/**
 * OpenAL cross platform audio library
 * Copyright (C) 2009 by Konstantinos Natsakis <konstantinos.natsakis@gmail.com>
 * Copyright (C) 2010 by Chris Robinson <chris.kcat@gmail.com>
 * This library is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Library General Public
 *  License as published by the Free Software Foundation; either
 *  version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *  Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public
 *  License along with this library; if not, write to the
 *  Free Software Foundation, Inc.,
 *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 * Or go to http://www.gnu.org/copyleft/lgpl.html
 */

#include "config.h"

#include "pulseaudio.h"

#include <algorithm>
#include <array>
#include <atomic>
#include <bitset>
#include <chrono>
#include <cmath>
#include <cstring>
#include <limits>
#include <mutex>
#include <optional>
#include <ranges>
#include <span>
#include <string>
#include <string_view>
#include <sys/types.h>
#include <utility>
#include <vector>

#include "alc/alconfig.h"
#include "alformat.hpp"
#include "alnumeric.h"
#include "base.h"
#include "core/devformat.h"
#include "core/device.h"
#include "core/logging.h"
#include "dynload.h"
#include "gsl/gsl"
#include "opthelpers.h"
#include "strutils.hpp"

#include <pulse/pulseaudio.h>


namespace {

using namespace std::string_view_literals;
using voidp = void*;
using cvoidp = const void*;

#if HAVE_DYNLOAD
#define PULSE_FUNCS(MAGIC)                                                    \
    MAGIC(pa_context_new);                                                    \
    MAGIC(pa_context_unref);                                                  \
    MAGIC(pa_context_get_state);                                              \
    MAGIC(pa_context_disconnect);                                             \
    MAGIC(pa_context_set_state_callback);                                     \
    MAGIC(pa_context_set_subscribe_callback);                                 \
    MAGIC(pa_context_subscribe);                                              \
    MAGIC(pa_context_errno);                                                  \
    MAGIC(pa_context_connect);                                                \
    MAGIC(pa_context_get_server_info);                                        \
    MAGIC(pa_context_get_sink_info_by_index);                                 \
    MAGIC(pa_context_get_sink_info_by_name);                                  \
    MAGIC(pa_context_get_sink_info_list);                                     \
    MAGIC(pa_context_get_source_info_by_index);                               \
    MAGIC(pa_context_get_source_info_by_name);                                \
    MAGIC(pa_context_get_source_info_list);                                   \
    MAGIC(pa_stream_new);                                                     \
    MAGIC(pa_stream_unref);                                                   \
    MAGIC(pa_stream_drop);                                                    \
    MAGIC(pa_stream_get_state);                                               \
    MAGIC(pa_stream_peek);                                                    \
    MAGIC(pa_stream_write);                                                   \
    MAGIC(pa_stream_connect_record);                                          \
    MAGIC(pa_stream_connect_playback);                                        \
    MAGIC(pa_stream_readable_size);                                           \
    MAGIC(pa_stream_writable_size);                                           \
    MAGIC(pa_stream_is_corked);                                               \
    MAGIC(pa_stream_cork);                                                    \
    MAGIC(pa_stream_is_suspended);                                            \
    MAGIC(pa_stream_get_device_name);                                         \
    MAGIC(pa_stream_get_latency);                                             \
    MAGIC(pa_stream_set_write_callback);                                      \
    MAGIC(pa_stream_set_buffer_attr);                                         \
    MAGIC(pa_stream_get_buffer_attr);                                         \
    MAGIC(pa_stream_get_sample_spec);                                         \
    MAGIC(pa_stream_get_time);                                                \
    MAGIC(pa_stream_set_read_callback);                                       \
    MAGIC(pa_stream_set_state_callback);                                      \
    MAGIC(pa_stream_set_moved_callback);                                      \
    MAGIC(pa_stream_set_underflow_callback);                                  \
    MAGIC(pa_stream_new_with_proplist);                                       \
    MAGIC(pa_stream_disconnect);                                              \
    MAGIC(pa_stream_set_buffer_attr_callback);                                \
    MAGIC(pa_stream_begin_write);                                             \
    MAGIC(pa_threaded_mainloop_free);                                         \
    MAGIC(pa_threaded_mainloop_get_api);                                      \
    MAGIC(pa_threaded_mainloop_lock);                                         \
    MAGIC(pa_threaded_mainloop_new);                                          \
    MAGIC(pa_threaded_mainloop_signal);                                       \
    MAGIC(pa_threaded_mainloop_start);                                        \
    MAGIC(pa_threaded_mainloop_stop);                                         \
    MAGIC(pa_threaded_mainloop_unlock);                                       \
    MAGIC(pa_threaded_mainloop_wait);                                         \
    MAGIC(pa_channel_map_init_auto);                                          \
    MAGIC(pa_channel_map_parse);                                              \
    MAGIC(pa_channel_map_snprint);                                            \
    MAGIC(pa_channel_map_equal);                                              \
    MAGIC(pa_channel_map_superset);                                           \
    MAGIC(pa_channel_position_to_string);                                     \
    MAGIC(pa_operation_get_state);                                            \
    MAGIC(pa_operation_unref);                                                \
    MAGIC(pa_sample_spec_valid);                                              \
    MAGIC(pa_frame_size);                                                     \
    MAGIC(pa_strerror);                                                       \
    MAGIC(pa_path_get_filename);                                              \
    MAGIC(pa_get_binary_name);                                                \
    MAGIC(pa_xmalloc);                                                        \
    MAGIC(pa_xfree);

void *pulse_handle;
#define MAKE_FUNC(x) decltype(x) * p##x
PULSE_FUNCS(MAKE_FUNC)
#undef MAKE_FUNC

#ifndef IN_IDE_PARSER
#define pa_context_new ppa_context_new
#define pa_context_unref ppa_context_unref
#define pa_context_get_state ppa_context_get_state
#define pa_context_disconnect ppa_context_disconnect
#define pa_context_set_state_callback ppa_context_set_state_callback
#define pa_context_set_subscribe_callback ppa_context_set_subscribe_callback
#define pa_context_subscribe ppa_context_subscribe
#define pa_context_errno ppa_context_errno
#define pa_context_connect ppa_context_connect
#define pa_context_get_server_info ppa_context_get_server_info
#define pa_context_get_sink_info_by_index ppa_context_get_sink_info_by_index
#define pa_context_get_sink_info_by_name ppa_context_get_sink_info_by_name
#define pa_context_get_sink_info_list ppa_context_get_sink_info_list
#define pa_context_get_source_info_by_index ppa_context_get_source_info_by_index
#define pa_context_get_source_info_by_name ppa_context_get_source_info_by_name
#define pa_context_get_source_info_list ppa_context_get_source_info_list
#define pa_stream_new ppa_stream_new
#define pa_stream_unref ppa_stream_unref
#define pa_stream_disconnect ppa_stream_disconnect
#define pa_stream_drop ppa_stream_drop
#define pa_stream_set_write_callback ppa_stream_set_write_callback
#define pa_stream_set_buffer_attr ppa_stream_set_buffer_attr
#define pa_stream_get_buffer_attr ppa_stream_get_buffer_attr
#define pa_stream_get_sample_spec ppa_stream_get_sample_spec
#define pa_stream_get_time ppa_stream_get_time
#define pa_stream_set_read_callback ppa_stream_set_read_callback
#define pa_stream_set_state_callback ppa_stream_set_state_callback
#define pa_stream_set_moved_callback ppa_stream_set_moved_callback
#define pa_stream_set_underflow_callback ppa_stream_set_underflow_callback
#define pa_stream_connect_record ppa_stream_connect_record
#define pa_stream_connect_playback ppa_stream_connect_playback
#define pa_stream_readable_size ppa_stream_readable_size
#define pa_stream_writable_size ppa_stream_writable_size
#define pa_stream_is_corked ppa_stream_is_corked
#define pa_stream_cork ppa_stream_cork
#define pa_stream_is_suspended ppa_stream_is_suspended
#define pa_stream_get_device_name ppa_stream_get_device_name
#define pa_stream_get_latency ppa_stream_get_latency
#define pa_stream_set_buffer_attr_callback ppa_stream_set_buffer_attr_callback
#define pa_stream_begin_write ppa_stream_begin_write
#define pa_threaded_mainloop_free ppa_threaded_mainloop_free
#define pa_threaded_mainloop_get_api ppa_threaded_mainloop_get_api
#define pa_threaded_mainloop_lock ppa_threaded_mainloop_lock
#define pa_threaded_mainloop_new ppa_threaded_mainloop_new
#define pa_threaded_mainloop_signal ppa_threaded_mainloop_signal
#define pa_threaded_mainloop_start ppa_threaded_mainloop_start
#define pa_threaded_mainloop_stop ppa_threaded_mainloop_stop
#define pa_threaded_mainloop_unlock ppa_threaded_mainloop_unlock
#define pa_threaded_mainloop_wait ppa_threaded_mainloop_wait
#define pa_channel_map_init_auto ppa_channel_map_init_auto
#define pa_channel_map_parse ppa_channel_map_parse
#define pa_channel_map_snprint ppa_channel_map_snprint
#define pa_channel_map_equal ppa_channel_map_equal
#define pa_channel_map_superset ppa_channel_map_superset
#define pa_channel_position_to_string ppa_channel_position_to_string
#define pa_operation_get_state ppa_operation_get_state
#define pa_operation_unref ppa_operation_unref
#define pa_sample_spec_valid ppa_sample_spec_valid
#define pa_frame_size ppa_frame_size
#define pa_strerror ppa_strerror
#define pa_stream_get_state ppa_stream_get_state
#define pa_stream_peek ppa_stream_peek
#define pa_stream_write ppa_stream_write
#define pa_xfree ppa_xfree
#define pa_path_get_filename ppa_path_get_filename
#define pa_get_binary_name ppa_get_binary_name
#define pa_xmalloc ppa_xmalloc
#endif /* IN_IDE_PARSER */

