#define _XOPEN_SOURCE
#include <string.h>
#include <stdlib.h>
#include <curl/curl.h>
#include <regex.h>
#include <stdio.h>
#include <libxml/parser.h>
#include <libxml/tree.h>
#include <time.h>
#include <math.h>
#include <zip.h>

#include "input_gadgets.h"

#define fh_temperature_regex   "<strong>\\s*\n\\s*Wetterdaten vom ([0-9]{2}\\.[0-9]{2}\\.[0-9]{4} um [0-9]{2}:[0-9]{2} MEZ)</strong>(.|\n)*>Temperatur</td>\\s*\n\\s*<td [^>]*><strong>([^<]*)</strong>"
#define wetter_warnung_filename_regex "^2\\.49\\.0\\.1\\.276\\.0\\.DWD\\.PVW\\.([0-9]+)\\."
#define warnings_future_timespan  (60*60*10)

static size_t
WriteMemoryCallback(void *contents, size_t size, size_t nmemb, void *userp)
{
  size_t realsize = size * nmemb;
  MemoryStruct *mem = (MemoryStruct *)userp;
 
  char *ptr = realloc(mem->memory, mem->size + realsize + 1);
  if(ptr == NULL) {
    /* out of memory! */ 
    printf("not enough memory (realloc returned NULL)\n");
    return 0;
  }
 
  mem->memory = ptr;
  memcpy(&(mem->memory[mem->size]), contents, realsize);
  mem->size += realsize;
  mem->memory[mem->size] = 0;
 
  return realsize;
}

int point_is_inside_polygon(double lat, double lon, char *text)
{
  char *input = malloc(strlen(text)+1);
  if (input == NULL) {
    fprintf(stderr, "malloc failed to allocate %d bytes\n", strlen(text)+1);
    return -1;
  }
  strcpy(input, text);
  double *lats = malloc(1);
  if (lats == NULL) {
    fprintf(stderr, "malloc failed to allocate 1 byte\n");
    free(input);
    return -1;
  }
  double *lons = malloc(1);
  if (lons == NULL) {
    fprintf(stderr, "malloc failed to allocate 1 byte\n");
    free(lats);
    free(input);
    return -1;
  }
  int len = 0;
  int alloc_len = 0;
  char *q = NULL;
  char *p = strtok_r(input, ",", &q);
  while (p != NULL) {
    if (alloc_len<=len) {
      double *n;
      alloc_len = len + 16;
      n = realloc(lons, alloc_len*sizeof(lons[0]));
      if (n == NULL) {
        fprintf(stderr, "malloc failed to allocate %d byte\n", alloc_len*sizeof(lons[0]));
        free(input);
        free(lats);
        free(lons);
        return -1;
      }
      lons = n;
      n = realloc(lats, alloc_len*sizeof(lats[0]));
      if (n == NULL) {
        fprintf(stderr, "malloc failed to allocate %d byte\n", alloc_len*sizeof(lats[0]));
        free(input);
        free(lats);
        free(lons);
        return -1;
      }
      lats = n;
    }
    lats[len] = atof(p);
    p=strtok_r(NULL, " ", &q);
    if (p == NULL) {
      fprintf(stderr, "point_is_inside_polygon misses a space\n");
      free(input);
      free(lats);
      free(lons);
      return -1;
    }
    lons[len] = atof(p);
    p=strtok_r(NULL, ",", &q);
    len++;
  }
  free(input);
  if ((lons[0] != lons[len-1]) || (lats[0] != lats[len-1])) {
    fprintf(stderr, "point_is_inside_polygon was given a non-closed polygon border\n");
    free(lats);
    free(lons);
    return -1;
  }
  int is_inside = 0;
  for (int i=0; i<len-1; i++) {
    if ((lat < lats[i]) && (lat <= lats[i+1]))
      continue;
    if ((lat > lats[i]) && (lat >= lats[i+1]))
      continue;
    if (lats[i] == lats[i+1])
      continue;
    if ((lat - lats[i]) / (lats[i+1] - lats[i]) * (lons[i+1] - lons[i]) + lons[i] < lon)
      is_inside = 1 - is_inside;
  }
  free(lats);
  free(lons);
  return is_inside;
}

