/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2019 Google LLC, written by Richard Kralovic <riso@google.com>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/types.h>
#include <sys/rtprio.h>
#include <sys/soundcard.h>

#include <dlfcn.h>
#include <err.h>
#include <fcntl.h>
#include <stdarg.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sysexits.h>
#include <time.h>
#include <unistd.h>
#include <poll.h>
#include <getopt.h>

#define L2CAP_SOCKET_CHECKED
#include <bluetooth.h>
#include <sdp.h>

#include "avdtp_signal.h"
#include "bt.h"

static int (*bt_receive_f)(struct bt_config *, void *, int, int);
static int (*avdtpACPHandlePacket_f)(struct bt_config *cfg);
static void (*avdtpACPFree_f)(struct bt_config *);

static int bt_in_background;

static void
message(const char *fmt,...)
{
        va_list list;

        if (bt_in_background)
                return;

        va_start(list, fmt);
        vfprintf(stderr, fmt, list);
        va_end(list);
}

struct bt_audio_receiver {
        const char *devname;
        const char *sdp_socket_path;
        uint16_t l2cap_psm;
        int     fd_listen;
        void   *sdp_session;
        uint32_t sdp_handle;
};

static int
register_sdp(struct bt_audio_receiver *r)
{
        struct sdp_audio_sink_profile record = {};

        r->sdp_session = sdp_open_local(r->sdp_socket_path);
        if (r->sdp_session == NULL || sdp_error(r->sdp_session)) {
                sdp_close(r->sdp_session);
                r->sdp_session = NULL;
                return (0);
        }

        record.psm = r->l2cap_psm;
        record.protover = 0x100;
        record.features = 0x01;         /* player only */

        if (sdp_register_service(r->sdp_session, SDP_SERVICE_CLASS_AUDIO_SINK,
            NG_HCI_BDADDR_ANY, (const uint8_t *)&record, sizeof(record),
            &r->sdp_handle)) {
                message("SDP failed to register: %s\n",
                    strerror(sdp_error(r->sdp_session)));
                sdp_close(r->sdp_session);
                r->sdp_session = NULL;
                return (0);
        }
        return (1);
}

static void
unregister_sdp(struct bt_audio_receiver *r)
{
        sdp_unregister_service(r->sdp_session, r->sdp_handle);
        sdp_close(r->sdp_session);
        r->sdp_session = NULL;
}

static int
start_listen(struct bt_audio_receiver *r)
{
        struct sockaddr_l2cap addr = {};

        r->fd_listen = socket(PF_BLUETOOTH, SOCK_SEQPACKET, BLUETOOTH_PROTO_L2CAP);
        if (r->fd_listen < 0)
                return (0);

        addr.l2cap_len = sizeof(addr);
        addr.l2cap_family = AF_BLUETOOTH;
        addr.l2cap_psm = r->l2cap_psm;

        if (bind(r->fd_listen, (struct sockaddr *)&addr, sizeof(addr)) < 0 ||
            listen(r->fd_listen, 4) < 0) {
                close(r->fd_listen);
                return (0);
        }
        return (1);
}

static void
stop_listen(struct bt_audio_receiver *r)
{
        close(r->fd_listen);
}

struct bt_audio_connection {
        struct bt_audio_receiver *r;
        struct sockaddr_l2cap peer_addr;
        struct bt_config cfg;
        int     oss_fd;
};

static void
close_connection(struct bt_audio_connection *c)
{
        avdtpACPFree_f(&c->cfg);
        if (c->cfg.fd != -1)
                close(c->cfg.fd);
        if (c->cfg.hc != -1)
                close(c->cfg.hc);
        if (c->oss_fd != -1)
                close(c->oss_fd);
        free(c);
}

static struct bt_audio_connection *
wait_for_connection(struct bt_audio_receiver *r)
{
        struct bt_audio_connection *c =
        malloc(sizeof(struct bt_audio_connection));
        socklen_t addrlen;