#endif


constexpr auto MonoChanMap = pa_channel_map{1, {PA_CHANNEL_POSITION_MONO}};
constexpr auto StereoChanMap = pa_channel_map{2,
    { PA_CHANNEL_POSITION_FRONT_LEFT, PA_CHANNEL_POSITION_FRONT_RIGHT }
};
constexpr auto QuadChanMap = pa_channel_map{4, {
    PA_CHANNEL_POSITION_FRONT_LEFT, PA_CHANNEL_POSITION_FRONT_RIGHT,
    PA_CHANNEL_POSITION_REAR_LEFT, PA_CHANNEL_POSITION_REAR_RIGHT } };
constexpr auto X51ChanMap = pa_channel_map{6, {
    PA_CHANNEL_POSITION_FRONT_LEFT, PA_CHANNEL_POSITION_FRONT_RIGHT,
    PA_CHANNEL_POSITION_FRONT_CENTER, PA_CHANNEL_POSITION_LFE,
    PA_CHANNEL_POSITION_SIDE_LEFT, PA_CHANNEL_POSITION_SIDE_RIGHT } };
constexpr auto X51RearChanMap = pa_channel_map{6, {
    PA_CHANNEL_POSITION_FRONT_LEFT, PA_CHANNEL_POSITION_FRONT_RIGHT,
    PA_CHANNEL_POSITION_FRONT_CENTER, PA_CHANNEL_POSITION_LFE,
    PA_CHANNEL_POSITION_REAR_LEFT, PA_CHANNEL_POSITION_REAR_RIGHT } };
constexpr auto X61ChanMap = pa_channel_map{7, {
    PA_CHANNEL_POSITION_FRONT_LEFT, PA_CHANNEL_POSITION_FRONT_RIGHT,
    PA_CHANNEL_POSITION_FRONT_CENTER, PA_CHANNEL_POSITION_LFE,
    PA_CHANNEL_POSITION_REAR_CENTER,
    PA_CHANNEL_POSITION_SIDE_LEFT, PA_CHANNEL_POSITION_SIDE_RIGHT } };
constexpr auto X71ChanMap = pa_channel_map{8, {
    PA_CHANNEL_POSITION_FRONT_LEFT, PA_CHANNEL_POSITION_FRONT_RIGHT,
    PA_CHANNEL_POSITION_FRONT_CENTER, PA_CHANNEL_POSITION_LFE,
    PA_CHANNEL_POSITION_REAR_LEFT, PA_CHANNEL_POSITION_REAR_RIGHT,
    PA_CHANNEL_POSITION_SIDE_LEFT, PA_CHANNEL_POSITION_SIDE_RIGHT } };
constexpr auto X714ChanMap = pa_channel_map{12, {
    PA_CHANNEL_POSITION_FRONT_LEFT, PA_CHANNEL_POSITION_FRONT_RIGHT,
    PA_CHANNEL_POSITION_FRONT_CENTER, PA_CHANNEL_POSITION_LFE,
    PA_CHANNEL_POSITION_REAR_LEFT, PA_CHANNEL_POSITION_REAR_RIGHT,
    PA_CHANNEL_POSITION_SIDE_LEFT, PA_CHANNEL_POSITION_SIDE_RIGHT,
    PA_CHANNEL_POSITION_TOP_FRONT_LEFT, PA_CHANNEL_POSITION_TOP_FRONT_RIGHT,
    PA_CHANNEL_POSITION_TOP_REAR_LEFT, PA_CHANNEL_POSITION_TOP_REAR_RIGHT } };


/* NOLINTBEGIN(*EnumCastOutOfRange) *grumble* Don't use enums for bitflags. */
[[nodiscard]]
constexpr auto operator|(pa_stream_flags_t lhs, pa_stream_flags_t rhs) -> pa_stream_flags_t
{ return gsl::narrow_cast<pa_stream_flags_t>(lhs | al::to_underlying(rhs)); }
constexpr auto operator|=(pa_stream_flags_t &lhs, pa_stream_flags_t rhs) -> pa_stream_flags_t&
{
    lhs = lhs | rhs;
    return lhs;
}
[[nodiscard]]
constexpr auto operator~(pa_stream_flags_t flag) -> pa_stream_flags_t
{ return gsl::narrow_cast<pa_stream_flags_t>(~al::to_underlying(flag)); }
constexpr auto operator&=(pa_stream_flags_t &lhs, pa_stream_flags_t rhs) -> pa_stream_flags_t&
{
    lhs = gsl::narrow_cast<pa_stream_flags_t>(al::to_underlying(lhs) & rhs);
    return lhs;
}

[[nodiscard]]
constexpr auto operator|(pa_context_flags_t lhs, pa_context_flags_t rhs) -> pa_context_flags_t
{ return gsl::narrow_cast<pa_context_flags_t>(lhs | al::to_underlying(rhs)); }
constexpr auto operator|=(pa_context_flags_t &lhs, pa_context_flags_t rhs) -> pa_context_flags_t&
{
    lhs = lhs | rhs;
    return lhs;
}

[[nodiscard]]
constexpr auto operator|(pa_subscription_mask_t lhs, pa_subscription_mask_t rhs)
    -> pa_subscription_mask_t
{ return gsl::narrow_cast<pa_subscription_mask_t>(lhs | al::to_underlying(rhs)); }
/* NOLINTEND(*EnumCastOutOfRange) */


struct DevMap {
    std::string name;
    std::string device_name;
    u32 index{};
};

auto checkName(std::span<DevMap const> const list, std::string_view const name) -> bool
{ return std::ranges::find(list, name, &DevMap::name) != list.end(); }

auto PlaybackDevices = std::vector<DevMap>{};
auto CaptureDevices = std::vector<DevMap>{};

auto DefaultPlaybackDevName = std::string{};
auto DefaultCaptureDevName = std::string{};


