#include <iostream>
#include <thread>
#include <cstdint>
#include <complex>
#include <optional>

#include <GLFW/glfw3.h>
#include <sndio.h>
#include <poll.h>
#include <math.h>

#include "imgui.h"
#include "imgui_impl_glfw.h"
#include "imgui_impl_opengl3.h"

#include "dsp_lib.h"
#include "fifo.h"

#define SND_BITS 24
#define SND_PCHAN 2
#define SND_RCHAN 2
#define SND_RATE 44100
#define SND_BUFLEN 4096

static std::atomic<bool> shutdown_threads;
static std::atomic<double> frequency[SND_PCHAN];
static std::atomic<double> amplitude[SND_PCHAN];
static std::atomic<double> lpf_bandwidth[SND_PCHAN];

static std::mutex li_hist_mutex;
static std::atomic<bool> li_hist_pause[SND_PCHAN];
static float li_hist_mag[SND_PCHAN][512];
static float li_hist_phase[SND_PCHAN][512];

static void dsp_thread()
{
    struct sio_hdl *hdl;
    struct sio_par par;

    hdl = sio_open(SIO_DEVANY, SIO_PLAY|SIO_REC, 1);
    if(hdl == nullptr) {
        std::cerr << "failed to open sound device" << std::endl;
        return;
    }
    sio_initpar(&par);
    par.sig = 1;
    par.bits = SND_BITS;
    par.pchan = SND_PCHAN;
    par.rchan = SND_RCHAN;
    par.rate = SND_RATE;
    par.le = SIO_LE_NATIVE;
    par.xrun = SIO_ERROR;
    if(!sio_setpar(hdl, &par)) {
        std::cerr << "failed to set sound device parameters" << std::endl;
        sio_close(hdl);
        return;
    }
    if(!sio_getpar(hdl, &par)) {
        std::cerr << "failed to get back sound device parameters" << std::endl;
        sio_close(hdl);
        return;
    }

    if(!sio_start(hdl)) {
        std::cerr << "failed to start sound device" << std::endl;
        sio_close(hdl);
        return;
    }

    DDS dds[SND_PCHAN];
    int32_t buf_out[SND_BUFLEN*SND_PCHAN];
    size_t buf_out_offset = sizeof(buf_out);

    int32_t buf_in[SND_BUFLEN*SND_RCHAN];
    size_t buf_in_offset = sizeof(buf_in);

    FIFO<phase_t, 8> ftw_fifo[SND_PCHAN];

    Lockin<4> lockin[SND_PCHAN];
    for(int i=0;i<SND_PCHAN;i++)
        // input channels are averaged together to reduce uncorrelated noise
        lockin[i].set_scale(pow(0.5, SND_BITS-1)/SND_RCHAN);
    int li_count[SND_PCHAN] = { 0 };

    nfds_t nfds = sio_nfds(hdl);
    struct pollfd pfd[nfds];
    while(!shutdown_threads) {
        sio_pollfd(hdl, pfd, POLLOUT|POLLIN);
        poll(pfd, nfds, INFTIM);
        int revents = sio_revents(hdl, pfd);

        for(int i=0;i<SND_PCHAN;i++)
            lockin[i].set_bandwidth(lpf_bandwidth[i]/SND_RATE);

        if(revents & POLLOUT) {
            if(buf_out_offset == sizeof(buf_out)) {
                for(int i=0;i<SND_PCHAN;i++) {
                    phase_t ftw = frequency_to_ftw(frequency[i]/SND_RATE);
                    dds[i].ftw = ftw;
                    if(!ftw_fifo[i].push(ftw))
                        std::cerr << "FTW FIFO overflow" << std::endl;
                }
                for(int i=0;i<SND_PCHAN;i++) {
                    double scale = amplitude[i]*(pow(2.0, SND_BITS-1) - 1.0);
                    for(int j=0;j<SND_BUFLEN;j++)
                        buf_out[SND_PCHAN*j+i] = scale*dds[i].get();
                }
                buf_out_offset = 0;
            }
            size_t written = sio_write(hdl, (const char *)buf_out + buf_out_offset, sizeof(buf_out) - buf_out_offset);
            buf_out_offset += written;
        }

        if(revents & POLLIN) {
            size_t read = sio_read(hdl, buf_in, sizeof(buf_in));
            buf_in_offset += read;
            if(buf_in_offset >= sizeof(buf_in)) {
                for(int i=0;i<SND_PCHAN;i++) {
                    std::optional<phase_t> ftw = ftw_fifo[i].pull();
                    if(ftw.has_value())
                        lockin[i].ftw = ftw.value();
                    else
                        std::cerr << "FTW FIFO underflow" << std::endl;
                }
                buf_in_offset -= sizeof(buf_in);
            }
            for(int i=0;i<SND_PCHAN;i++)
                for(int j=0;j<read/(SND_RCHAN*sizeof(buf_in[0]));j++) {
                    double sample = 0.0;
                    for(int k=0;k<SND_RCHAN;k++)
                        sample += (double)buf_in[SND_RCHAN*j+k];
                    std::complex<double> lockin_out = lockin[i].update(sample);

                    if(!li_hist_pause[i]) {
                        li_count[i]++;
                        if(li_count[i] == 200) {
                            li_count[i] = 0;
                            std::lock_guard<std::mutex> guard(li_hist_mutex);
                            std::memmove(&li_hist_mag[i][0], &li_hist_mag[i][1], 511*sizeof(float));
                            li_hist_mag[i][511] = std::abs(lockin_out);
                            std::memmove(&li_hist_phase[i][0], &li_hist_phase[i][1], 511*sizeof(float));
                            li_hist_phase[i][511] = std::arg(lockin_out);
                        }
                    }
                }
        }