        memset(c, 0, sizeof(*c));

        c->r = r;
        c->cfg.fd = -1;
        c->oss_fd = -1;

        addrlen = sizeof(c->peer_addr);
        c->cfg.hc = accept(r->fd_listen, (struct sockaddr *)&c->peer_addr, &addrlen);

        message("Accepted control connection, %d\n", c->cfg.hc);
        if (c->cfg.hc < 0) {
                close_connection(c);
                return NULL;
        }
        c->cfg.sep = 0;                 /* to be set later */
        c->cfg.media_Type = mediaTypeAudio;
        c->cfg.chmode = MODE_DUAL;
        c->cfg.aacMode1 = 0;            /* TODO: support AAC */
        c->cfg.aacMode2 = 0;
        c->cfg.acceptor_state = acpInitial;

        return (c);
}

static void
setup_oss(struct bt_audio_connection *c)
{
        c->oss_fd = open(c->r->devname, O_WRONLY);

        if (c->oss_fd < 0)
                goto err;

        int v;

        switch (c->cfg.chmode) {
        case MODE_STEREO:
        case MODE_JOINT:
        case MODE_DUAL:
                v = 2;
                break;
        case MODE_MONO:
                v = 1;
                break;
        default:
                message("Wrong chmode\n");
                goto err;
        }

        if (ioctl(c->oss_fd, SNDCTL_DSP_CHANNELS, &v) < 0) {
                message("SNDCTL_DSP_CHANNELS failed\n");
                goto err;
        }
        v = AFMT_S16_NE;
        if (ioctl(c->oss_fd, SNDCTL_DSP_SETFMT, &v) < 0) {
                message("SNDCTL_DSP_SETFMT failed\n");
                goto err;
        }
        switch (c->cfg.freq) {
        case FREQ_16K:
                v = 16000;
                break;
        case FREQ_32K:
                v = 32000;
                break;
        case FREQ_44_1K:
                v = 44100;
                break;
        case FREQ_48K:
                v = 48000;
                break;
        default:
                message("Wrong freq\n");
                goto err;
        }

        if (ioctl(c->oss_fd, SNDCTL_DSP_SPEED, &v) < 0) {
                message("SNDCTL_DSP_SETFMT failed\n");
                goto err;
        }
        v = (2 << 16) | 15;             /* 2 fragments of 32k each */
        if (ioctl(c->oss_fd, SNDCTL_DSP_SETFRAGMENT, &v) < 0) {
                message("SNDCTL_DSP_SETFRAGMENT failed\n");
                goto err;
        }
        return;

err:
        c->oss_fd = -1;
        message("Cannot open oss device %s\n", c->r->devname);
}

static void
process_connection(struct bt_audio_connection *c)
{
        struct pollfd pfd[3] = {};
        time_t oss_attempt = 0;

        while (c->cfg.acceptor_state != acpStreamClosed) {
                int np;

                pfd[0].fd = c->r->fd_listen;
                pfd[0].events = POLLIN | POLLRDNORM;
                pfd[0].revents = 0;

                pfd[1].fd = c->cfg.hc;
                pfd[1].events = POLLIN | POLLRDNORM;
                pfd[1].revents = 0;

                pfd[2].fd = c->cfg.fd;
                pfd[2].events = POLLIN | POLLRDNORM;
                pfd[2].revents = 0;

                if (c->cfg.fd != -1)
                        np = 3;
                else
                        np = 2;

                if (poll(pfd, np, INFTIM) < 0)
                        return;

                if (pfd[1].revents != 0) {
                        int retval;

                        message("Handling packet: state = %d, ",
                            c->cfg.acceptor_state);
                        retval = avdtpACPHandlePacket_f(&c->cfg);
                        message("retval = %d\n", retval);
                        if (retval < 0)
                                return;
                }
                if (pfd[0].revents != 0) {
                        socklen_t addrlen = sizeof(c->peer_addr);
                        int fd = accept4(c->r->fd_listen,
                            (struct sockaddr *)&c->peer_addr, &addrlen,
                            SOCK_NONBLOCK);