/* Global flags and properties */
auto pulse_ctx_flags = pa_context_flags_t{};

class PulseMainloop {
    pa_threaded_mainloop *mLoop{};
    pa_context *mContext{};

public:
    PulseMainloop() = default;
    PulseMainloop(const PulseMainloop&) = delete;
    PulseMainloop(PulseMainloop&& rhs) noexcept : mLoop{rhs.mLoop} { rhs.mLoop = nullptr; }
    explicit PulseMainloop(pa_threaded_mainloop *loop) noexcept : mLoop{loop} { }
    ~PulseMainloop();

    auto operator=(const PulseMainloop&) -> PulseMainloop& = delete;
    auto operator=(PulseMainloop&& rhs) noexcept -> PulseMainloop&
    { std::swap(mLoop, rhs.mLoop); return *this; }
    auto operator=(std::nullptr_t) noexcept -> PulseMainloop&
    {
        if(mLoop)
            pa_threaded_mainloop_free(mLoop);
        mLoop = nullptr;
        return *this;
    }

    explicit operator bool() const noexcept { return mLoop != nullptr; }

    [[nodiscard]]
    auto start() const { return pa_threaded_mainloop_start(mLoop); }
    auto stop() const { return pa_threaded_mainloop_stop(mLoop); }

    [[nodiscard]] auto getApi() const { return pa_threaded_mainloop_get_api(mLoop); }
    [[nodiscard]] auto getContext() const noexcept { return mContext; }

    auto lock() const { return pa_threaded_mainloop_lock(mLoop); }
    auto unlock() const { return pa_threaded_mainloop_unlock(mLoop); }

    auto signal(bool const wait=false) const { return pa_threaded_mainloop_signal(mLoop, wait); }

    static auto Create() { return PulseMainloop{pa_threaded_mainloop_new()}; }


    void streamSuccessCallback(pa_stream*, int) const noexcept { signal(); }
    static void streamSuccessCallbackC(pa_stream *stream, int const success, void *const pdata)
        noexcept
    { static_cast<PulseMainloop*>(pdata)->streamSuccessCallback(stream, success); }

    void close(pa_stream *stream=nullptr);


    void updateDefaultDevice(pa_context*, pa_server_info const *const info) const
    {
        auto default_sink = info->default_sink_name ? std::string_view{info->default_sink_name}
            : std::string_view{};
        auto default_src = info->default_source_name ? std::string_view{info->default_source_name}
            : std::string_view{};

        if(default_sink != DefaultPlaybackDevName)
        {
            TRACE("Default playback device: {}", default_sink);
            DefaultPlaybackDevName = default_sink;

            const auto msg = al::format("Default playback device changed: {}", default_sink);
            alc::Event(alc::EventType::DefaultDeviceChanged, alc::DeviceType::Playback, msg);
        }
        if(default_src != DefaultCaptureDevName)
        {
            TRACE("Default capture device: {}", default_src);
            DefaultCaptureDevName = default_src;

            const auto msg = al::format("Default capture device changed: {}", default_src);
            alc::Event(alc::EventType::DefaultDeviceChanged, alc::DeviceType::Capture, msg);
        }
        signal();
    }

    void deviceSinkCallback(pa_context*, pa_sink_info const *const info, int const eol)
        const noexcept
    {
        if(eol)
        {
            signal();
            return;
        }

        /* Skip this device is if it's already in the list. */
        auto const match = std::ranges::find(PlaybackDevices, info->name, &DevMap::device_name);
        if(match != PlaybackDevices.end()) return;

        /* Make sure the display name (description) is unique. Append a number
         * counter as needed.
         */
        auto count = 1;
        auto newname = std::string{info->description};
        while(checkName(PlaybackDevices, newname))
            newname = al::format("{} #{}", info->description, ++count);

        const auto &newentry = PlaybackDevices.emplace_back(DevMap{std::move(newname),
            info->name, info->index});
        TRACE(R"(Got device "{}", "{}" ({}))", newentry.name, newentry.device_name,
            newentry.index);

        const auto msg = al::format("Device added: {}", newentry.device_name);
        alc::Event(alc::EventType::DeviceAdded, alc::DeviceType::Playback, msg);
    }

    void deviceSourceCallback(pa_context*, pa_source_info const *const info, int const eol)
        const noexcept
    {
        if(eol)
        {
            signal();
            return;
        }

        /* Skip this device is if it's already in the list. */
        auto const match = std::ranges::find(CaptureDevices, info->name, &DevMap::device_name);
        if(match != CaptureDevices.end()) return;

        /* Make sure the display name (description) is unique. Append a number
         * counter as needed.
         */
        auto count = 1;
        auto newname = std::string{info->description};
        while(checkName(CaptureDevices, newname))
            newname = al::format("{} #{}", info->description, ++count);

        const auto &newentry = CaptureDevices.emplace_back(DevMap{std::move(newname), info->name,
            info->index});
        TRACE(R"(Got device "{}", "{}" ({}))", newentry.name, newentry.device_name,
            newentry.index);

        const auto msg = al::format("Device added: {}", newentry.device_name);
        alc::Event(alc::EventType::DeviceAdded, alc::DeviceType::Capture, msg);
    }

    void eventCallback(pa_context *const context, pa_subscription_event_type_t const t,
        u32 const idx) noexcept
    {
        const auto eventFacility = (t & PA_SUBSCRIPTION_EVENT_FACILITY_MASK);
        const auto eventType = (t & PA_SUBSCRIPTION_EVENT_TYPE_MASK);

        if(eventFacility == PA_SUBSCRIPTION_EVENT_SERVER
            && eventType == PA_SUBSCRIPTION_EVENT_CHANGE)
        {
            static constexpr auto server_cb = [](pa_context *const ctx,
                pa_server_info const *const info, void *const pdata) noexcept
            { return static_cast<PulseMainloop*>(pdata)->updateDefaultDevice(ctx, info); };
            if(auto *const op = pa_context_get_server_info(context, server_cb, this))
                pa_operation_unref(op);
        }

        if(eventFacility != PA_SUBSCRIPTION_EVENT_SINK
            && eventFacility != PA_SUBSCRIPTION_EVENT_SOURCE)
            return;

        const auto devtype = (eventFacility == PA_SUBSCRIPTION_EVENT_SINK)
            ? alc::DeviceType::Playback : alc::DeviceType::Capture;

        if(eventType == PA_SUBSCRIPTION_EVENT_NEW)
        {
            if(eventFacility == PA_SUBSCRIPTION_EVENT_SINK)
            {
                static constexpr auto devcallback = [](pa_context *const ctx,
                    pa_sink_info const *const info, int const eol, void *const pdata) noexcept
                { return static_cast<PulseMainloop*>(pdata)->deviceSinkCallback(ctx, info, eol); };
                if(auto *op = pa_context_get_sink_info_by_index(context, idx, devcallback, this))
                    pa_operation_unref(op);
            }
            else
            {
                static constexpr auto devcallback = [](pa_context *const ctx,
                    pa_source_info const *const info, int const eol, void *const pdata) noexcept
                {
                    return static_cast<PulseMainloop*>(pdata)->deviceSourceCallback(ctx, info,
                        eol);
                };
                if(auto *op = pa_context_get_source_info_by_index(context, idx, devcallback, this))
                    pa_operation_unref(op);
            }
        }
        else if(eventType == PA_SUBSCRIPTION_EVENT_REMOVE)
        {
            auto &devlist = (eventFacility == PA_SUBSCRIPTION_EVENT_SINK)
                ? PlaybackDevices : CaptureDevices;
            auto iter = std::ranges::find(devlist, idx, &DevMap::index);
            if(iter != devlist.end())
            {
                devlist.erase(iter);

                const auto msg = al::format("Device removed: {}", idx);
                alc::Event(alc::EventType::DeviceRemoved, devtype, msg);
            }
        }
    }

    friend struct MainloopUniqueLock;
};
struct MainloopUniqueLock : public std::unique_lock<PulseMainloop> {
    using std::unique_lock<PulseMainloop>::unique_lock;
    MainloopUniqueLock& operator=(MainloopUniqueLock&&) = default;

    auto wait() const -> void
    { pa_threaded_mainloop_wait(mutex()->mLoop); }

    template<typename Predicate>
    auto wait(Predicate done_waiting) const -> void
    { while(!done_waiting()) wait(); }

    void waitForOperation(pa_operation *op) const
    {
        if(op)
        {
            wait([op]{ return pa_operation_get_state(op) != PA_OPERATION_RUNNING; });
            pa_operation_unref(op);
        }
    }


    void setEventHandler() const
    {
        auto *context = mutex()->mContext;

