input_gadgets.c: api.met.no: von Version 1.9 zu 2.0 aktualisiert - jetzt als json statt xml

2 files changed, 170 insertions, 85 deletions

diff --git a/Makefile b/Makefile
index 8a71475..3b97623 100644
--- a/Makefile
+++ b/Makefile
@@ -1,7 +1,7 @@
 CFLAGS=-Werror -O3 -pedantic -g
 
 anzeige: anzeige.c fonts.o humidity.o input_gadgets.o multiplexer.o
-	gcc -o "$@" $(CFLAGS) -lpthread -lzip -lxml2 -lcurl $^
+	gcc -o "$@" $(CFLAGS) -lpthread -lzip -lxml2 -ljson-c -lcurl $^
 
 fonts.o: fonts.c fonts.h
 	gcc -o "$@" $(CFLAGS) -c "$<"
@@ -10,7 +10,7 @@ humidity.o: humidity.c humidity.h
 	gcc -o "$@" $(CFLAGS) -c "$<"
 
 input_gadgets.o: input_gadgets.c input_gadgets.h
-	gcc -o "$@" $(CFLAGS) -c -I/usr/include/libxml2 -lzip -lxml2 -lcurl "$<"
+	gcc -o "$@" $(CFLAGS) -c -I/usr/include/libxml2 -I/usr/include/json-c -lzip -lxml2 -ljson-c -lcurl "$<"
 
 multiplexer.o: multiplexer.c multiplexer.h
 	gcc -o "$@" $(CFLAGS) -c -lpthread "$<"
diff --git a/input_gadgets.c b/input_gadgets.c
index 6c3544d..ccfcc87 100644
--- a/input_gadgets.c
+++ b/input_gadgets.c
@@ -1,8 +1,11 @@
 #define _GNU_SOURCE
 
 #include <curl/curl.h>
+#include <errno.h>
+#include <json-c/json.h>
 #include <libxml/parser.h>
 #include <libxml/tree.h>
+#include <locale.h>
 #include <math.h>
 #include <netdb.h>
 #include <regex.h>
@@ -314,118 +317,193 @@ double xml_extract_float(xmlNode *node, char *key)
   return res;
 }
 
-char *gadgets_retrieve_weather_forecast(char *output, int max_len)
+size_t lookForExpirationHeader(char *buffer, size_t size, size_t nitems, time_t *userdata) {
+  if (nitems * size <= 9)
+    return nitems * size;
+  if (memcmp(buffer, "Expires: ", 9) != 0)
+    return nitems * size;
+  buffer += 9;
+  struct tm temp_data;
+  memset(&temp_data, 0, sizeof(temp_data));
+  temp_data.tm_isdst = -1;
+  strptime(buffer, "%a, %d %b %Y %H:%M:%S %Z", &temp_data);
+  *userdata = mktime(&temp_data);
+
+  memset(&temp_data, 0, sizeof(temp_data));
+  temp_data.tm_year = 70;
+  temp_data.tm_mday = 1;
+  temp_data.tm_isdst = -1;
+  *userdata -= mktime(&temp_data);
+
+  return nitems * size;
+}
+
+char *gadgets_retrieve_weather_forecast(MemoryStruct *chunk, time_t *expiration, char *output, int max_len)
 {
-  CURL *curl_handle;
-  CURLcode res;
-  MemoryStruct chunk;
-  int ret_val;
+  if (*expiration < time(NULL)) {
+    // cached version expired, we get a new one
+    chunk->size = 0;
 
-  chunk.memory = malloc(1);
-  chunk.size = 0;
+    CURL *curl_handle;
+    CURLcode res;
+    int ret_val;
 
