#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <time.h>
#include <curl/curl.h>
#include <event2\event.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <errno.h>
#include "http.h"
#include <string>

#define MSG_OUT stdout

/* Global information, common to all connections */
typedef struct _GlobalInfo {
  struct event_base* base;
  struct event* timer_event;
  CURLM *multi;
  int still_running;
  http_handler_fn callback;
} GlobalInfo;

/* Information associated with a specific easy handle */
typedef struct _ConnInfo {
  CURL *easy;
  char *url;
  GlobalInfo *global;
  char error[CURL_ERROR_SIZE];
  char* data;
  int data_size;
  int data_pos;
//  std::string data;
} ConnInfo;


/* Information associated with a specific socket */
typedef struct _SockInfo {
  curl_socket_t sockfd;
  CURL *easy;
  int action;
  long timeout;
  struct event* ev;
  int evset;
  GlobalInfo *global;
} SockInfo;

/* Update the event timer after curl_multi library calls */
static int multi_timer_cb(CURLM *multi, long timeout_ms, GlobalInfo *g)
{
  struct timeval timeout;
  (void)multi; /* unused */

  timeout.tv_sec = timeout_ms/1000;
  timeout.tv_usec = (timeout_ms%1000)*1000;
  fprintf(MSG_OUT, "multi_timer_cb: Setting timeout to %ld ms\n", timeout_ms);
  evtimer_del(g->timer_event);
  if( timeout_ms != -1 ) evtimer_add(g->timer_event, &timeout);
  return 0;
}

/* Die if we get a bad CURLMcode somewhere */
static void mcode_or_die(const char *where, CURLMcode code, GlobalInfo *g)
{
  char error_str[256];
  if ( CURLM_OK != code ) {
    const char *s;
    switch (code) {
      case     CURLM_CALL_MULTI_PERFORM: s="CURLM_CALL_MULTI_PERFORM"; break;
      case     CURLM_BAD_HANDLE:         s="CURLM_BAD_HANDLE";         break;
      case     CURLM_BAD_EASY_HANDLE:    s="CURLM_BAD_EASY_HANDLE";    break;
      case     CURLM_OUT_OF_MEMORY:      s="CURLM_OUT_OF_MEMORY";      break;
      case     CURLM_INTERNAL_ERROR:     s="CURLM_INTERNAL_ERROR";     break;
      case     CURLM_UNKNOWN_OPTION:     s="CURLM_UNKNOWN_OPTION";     break;
      case     CURLM_LAST:               s="CURLM_LAST";               break;
      default: s="CURLM_unknown";
        break;
    case     CURLM_BAD_SOCKET:         s="CURLM_BAD_SOCKET";
      //sprintf(error_str, "ERROR: %s returns %s", where, s);
      /* ignore this error */
      return;
    }
    sprintf(error_str, "ERROR: %s returns %s", where, s);
    g->callback(-1, 0, 0, error_str);
  }
}

/* Check for completed transfers, and remove their easy handles */
static void check_multi_info(GlobalInfo *g)
{
  char *eff_url;
  CURLMsg *msg;
  int msgs_left;
  ConnInfo *conn;
  CURL *easy;
  CURLcode res;
  while ((msg = curl_multi_info_read(g->multi, &msgs_left))) {
    if (msg->msg == CURLMSG_DONE) {
      easy = msg->easy_handle;
      res = msg->data.result;
      curl_easy_getinfo(easy, CURLINFO_PRIVATE, &conn);
      curl_easy_getinfo(easy, CURLINFO_EFFECTIVE_URL, &eff_url);
      // get http response code
      unsigned long rc = 0;
      curl_easy_getinfo(easy, CURLINFO_RESPONSE_CODE, &rc);
      // call callback before we clean up the connection
      g->callback(rc, conn->data, conn->data_pos, conn->error);
      // clean up connection
      curl_multi_remove_handle(g->multi, easy);
      free(conn->url);
      free(conn->data);
      curl_easy_cleanup(easy);
      free(conn);
    }
  }
}