        /* Watch for device added/removed and server changed events. */
        static constexpr auto submask = PA_SUBSCRIPTION_MASK_SINK | PA_SUBSCRIPTION_MASK_SOURCE
            | PA_SUBSCRIPTION_MASK_SERVER;
        static constexpr auto do_signal = [](pa_context*, int, void *pdata) noexcept
        { static_cast<PulseMainloop*>(pdata)->signal(); };
        auto *op = pa_context_subscribe(context, submask, do_signal, mutex());
        waitForOperation(op);

        static constexpr auto handler = [](pa_context *const ctx,
            pa_subscription_event_type_t const t, uint32_t const index, void *const pdata) noexcept
        { return static_cast<PulseMainloop*>(pdata)->eventCallback(ctx, t, index); };
        pa_context_set_subscribe_callback(context, handler, mutex());

        /* Fill in the initial device lists, and get the defaults. */
        static constexpr auto sink_callback = [](pa_context *const ctx,
            pa_sink_info const *const info, int const eol, void *const pdata) noexcept
        { return static_cast<PulseMainloop*>(pdata)->deviceSinkCallback(ctx, info, eol); };

        static constexpr auto src_callback = [](pa_context *const ctx,
            pa_source_info const *const info, int const eol, void *const pdata) noexcept
        { return static_cast<PulseMainloop*>(pdata)->deviceSourceCallback(ctx, info, eol); };

        static constexpr auto server_callback = [](pa_context *const ctx,
            pa_server_info const *const info, void *const pdata) noexcept
        { return static_cast<PulseMainloop*>(pdata)->updateDefaultDevice(ctx, info); };

        auto *const sinkop = pa_context_get_sink_info_list(context, sink_callback, mutex());
        auto *const srcop = pa_context_get_source_info_list(context, src_callback, mutex());
        auto *const serverop = pa_context_get_server_info(context, server_callback, mutex());

        waitForOperation(sinkop);
        waitForOperation(srcop);
        waitForOperation(serverop);
    }


    void contextStateCallback(pa_context *const context) const noexcept
    {
        const auto state = pa_context_get_state(context);
        if(state == PA_CONTEXT_READY || !PA_CONTEXT_IS_GOOD(state))
            mutex()->signal();
    }

    void streamStateCallback(pa_stream *const stream) const noexcept
    {
        const auto state = pa_stream_get_state(stream);
        if(state == PA_STREAM_READY || !PA_STREAM_IS_GOOD(state))
            mutex()->signal();
    }

    void connectContext();
    auto connectStream(gsl::czstring device_name, pa_stream_flags_t flags, pa_buffer_attr *attr,
        pa_sample_spec *spec, pa_channel_map *chanmap, BackendType type) -> pa_stream*;

    auto connectStream(std::string const &device_name, pa_stream_flags_t const flags,
        pa_buffer_attr *const attr, pa_sample_spec *const spec, pa_channel_map *const chanmap,
        BackendType const type) -> pa_stream*
    {
        return connectStream(device_name.empty() ? nullptr : device_name.c_str(), flags, attr,
            spec, chanmap, type);
    }
};

PulseMainloop::~PulseMainloop()
{
    if(mContext)
    {
        auto looplock = MainloopUniqueLock{*this};
        pa_context_disconnect(mContext);
        pa_context_unref(mContext);
    }
    if(mLoop)
        pa_threaded_mainloop_free(mLoop);
}


void MainloopUniqueLock::connectContext()
{
    if(mutex()->mContext)
        return;

    mutex()->mContext = pa_context_new(mutex()->getApi(), nullptr);
    if(!mutex()->mContext) throw al::backend_exception{al::backend_error::OutOfMemory,
        "pa_context_new() failed"};

    pa_context_set_state_callback(mutex()->mContext, [](pa_context *ctx, void *pdata) noexcept
    { return static_cast<MainloopUniqueLock*>(pdata)->contextStateCallback(ctx); }, this);

    auto err = pa_context_connect(mutex()->mContext, nullptr, pulse_ctx_flags, nullptr);
    if(err >= 0)
    {
        wait([&err,this]
        {
            auto state = pa_context_get_state(mutex()->mContext);
            if(!PA_CONTEXT_IS_GOOD(state))
            {
                err = pa_context_errno(mutex()->mContext);
                if(err > 0) err = -err;
                return true;
            }
            return state == PA_CONTEXT_READY;
        });
    }
    pa_context_set_state_callback(mutex()->mContext, nullptr, nullptr);

    if(err < 0)
    {
        pa_context_unref(mutex()->mContext);
        mutex()->mContext = nullptr;
        throw al::backend_exception{al::backend_error::DeviceError, "Context did not connect ({})",
            pa_strerror(err)};
    }
}

auto MainloopUniqueLock::connectStream(const char *device_name, pa_stream_flags_t flags,
    pa_buffer_attr *attr, pa_sample_spec *spec, pa_channel_map *chanmap, BackendType type)
    -> pa_stream*
{
    auto *stream_id = (type==BackendType::Playback) ? "Playback Stream" : "Capture Stream";
    auto *stream = pa_stream_new(mutex()->mContext, stream_id, spec, chanmap);
    if(!stream)
        throw al::backend_exception{al::backend_error::OutOfMemory, "pa_stream_new() failed ({})",
            pa_strerror(pa_context_errno(mutex()->mContext))};

    pa_stream_set_state_callback(stream, [](pa_stream *strm, void *pdata) noexcept
    { return static_cast<MainloopUniqueLock*>(pdata)->streamStateCallback(strm); }, this);

    auto err = (type==BackendType::Playback) ?
        pa_stream_connect_playback(stream, device_name, attr, flags, nullptr, nullptr) :
        pa_stream_connect_record(stream, device_name, attr, flags);
    if(err < 0)
    {
        pa_stream_unref(stream);
        throw al::backend_exception{al::backend_error::DeviceError, "%s did not connect ({})",
            stream_id, pa_strerror(err)};
    }

    wait([&err,stream,stream_id,this]
    {
        auto state = pa_stream_get_state(stream);
        if(!PA_STREAM_IS_GOOD(state))
        {
            err = pa_context_errno(mutex()->mContext);
            pa_stream_unref(stream);
            throw al::backend_exception{al::backend_error::DeviceError,
                "{} did not get ready ({})", stream_id, pa_strerror(err)};
        }
        return state == PA_STREAM_READY;
    });

    pa_stream_set_state_callback(stream, nullptr, nullptr);

    return stream;
}

void PulseMainloop::close(pa_stream *stream)
{
    if(!stream)
        return;

    auto looplock = MainloopUniqueLock{*this};
    pa_stream_set_state_callback(stream, nullptr, nullptr);
    pa_stream_set_moved_callback(stream, nullptr, nullptr);
    pa_stream_set_write_callback(stream, nullptr, nullptr);
    pa_stream_set_buffer_attr_callback(stream, nullptr, nullptr);
    pa_stream_disconnect(stream);
    pa_stream_unref(stream);
}


/* Used for initial connection test and enumeration. */
auto gGlobalMainloop = PulseMainloop{};


struct PulsePlayback final : BackendBase {
    explicit PulsePlayback(gsl::not_null<DeviceBase*> const device) noexcept : BackendBase{device}
    { }
    ~PulsePlayback() override;

    void bufferAttrCallback(pa_stream *stream) noexcept;
    void streamStateCallback(pa_stream *stream) const noexcept;
    void streamWriteCallback(pa_stream *stream, usize nbytes) const noexcept;
    void sinkInfoCallback(pa_context *context, const pa_sink_info *info, int eol) noexcept;
    void sinkNameCallback(pa_context *context, const pa_sink_info *info, int eol) noexcept;
    void streamMovedCallback(pa_stream *stream) noexcept;

    void open(std::string_view name) override;
    auto reset() -> bool override;
    void start() override;
    void stop() override;
    auto getClockLatency() -> ClockLatency override;

