/**
 * net_ingest.c — Network source (RTMP/SRT) → framecache slot ingest.
 *
 * Spawns ffmpeg to decode a network stream to raw UYVY422 on stdout, then
 * reads those frames and writes them into a framecache slot via the shm
 * ring buffer. Registers the slot with the framecache HTTP API on startup
 * and deregisters on clean exit.
 *
 * Usage:
 *   net_ingest --url <srt://...|rtmp://...>
 *              --slot-id <recorder-uuid>
 *              --fc-url http://framecache:7435
 *              --width <W> --height <H>
 *              --fps-num <N> --fps-den <D>
 *              [--source-type srt|rtmp]
 *              [--listen]          # SRT/RTMP listener mode
 *              [--listen-port <N>] # listener port (SRT default 9000, RTMP 1935)
 *              [--stream-key <k>]  # RTMP stream key (default "stream")
 *
 * Emits one JSON line to stderr on first frame:
 *   {"slot_id":"<id>","width":W,"height":H,"fps_num":N,"fps_den":D,
 *    "source_type":"srt","pix_fmt":"uyvy422"}
 *
 * Exits 0 on clean stop (SIGTERM), 1 on error.
 *
 * The framecache slot stays alive between ffmpeg reconnects (listener mode):
 * net_ingest keeps the slot open and restarts ffmpeg on disconnect.
 */

#include "slot.h"

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdint.h>
#include <stdatomic.h>
#include <errno.h>
#include <fcntl.h>
#include <signal.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <time.h>
#include <unistd.h>
#include <netdb.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netinet/in.h>

/* Re-use fc_writer helpers inline (no external dep) */
#define FC_URL_DEFAULT "http://localhost:7435"

static volatile int g_stop = 0;
static void on_signal(int s) { (void)s; g_stop = 1; }

/* ── Tiny HTTP POST/DELETE (same approach as fc_writer.c) ─────────── */
static int http_req(const char *method, const char *host, int port,
                    const char *path, const char *body,
                    char *resp, size_t resp_len)
{
    struct sockaddr_in sa;
    memset(&sa, 0, sizeof sa);
    sa.sin_family = AF_INET;
    sa.sin_port   = htons((uint16_t)port);
    struct hostent *he = gethostbyname(host);
    if (!he) return -1;
    memcpy(&sa.sin_addr, he->h_addr_list[0], (size_t)he->h_length);

    int fd = socket(AF_INET, SOCK_STREAM, 0);
    if (fd < 0) return -1;
    struct timeval tv = { .tv_sec = 5 };
    setsockopt(fd, SOL_SOCKET, SO_RCVTIMEO, &tv, sizeof tv);
    setsockopt(fd, SOL_SOCKET, SO_SNDTIMEO, &tv, sizeof tv);
    if (connect(fd, (struct sockaddr *)&sa, sizeof sa) < 0) { close(fd); return -1; }

    char req[4096];
    int rlen;
    if (body)
        rlen = snprintf(req, sizeof req,
            "%s %s HTTP/1.0\r\nHost: %s:%d\r\n"
            "Content-Type: application/json\r\nContent-Length: %zu\r\n"
            "Connection: close\r\n\r\n%s",
            method, path, host, port, strlen(body), body);
    else
        rlen = snprintf(req, sizeof req,
            "%s %s HTTP/1.0\r\nHost: %s:%d\r\nConnection: close\r\n\r\n",
            method, path, host, port);

    send(fd, req, (size_t)rlen, 0);

    int status = -1;
    size_t got = 0;
    char buf[8192];
    ssize_t n;
    while ((n = recv(fd, buf + got, sizeof buf - got - 1, 0)) > 0) got += (size_t)n;
    buf[got] = '\0';
    sscanf(buf, "HTTP/%*s %d", &status);
    if (resp && resp_len) {
        const char *b = strstr(buf, "\r\n\r\n");
        if (b) { strncpy(resp, b + 4, resp_len - 1); resp[resp_len-1] = '\0'; }
    }
    close(fd);
    return status;
}

static void parse_url(const char *url, char *host, size_t hl, int *port) {
    const char *p = url;
    if (!strncmp(p, "http://", 7)) p += 7;
    *port = 7435;
    const char *colon = strchr(p, ':');
    if (colon) {
        size_t n = (size_t)(colon - p) < hl ? (size_t)(colon - p) : hl - 1;
        strncpy(host, p, n); host[n] = '\0';
        *port = atoi(colon + 1);
    } else { strncpy(host, p, hl - 1); host[hl-1] = '\0'; }
}

static int json_str(const char *j, const char *k, char *out, size_t len) {
    char pat[128]; snprintf(pat, sizeof pat, "\"%s\":", k);
    const char *p = strstr(j, pat); if (!p) return -1;
    p += strlen(pat); while (*p == ' ') p++;
    if (*p != '"') return -1; p++;
    size_t i = 0;
    while (*p && *p != '"' && i < len - 1) out[i++] = *p++;
    out[i] = '\0'; return 0;
}