char *gadgets_retrieve_current_temperature(char *output, int max_len)
{
  CURL *curl_handle;
  CURLcode res;
  MemoryStruct chunk;
  int ret_val;

  chunk.memory = malloc(1);
  chunk.size = 0;

  curl_global_init(CURL_GLOBAL_ALL);

  curl_handle = curl_easy_init();
  if (!curl_handle) {
    perror("Failed to init curl");
    free(chunk.memory);
    return NULL;
  }
  curl_easy_setopt(curl_handle, CURLOPT_URL, "https://wetter.mb.fh-jena.de/station/datenbank/php_giese/online.php");
  curl_easy_setopt(curl_handle, CURLOPT_FOLLOWLOCATION, 1L);
  curl_easy_setopt(curl_handle, CURLOPT_WRITEFUNCTION, WriteMemoryCallback);
  curl_easy_setopt(curl_handle, CURLOPT_WRITEDATA, (void *)&chunk);
  curl_easy_setopt(curl_handle, CURLOPT_USERAGENT, "libcurl-agent/1.0");
  res = curl_easy_perform(curl_handle);
  curl_easy_cleanup(curl_handle);
  if (res != CURLE_OK) {
    fprintf(
      stderr,
      "curl_easy_perform(%s) failed: %s\n",
      "https://wetter.mb.fh-jena.de/station/datenbank/php_giese/online.php",
      curl_easy_strerror(res)
    );
    free(chunk.memory);
    return NULL;
  }

  regex_t re;
  regmatch_t rm[4];
  if (regcomp(&re, fh_temperature_regex, REG_EXTENDED|REG_NEWLINE) != 0) {
    fprintf(stderr, "Failed to compile regex '%s'\n", fh_temperature_regex);
    free(chunk.memory);
    return NULL;
  }
  if (ret_val = regexec(&re, chunk.memory, 4, rm, 0)) {
    char *reg_err;
    reg_err = malloc(1024);
    regerror(ret_val, &re, reg_err, 1024);
    fprintf(stderr, "%d %s\n",ret_val,reg_err);
    regfree(&re);
    free(chunk.memory);
    return NULL;
  }
  regfree(&re);
  char* ende = output;
  if (max_len > 0) {
    struct tm time_struct;
    memset(&time_struct, 0, sizeof(time_struct));
    if (strptime((char*)(chunk.memory + rm[1].rm_so),"%d.%m.%Y um %H:%M MEZ",&time_struct) == NULL) {
      fprintf(stderr, "Failed to parse time '%.*s'\n", (int)(rm[1].rm_eo - rm[1].rm_so), (char*)(chunk.memory + rm[1].rm_so));
      free(chunk.memory);
      return NULL;
    }
    time_struct.tm_isdst = 0; // the fh gives CET all the time
    mktime(&time_struct);
    ende += snprintf(output, max_len, "%.*s",
      (int)(rm[3].rm_eo - rm[3].rm_so), (char*)(chunk.memory + rm[3].rm_so) // temperature
    );
    for (char *i = output; i < ende; i++)
      if (*i == '.')
        *i = ',';
    ende += strftime(ende, output + max_len - ende, " (%m-%d %H:%M)", &time_struct);
  }
  free(chunk.memory);
  return ende;
}

xmlNode *xml_find_node_by_name(xmlNode *cur_node, char *name)
{
  while (cur_node) {
    if ((cur_node -> type == XML_ELEMENT_NODE) &&
      (strcmp((char *)cur_node -> name, name) == 0))
      return cur_node;
    cur_node = cur_node -> next;
  }
  return NULL;
}

xmlChar *xml_extract_string(xmlDoc *doc, xmlNode *cur_node, char *name)
{
  xmlNode *sub_node = xml_find_node_by_name(cur_node, name);
  if (! sub_node)
    return NULL;
  else
    return xmlNodeListGetString(doc, sub_node -> xmlChildrenNode, 0);
}

int xml_strcmp_property_value(xmlNode *node, char *key, char *check_value)
{
  xmlChar *is_value = xmlGetProp(node,(xmlChar *)key);
  int res = strcmp((char *)is_value, check_value);
  xmlFree(is_value);
  return res;
}

double xml_extract_float(xmlNode *node, char *key)
{
  xmlChar *value = xmlGetProp(node, (xmlChar *)key);
  double res = atof((char *)value);
  xmlFree(value);
  return res;
}