    PulseMainloop mMainloop;

    std::optional<std::string> mDeviceId{std::nullopt};

    bool mIs51Rear{false};
    pa_buffer_attr mAttr{};
    pa_sample_spec mSpec{};

    pa_stream *mStream{nullptr};

    u32 mFrameSize{0u};
};

PulsePlayback::~PulsePlayback()
{ if(mStream) mMainloop.close(mStream); }


void PulsePlayback::bufferAttrCallback(pa_stream *const stream) noexcept
{
    /* FIXME: Update the device's UpdateSize (and/or BufferSize) using the new
     * buffer attributes? Changing UpdateSize will change the ALC_REFRESH
     * property, which probably shouldn't change between device resets. But
     * leaving it alone means ALC_REFRESH will be off.
     */
    mAttr = *(pa_stream_get_buffer_attr(stream));
    TRACE("minreq={}, tlength={}, prebuf={}", mAttr.minreq, mAttr.tlength, mAttr.prebuf);
}

void PulsePlayback::streamStateCallback(pa_stream *const stream) const noexcept
{
    if(pa_stream_get_state(stream) == PA_STREAM_FAILED)
    {
        ERR("Received stream failure!");
        mDevice->handleDisconnect("Playback stream failure");
    }
    mMainloop.signal();
}

void PulsePlayback::streamWriteCallback(pa_stream *const stream, usize nbytes) const noexcept
{
    do {
        auto free_func = pa_free_cb_t{nullptr};
        auto buflen = ~1_uz;
        auto *buf = voidp{};
        if(pa_stream_begin_write(stream, &buf, &buflen) || !buf) [[unlikely]]
        {
            buflen = nbytes;
            buf = pa_xmalloc(buflen);
            free_func = pa_xfree;
        }
        else
            buflen = std::min(buflen, nbytes);
        nbytes -= buflen;

        mDevice->renderSamples(buf, gsl::narrow_cast<u32>(buflen/mFrameSize), mSpec.channels);

        if(auto const ret = pa_stream_write(stream, buf, buflen, free_func, 0, PA_SEEK_RELATIVE);
            ret != PA_OK) [[unlikely]]
            ERR("Failed to write to stream: {}, {}", ret, pa_strerror(ret));
    } while(nbytes > 0);
}

void PulsePlayback::sinkInfoCallback(pa_context*, pa_sink_info const *const info, int const eol)
    noexcept
{
    struct ChannelMap {
        DevFmtChannels fmt;
        pa_channel_map map;
        bool is_51rear;
    };
    static constexpr auto chanmaps = std::array{
        ChannelMap{DevFmtX714, X714ChanMap, false},
        ChannelMap{DevFmtX71, X71ChanMap, false},
        ChannelMap{DevFmtX61, X61ChanMap, false},
        ChannelMap{DevFmtX51, X51ChanMap, false},
        ChannelMap{DevFmtX51, X51RearChanMap, true},
        ChannelMap{DevFmtQuad, QuadChanMap, false},
        ChannelMap{DevFmtStereo, StereoChanMap, false},
        ChannelMap{DevFmtMono, MonoChanMap, false}
    };

    if(eol)
    {
        mMainloop.signal();
        return;
    }

    auto const chaniter = std::ranges::find_if(chanmaps, [info](ChannelMap const &chanmap) -> bool
    { return pa_channel_map_superset(&info->channel_map, &chanmap.map); });
    if(chaniter != chanmaps.end())
    {
        if(!mDevice->Flags.test(ChannelsRequest))
            mDevice->FmtChans = chaniter->fmt;
        mIs51Rear = chaniter->is_51rear;
    }
    else
    {
        mIs51Rear = false;
        auto chanmap_str = std::array<char, PA_CHANNEL_MAP_SNPRINT_MAX>{};
        pa_channel_map_snprint(chanmap_str.data(), chanmap_str.size(), &info->channel_map);
        WARN("Failed to find format for channel map:\n    {}", chanmap_str.data());
    }

    if(info->active_port)
        TRACE("Active port: {} ({})", info->active_port->name, info->active_port->description);
    mDevice->Flags.set(DirectEar, (info->active_port
        && info->active_port->name == "analog-output-headphones"sv));
}

void PulsePlayback::sinkNameCallback(pa_context*, pa_sink_info const *const info, int const eol)
    noexcept
{
    if(eol)
    {
        mMainloop.signal();
        return;
    }
    mDeviceName = info->description;
}

void PulsePlayback::streamMovedCallback(pa_stream *const stream) noexcept
{
    mDeviceId = pa_stream_get_device_name(stream);
    TRACE("Stream moved to {}", *mDeviceId);
}


void PulsePlayback::open(std::string_view name)
{
    mMainloop = PulseMainloop::Create();
    if(mMainloop.start() != 0)
        throw al::backend_exception{al::backend_error::DeviceError,
            "Failed to start device mainloop"};

    auto pulse_name = std::string{};
    if(!name.empty())
    {
        auto plock = MainloopUniqueLock{gGlobalMainloop};

        auto iter = std::ranges::find(PlaybackDevices, name, &DevMap::name);
        if(iter == PlaybackDevices.end())
            iter = std::ranges::find(PlaybackDevices, name, &DevMap::device_name);
        if(iter == PlaybackDevices.end())
            throw al::backend_exception{al::backend_error::NoDevice,
                "Device name \"{}\" not found", name};

        pulse_name = iter->device_name;
        mDeviceName = iter->name;
    }

    auto plock = MainloopUniqueLock{mMainloop};
    plock.connectContext();

    auto flags = PA_STREAM_START_CORKED | PA_STREAM_FIX_FORMAT | PA_STREAM_FIX_RATE |
        PA_STREAM_FIX_CHANNELS;
    if(!GetConfigValueBool({}, "pulse", "allow-moves", true))
        flags |= PA_STREAM_DONT_MOVE;

    auto spec = pa_sample_spec{};
    spec.format = PA_SAMPLE_S16NE;
    spec.rate = 44100;
    spec.channels = 2;

    if(pulse_name.empty())
    {
        static const auto defname = al::getenv("ALSOFT_PULSE_DEFAULT");
        if(defname) pulse_name = *defname;
    }
    TRACE("Connecting to \"{}\"", pulse_name.empty() ? "(default)"sv:std::string_view{pulse_name});
    mStream = plock.connectStream(pulse_name, flags, nullptr, &spec, nullptr,
        BackendType::Playback);

    static constexpr auto move_callback = [](pa_stream *const stream, void *const pdata) noexcept
    { return static_cast<PulsePlayback*>(pdata)->streamMovedCallback(stream); };
    pa_stream_set_moved_callback(mStream, move_callback, this);
    mFrameSize = gsl::narrow_cast<u32>(pa_frame_size(pa_stream_get_sample_spec(mStream)));

    if(!pulse_name.empty())
        mDeviceId.emplace(std::move(pulse_name));

    if(mDeviceName.empty())
    {
        static constexpr auto name_callback = [](pa_context *const context,
            pa_sink_info const *const info, int const eol, void *const pdata) noexcept
        { return static_cast<PulsePlayback*>(pdata)->sinkNameCallback(context, info, eol); };
        auto *op = pa_context_get_sink_info_by_name(mMainloop.getContext(),
            pa_stream_get_device_name(mStream), name_callback, this);
        plock.waitForOperation(op);
    }
}

auto PulsePlayback::reset() -> bool
{
    auto plock = MainloopUniqueLock{mMainloop};
    const auto deviceName = mDeviceId ? mDeviceId->c_str() : nullptr;

    if(mStream)
    {
        pa_stream_set_state_callback(mStream, nullptr, nullptr);
        pa_stream_set_moved_callback(mStream, nullptr, nullptr);
        pa_stream_set_write_callback(mStream, nullptr, nullptr);
        pa_stream_set_buffer_attr_callback(mStream, nullptr, nullptr);
        pa_stream_disconnect(mStream);
        pa_stream_unref(mStream);
        mStream = nullptr;
    }

