#include "snapshot_notify.h"

#include <arpa/inet.h>
#include <errno.h>
#include <netinet/in.h>
#include <stdio.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <unistd.h>

static int g_snapshot_fd = -1;
static struct sockaddr_in g_snapshot_addr;
static unsigned long g_notify_seq = 0;

static void set_reason(char *reason, int reason_size, const char *text)
{
    if (reason && reason_size > 0) {
        snprintf(reason, reason_size, "%s", text ? text : "unknown");
    }
}

static int json_escape(char *out, int out_size, const char *in)
{
    if (!out || out_size <= 0) {
        return -1;
    }

    int used = 0;
    const char *src = in ? in : "";
    for (const char *p = src; *p; ++p) {
        const char *rep = NULL;
        char tmp[7];

        switch (*p) {
        case '\\':
            rep = "\\\\";
            break;
        case '"':
            rep = "\\\"";
            break;
        case '\b':
            rep = "\\b";
            break;
        case '\f':
            rep = "\\f";
            break;
        case '\n':
            rep = "\\n";
            break;
        case '\r':
            rep = "\\r";
            break;
        case '\t':
            rep = "\\t";
            break;
        default:
            if ((unsigned char)*p < 0x20) {
                snprintf(tmp, sizeof(tmp), "\\u%04x", (unsigned char)*p);
                rep = tmp;
            }
            break;
        }

        if (rep) {
            int len = strlen(rep);
            if (used + len >= out_size) {
                return -1;
            }
            memcpy(out + used, rep, len);
            used += len;
        } else {
            if (used + 1 >= out_size) {
                return -1;
            }
            out[used++] = *p;
        }
    }
    out[used] = '\0';
    return 0;
}

int snapshot_notify_init(void)
{
    if (g_snapshot_fd >= 0) {
        return 0;
    }

    g_snapshot_fd = socket(AF_INET, SOCK_DGRAM, 0);
    if (g_snapshot_fd < 0) {
        return -1;
    }

    struct timeval tv;
    tv.tv_sec = 0;
    tv.tv_usec = 20000;
    setsockopt(g_snapshot_fd, SOL_SOCKET, SO_RCVTIMEO, &tv, sizeof(tv));

    memset(&g_snapshot_addr, 0, sizeof(g_snapshot_addr));
    g_snapshot_addr.sin_family = AF_INET;
    g_snapshot_addr.sin_port = htons(SNAPSHOT_NOTIFY_DEFAULT_PORT);
    if (inet_pton(AF_INET, SNAPSHOT_NOTIFY_DEFAULT_HOST, &g_snapshot_addr.sin_addr) != 1) {
        close(g_snapshot_fd);
        g_snapshot_fd = -1;
        return -1;
    }

    return 0;
}

void snapshot_notify_close(void)
{
    if (g_snapshot_fd >= 0) {
        close(g_snapshot_fd);
        g_snapshot_fd = -1;
    }
}

int snapshot_notify_send(const snapshot_notify_event_t *event, char *reason, int reason_size)
{
    if (!event) {
        set_reason(reason, reason_size, "invalid_event");
        return -1;
    }
    if (snapshot_notify_init() != 0) {
        set_reason(reason, reason_size, "socket_init_failed");
        return -1;
    }

    char camera_id[256];
    char rtsp[1024];
    char label[256];
    if (json_escape(camera_id, sizeof(camera_id), event->camera_id) != 0 ||
        json_escape(rtsp, sizeof(rtsp), event->rtsp) != 0 ||
        json_escape(label, sizeof(label), event->label) != 0) {
        set_reason(reason, reason_size, "json_escape_failed");
        return -1;
    }

    unsigned long notify_id = ++g_notify_seq;
    char notify_id_text[32];
    snprintf(notify_id_text, sizeof(notify_id_text), "%lu", notify_id);

    char payload[2048];
    int n = snprintf(payload, sizeof(payload),
                     "{\"notify_id\":\"%s\",\"camera_id\":\"%s\",\"rtsp\":\"%s\",\"ts\":%ld,\"frame\":%lld,"
                     "\"ccid\":%d,\"label\":\"%s\",\"confidence\":%.3f,"
                     "\"box\":[%d,%d,%d,%d]}",
                     notify_id_text,
                     camera_id,
                     rtsp,
                     event->ts,
                     event->frame,
                     event->ccid,
                     label,
                     event->confidence,
                     event->box_left,
                     event->box_top,
                     event->box_right,
                     event->box_bottom);
    if (n <= 0 || n >= (int)sizeof(payload)) {
        set_reason(reason, reason_size, "payload_too_large");
        return -1;
    }

    ssize_t sent = sendto(g_snapshot_fd, payload, n, 0,
                          (struct sockaddr *)&g_snapshot_addr,
                          sizeof(g_snapshot_addr));
    if (sent != n) {
        char buf[64];
        snprintf(buf, sizeof(buf), "send_failed_%d", errno);
        set_reason(reason, reason_size, buf);
        return -1;
    }

    char ack[128];
    ssize_t got = recv(g_snapshot_fd, ack, sizeof(ack) - 1, 0);
    if (got <= 0) {
        if (errno == EAGAIN || errno == EWOULDBLOCK) {
            set_reason(reason, reason_size, "ack_timeout");
        } else {
            char buf[64];
            snprintf(buf, sizeof(buf), "ack_failed_%d", errno);
            set_reason(reason, reason_size, buf);
        }
        return -1;
    }

    ack[got] = '\0';
    char expected_ack[64];
    snprintf(expected_ack, sizeof(expected_ack), "OK %s", notify_id_text);
    if (strncmp(ack, expected_ack, strlen(expected_ack)) == 0) {
        set_reason(reason, reason_size, "ok");
        return 0;
    }

    set_reason(reason, reason_size, ack);
    return -1;
}