char *gadgets_retrieve_weather_forecast(char *output, int max_len)
{
  CURL *curl_handle;
  CURLcode res;
  MemoryStruct chunk;
  int ret_val;

  chunk.memory = malloc(1);
  chunk.size = 0;

  curl_global_init(CURL_GLOBAL_ALL);

  curl_handle = curl_easy_init();
  if (!curl_handle) {
    perror("Failed to init curl");
    free(chunk.memory);
    return NULL;
  }
  curl_easy_setopt(curl_handle, CURLOPT_URL, "https://api.met.no/weatherapi/locationforecast/1.9/?lat=50.8830&lon=11.6223&msl=170");
  curl_easy_setopt(curl_handle, CURLOPT_FOLLOWLOCATION, 1L);
  curl_easy_setopt(curl_handle, CURLOPT_WRITEFUNCTION, WriteMemoryCallback);
  curl_easy_setopt(curl_handle, CURLOPT_WRITEDATA, (void *)&chunk);
  curl_easy_setopt(curl_handle, CURLOPT_USERAGENT, "libcurl-agent/1.0");
  res = curl_easy_perform(curl_handle);
  curl_easy_cleanup(curl_handle);
  if (res != CURLE_OK) {
    fprintf(
      stderr,
      "curl_easy_perform(%s) failed: %s\n",
      "https://api.met.no/weatherapi/locationforecast/1.9/?lat=50.8830&lon=11.6223&msl=170",
      curl_easy_strerror(res)
    );
    free(chunk.memory);
    return NULL;
  }

  LIBXML_TEST_VERSION

  xmlDocPtr doc;
  doc = xmlReadMemory(chunk.memory, chunk.size, "noname.xml", NULL, 0);
  free(chunk.memory);
  if (doc == NULL) {
    fprintf(stderr, "Failed to parse document\n");
    return NULL;
  }

  xmlNode *cur_node = NULL;
  xmlNode *sub_node = NULL;
  cur_node = xmlDocGetRootElement(doc);
  if (!cur_node) {
    fprintf(stderr, "Failed to reach root node of xml\n");
    xmlFreeDoc(doc);
    return NULL;
  }
  cur_node = xml_find_node_by_name(cur_node, "weatherdata");
  if (!cur_node) {
    fprintf(stderr, "Failed to enter <weatherdata>\n");
    xmlFreeDoc(doc);
    return NULL;
  }
  cur_node = xml_find_node_by_name(cur_node -> children, "product");
  if (!cur_node) {
    fprintf(stderr, "Failed to enter <product>\n");
    xmlFreeDoc(doc);
    return NULL;
  }

  float rain_total = 0, temp_min = NAN, temp_max = NAN, wind_max = NAN, cur_val;

  char time_str[2][21];
  time_t now;
  time(&now);
  now = ((int)(now/60/60))*60*60;

  for (cur_node = cur_node -> children; cur_node; cur_node = cur_node->next) {
    if ((cur_node->type == XML_ELEMENT_NODE) && (strcmp((char *)cur_node->name,"time")==0) && (xml_strcmp_property_value(cur_node, "datatype", "forecast")==0)) {
      for (int i=0; i<=14; i++) {
        now += i*60*60;
        strftime(time_str[0],21,"%Y-%m-%dT%H:%M:%SZ",gmtime(&now));
        now += 60*60;
        strftime(time_str[1],21,"%Y-%m-%dT%H:%M:%SZ",gmtime(&now));
        now -= (i+1)*60*60;
        if ((xml_strcmp_property_value(cur_node, "from", time_str[1])==0) && (xml_strcmp_property_value(cur_node, "to", time_str[1])==0)) {
          sub_node = xml_find_node_by_name(cur_node -> children,"location");
          cur_val = xml_extract_float(xml_find_node_by_name(sub_node -> children, "temperature"), "value");
          if (isnan(temp_max) || (cur_val > temp_max))
            temp_max = cur_val;
          if (isnan(temp_min) || (cur_val < temp_min))
            temp_min = cur_val;
          cur_val = xml_extract_float(xml_find_node_by_name(sub_node -> children, "windSpeed"), "mps");
          if (isnan(wind_max) || (cur_val > wind_max))
            wind_max = cur_val;
        }
        if ((xml_strcmp_property_value(cur_node, "from", time_str[0])==0) && (xml_strcmp_property_value(cur_node, "to", time_str[1])==0)) {
          sub_node = xml_find_node_by_name(cur_node -> children,"location");
          if (!sub_node)
            continue;
          sub_node = xml_find_node_by_name(sub_node -> children, "precipitation");
          if (!sub_node)
            continue;
          rain_total += xml_extract_float(sub_node, "value");
        }
      }
    }
  }