    static constexpr auto info_cb = [](pa_context *const context, pa_sink_info const *const info,
        int const eol, void *const pdata) noexcept
    { return static_cast<PulsePlayback*>(pdata)->sinkInfoCallback(context, info, eol); };
    auto *op = pa_context_get_sink_info_by_name(mMainloop.getContext(), deviceName, info_cb, this);
    plock.waitForOperation(op);

    auto flags = PA_STREAM_START_CORKED | PA_STREAM_INTERPOLATE_TIMING
        | PA_STREAM_AUTO_TIMING_UPDATE | PA_STREAM_EARLY_REQUESTS;
    if(!GetConfigValueBool({}, "pulse", "allow-moves", true))
        flags |= PA_STREAM_DONT_MOVE;
    if(GetConfigValueBool(mDevice->mDeviceName, "pulse", "adjust-latency", false))
    {
        /* ADJUST_LATENCY can't be specified with EARLY_REQUESTS, for some
         * reason. So if the user wants to adjust the overall device latency,
         * we can't ask to get write signals as soon as minreq is reached.
         */
        flags &= ~PA_STREAM_EARLY_REQUESTS;
        flags |= PA_STREAM_ADJUST_LATENCY;
    }
    if(GetConfigValueBool(mDevice->mDeviceName, "pulse", "fix-rate", false)
        || !mDevice->Flags.test(FrequencyRequest))
        flags |= PA_STREAM_FIX_RATE;

    auto chanmap = pa_channel_map{};
    switch(mDevice->FmtChans)
    {
    case DevFmtMono:
        chanmap = MonoChanMap;
        break;
    case DevFmtAmbi3D:
        mDevice->FmtChans = DevFmtStereo;
        [[fallthrough]];
    case DevFmtStereo:
        chanmap = StereoChanMap;
        break;
    case DevFmtQuad:
        chanmap = QuadChanMap;
        break;
    case DevFmtX51:
        chanmap = (mIs51Rear ? X51RearChanMap : X51ChanMap);
        break;
    case DevFmtX61:
        chanmap = X61ChanMap;
        break;
    case DevFmtX71:
    case DevFmtX3D71:
        chanmap = X71ChanMap;
        break;
    case DevFmtX7144:
        mDevice->FmtChans = DevFmtX714;
        [[fallthrough]];
    case DevFmtX714:
        chanmap = X714ChanMap;
        break;
    }
    setDefaultWFXChannelOrder();

    switch(mDevice->FmtType)
    {
    case DevFmtByte:
        mDevice->FmtType = DevFmtUByte;
        [[fallthrough]];
    case DevFmtUByte:
        mSpec.format = PA_SAMPLE_U8;
        break;
    case DevFmtUShort:
        mDevice->FmtType = DevFmtShort;
        [[fallthrough]];
    case DevFmtShort:
        mSpec.format = PA_SAMPLE_S16NE;
        break;
    case DevFmtUInt:
        mDevice->FmtType = DevFmtInt;
        [[fallthrough]];
    case DevFmtInt:
        mSpec.format = PA_SAMPLE_S32NE;
        break;
    case DevFmtFloat:
        mSpec.format = PA_SAMPLE_FLOAT32NE;
        break;
    }
    mSpec.rate = mDevice->mSampleRate;
    mSpec.channels = gsl::narrow_cast<u8>(mDevice->channelsFromFmt());
    if(pa_sample_spec_valid(&mSpec) == 0)
        throw al::backend_exception{al::backend_error::DeviceError, "Invalid sample spec"};

    const auto frame_size = gsl::narrow_cast<u32>(pa_frame_size(&mSpec));
    mAttr.maxlength = ~0_u32;
    mAttr.tlength = mDevice->mBufferSize * frame_size;
    mAttr.prebuf = 0_u32;
    mAttr.minreq = mDevice->mUpdateSize * frame_size;
    mAttr.fragsize = ~0_u32;

    mStream = plock.connectStream(deviceName, flags, &mAttr, &mSpec, &chanmap,
        BackendType::Playback);

    static constexpr auto state_callback = [](pa_stream *const stream, void *const pdata) noexcept
    { return static_cast<PulsePlayback*>(pdata)->streamStateCallback(stream); };
    pa_stream_set_state_callback(mStream, state_callback, this);

    static constexpr auto move_callback = [](pa_stream *const stream, void *const pdata) noexcept
    { return static_cast<PulsePlayback*>(pdata)->streamMovedCallback(stream); };
    pa_stream_set_moved_callback(mStream, move_callback, this);

    mSpec = *(pa_stream_get_sample_spec(mStream));
    mFrameSize = gsl::narrow_cast<u32>(pa_frame_size(&mSpec));

    if(mDevice->mSampleRate != mSpec.rate)
    {
        /* Server updated our playback rate, so modify the buffer attribs
         * accordingly.
         */
        const auto scale = gsl::narrow_cast<f64>(mSpec.rate) / mDevice->mSampleRate;
        const auto perlen = std::clamp(std::round(scale*mDevice->mUpdateSize), 64.0, 8192.0);
        const auto bufmax = u32{std::numeric_limits<i32>::max()} / mFrameSize;
        const auto buflen = std::clamp(std::round(scale*mDevice->mBufferSize), perlen*2.0,
            gsl::narrow_cast<f64>(bufmax));

        mAttr.maxlength = ~0_u32;
        mAttr.tlength = gsl::narrow_cast<u32>(buflen) * mFrameSize;
        mAttr.prebuf = 0_u32;
        mAttr.minreq = gsl::narrow_cast<u32>(perlen) * mFrameSize;

        op = pa_stream_set_buffer_attr(mStream, &mAttr, &PulseMainloop::streamSuccessCallbackC,
            &mMainloop);
        plock.waitForOperation(op);

        mDevice->mSampleRate = mSpec.rate;
    }

    static constexpr auto attr_callback = [](pa_stream *stream, void *pdata) noexcept
    { return static_cast<PulsePlayback*>(pdata)->bufferAttrCallback(stream); };
    pa_stream_set_buffer_attr_callback(mStream, attr_callback, this);
    bufferAttrCallback(mStream);

    mDevice->mBufferSize = mAttr.tlength / mFrameSize;
    mDevice->mUpdateSize = mAttr.minreq / mFrameSize;

    return true;
}

void PulsePlayback::start()
{
    auto plock = MainloopUniqueLock{mMainloop};

    /* Write some samples to fill the buffer before we start feeding it newly
     * mixed samples.
     */
    if(const auto todo = pa_stream_writable_size(mStream))
    {
        auto *const buf = pa_xmalloc(todo);
        mDevice->renderSamples(buf, gsl::narrow_cast<u32>(todo/mFrameSize), mSpec.channels);
        pa_stream_write(mStream, buf, todo, pa_xfree, 0, PA_SEEK_RELATIVE);
    }

    static constexpr auto stream_write = [](pa_stream *const stream, usize const nbytes,
        void *const pdata) noexcept
    { return static_cast<PulsePlayback*>(pdata)->streamWriteCallback(stream, nbytes); };
    pa_stream_set_write_callback(mStream, stream_write, this);

    auto *const op = pa_stream_cork(mStream, 0, &PulseMainloop::streamSuccessCallbackC,
        &mMainloop);
    plock.waitForOperation(op);
}

void PulsePlayback::stop()
{
    auto const plock = MainloopUniqueLock{mMainloop};

    auto *const op = pa_stream_cork(mStream, 1, &PulseMainloop::streamSuccessCallbackC,
        &mMainloop);
    plock.waitForOperation(op);

    pa_stream_set_write_callback(mStream, nullptr, nullptr);
}


auto PulsePlayback::getClockLatency() -> ClockLatency
{
    auto ret = ClockLatency{};
    auto latency = pa_usec_t{};
    auto neg = int{};
    auto err = int{};

