 2048, 1024, 512, 256, etc.
const CHUNKSIZE=128

# ringbuffer to receive errors from the audio processing thread
const ERR_BUFSIZE=512

function versioninfo(io::IO=stdout)
    println(io, Pa_GetVersionText())
    println(io, "Version: ", Pa_GetVersion())
    println(io, "Shim Source Hash: ", shimhash()[1:10])
end

mutable struct PortAudioDevice
    name::String
    hostapi::String
    maxinchans::Int
    maxoutchans::Int
    defaultsamplerate::Float64
    idx::PaDeviceIndex
end

PortAudioDevice(info::PaDeviceInfo, idx) = PortAudioDevice(
        unsafe_string(info.name),
        unsafe_string(Pa_GetHostApiInfo(info.host_api).name),
        info.max_input_channels,
        info.max_output_channels,
        info.default_sample_rate,
        idx)

function devices()
    ndevices = Pa_GetDeviceCount()
    infos = PaDeviceInfo[Pa_GetDeviceInfo(i) for i in 0:(ndevices - 1)]
    PortAudioDevice[PortAudioDevice(info, idx-1) for (idx, info) in enumerate(infos)]
end

# not for external use, used in error message printing
devnames() = join(["\"$(dev.name)\"" for dev in devices()], "\n")

##################
# PortAudioStream
##################

mutable struct PortAudioStream{T}
    samplerate::Float64
    blocksize::Int
    stream::PaStream
    sink # untyped because of circular type definition
    source # untyped because of circular type definition
    errbuf::RingBuffer{pa_shim_errmsg_t} # used to send errors from the portaudio callback
    errtask::Task
    bufinfo::pa_shim_info_t # data used in the portaudio callback

    # this inner constructor is generally called via the top-level outer
    # constructor below
    function PortAudioStream{T}(indev::PortAudioDevice, outdev::PortAudioDevice,
                                inchans, outchans, sr, blocksize, synced) where {T}
        inchans = inchans == -1 ? indev.maxinchans : inchans
        outchans = outchans == -1 ? outdev.maxoutchans : outchans
        inparams = (inchans == 0) ?
            Ptr{Pa_StreamParameters}(0) :
            Ref(Pa_StreamParameters(indev.idx, inchans, type_to_fmt[T], 0.0, C_NULL))
        outparams = (outchans == 0) ?
            Ptr{Pa_StreamParameters}(0) :
            Ref(Pa_StreamParameters(outdev.idx, outchans, type_to_fmt[T], 0.0, C_NULL))
        this = new(sr, blocksize, C_NULL)
        @compat finalizer(close, this)
        this.sink = PortAudioSink{T}(outdev.name, this, outchans, blocksize*2)
        this.source = PortAudioSource{T}(indev.name, this, inchans, blocksize*2)
        this.errbuf = RingBuffer{pa_shim_errmsg_t}(1, ERR_BUFSIZE)
        if synced && inchans > 0 && outchans > 0
            # we've got a synchronized duplex stream. initialize with the output buffer full
            write(this.sink, SampleBuf(zeros(T, blocksize*2, outchans), sr))
        end
        # pass NULL for input/output we're not using
        this.bufinfo = pa_shim_info_t(
                inchans > 0 ? bufpointer(this.source) : C_NULL,
                outchans > 0 ? bufpointer(this.sink) : C_NULL,
                pointer(this.errbuf),
                synced, notifycb_c,
                inchans > 0 ? notifyhandle(this.source) : C_NULL,
                outchans > 0 ? notifyhandle(this.sink) : C_NULL,
                notifyhandle(this.errbuf),
                global_cond[].handle) # this is only needed for the libuv workaround
        this.stream = suppress_err() do
            Pa_OpenStream(inparams, outparams, float(sr), blocksize, paNoFlag,
                          shim_processcb_c, this.bufinfo)
        end

        Pa_StartStream(this.stream)
        this.errtask = @async handle_errors(this)
        push!(active_streams, this)

        this
    end
end

# this is the top-level outer constructor that all the other outer constructors end up calling
"""
    PortAudioStream(inchannels=2, outchannels=2; options...)
    PortAudioStream(duplexdevice, inchannels=2, outchannels=2; options...)
    PortAudioStream(indevice, outdevice, inchannels=2, outchannels=2; options...)