  xmlFreeDoc(doc);

  if (max_len > 0) {
    int i = snprintf(output, max_len, "%0.1f ,, %0.1f °C; %0.1f mm; %0.1f m/s", temp_min, temp_max, rain_total, wind_max);
    char *ende = output + i;
    for (; i>=0; i--)
      if (output[i] == '.')
        output[i] = ',';
      else if (output[i] == ',')
        output[i] = '.';

    return ende;
  }
  else
    return output;
}

char *gadgets_retrieve_weather_warnings(char *output, int max_len)
{
  CURL *curl_handle;
  CURLcode res;
  MemoryStruct chunk;
  int ret_val;

  chunk.memory = malloc(1);
  chunk.size = 0;

  curl_global_init(CURL_GLOBAL_ALL);

  curl_handle = curl_easy_init();
  if (!curl_handle) {
    perror("Failed to init curl");
    free(chunk.memory);
    return NULL;
  }
  curl_easy_setopt(curl_handle, CURLOPT_URL, "https://opendata.dwd.de/weather/alerts/cap/COMMUNEUNION_DWD_STAT/Z_CAP_C_EDZW_LATEST_PVW_STATUS_PREMIUMDWD_COMMUNEUNION_DE.zip");
  curl_easy_setopt(curl_handle, CURLOPT_FOLLOWLOCATION, 1L);
  curl_easy_setopt(curl_handle, CURLOPT_WRITEFUNCTION, WriteMemoryCallback);
  curl_easy_setopt(curl_handle, CURLOPT_WRITEDATA, (void *)&chunk);
  curl_easy_setopt(curl_handle, CURLOPT_USERAGENT, "libcurl-agent/1.0");
  res = curl_easy_perform(curl_handle);
  curl_easy_cleanup(curl_handle);
  if (res != CURLE_OK) {
    fprintf(
      stderr,
      "curl_easy_perform(%s) failed: %s\n",
      "https://opendata.dwd.de/weather/alerts/cap/COMMUNEUNION_DWD_STAT/Z_CAP_C_EDZW_LATEST_PVW_STATUS_PREMIUMDWD_COMMUNEUNION_DE.zip",
      curl_easy_strerror(res)
    );
    free(chunk.memory);
    return NULL;
  }

/*  FILE *f = fopen("Z_CAP_C_EDZW_LATEST_PVW_STATUS_PREMIUMDWD_COMMUNEUNION_DE.zip","rb");
  if (f == NULL) {
    perror("failed to open file");
    return NULL;
  }
  fseek(f, 0, SEEK_END);
  chunk.size = ftell(f);
  chunk.memory = malloc(chunk.size);
  if (chunk.memory == NULL) {
    fprintf(stderr, "malloc failed to allocate %d bytes", chunk.size);
    fclose(f);
    return NULL;
  }
  fseek(f, 0, SEEK_SET);
  fread(chunk.memory, chunk.size, 1, f);
  fclose(f); */

  zip_error_t error;
  zip_source_t *src;
  zip_t *za;
  zip_file_t *zf;
  zip_stat_t zs;

  zip_error_init(&error);
  if ((src = zip_source_buffer_create(chunk.memory, chunk.size, 0, &error)) == NULL) {
    fprintf(stderr, "can't create zip source: %s\n", zip_error_strerror(&error));
    zip_error_fini(&error);
    free(chunk.memory);
    return NULL;
  }
  if ((za = zip_open_from_source(src, ZIP_RDONLY, &error)) == NULL) {
    fprintf(stderr, "can't open zip from source: %s\n", zip_error_strerror(&error));
    zip_source_free(src);
    zip_error_fini(&error);
    free(chunk.memory);
    return NULL;
  }
  zip_error_fini(&error);

