#include "hygate.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <signal.h>
#include <stdint.h>
#include <errno.h>
#include <pthread.h>
#include <semaphore.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <curl/curl.h>

static config_t g_cfg;
static sem_t g_conn_sem;

static void *worker(void *arg) {
  int fd = (int)(intptr_t)arg;
  handle_connection(fd, &g_cfg);
  close(fd);
  sem_post(&g_conn_sem);
  return NULL;
}

int main(int argc, char **argv) {
  config_t cfg;
  cfg.port = DEFAULT_PORT;
  cfg.endpoint = DEFAULT_ENDPOINT;
  cfg.model = DEFAULT_MODEL;
  cfg.user_agent = "";
  cfg.max_body_bytes = (long)MAX_BODY_BYTES;
  cfg.max_connections = MAX_CONCURRENT_THREADS;

  /* Simple flag parsing: -key value  or  -key=value */
  for (int i = 1; i < argc; i++) {
    char *a = argv[i];
    char *val = NULL;
    if (a[0] == '-') {
      char *eq = strchr(a, '=');
      if (eq) {
        *eq = 0;
        val = eq + 1;
      } else if (i + 1 < argc) {
        val = argv[i + 1];
        i++;
      }
      if (strcmp(a, "-port") == 0) { if (val) cfg.port = val; }
      else if (strcmp(a, "-endpoint") == 0) { if (val) cfg.endpoint = val; }
      else if (strcmp(a, "-model") == 0) { if (val) cfg.model = val; }
      else if (strcmp(a, "-user-agent") == 0 || strcmp(a, "-ua") == 0) {
        if (val) cfg.user_agent = val;
      } else if (strcmp(a, "-max-body") == 0) {
        if (val) {
          long v = (long)strtoul(val, NULL, 10);
          if (v > 0) cfg.max_body_bytes = v;
        }
      } else if (strcmp(a, "-max-conn") == 0) {
        if (val) {
          int v = atoi(val);
          if (v > 0) cfg.max_connections = v;
        }
      } else {
        fprintf(stderr, "unknown flag: %s\n", a);
        return 2;
      }
    }
  }
  g_cfg = cfg;

  if (sem_init(&g_conn_sem, 0, (unsigned int)cfg.max_connections) != 0) {
    perror("sem_init");
    return 1;
  }

  curl_global_init(CURL_GLOBAL_ALL);
  signal(SIGPIPE, SIG_IGN);

  int srv = socket(AF_INET, SOCK_STREAM, 0);
  if (srv < 0) { perror("socket"); return 1; }
  int one = 1;
  setsockopt(srv, SOL_SOCKET, SO_REUSEADDR, &one, sizeof one);
  struct sockaddr_in addr;
  memset(&addr, 0, sizeof addr);
  addr.sin_family = AF_INET;
  addr.sin_port = htons((uint16_t)atoi(cfg.port));
  addr.sin_addr.s_addr = INADDR_ANY;
  if (bind(srv, (struct sockaddr *)&addr, sizeof addr) < 0) { perror("bind"); return 1; }
  if (listen(srv, 128) < 0) { perror("listen"); return 1; }

  printf("hygate starting on port %s...\n", cfg.port);
  printf("Target Endpoint: %s\n", cfg.endpoint);
  printf("Model Name: %s\n", cfg.model);
  printf("User-Agent: %s\n", cfg.user_agent && cfg.user_agent[0] ? cfg.user_agent : DEFAULT_UA);
  printf("Max request body: %ld bytes\n", cfg.max_body_bytes);
  printf("Max concurrent connections: %d\n", cfg.max_connections);
  printf("Endpoints:\n");
  printf("  GET  http://localhost:%s/v1/models\n", cfg.port);
  printf("  POST http://localhost:%s/v1/chat/completions\n", cfg.port);

  for (;;) {
    /* Wait for a free worker slot before accepting, so the number of
       in-flight connections (and thus worker threads) is capped at
       cfg.max_connections. Excess connections queue in the kernel
       listen backlog. */
    while (sem_wait(&g_conn_sem) != 0) {
      if (errno == EINTR) continue;
      perror("sem_wait");
      break;
    }
    int cfd = accept(srv, NULL, NULL);
    if (cfd < 0) {
      if (errno == EINTR) { sem_post(&g_conn_sem); continue; }
      perror("accept");
      sem_post(&g_conn_sem);
      continue;
    }
    pthread_t tid;
    if (pthread_create(&tid, NULL, worker, (void *)(intptr_t)cfd) == 0) {
      pthread_detach(tid);
    } else {
      handle_connection(cfd, &g_cfg);
      close(cfd);
      sem_post(&g_conn_sem);
    }
  }
  return 0;
}