/* ── Frame size helpers ────────────────────────────────────────────── */
static inline size_t frame_bytes(uint32_t w, uint32_t h) {
    return (size_t)w * h * 2; /* UYVY422 */
}

/* ── Register slot with framecache ────────────────────────────────── */
static int register_slot(const char *fc_url, const char *slot_id,
                          uint32_t w, uint32_t h,
                          uint32_t fps_num, uint32_t fps_den,
                          const char *source_type,
                          char *shm_path, size_t sp_len,
                          char *sem_name, size_t sn_len)
{
    char host[128]; int port;
    parse_url(fc_url, host, sizeof host, &port);

    char body[512];
    snprintf(body, sizeof body,
        "{\"slot_id\":\"%s\",\"width\":%u,\"height\":%u,"
        "\"fps_num\":%u,\"fps_den\":%u,\"source_type\":\"%s\"}",
        slot_id, w, h, fps_num, fps_den, source_type);

    char resp[1024] = {0};
    int st = http_req("POST", host, port, "/slots", body, resp, sizeof resp);
    if (st != 201) {
        fprintf(stderr, "[net_ingest] POST /slots failed HTTP %d: %s\n", st, resp);
        return -1;
    }
    json_str(resp, "shm_path", shm_path, sp_len);
    json_str(resp, "sem_name", sem_name, sn_len);
    return 0;
}

static void deregister_slot(const char *fc_url, const char *slot_id) {
    char host[128]; int port;
    parse_url(fc_url, host, sizeof host, &port);
    char path[192]; snprintf(path, sizeof path, "/slots/%s", slot_id);
    http_req("DELETE", host, port, path, NULL, NULL, 0);
}

/* ── Open shm + semaphore for writing ─────────────────────────────── */
#include <sys/mman.h>
#include <semaphore.h>

typedef struct {
    void    *base;
    size_t   size;
    int      fd;
    sem_t   *sem;
} ShmWriter;

static int shm_writer_open(const char *shm_path, const char *sem_name,
                            ShmWriter *sw)
{
    sw->fd = open(shm_path, O_RDWR);
    if (sw->fd < 0) return -1;
    fc_header_t hdr;
    if (pread(sw->fd, &hdr, sizeof hdr, 0) != sizeof hdr || hdr.magic != FC_MAGIC) {
        close(sw->fd); return -1;
    }
    sw->size = fc_slot_shm_size(hdr.frame_size);
    sw->base = mmap(NULL, sw->size, PROT_READ | PROT_WRITE, MAP_SHARED, sw->fd, 0);
    if (sw->base == MAP_FAILED) { close(sw->fd); return -1; }
    sw->sem = sem_open(sem_name, 0);
    if (sw->sem == SEM_FAILED) { munmap(sw->base, sw->size); close(sw->fd); return -1; }
    return 0;
}

static void shm_write_frame(ShmWriter *sw, const uint8_t *data,
                              uint32_t size, uint64_t pts_us)
{
    fc_header_t *hdr = (fc_header_t *)sw->base;
    uint64_t cur = atomic_load_explicit(&hdr->write_cursor, memory_order_relaxed);
    fc_frame_t *frame = fc_frame_at(sw->base, hdr->frame_size, cur);
    struct timespec ts; clock_gettime(CLOCK_REALTIME, &ts);
    frame->pts_us  = pts_us;
    frame->wall_us = (uint64_t)ts.tv_sec * 1000000ULL + ts.tv_nsec / 1000ULL;
    frame->size    = size < hdr->frame_size ? size : hdr->frame_size;
    memcpy(frame->data, data, frame->size);
    atomic_store_explicit(&hdr->write_cursor, cur + 1, memory_order_release);
    sem_post(sw->sem);
}

static void shm_writer_close(ShmWriter *sw) {
    if (sw->sem)  { sem_close(sw->sem);          sw->sem  = NULL; }
    if (sw->base) { munmap(sw->base, sw->size);  sw->base = NULL; }
    if (sw->fd >= 0) { close(sw->fd);            sw->fd   = -1;   }
}