                        if (fd < 0)
                                return;

                        if (c->cfg.fd < 0) {
                                if (c->cfg.acceptor_state == acpStreamOpened) {
                                        socklen_t mtusize = sizeof(uint16_t);
                                        c->cfg.fd = fd;

                                        if (getsockopt(c->cfg.fd, SOL_L2CAP, SO_L2CAP_IMTU, &c->cfg.mtu, &mtusize) == -1) {
                                                message("Could not get MTU size\n");
                                                return;
                                        }

                                        int temp = c->cfg.mtu * 32;

                                        if (setsockopt(c->cfg.fd, SOL_SOCKET, SO_RCVBUF, &temp, sizeof(temp)) == -1) {
                                                message("Could not set send buffer size\n");
                                                return;
                                        }

                                        temp = 1;
                                        if (setsockopt(c->cfg.fd, SOL_SOCKET, SO_RCVLOWAT, &temp, sizeof(temp)) == -1) {
                                                message("Could not set low water mark\n");
                                                return;
                                        }
                                        message("Accepted data connection, %d\n", c->cfg.fd);
                                }
                        } else {
                                close(fd);
                        }
                }
                if (pfd[2].revents != 0) {
                        uint8_t data[65536];
                        int len;

                        if ((len = bt_receive_f(&c->cfg, data, sizeof(data), 0)) < 0) {
                                return;
                        }
                        if (c->cfg.acceptor_state != acpStreamSuspended &&
                            c->oss_fd < 0 &&
                            time(NULL) != oss_attempt) {
                                message("Trying to open dsp\n");
                                setup_oss(c);
                                oss_attempt = time(NULL);
                        }
                        if (c->oss_fd > -1) {
                                uint8_t *end = data + len;
                                uint8_t *ptr = data;
                                unsigned delay;
                                unsigned jitter_limit;

                                switch (c->cfg.freq) {
                                case FREQ_16K:
                                        jitter_limit = (16000 / 20);
                                        break;
                                case FREQ_32K:
                                        jitter_limit = (32000 / 20);
                                        break;
                                case FREQ_44_1K:
                                        jitter_limit = (44100 / 20);
                                        break;
                                default:
                                        jitter_limit = (48000 / 20);
                                        break;
                                }

                                if (c->cfg.chmode == MODE_MONO) {
                                        if (len >= 2 &&
                                            ioctl(c->oss_fd, SNDCTL_DSP_GETODELAY, &delay) == 0 &&
                                            delay < (jitter_limit * 2)) {
                                                uint8_t jitter[jitter_limit * 4] __aligned(4);
                                                size_t x;

                                                /* repeat last sample */
                                                for (x = 0; x != sizeof(jitter); x++)
                                                        jitter[x] = ptr[x % 2];

                                                write(c->oss_fd, jitter, sizeof(jitter));
                                        }
                                } else {
                                        if (len >= 4 &&
                                            ioctl(c->oss_fd, SNDCTL_DSP_GETODELAY, &delay) == 0 &&
                                            delay < (jitter_limit * 4)) {
                                                uint8_t jitter[jitter_limit * 8] __aligned(4);
                                                size_t x;

                                                /* repeat last sample */
                                                for (x = 0; x != sizeof(jitter); x++)
                                                        jitter[x] = ptr[x % 4];

                                                write(c->oss_fd, jitter, sizeof(jitter));
                                        }
                                }
                                while (ptr != end) {
                                        int written = write(c->oss_fd, ptr, end - ptr);