        if(sio_eof(hdl)) {
            std::cerr << "sound I/O error" << std::endl;
            sio_close(hdl);
            return;
        }
    }

    sio_stop(hdl);
    sio_close(hdl);
}

int main(int argc, char* argv[])
{
    if(!glfwInit()) {
        std::cerr << "failed to initialize GLFW" << std::endl;
        return 1;
    }
    std::atexit(glfwTerminate);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 0);
    static GLFWwindow* window = glfwCreateWindow(1024, 1200, "sndlock", nullptr, nullptr);
    if(window == nullptr) {
        std::cerr << "failed to create GLFW window" << std::endl;
        return 1;
    }
    static auto DestroyWindow = []() {
        glfwDestroyWindow(window);
    };
    std::atexit(DestroyWindow);
    glfwMakeContextCurrent(window);
    glfwSwapInterval(1);

    IMGUI_CHECKVERSION();
    ImGui::CreateContext();
    static auto ImGuiDestroyContext = []() {
        ImGui::DestroyContext();
    };
    std::atexit(ImGuiDestroyContext);
    ImGuiIO& io = ImGui::GetIO();
    io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;
    ImGui::StyleColorsDark();
    ImGui_ImplGlfw_InitForOpenGL(window, true);
    std::atexit(ImGui_ImplGlfw_Shutdown);
    ImGui_ImplOpenGL3_Init("#version 130");
    std::atexit(ImGui_ImplOpenGL3_Shutdown);

    for(int i=0;i<SND_PCHAN;i++) {
        frequency[i] = 441.0 + 202.0*i;
        amplitude[i] = 1.0;
        lpf_bandwidth[i] = 10.0;
    }

    static std::thread dsp_thread_h = std::thread(dsp_thread);
    static auto JoinDSP = []() {
        dsp_thread_h.join();
    };
    std::atexit(JoinDSP);

    shutdown_threads = false;
    static auto SetShutdown = []() {
        shutdown_threads = true;
    };
    std::atexit(SetShutdown);

    float plot_scale[SND_PCHAN];
    for(int i=0;i<SND_PCHAN;i++)
        plot_scale[i] = 0.05f;
    while(!glfwWindowShouldClose(window)) {
        glfwPollEvents();
        glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
        glClear(GL_COLOR_BUFFER_BIT);

        ImGui_ImplOpenGL3_NewFrame();
        ImGui_ImplGlfw_NewFrame();
        ImGui::NewFrame();

        ImGui::SetNextWindowPos(ImVec2(0.0f, 0.0f));
        ImGui::SetNextWindowSize(io.DisplaySize);
        ImGui::PushStyleVar(ImGuiStyleVar_WindowRounding, 0.0f);
        ImGui::Begin("sndlock", nullptr, ImGuiWindowFlags_NoDecoration | ImGuiWindowFlags_NoResize);

        if(ImGui::CollapsingHeader("Modulation")) {
            for(int i=0;i<SND_PCHAN;i++) {
                char str[64];
                sprintf(str, "Channel %d", i);
                ImGui::SeparatorText(str);
                sprintf(str, "frequency##%d", i);
                float frequency_l = frequency[i];
                ImGui::SliderFloat(str, &frequency_l, 50.0f, 8000.0f);
                frequency[i] = frequency_l;
                sprintf(str, "amplitude##%d", i);
                float amplitude_l = amplitude[i];
                ImGui::SliderFloat(str, &amplitude_l, 0.0f, 1.0f);
                amplitude[i] = amplitude_l;
            }
        }
        if(ImGui::CollapsingHeader("Demodulation", ImGuiTreeNodeFlags_DefaultOpen)) {
            for(int i=0;i<SND_PCHAN;i++) {
                char str[64];

                sprintf(str, "Channel %d", i);
                ImGui::SeparatorText(str);
                sprintf(str, "LPF BW##%d", i);
                float lpf_bandwidth_l = lpf_bandwidth[i];
                ImGui::SliderFloat(str, &lpf_bandwidth_l, 0.5f, 200.0f);
                lpf_bandwidth[i] = lpf_bandwidth_l;

                sprintf(str, "mag scale##%d", i);
                ImGui::SliderFloat(str, &plot_scale[i], 0.01f, 0.1f);
                {
                    std::lock_guard<std::mutex> guard(li_hist_mutex);
                    sprintf(str, "magnitude##%d", i);
                    ImGui::PlotLines(str, li_hist_mag[i], 512, 0, 0, -0.0f, 0.1f*plot_scale[i], ImVec2(0.0f, 200.0f));
                    sprintf(str, "phase##%d", i);
                    ImGui::PlotLines(str, li_hist_phase[i], 512, 0, 0, -M_PI, M_PI, ImVec2(0.0f, 200.0f));
                }
                bool pause_l = li_hist_pause[i];
                sprintf(str, "pause##%d", i);
                ImGui::Checkbox(str, &pause_l);
                li_hist_pause[i] = pause_l;
                ImGui::SameLine();
                {
                    std::lock_guard<std::mutex> guard(li_hist_mutex);
                    ImGui::Text("values: %8.5f %8.5f rad", li_hist_mag[i][511], li_hist_phase[i][511]);
                }
            }
        }

        ImGui::End();
        ImGui::PopStyleVar(1);

        ImGui::Render();
        ImGui_ImplOpenGL3_RenderDrawData(ImGui::GetDrawData());
        int display_w, display_h;
        glfwGetFramebufferSize(window, &display_w, &display_h);
        glViewport(0, 0, display_w, display_h);
        glfwSwapBuffers(window);
    }

    return 0;
}