/* ── Build ffmpeg args for network decode → rawvideo stdout ──────────
 * All dynamic strings are written into CALLER-OWNED buffers (passed in) so
 * there is no per-call strdup leak across listener reconnects. The video
 * filter forces the EXACT target W:H (scale=W:H, not iw:ih) so a mid-stream
 * source resolution change cannot desync the fixed-size frame reassembly —
 * ffmpeg's scaler always emits width*height*2 bytes per frame.
 *
 * Caller must provide:
 *   url_buf  — at least 320 bytes (built listener URL, or copied caller URL)
 *   vf_buf   — at least 64 bytes  (scale/format filter)
 */
static int build_ffmpeg_args(
    char **argv, int max_args,
    const char *url, const char *source_type,
    int listen, int listen_port, const char *stream_key,
    uint32_t w, uint32_t h,
    char *url_buf, size_t url_buf_len,
    char *vf_buf,  size_t vf_buf_len)
{
    (void)max_args;
    char port_str[16];

    int i = 0;
    argv[i++] = "ffmpeg";
    argv[i++] = "-hide_banner";
    argv[i++] = "-loglevel"; argv[i++] = "warning";

    /* Input */
    argv[i++] = "-probesize";        argv[i++] = "32M";
    argv[i++] = "-analyzeduration"; argv[i++] = "10M";
    argv[i++] = "-fflags";          argv[i++] = "+genpts";

    if (!strcmp(source_type, "srt") && listen) {
        snprintf(port_str, sizeof port_str, "%d", listen_port ? listen_port : 9000);
        snprintf(url_buf, url_buf_len, "srt://0.0.0.0:%s?mode=listener", port_str);
        argv[i++] = "-i"; argv[i++] = url_buf;
    } else if (!strcmp(source_type, "rtmp") && listen) {
        snprintf(port_str, sizeof port_str, "%d", listen_port ? listen_port : 1935);
        snprintf(url_buf, url_buf_len, "rtmp://0.0.0.0:%s/live/%s",
                 port_str, stream_key ? stream_key : "stream");
        argv[i++] = "-listen"; argv[i++] = "1";
        argv[i++] = "-i"; argv[i++] = url_buf;
    } else {
        argv[i++] = "-i"; argv[i++] = (char *)url;
    }

    /* Force EXACT output dimensions so every frame is exactly w*h*2 bytes,
     * even if the source resolution changes mid-stream (SRT/RTMP reconnect to
     * a different encoder). This is the resync guarantee for the fixed-size
     * frame reassembly loop in main(). */
    snprintf(vf_buf, vf_buf_len, "scale=%u:%u,format=uyvy422", w, h);

    /* Video output: raw UYVY422 to stdout */
    argv[i++] = "-map";       argv[i++] = "0:v:0";
    argv[i++] = "-vf";        argv[i++] = vf_buf;
    argv[i++] = "-f";         argv[i++] = "rawvideo";
    argv[i++] = "-pix_fmt";   argv[i++] = "uyvy422";
    argv[i++] = "pipe:1";

    argv[i] = NULL;
    return i;
}

/* ── Main ──────────────────────────────────────────────────────────── */
int main(int argc, char *argv[]) {
    const char *url         = NULL;
    const char *slot_id     = NULL;
    const char *fc_url      = getenv("FC_URL") ? getenv("FC_URL") : FC_URL_DEFAULT;
    const char *source_type = "srt";
    uint32_t width   = 1920, height = 1080;
    uint32_t fps_num = 30000, fps_den = 1001;
    int listen = 0, listen_port = 0;
    const char *stream_key = "stream";

    for (int i = 1; i < argc; i++) {
        if      (!strcmp(argv[i], "--url")          && i+1 < argc) url         = argv[++i];
        else if (!strcmp(argv[i], "--slot-id")      && i+1 < argc) slot_id     = argv[++i];
        else if (!strcmp(argv[i], "--fc-url")       && i+1 < argc) fc_url      = argv[++i];
        else if (!strcmp(argv[i], "--source-type")  && i+1 < argc) source_type = argv[++i];
        else if (!strcmp(argv[i], "--width")        && i+1 < argc) width       = (uint32_t)atoi(argv[++i]);
        else if (!strcmp(argv[i], "--height")       && i+1 < argc) height      = (uint32_t)atoi(argv[++i]);
        else if (!strcmp(argv[i], "--fps-num")      && i+1 < argc) fps_num     = (uint32_t)atoi(argv[++i]);
        else if (!strcmp(argv[i], "--fps-den")      && i+1 < argc) fps_den     = (uint32_t)atoi(argv[++i]);
        else if (!strcmp(argv[i], "--listen"))                      listen      = 1;
        else if (!strcmp(argv[i], "--listen-port")  && i+1 < argc) listen_port = atoi(argv[++i]);
        else if (!strcmp(argv[i], "--stream-key")   && i+1 < argc) stream_key  = argv[++i];
    }

    if (!slot_id) {
        fprintf(stderr, "[net_ingest] --slot-id required\n");
        return 1;
    }
    if (!url && !listen) {
        fprintf(stderr, "[net_ingest] --url or --listen required\n");
        return 1;
    }

    signal(SIGTERM, on_signal);
    signal(SIGINT,  on_signal);
    signal(SIGPIPE, SIG_IGN);
    signal(SIGCHLD, SIG_DFL);