  LIBXML_TEST_VERSION

  int warnings_len = 0;
  warning_t *warnings = malloc(sizeof(warning_t));
  if (warnings == NULL) {
    fprintf(stderr, "malloc failed allocating %d bytes\n", sizeof(warning_t));
    zip_discard(za);
    free(chunk.memory);
    return NULL;
  }

  for (int i=0; i<zip_get_num_entries(za, 0); i++) {
    zip_stat_index(za, i, 0, &zs);
    zf = zip_fopen_index(za, i, 0);

    void *inflated = malloc(zs.size);
    if (inflated == NULL) {
      fprintf(stderr, "malloc failed allocating %d bytes\n", zs.size);
      free(chunk.memory);
      for (int i=0; i<warnings_len; i++) {
        free(warnings[i].headline);
        free(warnings[i].event);
      }
      free(warnings);
      zip_discard(za);
      return NULL;
    }
    int read = zip_fread(zf, inflated, zs.size);
    zip_fclose(zf);
    if (read != zs.size) {
      fprintf(stderr, "failed reading %d bytes from zip - read %d instead\n", zs.size, read);
      free(inflated);
      free(chunk.memory);
      for (int i=0; i<warnings_len; i++) {
        free(warnings[i].headline);
        free(warnings[i].event);
      }
      free(warnings);
      zip_discard(za);
      return NULL;
    }

    xmlDocPtr doc;
    doc = xmlReadMemory(inflated, zs.size, "noname.xml", NULL, 0);
    free(inflated);
    if (doc == NULL) {
      fprintf(stderr, "Failed to parse document\n");
      free(chunk.memory);
      for (int i=0; i<warnings_len; i++) {
        free(warnings[i].headline);
        free(warnings[i].event);
      }
      free(warnings);
      zip_discard(za);
      return NULL;
    }

    xmlNode *cur_node = NULL;
    xmlNode *sub_node = NULL;
    xmlChar *text = NULL;

    cur_node = xmlDocGetRootElement(doc);
    if (cur_node == NULL) {
      fprintf(stderr, "Failed to reach root node of xml\n");
      free(chunk.memory);
      for (int i=0; i<warnings_len; i++) {
        free(warnings[i].headline);
        free(warnings[i].event);
      }
      free(warnings);
      xmlFreeDoc(doc);
      zip_discard(za);
      return NULL;
    }
    cur_node = xml_find_node_by_name(cur_node, "alert");
    if (cur_node == NULL) {
      fprintf(stderr, "Failed to enter <alert>\n");
      free(chunk.memory);
      for (int i=0; i<warnings_len; i++) {
        free(warnings[i].headline);
        free(warnings[i].event);
      }
      free(warnings);
      xmlFreeDoc(doc);
      zip_discard(za);
      return NULL;
    }