/* Called by libevent when we get action on a multi socket */
static void event_cb(int fd, short kind, void *userp)
{
  GlobalInfo *g = (GlobalInfo*) userp;
  CURLMcode rc;

  int action =
    (kind & EV_READ ? CURL_CSELECT_IN : 0) |
    (kind & EV_WRITE ? CURL_CSELECT_OUT : 0);

  rc = curl_multi_socket_action(g->multi, fd, action, &g->still_running);
  mcode_or_die("event_cb: curl_multi_socket_action", rc, g);

  check_multi_info(g);
  if ( g->still_running <= 0 ) {
    fprintf(MSG_OUT, "last transfer done, kill timeout\n");
    if (evtimer_pending(g->timer_event, NULL)) {
      evtimer_del(g->timer_event);
    }
    curl_multi_cleanup(g->multi);
    free(g);
  }
}



/* Called by libevent when our timeout expires */
static void timer_cb(int fd, short kind, void *userp)
{
  GlobalInfo *g = (GlobalInfo *)userp;
  CURLMcode rc;
  (void)fd;
  (void)kind;

  rc = curl_multi_socket_action(g->multi,
                                  CURL_SOCKET_TIMEOUT, 0, &g->still_running);
  mcode_or_die("timer_cb: curl_multi_socket_action", rc, g);
  check_multi_info(g);
}



/* Clean up the SockInfo structure */
static void remsock(SockInfo *f)
{
  if (f) {
    if (f->evset)
      event_del(f->ev);
    free(f);
  }
}



/* Assign information to a SockInfo structure */
static void setsock(SockInfo*f, curl_socket_t s, CURL*e, int act, GlobalInfo*g)
{
  int kind =
     (act&CURL_POLL_IN?EV_READ:0)|(act&CURL_POLL_OUT?EV_WRITE:0)|EV_PERSIST;

  f->sockfd = s;
  f->action = act;
  f->easy = e;
  if (f->evset) event_del(f->ev);
  f->ev = event_new(g->base, f->sockfd, kind, event_cb, g);
  f->evset=1;
  event_add(f->ev, NULL);
}



/* Initialize a new SockInfo structure */
static void addsock(curl_socket_t s, CURL *easy, int action, GlobalInfo *g) {
  SockInfo *fdp = (SockInfo*)calloc(sizeof(SockInfo), 1);
  fdp->global = g;
  setsock(fdp, s, easy, action, g);
  curl_multi_assign(g->multi, s, fdp);
}

/* CURLMOPT_SOCKETFUNCTION */
static int sock_cb(CURL *e, curl_socket_t s, int what, void *cbp, void *sockp)
{
  GlobalInfo *g = (GlobalInfo*) cbp;
  SockInfo *fdp = (SockInfo*) sockp;
  const char *whatstr[]={ "none", "IN", "OUT", "INOUT", "REMOVE" };

  fprintf(MSG_OUT,
          "socket callback: s=%d e=%p what=%s ", s, e, whatstr[what]);
  if (what == CURL_POLL_REMOVE) {
    fprintf(MSG_OUT, "\n");
    remsock(fdp);
  }
  else {
    if (!fdp) {
      fprintf(MSG_OUT, "Adding data: %s\n", whatstr[what]);
      fprintf(MSG_OUT, "Adding data: %s\n", whatstr[what]);
      addsock(s, e, what, g);
    }
    else {
      fprintf(MSG_OUT,
              "Changing action from %s to %s\n",
              whatstr[fdp->action], whatstr[what]);
      setsock(fdp, s, e, what, g);
    }
  }
  return 0;
}