    /* ── Register slot ──────────────────────────────────────────────── */
    char shm_path[128] = {0}, sem_name[128] = {0};
    if (register_slot(fc_url, slot_id, width, height, fps_num, fps_den,
                      source_type, shm_path, sizeof shm_path,
                      sem_name, sizeof sem_name) < 0) {
        return 1;
    }

    ShmWriter sw = { .fd = -1 };
    if (shm_writer_open(shm_path, sem_name, &sw) < 0) {
        fprintf(stderr, "[net_ingest] failed to open shm %s\n", shm_path);
        deregister_slot(fc_url, slot_id);
        return 1;
    }

    size_t fsz = frame_bytes(width, height);
    uint8_t *frame_buf = malloc(fsz);
    if (!frame_buf) { shm_writer_close(&sw); deregister_slot(fc_url, slot_id); return 1; }

    uint64_t frame_seq = 0;
    int reported = 0;

    fprintf(stderr, "[net_ingest] slot=%s %ux%u %.2ffps source=%s%s\n",
            slot_id, width, height,
            fps_den ? (double)fps_num / fps_den : 0.0,
            source_type, listen ? " (listener)" : "");

    /* Caller-owned arg buffers — reused each reconnect, no per-loop leak. */
    char ff_url_buf[320];
    char ff_vf_buf[64];

    /* ── Outer reconnect loop (listener mode stays alive between sessions) */
    while (!g_stop) {
        /* Build ffmpeg argv (writes into ff_url_buf / ff_vf_buf, no strdup) */
        char *ff_argv[64];
        build_ffmpeg_args(ff_argv, 64, url, source_type,
                          listen, listen_port, stream_key, width, height,
                          ff_url_buf, sizeof ff_url_buf,
                          ff_vf_buf,  sizeof ff_vf_buf);

        /* Spawn ffmpeg with stdout pipe */
        int pfd[2];
        if (pipe(pfd) < 0) break;

        pid_t pid = fork();
        if (pid < 0) { close(pfd[0]); close(pfd[1]); break; }

        if (pid == 0) {
            /* Child: redirect stdout to pipe write end */
            dup2(pfd[1], STDOUT_FILENO);
            close(pfd[0]); close(pfd[1]);
            execvp("ffmpeg", ff_argv);
            _exit(127);
        }

        /* Parent: read from pipe read end */
        close(pfd[1]);
        int rfd = pfd[0];

        size_t buf_off = 0;
        while (!g_stop) {
            ssize_t n = read(rfd, frame_buf + buf_off, fsz - buf_off);
            if (n <= 0) break; /* ffmpeg exited or pipe closed */
            buf_off += (size_t)n;
            if (buf_off < fsz) continue; /* incomplete frame — keep reading */

            /* Full frame assembled */
            uint64_t pts_us = fps_num > 0
                ? frame_seq * 1000000ULL * fps_den / fps_num
                : 0;
            shm_write_frame(&sw, frame_buf, (uint32_t)fsz, pts_us);
            frame_seq++;
            buf_off = 0;

            if (!reported) {
                fprintf(stderr,
                    "{\"slot_id\":\"%s\",\"width\":%u,\"height\":%u,"
                    "\"fps_num\":%u,\"fps_den\":%u,"
                    "\"source_type\":\"%s\",\"pix_fmt\":\"uyvy422\"}\n",
                    slot_id, width, height, fps_num, fps_den, source_type);
                fflush(stderr);
                reported = 1;
            }
        }

        close(rfd);
        /* Reap ffmpeg child */
        int wstatus;
        kill(pid, SIGTERM);
        waitpid(pid, &wstatus, 0);

        if (!listen || g_stop) break;

        /* Listener mode: wait 1s then reconnect */
        fprintf(stderr, "[net_ingest] listener: waiting for next connection\n");
        struct timespec ts = { .tv_sec = 1 };
        nanosleep(&ts, NULL);
    }

    free(frame_buf);
    shm_writer_close(&sw);
    deregister_slot(fc_url, slot_id);
    fprintf(stderr, "[net_ingest] done frames=%llu\n", (unsigned long long)frame_seq);
    return 0;
}