    cur_node = cur_node -> children;
    text = xml_extract_string(doc, cur_node, "status");
    if (text == NULL) {
      fprintf(stderr, "Failed to enter <status>\n");
      free(chunk.memory);
      for (int i=0; i<warnings_len; i++) {
        free(warnings[i].headline);
        free(warnings[i].event);
      }
      free(warnings);
      xmlFreeDoc(doc);
      zip_discard(za);
      return NULL;
    }
    if (strcmp((char *)text, "Actual") != 0) { // Warning is not an Actual warning
      printf("no warning, but '%s'\n",text);
      xmlFree(text);
      xmlFreeDoc(doc);
      zip_discard(za);
      continue;
    }
    xmlFree(text);
    text = xml_extract_string(doc, cur_node, "msgType");
    if (text == NULL) {
      fprintf(stderr, "Failed to enter <msgType>\n");
      free(chunk.memory);
      for (int i=0; i<warnings_len; i++) {
        free(warnings[i].headline);
        free(warnings[i].event);
      }
      free(warnings);
      xmlFreeDoc(doc);
      zip_discard(za);
      return NULL;
    }
    if (strcmp((char *)text, "Update") == 0)
      warnings[warnings_len].is_update=1;
    else if (strcmp((char *)text, "Alert") == 0)
      warnings[warnings_len].is_update=0;
    else if (strcmp((char *)text, "Cancel") == 0)
      warnings[warnings_len].is_update=-1;
    else
      warnings[warnings_len].is_update=-2;
    xmlFree(text);
    if (warnings[warnings_len].is_update < 0) {
      if (warnings[warnings_len].is_update == -1) // "Cancel"
        continue;
      fprintf(stderr, "<msgType> is neither 'Alert' nor 'Cancel' nor 'Update'\n");
      free(chunk.memory);
      for (int i=0; i<warnings_len; i++) {
        free(warnings[i].headline);
        free(warnings[i].event);
      }
      free(warnings);
      xmlFreeDoc(doc);
      zip_discard(za);
      return NULL;
    }
    cur_node = xml_find_node_by_name(cur_node, "info");
    if (cur_node == NULL) {
      fprintf(stderr, "Failed to enter <info>\n");
      free(chunk.memory);
      for (int i=0; i<warnings_len; i++) {
        free(warnings[i].headline);
        free(warnings[i].event);
      }
      free(warnings);
      xmlFreeDoc(doc);
      zip_discard(za);
      return NULL;
    }
    cur_node = cur_node -> children;
    text = xml_extract_string(doc, cur_node, "category");
    if (text == NULL) {
      fprintf(stderr, "Failed to enter <category> %s\n",zs.name);
      free(chunk.memory);
      for (int i=0; i<warnings_len; i++) {
        free(warnings[i].headline);
        free(warnings[i].event);
      }
      free(warnings);
      xmlFreeDoc(doc);
      zip_discard(za);
      return NULL;
    }
    if (strcmp((char *)text,"Met") == 0)
      warnings[warnings_len].category = 0;
    else if (strcmp((char *)text,"Health") == 0)
      warnings[warnings_len].category = 1;
    else
      warnings[warnings_len].category = -1;
    xmlFree(text);
    if (warnings[warnings_len].category == -1) {
      fprintf(stderr, "<category> is neither 'Met' nor 'Health'\n");
      free(chunk.memory);
      for (int i=0; i<warnings_len; i++) {
        free(warnings[i].headline);
        free(warnings[i].event);
      }
      free(warnings);
      xmlFreeDoc(doc);
      zip_discard(za);
      return NULL;
    }
    text = xml_extract_string(doc, cur_node, "responseType");
    if (text == NULL) {
      fprintf(stderr, "Failed to enter <responseType> %s\n",zs.name);
      free(chunk.memory);
      for (int i=0; i<warnings_len; i++) {
        free(warnings[i].headline);
        free(warnings[i].event);
      }
      free(warnings);
      xmlFreeDoc(doc);
      zip_discard(za);
      return NULL;
    }
    if ((strcmp((char *)text,"Prepare") != 0) && (strcmp((char *)text,"None")!=0)) {
      fprintf(stderr, "responseType is '%s', not Prepare nor None\n", text);
      xmlFree(text);
      xmlFreeDoc(doc);
      continue;
    }
    xmlFree(text);
    if (warnings[warnings_len].category == -1) {
      fprintf(stderr, "<category> is neither 'Met' nor 'Health'\n");
      free(chunk.memory);
      for (int i=0; i<warnings_len; i++) {
        free(warnings[i].headline);
        free(warnings[i].event);
      }
      free(warnings);
      xmlFreeDoc(doc);
      zip_discard(za);
      return NULL;
    }
    text = xml_extract_string(doc, cur_node, "severity");
    if (text == NULL) {
      fprintf(stderr, "Failed to enter <severity> %s\n",zs.name);
      free(chunk.memory);
      for (int i=0; i<warnings_len; i++) {
        free(warnings[i].headline);
        free(warnings[i].event);
      }
      free(warnings);
      xmlFreeDoc(doc);
      zip_discard(za);
      return NULL;
    }
    if (strcmp((char *)text,"Minor") == 0)
      warnings[warnings_len].severity = 0;
    else if (strcmp((char *)text,"Moderate") == 0)
      warnings[warnings_len].severity = 1;
    else if (strcmp((char *)text,"Severe") == 0)
      warnings[warnings_len].severity = 2;
    else if (strcmp((char *)text,"Extreme") == 0)
      warnings[warnings_len].severity = 3;
    else {
      fprintf(stderr, "Unknown severity '%s'\n",text);
      xmlFree(text);
      free(chunk.memory);
      for (int i=0; i<warnings_len; i++) {
        free(warnings[i].headline);
        free(warnings[i].event);
      }
      free(warnings);
      xmlFreeDoc(doc);
      zip_discard(za);
      return NULL;
    }
    xmlFree(text);
    struct tm time_struct;
    memset(&time_struct, 0, sizeof(time_struct));
    text = xml_extract_string(doc, cur_node, "onset");
    if (text == NULL) {
      fprintf(stderr, "Failed to enter <onset> %s\n",zs.name);
      free(chunk.memory);
      for (int i=0; i<warnings_len; i++) {
        free(warnings[i].headline);
        free(warnings[i].event);
      }
      free(warnings);
      xmlFreeDoc(doc);
      zip_discard(za);
      return NULL;
    }
    if (strptime((char *)text,"%FT%T+",&time_struct) == NULL) {
      fprintf(stderr, "Failed to parse time '%s'\n",text);
      xmlFree(text);
      free(chunk.memory);
      for (int i=0; i<warnings_len; i++) {
        free(warnings[i].headline);
        free(warnings[i].event);
      }
      free(warnings);
      xmlFreeDoc(doc);
      zip_discard(za);
      return NULL;
    }
    xmlFree(text);
    warnings[warnings_len].onset = mktime(&time_struct);
    text = xml_extract_string(doc, cur_node, "expires");
    if (text != NULL) {
      if (strptime((char *)text,"%FT%T+",&time_struct) == NULL) {
        fprintf(stderr, "Failed to parse time '%s'\n",text);
        xmlFree(text);
        free(chunk.memory);
        for (int i=0; i<warnings_len; i++) {
          free(warnings[i].headline);
          free(warnings[i].event);
        }
        free(warnings);
        xmlFreeDoc(doc);
        zip_discard(za);
        return NULL;
      }
      xmlFree(text);
      warnings[warnings_len].expires = mktime(&time_struct);
    } else
      warnings[warnings_len].expires = LONG_MAX;