Audio devices can either be `PortAudioDevice` instances as returned
by `PortAudio.devices()`, or strings with the device name as reported by the
operating system. If a single `duplexdevice` is given it will be used for both
input and output. If no devices are given the system default devices will be
used.

Options:

* `eltype`:       Sample type of the audio stream (defaults to Float32)
* `samplerate`:   Sample rate (defaults to device sample rate)
* `blocksize`:    Size of the blocks that are written to and read from the audio
                  device. (Defaults to $DEFAULT_BLOCKSIZE)
* `synced`:       Determines whether the input and output streams are kept in
                  sync. If `true`, you must read and write an equal number of
                  frames, and the round-trip latency is guaranteed constant. If
                  `false`, you are free to read and write separately, but
                  overflow or underflow can affect the round-trip latency.
"""
function PortAudioStream(indev::PortAudioDevice, outdev::PortAudioDevice,
        inchans=2, outchans=2; eltype=Float32, samplerate=-1, blocksize=DEFAULT_BLOCKSIZE, synced=false)
    if samplerate == -1
        sampleratein = indev.defaultsamplerate
        samplerateout = outdev.defaultsamplerate
        if inchans > 0 && outchans > 0 && sampleratein != samplerateout
            error("""
            Can't open duplex stream with mismatched samplerates (in: $sampleratein, out: $samplerateout).
                   Try changing your sample rate in your driver settings or open separate input and output
                   streams""")
        elseif inchans > 0
            samplerate = sampleratein
        else
            samplerate = samplerateout
        end
    end
    PortAudioStream{eltype}(indev, outdev, inchans, outchans, samplerate, blocksize, synced)
end

# handle device names given as streams
function PortAudioStream(indevname::AbstractString, outdevname::AbstractString, args...; kwargs...)
    indev = nothing
    outdev = nothing
    for d in devices()
        if d.name == indevname
            indev = d
        end
        if d.name == outdevname
            outdev = d
        end
    end
    if indev == nothing
        error("No device matching \"$indevname\" found.\nAvailable Devices:\n$(devnames())")
    end
    if outdev == nothing
        error("No device matching \"$outdevname\" found.\nAvailable Devices:\n$(devnames())")
    end

    PortAudioStream(indev, outdev, args...; kwargs...)
end

# if one device is given, use it for input and output, but set inchans=0 so we
# end up with an output-only stream
function PortAudioStream(device::PortAudioDevice, inchans=2, outchans=2; kwargs...)
    PortAudioStream(device, device, inchans, outchans; kwargs...)
end
function PortAudioStream(device::AbstractString, inchans=2, outchans=2; kwargs...)
    PortAudioStream(device, device, inchans, outchans; kwargs...)
end

# use the default input and output devices
function PortAudioStream(inchans=2, outchans=2; kwargs...)
    inidx = Pa_GetDefaultInputDevice()
    indevice = PortAudioDevice(Pa_GetDeviceInfo(inidx), inidx)
    outidx = Pa_GetDefaultOutputDevice()
    outdevice = PortAudioDevice(Pa_GetDeviceInfo(outidx), outidx)
    PortAudioStream(indevice, outdevice, inchans, outchans; kwargs...)
end

# handle do-syntax
# TODO: there seems to be a buffering issue here. Running this multiple
# times creates weird echos, and even the first time there might be something
# fishy going on. Needs investigation
function PortAudioStream(fn::Function, args...; kwargs...)
    str = PortAudioStream(args...; kwargs...)
    try
        fn(str)
    finally
        close(str)
    end
end

const pa_inited = Ref(false)
const active_streams = Set{PortAudioStream}()

function notify_active_streams()
    # errors here can cause the system to hang if they're waiting on these
    # conditions, so we do our own exception display for easier debugging
    try
        while true
            wait(global_cond[])
            pa_inited[] || break