/* CURLOPT_WRITEFUNCTION */
static size_t write_cb(void *ptr, size_t size, size_t nmemb, void *data)
{
  size_t realsize = size * nmemb;
  ConnInfo *conn = (ConnInfo*) data;
  while( conn->data_size - conn->data_pos < realsize )
  {
    fprintf(MSG_OUT, "!! resize buf size %i data_pos %i realsize %i\n", conn->data_size, conn->data_pos, realsize);
    conn->data = (char*)realloc(conn->data, 2*conn->data_size);
    conn->data_size *=2;
  }
  memcpy(conn->data + conn->data_pos, ptr, realsize);
  conn->data_pos += realsize;
  fprintf(MSG_OUT, "write_cb: %i\n", realsize);
  return realsize;
}


/* CURLOPT_PROGRESSFUNCTION */
static int prog_cb (void *p, double dltotal, double dlnow, double ult,
                    double uln)
{
  ConnInfo *conn = (ConnInfo *)p;
  (void)ult;
  (void)uln;

  fprintf(MSG_OUT, "Progress: %s (%g/%g)\n", conn->url, dlnow, dltotal);
  return 0;
}


/* Create a new easy handle, and add it to the global curl_multi */
static void new_conn(const char *url, GlobalInfo *g )
{
  ConnInfo *conn;
  CURLMcode rc;

  conn = (ConnInfo *)calloc(1, sizeof(ConnInfo));
  memset(conn, 0, sizeof(ConnInfo));
  conn->error[0]='\0';
  conn->data_size = 4096;
  conn->data_pos = 0;
  conn->data = (char*)malloc(4096);
  conn->easy = curl_easy_init();
  if (!conn->easy)
  {
    g->callback(-1, 0, 0, "curl_easy_init() failed" );
    return;
  }
  conn->global = g;
  conn->url = strdup(url);
  curl_easy_setopt(conn->easy, CURLOPT_URL, conn->url);
  curl_easy_setopt(conn->easy, CURLOPT_WRITEFUNCTION, write_cb);
  curl_easy_setopt(conn->easy, CURLOPT_WRITEDATA, conn);
  curl_easy_setopt(conn->easy, CURLOPT_VERBOSE, 1L);
  curl_easy_setopt(conn->easy, CURLOPT_ERRORBUFFER, conn->error);
  curl_easy_setopt(conn->easy, CURLOPT_PRIVATE, conn);
  curl_easy_setopt(conn->easy, CURLOPT_NOPROGRESS, 0L);
  curl_easy_setopt(conn->easy, CURLOPT_PROGRESSFUNCTION, prog_cb);
  curl_easy_setopt(conn->easy, CURLOPT_PROGRESSDATA, conn);
  fprintf(MSG_OUT, "Adding easy %p to multi %p (%s)\n", conn->easy, g->multi, url);
  rc = curl_multi_add_handle(g->multi, conn->easy);
  mcode_or_die("new_conn: curl_multi_add_handle", rc, g);
  /* note that the add_handle() will set a time-out to trigger very soon so
     that the necessary socket_action() call will be called by this app */
}

typedef void (*http_handler_fn)(int response_code, const char* data, size_t len, const char* error);

void add_http(const char* url, struct event_base* base, http_handler_fn callback)
{
  GlobalInfo* g = (GlobalInfo *)calloc(1, sizeof(GlobalInfo));
  memset(g, 0, sizeof(GlobalInfo));
  g->base = base;
  g->multi = curl_multi_init();
  g->callback = callback;
  g->timer_event = event_new(base, -1, EV_PERSIST, timer_cb, g);
  curl_multi_setopt(g->multi, CURLMOPT_SOCKETFUNCTION, sock_cb);
  curl_multi_setopt(g->multi, CURLMOPT_SOCKETDATA, g);
  curl_multi_setopt(g->multi, CURLMOPT_TIMERFUNCTION, multi_timer_cb);
  curl_multi_setopt(g->multi, CURLMOPT_TIMERDATA, g);
  new_conn(url, g);
}