                                        if (written < 0) {
                                                if (errno != EINTR && errno != EAGAIN)
                                                        break;
                                                written = 0;
                                        }
                                        ptr += written;
                                }
                                if (ptr != end) {
                                        message("Not all written, closing dsp\n");
                                        close(c->oss_fd);
                                        c->oss_fd = -1;
                                        oss_attempt = time(NULL);
                                }
                        }
                }

                if (c->cfg.acceptor_state == acpStreamSuspended &&
                    c->oss_fd > -1) {
                        close(c->oss_fd);
                        c->oss_fd = -1;
                }
        }
}

static struct option bt_speaker_opts[] = {
        {"device", required_argument, NULL, 'd'},
        {"sdp_socket_path", required_argument, NULL, 'p'},
        {"rtprio", required_argument, NULL, 'i'},
        {"background", no_argument, NULL, 'B'},
        {"help", no_argument, NULL, 'h'},
        {NULL, 0, NULL, 0}
};

static void
usage(void)
{
        fprintf(stderr, "Usage: virtual_bt_speaker -d /dev/dsp\n"
            "\t" "-d, --device [device]\n"
            "\t" "-p, --sdp_socket_path [path]\n"
            "\t" "-i, --rtprio [priority]\n"
            "\t" "-B, --background\n"
        );
        exit(EX_USAGE);
}

int
main(int argc, char **argv)
{
        struct bt_audio_receiver r = {};
        struct rtprio rtp = {};
        void *hdl;
        int ch;

        r.devname = NULL;
        r.sdp_socket_path = NULL;
        r.l2cap_psm = SDP_UUID_PROTOCOL_AVDTP;

        while ((ch = getopt_long(argc, argv, "p:i:d:Bh", bt_speaker_opts, NULL)) != -1) {
                switch (ch) {
                case 'd':
                        r.devname = optarg;
                        break;
                case 'p':
                        r.sdp_socket_path = optarg;
                        break;
                case 'B':
                        bt_in_background = 1;
                        break;
                case 'i':
                        rtp.type = RTP_PRIO_REALTIME;
                        rtp.prio = atoi(optarg);
                        if (rtprio(RTP_SET, getpid(), &rtp) != 0) {
                                message("Cannot set realtime priority\n");
                        }
                        break;
                default:
                        usage();
                        break;
                }
        }

        if (r.devname == NULL)
                errx(EX_USAGE, "No devicename specified");

        if (bt_in_background) {
                if (daemon(0, 0) != 0)
                        errx(EX_SOFTWARE, "Cannot become daemon");
        }

        if ((hdl = dlopen("/usr/lib/virtual_oss/voss_bt.so", RTLD_NOW)) == NULL)
                errx(1, "%s", dlerror());
        if ((bt_receive_f = dlsym(hdl, "bt_receive")) == NULL)
                goto err_dlsym;
        if ((avdtpACPHandlePacket_f = dlsym(hdl, "avdtpACPHandlePacket")) ==
            NULL)
                goto err_dlsym;
        if ((avdtpACPFree_f = dlsym(hdl, "avdtpACPFree")) == NULL)
                goto err_dlsym;

        while (1) {
                message("Starting to listen\n");
                if (!start_listen(&r)) {
                        message("Failed to initialize server socket\n");
                        goto err_listen;
                }
                message("Registering service via SDP\n");
                if (!register_sdp(&r)) {
                        message("Failed to register in SDP\n");
                        goto err_sdp;
                }
                while (1) {
                        message("Waiting for connection...\n");
                        struct bt_audio_connection *c = wait_for_connection(&r);

                        if (c == NULL) {
                                message("Failed to get connection\n");
                                goto err_conn;
                        }
                        message("Got connection...\n");

                        process_connection(c);

                        message("Connection finished...\n");

                        close_connection(c);
                }
err_conn:
                message("Unregistering service\n");
                unregister_sdp(&r);
err_sdp:
                stop_listen(&r);
err_listen:
                sleep(5);
        }
        return (0);

err_dlsym:
        warnx("%s", dlerror());
        dlclose(hdl);
        exit(EXIT_FAILURE);
}