            for stream in active_streams
                notify(stream.source.ringbuf.datanotify.cond)
                notify(stream.sink.ringbuf.datanotify.cond)
                notify(stream.errbuf.datanotify.cond)
            end
        end
    catch ex
        showerror(stderr, ex, backtrace())
    end
end

function close(stream::PortAudioStream)
    if stream.stream != C_NULL
        Pa_StopStream(stream.stream)
        Pa_CloseStream(stream.stream)
        close(stream.source)
        close(stream.sink)
        close(stream.errbuf)
        stream.stream = C_NULL
        # wait for the error task to clean up
        fetch(stream.errtask)
        delete!(active_streams, stream)
    end

    nothing
end

isopen(stream::PortAudioStream) = stream.stream != C_NULL

SampledSignals.samplerate(stream::PortAudioStream) = stream.samplerate
eltype(stream::PortAudioStream{T}) where T = T

read(stream::PortAudioStream, args...) = read(stream.source, args...)
read!(stream::PortAudioStream, args...) = read!(stream.source, args...)
write(stream::PortAudioStream, args...) = write(stream.sink, args...)
write(sink::PortAudioStream, source::PortAudioStream, args...) = write(sink.sink, source.source, args...)
flush(stream::PortAudioStream) = flush(stream.sink)

function show(io::IO, stream::PortAudioStream)
    println(io, typeof(stream))
    println(io, "  Samplerate: ", samplerate(stream), "Hz")
    print(io, "  Buffer Size: ", stream.blocksize, " frames")
    if nchannels(stream.sink) > 0
        print(io, "\n  ", nchannels(stream.sink), " channel sink: \"", name(stream.sink), "\"")
    end
    if nchannels(stream.source) > 0
        print(io, "\n  ", nchannels(stream.source), " channel source: \"", name(stream.source), "\"")
    end
end

"""
    handle_errors(stream::PortAudioStream)

Handle errors coming over the error stream from PortAudio. This is run as an
independent task while the stream is active.
"""
function handle_errors(stream::PortAudioStream)
    err = Vector{pa_shim_errmsg_t}(undef, 1)
    while true
        nread = read!(stream.errbuf, err)
        nread == 1 || break
        if err[1] == PA_SHIM_ERRMSG_ERR_OVERFLOW
            warn("Error buffer overflowed on portaudio stream")
        elseif err[1] == PA_SHIM_ERRMSG_OVERFLOW
            # warn("Input overflowed from $(name(stream.source))")
        elseif err[1] == PA_SHIM_ERRMSG_UNDERFLOW
            # warn("Output underflowed to $(name(stream.sink))")
        else
            error("""
                Got unrecognized error code $(err[1]) from audio thread for
                portaudio stream. Please file an issue at
                https://github.com/juliaaudio/portaudio.jl/issues""")
        end
    end
end

##################################
# PortAudioSink & PortAudioSource
##################################

# Define our source and sink types
for (TypeName, Super) in ((:PortAudioSink, :SampleSink),
                          (:PortAudioSource, :SampleSource))
    @eval mutable struct $TypeName{T} <: $Super
        name::String
        stream::PortAudioStream{T}
        chunkbuf::Array{T, 2}
        ringbuf::RingBuffer{T}
        nchannels::Int

        function $TypeName{T}(name, stream, channels, ringbufsize) where {T}
            # portaudio data comes in interleaved, so we'll end up transposing
            # it back and forth to julia column-major
            chunkbuf = zeros(T, channels, CHUNKSIZE)
            ringbuf = RingBuffer{T}(channels, ringbufsize)
            new(name, stream, chunkbuf, ringbuf, channels)
        end
    end
end