    {
        auto plock = MainloopUniqueLock{mMainloop};
        ret.ClockTime = mDevice->getClockTime();
        err = pa_stream_get_latency(mStream, &latency, &neg);
    }

    if(err != 0) [[unlikely]]
    {
        /* If err = -PA_ERR_NODATA, it means we were called too soon after
         * starting the stream and no timing info has been received from the
         * server yet. Give a generic value since nothing better is available.
         */
        if(err != -PA_ERR_NODATA)
            ERR("Failed to get stream latency: {:#x}", as_unsigned(err));
        latency = mDevice->mBufferSize - mDevice->mUpdateSize;
        neg = 0;
    }
    else if(neg) [[unlikely]]
        latency = 0;
    ret.Latency = std::chrono::microseconds{latency};

    return ret;
}


struct PulseCapture final : public BackendBase {
    explicit PulseCapture(gsl::not_null<DeviceBase*> device) noexcept : BackendBase{device} { }
    ~PulseCapture() override;

    void streamStateCallback(pa_stream *stream) const noexcept;
    void sourceNameCallback(pa_context *context, const pa_source_info *info, int eol) noexcept;
    void streamMovedCallback(pa_stream *stream) noexcept;

    void open(std::string_view name) override;
    void start() override;
    void stop() override;
    void captureSamples(std::span<std::byte> outbuffer) override;
    auto availableSamples() -> usize override;
    auto getClockLatency() -> ClockLatency override;

    PulseMainloop mMainloop;

    std::optional<std::string> mDeviceId{std::nullopt};

    std::span<const std::byte> mCapBuffer;
    usize mHoleLength{0};
    usize mPacketLength{0};

    usize mLastReadable{0};
    std::byte mSilentVal{};

    pa_buffer_attr mAttr{};
    pa_sample_spec mSpec{};

    pa_stream *mStream{nullptr};
};

PulseCapture::~PulseCapture()
{ if(mStream) mMainloop.close(mStream); }


void PulseCapture::streamStateCallback(pa_stream *const stream) const noexcept
{
    if(pa_stream_get_state(stream) == PA_STREAM_FAILED)
    {
        ERR("Received stream failure!");
        mDevice->handleDisconnect("Capture stream failure");
    }
    mMainloop.signal();
}

void PulseCapture::sourceNameCallback(pa_context*, const pa_source_info *info, int eol) noexcept
{
    if(eol)
    {
        mMainloop.signal();
        return;
    }
    mDeviceName = info->description;
}

void PulseCapture::streamMovedCallback(pa_stream *stream) noexcept
{
    mDeviceId = pa_stream_get_device_name(stream);
    TRACE("Stream moved to {}", *mDeviceId);
}


void PulseCapture::open(std::string_view name)
{
    if(!mMainloop)
    {
        mMainloop = PulseMainloop::Create();
        if(mMainloop.start() != 0)
            throw al::backend_exception{al::backend_error::DeviceError,
                "Failed to start device mainloop"};
    }

    auto pulse_name = std::string{};
    if(!name.empty())
    {
        auto plock = MainloopUniqueLock{gGlobalMainloop};

        auto iter = std::ranges::find(CaptureDevices, name, &DevMap::name);
        if(iter == CaptureDevices.end())
            iter = std::ranges::find(CaptureDevices, name, &DevMap::device_name);
        if(iter == CaptureDevices.end())
            throw al::backend_exception{al::backend_error::NoDevice,
                "Device name \"{}\" not found", name};

        pulse_name = iter->device_name;
        mDeviceName = iter->name;
    }

    auto plock = MainloopUniqueLock{mMainloop};
    plock.connectContext();

    auto chanmap = pa_channel_map{};
    switch(mDevice->FmtChans)
    {
    case DevFmtMono: chanmap = MonoChanMap; break;
    case DevFmtStereo: chanmap = StereoChanMap; break;
    case DevFmtQuad: chanmap = QuadChanMap; break;
    case DevFmtX51: chanmap = X51ChanMap; break;
    case DevFmtX61: chanmap = X61ChanMap; break;
    case DevFmtX71: chanmap = X71ChanMap; break;
    case DevFmtX714: chanmap = X714ChanMap; break;
    case DevFmtX7144:
    case DevFmtX3D71:
    case DevFmtAmbi3D:
        throw al::backend_exception{al::backend_error::DeviceError, "{} capture not supported",
            DevFmtChannelsString(mDevice->FmtChans)};
    }
    setDefaultWFXChannelOrder();

    switch(mDevice->FmtType)
    {
    case DevFmtUByte:
        mSilentVal = std::byte{0x80};
        mSpec.format = PA_SAMPLE_U8;
        break;
    case DevFmtShort:
        mSpec.format = PA_SAMPLE_S16NE;
        break;
    case DevFmtInt:
        mSpec.format = PA_SAMPLE_S32NE;
        break;
    case DevFmtFloat:
        mSpec.format = PA_SAMPLE_FLOAT32NE;
        break;
    case DevFmtByte:
    case DevFmtUShort:
    case DevFmtUInt:
        throw al::backend_exception{al::backend_error::DeviceError,
            "{} capture samples not supported", DevFmtTypeString(mDevice->FmtType)};
    }
    mSpec.rate = mDevice->mSampleRate;
    mSpec.channels = gsl::narrow_cast<u8>(mDevice->channelsFromFmt());
    if(pa_sample_spec_valid(&mSpec) == 0)
        throw al::backend_exception{al::backend_error::DeviceError, "Invalid sample format"};

    const auto frame_size = gsl::narrow_cast<u32>(pa_frame_size(&mSpec));
    const auto samples = std::max(mDevice->mBufferSize, mDevice->mSampleRate*100_u32/1000_u32);
    mAttr.minreq = ~0_u32;
    mAttr.prebuf = ~0_u32;
    mAttr.maxlength = samples * frame_size;
    mAttr.tlength = ~0_u32;
    mAttr.fragsize = std::min(samples, mDevice->mSampleRate*50_u32/1000_u32) * frame_size;

    auto flags = PA_STREAM_START_CORKED | PA_STREAM_ADJUST_LATENCY;
    if(!GetConfigValueBool({}, "pulse", "allow-moves", true))
        flags |= PA_STREAM_DONT_MOVE;

    TRACE("Connecting to \"{}\"", pulse_name.empty() ? "(default)"sv:std::string_view{pulse_name});
    mStream = plock.connectStream(pulse_name, flags, &mAttr, &mSpec, &chanmap,
        BackendType::Capture);

    static constexpr auto move_callback = [](pa_stream *const stream, void *const pdata) noexcept
    { return static_cast<PulseCapture*>(pdata)->streamMovedCallback(stream); };
    pa_stream_set_moved_callback(mStream, move_callback, this);

    static constexpr auto state_callback = [](pa_stream *const stream, void *const pdata) noexcept
    { return static_cast<PulseCapture*>(pdata)->streamStateCallback(stream); };
    pa_stream_set_state_callback(mStream, state_callback, this);

    if(!pulse_name.empty())
        mDeviceId.emplace(std::move(pulse_name));

    if(mDeviceName.empty())
    {
        static constexpr auto name_callback = [](pa_context *const context,
            pa_source_info const *const info, int const eol, void *const pdata) noexcept
        { return static_cast<PulseCapture*>(pdata)->sourceNameCallback(context, info, eol); };
        auto *op = pa_context_get_source_info_by_name(mMainloop.getContext(),
            pa_stream_get_device_name(mStream), name_callback, this);
        plock.waitForOperation(op);
    }
}

void PulseCapture::start()
{
    auto const plock = MainloopUniqueLock{mMainloop};
    auto *const op = pa_stream_cork(mStream, 0, &PulseMainloop::streamSuccessCallbackC,
        &mMainloop);
    plock.waitForOperation(op);
}

void PulseCapture::stop()
{
    auto const plock = MainloopUniqueLock{mMainloop};
    auto *const op = pa_stream_cork(mStream, 1, &PulseMainloop::streamSuccessCallbackC,
        &mMainloop);
    plock.waitForOperation(op);
}

void PulseCapture::captureSamples(std::span<std::byte> outbuffer)
{
    /* Capture is done in fragment-sized chunks, so we loop until we get all
     * that's available.
     */
    mLastReadable -= outbuffer.size();
    while(!outbuffer.empty())
    {
        if(mHoleLength > 0) [[unlikely]]
        {
            const auto rem = std::min(outbuffer.size(), mHoleLength);
            std::ranges::fill(outbuffer | std::views::take(rem), mSilentVal);
            outbuffer = outbuffer.subspan(rem);
            mHoleLength -= rem;