    int is_relevant = 0;
    for (sub_node = cur_node; sub_node = xml_find_node_by_name(sub_node, "area"); sub_node = sub_node -> next) {
      xmlNode *sub_sub_node;
      for (sub_sub_node = sub_node -> children; sub_sub_node = xml_find_node_by_name(sub_sub_node, "geocode"); sub_sub_node = sub_sub_node -> next) {
        text = xml_extract_string(doc, sub_sub_node -> children, "valueName");
        if (text == NULL) {
          fprintf(stderr, "Failed to enter <valueName>\n");
          free(chunk.memory);
          for (int i=0; i<warnings_len; i++) {
            free(warnings[i].headline);
            free(warnings[i].event);
          }
          free(warnings);
          xmlFreeDoc(doc);
          zip_discard(za);
          return NULL;
        }
        if (strcmp((char *)text,"WARNCELLID")!=0) {
          xmlFree(text);
          continue;
        }
        xmlFree(text);
        text = xml_extract_string(doc, sub_sub_node -> children, "value");
        if (text == NULL) {
          fprintf(stderr, "Failed to enter <value>\n");
          free(chunk.memory);
          for (int i=0; i<warnings_len; i++) {
            free(warnings[i].headline);
            free(warnings[i].event);
          }
          free(warnings);
          xmlFreeDoc(doc);
          zip_discard(za);
          return NULL;
        }
        if (strcmp((char *)text,"816053000")==0) // Stadt Jena
          is_relevant = 1;
        xmlFree(text);
      }
      for (sub_sub_node = sub_node -> children; sub_sub_node = xml_find_node_by_name(sub_sub_node, "polygon"); sub_sub_node = sub_sub_node -> next) {
        text = xmlNodeListGetString(doc, sub_sub_node -> children, 0);
        if (text == NULL) {
          fprintf(stderr, "Failed to read text of <polygon>\n");
          free(chunk.memory);
          for (int i=0; i<warnings_len; i++) {
            free(warnings[i].headline);
            free(warnings[i].event);
          }
          free(warnings);
          xmlFreeDoc(doc);
          zip_discard(za);
          return NULL;
        }
        int ret = point_is_inside_polygon(50.8830, 11.6223, (char *)text);
        if (ret == 1)
          is_relevant = 1;
        else if (ret != 0) {
          fprintf(stderr, "point_is_inside_polygon failed to parse '%s'\n", (char *)text);
          xmlFree(text);
          free(chunk.memory);
          for (int i=0; i<warnings_len; i++) {
            free(warnings[i].headline);
            free(warnings[i].event);
          }
          free(warnings);
          xmlFreeDoc(doc);
          zip_discard(za);
          return NULL;
        }
        xmlFree(text);
      }
    }
    if (warnings[warnings_len].onset >= time(NULL) + warnings_future_timespan)
      is_relevant = 0; // start is too far ahead
    if (warnings[warnings_len].expires < time(NULL))
      is_relevant = 0; // warning has expired
    if (!is_relevant) {
      xmlFreeDoc(doc);
      continue;
    }