SampledSignals.nchannels(s::Union{PortAudioSink, PortAudioSource}) = s.nchannels
SampledSignals.samplerate(s::Union{PortAudioSink, PortAudioSource}) = samplerate(s.stream)
SampledSignals.blocksize(s::Union{PortAudioSink, PortAudioSource}) = s.stream.blocksize
eltype(::Union{PortAudioSink{T}, PortAudioSource{T}}) where {T} = T
close(s::Union{PortAudioSink, PortAudioSource}) = close(s.ringbuf)
isopen(s::Union{PortAudioSink, PortAudioSource}) = isopen(s.ringbuf)
RingBuffers.notifyhandle(s::Union{PortAudioSink, PortAudioSource}) = notifyhandle(s.ringbuf)
bufpointer(s::Union{PortAudioSink, PortAudioSource}) = pointer(s.ringbuf)
name(s::Union{PortAudioSink, PortAudioSource}) = s.name

function show(io::IO, stream::T) where {T <: Union{PortAudioSink, PortAudioSource}}
    println(io, T, "(\"", stream.name, "\")")
    print(io, nchannels(stream), " channels")
end

flush(sink::PortAudioSink) = flush(sink.ringbuf)

function SampledSignals.unsafe_write(sink::PortAudioSink, buf::Array, frameoffset, framecount)
    nwritten = 0
    while nwritten < framecount
        towrite = min(framecount-nwritten, CHUNKSIZE)
        # make a buffer of interleaved samples
        transpose!(view(sink.chunkbuf, :, 1:towrite),
                   view(buf, (1:towrite) .+ nwritten .+ frameoffset, :))
        n = write(sink.ringbuf, sink.chunkbuf, towrite)
        nwritten += n
        # break early if the stream is closed
        n < towrite && break
    end

    nwritten
end

function SampledSignals.unsafe_read!(source::PortAudioSource, buf::Array, frameoffset, framecount)
    nread = 0
    while nread < framecount
        toread = min(framecount-nread, CHUNKSIZE)
        n = read!(source.ringbuf, source.chunkbuf, toread)
        # de-interleave the samples
        transpose!(view(buf, (1:toread) .+ nread .+ frameoffset, :),
                   view(source.chunkbuf, :, 1:toread))

        nread += toread
        # break early if the stream is closed
        n < toread && break
    end

    nread
end


const libpa_shim = find_pa_shim()

"""
    PortAudio.shimhash()

Return the sha256 hash(as a string) of the source file used to build the shim.
We may use this sometime to verify that the distributed binary stays in sync
with the rest of the package.
"""
shimhash() = unsafe_string(ccall((:pa_shim_getsourcehash, libpa_shim), Cstring, ()))


# this is called by the shim process callback to notify that there is new data.
# it's run in the audio context so don't do anything besides wake up the
# AsyncCondition handle associated with that ring buffer
notifycb(handle) = ccall(:uv_async_send, Cint, (Ref{Cvoid},), handle)

global shim_processcb_c, notifycb_c

function set_global_callbacks()
    shim_dlib = Libdl.dlopen(libpa_shim)

    # pointer to the shim's process callback
    global shim_processcb_c = Libdl.dlsym(shim_dlib, :pa_shim_processcb)
    if shim_processcb_c == C_NULL
        error("Got NULL pointer loading `pa_shim_processcb`")
    end

    global notifycb_c = @cfunction notifycb Cint (Ptr{Cvoid},)
end

function suppress_err(dofunc::Function)
    nullfile = @static iswindows() ? "nul" : "/dev/null"
    open(nullfile, "w") do io
        redirect_stdout(dofunc, io)
    end
end

# this ref has to be set during __init__ to register itself properly with libuv
const global_cond = Ref{Base.AsyncCondition}()
function __init__()
    # currently libuv has issues when you try to notify more than one condition
    # (see https://github.com/libuv/libuv/issues/1951). So as a workaround we use
    # a global AsyncCondition that gets notified from the audio callback, and it
    # handles notifying the individual RingBuffer AsyncConditions.
    global_cond[] = Base.AsyncCondition()
    set_global_callbacks()

    # initialize PortAudio on module load
    suppress_err() do
        Pa_Initialize()
    end
    pa_inited[] = true
    notifier = @async notify_active_streams()

    atexit() do
        for str in active_streams
            close(str)
        end
        Pa_Terminate()
        pa_inited[] = false
        notify(global_cond[].cond)
        fetch(notifier)
    end
end

end # module PortAudio