            continue;
        }
        if(!mCapBuffer.empty())
        {
            const auto rem = std::min(outbuffer.size(), mCapBuffer.size());
            std::ranges::copy(mCapBuffer | std::views::take(rem), outbuffer.begin());
            outbuffer = outbuffer.subspan(rem);
            mCapBuffer = mCapBuffer.subspan(rem);

            continue;
        }

        if(!mDevice->Connected.load(std::memory_order_acquire)) [[unlikely]]
            break;

        auto plock = MainloopUniqueLock{mMainloop};
        if(mPacketLength > 0)
        {
            pa_stream_drop(mStream);
            mPacketLength = 0;
        }

        if(const auto state = pa_stream_get_state(mStream); !PA_STREAM_IS_GOOD(state)) [[unlikely]]
        {
            mDevice->handleDisconnect("Bad capture state: {}", al::to_underlying(state));
            break;
        }

        auto *capbuf = cvoidp{};
        auto caplen = usize{};
        if(pa_stream_peek(mStream, &capbuf, &caplen) < 0) [[unlikely]]
        {
            mDevice->handleDisconnect("Failed retrieving capture samples: {}",
                pa_strerror(pa_context_errno(mMainloop.getContext())));
            break;
        }
        plock.unlock();

        if(caplen == 0) break;
        if(!capbuf) [[unlikely]]
            mHoleLength = caplen;
        else
            mCapBuffer = {static_cast<const std::byte*>(capbuf), caplen};
        mPacketLength = caplen;
    }
    if(!outbuffer.empty())
        std::ranges::fill(outbuffer, mSilentVal);
}

auto PulseCapture::availableSamples() -> usize
{
    auto readable = std::max(mCapBuffer.size(), mHoleLength);

    if(mDevice->Connected.load(std::memory_order_acquire))
    {
        auto plock = MainloopUniqueLock{mMainloop};
        if(auto const got = pa_stream_readable_size(mStream); as_signed(got) < 0) [[unlikely]]
        {
            auto *err = pa_strerror(gsl::narrow_cast<int>(as_signed(got)));
            ERR("pa_stream_readable_size() failed: {}", err);
            mDevice->handleDisconnect("Failed getting readable size: {}", err);
        }
        else
        {
            /* "readable" is the number of bytes from the last packet that have
             * not yet been read by the caller. So add the stream's readable
             * size excluding the last packet (the stream size includes the
             * last packet until it's dropped).
             */
            if(got > mPacketLength)
                readable += got - mPacketLength;
        }
    }

    /* Avoid decreasing the readable count. */
    mLastReadable = std::max(mLastReadable, readable);
    return mLastReadable / pa_frame_size(&mSpec);
}


auto PulseCapture::getClockLatency() -> ClockLatency
{
    auto ret = ClockLatency{};
    auto latency = pa_usec_t{};
    auto neg = int{};
    auto err = int{};

    {
        auto plock = MainloopUniqueLock{mMainloop};
        ret.ClockTime = mDevice->getClockTime();
        err = pa_stream_get_latency(mStream, &latency, &neg);
    }

    if(err != 0) [[unlikely]]
    {
        ERR("Failed to get stream latency: {:#x}", as_unsigned(err));
        latency = 0;
        neg = 0;
    }
    else if(neg) [[unlikely]]
        latency = 0;
    ret.Latency = std::chrono::microseconds{latency};

    return ret;
}

#ifdef _WIN32
#define PULSE_LIB "libpulse-0.dll"
#elif defined(__CYGWIN__)
#define PULSE_LIB "cygpulse-0.dll"
#elif defined(__APPLE__) && defined(__MACH__)
#define PULSE_LIB "libpulse.0.dylib"
#else
#define PULSE_LIB "libpulse.so.0"
#endif

#if HAVE_DYNLOAD
OAL_ELF_NOTE_DLOPEN(
    "backend-pulseaudio",
    "Support for the PulseAudio backend",
    OAL_ELF_NOTE_DLOPEN_PRIORITY_RECOMMENDED,
    PULSE_LIB
);
#endif

} // namespace

auto PulseBackendFactory::init() -> bool
{
#if HAVE_DYNLOAD
    if(!pulse_handle)
    {
        auto *const pulse_lib = gsl::czstring{PULSE_LIB};
        if(auto const libresult = LoadLib(pulse_lib))
            pulse_handle = libresult.value();
        else
        {
            WARN("Failed to load {}: {}", pulse_lib, libresult.error());
            return false;
        }

        static constexpr auto load_func = [](auto *&func, gsl::czstring const name) -> bool
        {
            using func_t = std::remove_reference_t<decltype(func)>;
            auto const funcresult = GetSymbol(pulse_handle, name);
            if(!funcresult)
            {
                WARN("Failed to load function {}: {}", name, funcresult.error());
                return false;
            }
            /* NOLINTNEXTLINE(cppcoreguidelines-pro-type-reinterpret-cast) */
            func = reinterpret_cast<func_t>(funcresult.value());
            return true;
        };
        auto ok = true;
#define LOAD_FUNC(f) ok &= load_func(p##f, #f)
        PULSE_FUNCS(LOAD_FUNC)
#undef LOAD_FUNC
        if(!ok)
        {
            CloseLib(pulse_handle);
            pulse_handle = nullptr;
            return false;
        }
    }
#endif

    pulse_ctx_flags = PA_CONTEXT_NOFLAGS;
    if(!GetConfigValueBool({}, "pulse", "spawn-server", false))
        pulse_ctx_flags |= PA_CONTEXT_NOAUTOSPAWN;

    try {
        if(!gGlobalMainloop)
        {
            gGlobalMainloop = PulseMainloop::Create();
            if(gGlobalMainloop.start() != 0)
            {
                gGlobalMainloop = nullptr;
                return false;
            }
        }

        auto plock = MainloopUniqueLock{gGlobalMainloop};
        plock.connectContext();
        plock.setEventHandler();
        return true;
    }
    catch(...) {
        return false;
    }
}

auto PulseBackendFactory::querySupport(BackendType const type) -> bool
{ return type == BackendType::Playback || type == BackendType::Capture; }

auto PulseBackendFactory::enumerate(BackendType const type) -> std::vector<std::string>
{
    auto outnames = std::vector<std::string>{};

    auto plock = MainloopUniqueLock{gGlobalMainloop};
    switch(type)
    {
    case BackendType::Playback:
        outnames.reserve(PlaybackDevices.size());
        std::ranges::for_each(PlaybackDevices, [&outnames](const DevMap &entry)
        {
            if(entry.device_name == DefaultPlaybackDevName)
                outnames.emplace(outnames.cbegin(), entry.name);
            else
                outnames.push_back(entry.name);
        });
        break;

    case BackendType::Capture:
        outnames.reserve(CaptureDevices.size());
        std::ranges::for_each(CaptureDevices, [&outnames](const DevMap &entry)
        {
            if(entry.device_name == DefaultCaptureDevName)
                outnames.emplace(outnames.cbegin(), entry.name);
            else
                outnames.push_back(entry.name);
        });
        break;
    }

    return outnames;
}

auto PulseBackendFactory::createBackend(gsl::not_null<DeviceBase*> const device,
    BackendType const type) -> BackendPtr
{
    if(type == BackendType::Playback)
        return BackendPtr{new PulsePlayback{device}};
    if(type == BackendType::Capture)
        return BackendPtr{new PulseCapture{device}};
    return nullptr;
}

auto PulseBackendFactory::getFactory() -> BackendFactory&
{
    static PulseBackendFactory factory{};
    return factory;
}

auto PulseBackendFactory::queryEventSupport(alc::EventType const eventType, BackendType)
    -> alc::EventSupport
{
    switch(eventType)
    {
    case alc::EventType::DeviceAdded:
    case alc::EventType::DeviceRemoved:
    case alc::EventType::DefaultDeviceChanged:
        return alc::EventSupport::FullSupport;

    case alc::EventType::Count:
        break;
    }
    return alc::EventSupport::NoSupport;
}