    text = xml_extract_string(doc, cur_node, "headline");
    if (text == NULL) {
      fprintf(stderr, "Failed to enter <headline>\n");
      free(chunk.memory);
      for (int i=0; i<warnings_len; i++) {
        free(warnings[i].headline);
        free(warnings[i].event);
      }
      free(warnings);
      xmlFreeDoc(doc);
      zip_discard(za);
      return NULL;
    }
    warnings[warnings_len].headline = malloc(strlen((char *)text)+1);
    if (warnings[warnings_len].headline == NULL) {
      fprintf(stderr, "malloc failed allocating %d bytes\n", strlen((char *)text)+1);
      for (int i=0; i<warnings_len; i++) {
        free(warnings[i].headline);
        free(warnings[i].event);
      }
      free(warnings);
      free(chunk.memory);
      xmlFreeDoc(doc);
      zip_discard(za);
      return NULL;
    }
    strcpy(warnings[warnings_len].headline, (char *)text);
    xmlFree(text);

    text = xml_extract_string(doc, cur_node, "event");
    if (text == NULL) {
      fprintf(stderr, "Failed to enter <event>\n");
      free(chunk.memory);
      for (int i=0; i<warnings_len; i++) {
        free(warnings[i].headline);
        free(warnings[i].event);
      }
      free(warnings[warnings_len].headline);
      free(warnings);
      xmlFreeDoc(doc);
      zip_discard(za);
      return NULL;
    }
    warnings[warnings_len].event = malloc(strlen((char *)text)+1);
    if (warnings[warnings_len].event == NULL) {
      fprintf(stderr, "malloc failed allocating %d bytes\n", strlen((char *)text)+1);
      for (int i=0; i<warnings_len; i++) {
        free(warnings[i].headline);
        free(warnings[i].event);
      }
      free(warnings[warnings_len].headline);
      free(warnings);
      free(chunk.memory);
      xmlFreeDoc(doc);
      zip_discard(za);
      return NULL;
    }
    strcpy(warnings[warnings_len].event, (char *)text);
    xmlFree(text);

    warnings = (warning_t *)realloc(warnings, (++warnings_len + 1) * sizeof(warning_t));
    if (warnings == NULL) {
      fprintf(stderr, "realloc failed allocating %d bytes\n", (warnings_len + 1) * sizeof(warning_t));
      for (int i=0; i<warnings_len; i++) {
        free(warnings[i].headline);
        free(warnings[i].event);
      }
      free(warnings);
      free(chunk.memory);
      xmlFreeDoc(doc);
      zip_discard(za);
      return NULL;
    }
    xmlFreeDoc(doc);
  }
  zip_discard(za);
  free(chunk.memory);

  char *ende = output;
  if ((!warnings_len) && (max_len > 0))
    ende += snprintf(ende, max_len, "%s", "keine Warnungen");
  for (int i=0; i<warnings_len; i++) {
    if (output + max_len - ende > 0) {
      ende += snprintf(ende, output + max_len - ende, "%s", warnings[i].event);
      if (output + max_len - ende > 0) {
        if (warnings[i].onset > time(NULL))
          ende += strftime(ende, output + max_len - ende, " ab %m-%d %H:%M", localtime(&warnings[i].onset));
        if (warnings[i].expires < time(NULL) + warnings_future_timespan)
          ende += strftime(ende, output + max_len - ende, " bis %m-%d %H:%M", localtime(&warnings[i].expires));
        if ((i+1<warnings_len) && (output + max_len - ende > 0))
          ende += snprintf(ende, output + max_len - ende, "; ", warnings[i].event);
      }
    }

    free(warnings[i].headline);
    free(warnings[i].event);
  }
  free(warnings);

  return ende;
}