-  curl_global_init(CURL_GLOBAL_ALL);
+    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=50.9336&lon=11.5621&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=50.9336&lon=11.5621&msl=170",
-      curl_easy_strerror(res)
-    );
-    free(chunk.memory);
-    if (res != CURLE_COULDNT_RESOLVE_HOST && res != CURLE_COULDNT_CONNECT && res != CURLE_PEER_FAILED_VERIFICATION)
+    curl_handle = curl_easy_init();
+    if (!curl_handle) {
+      perror("Failed to init curl");
       return NULL;
-    char *ende = output;
-    if (max_len > 0)
-      ende += snprintf(ende, max_len, "%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c", 0xEE, 0x01, 0xEE, 0x02, 0xEE, 0x01, 0xEE, 0x02, 0xEE, 0x05, 0xEE, 0x06, 0xEE, 0x05, 0xEE, 0x06);
-    return ende;
+    }
+    curl_easy_setopt(curl_handle, CURLOPT_URL, "https://api.met.no/weatherapi/locationforecast/2.0/?lat=50.9336&lon=11.5621");
+    curl_easy_setopt(curl_handle, CURLOPT_FOLLOWLOCATION, 1L);
+    curl_easy_setopt(curl_handle, CURLOPT_WRITEFUNCTION, WriteMemoryCallback);
+    curl_easy_setopt(curl_handle, CURLOPT_WRITEDATA, chunk);
+    curl_easy_setopt(curl_handle, CURLOPT_HEADERFUNCTION, lookForExpirationHeader);
+    curl_easy_setopt(curl_handle, CURLOPT_HEADERDATA, expiration);
+    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=50.9336&lon=11.5621&msl=170",
+        curl_easy_strerror(res)
+      );
+      if (res != CURLE_COULDNT_RESOLVE_HOST && res != CURLE_COULDNT_CONNECT && res != CURLE_PEER_FAILED_VERIFICATION)
+        return NULL;
+      char *ende = output;
+      if (max_len > 0)
+        ende += snprintf(ende, max_len, "%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c", 0xEE, 0x01, 0xEE, 0x02, 0xEE, 0x01, 0xEE, 0x02, 0xEE, 0x05, 0xEE, 0x06, 0xEE, 0x05, 0xEE, 0x06);
+      return ende;
+    }
   }
 
-  LIBXML_TEST_VERSION
+  struct json_object *doc;
 
-  xmlDocPtr doc;
-  doc = xmlReadMemory(chunk.memory, chunk.size, "noname.xml", NULL, 0);
-  free(chunk.memory);
+  doc = json_tokener_parse(chunk->memory);
   if (doc == NULL) {
-    fprintf(stderr, "Failed to parse document\n");
+    fprintf(stderr, "Failed to parse json\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);
+  struct json_object *props;
+
+  if (!json_object_object_get_ex(doc, "properties", &props)) {
+    fprintf(stderr, "No 'properties:' at the root.\n");
+    json_object_put(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);
+
+  if (!json_object_object_get_ex(props, "timeseries", &props)) {
+    fprintf(stderr, "'properties:' has no 'timeseries:'\n");
+    json_object_put(doc);
     return NULL;
   }
 
   float rain_total = 0, temp_min = NAN, temp_max = NAN, wind_max = NAN, cur_val;
 
-  char time_str[2][21];
+  char time_str[21];
   time_t now;
   time(&now);
   now = ((int)(now/60/60))*60*60;
+  strftime(time_str,21,"%Y-%m-%dT%H:%M:%SZ",gmtime(&now));
+
+  struct json_object *data_point;
+  struct json_object *datum;
+  struct json_object *details;
+
+  for (int i=0; i<json_object_array_length(props); i++) {
+    data_point = json_object_array_get_idx(props, i);
+    if (!data_point) {
+      fprintf(stderr, "Failed to retrieve index %d from 'timeseries:'\n", i);
+      json_object_put(doc);
+      return NULL;
+    }
+    if (!json_object_object_get_ex(data_point, "time", &datum)) {
+      fprintf(stderr, "'timeseries:[%d]' has no 'time:'\n", i);
+      json_object_put(doc);
+      return NULL;
+    }
+    if (strcmp(time_str,json_object_get_string(datum)) == 0) {
+      for (int j=0; (j<15) && (i+j<json_object_array_length(props)); j++) {
+        data_point = json_object_array_get_idx(props, i+j);
+        if (!data_point) {
+          fprintf(stderr, "Failed to retrieve index %d from 'timeseries:'\n", i);
+          json_object_put(doc);
+          return NULL;
+        }
+        if (!json_object_object_get_ex(data_point, "data", &data_point)) {
+          fprintf(stderr, "'timeseries:[%d]' has no 'data:'\n", i);
+          json_object_put(doc);
+          return NULL;
+        }
+        if (!json_object_object_get_ex(data_point, "instant", &datum)) {
+          fprintf(stderr, "'timeseries:[%d] data:' has no 'instant:'\n", i);
+          json_object_put(doc);
+          return NULL;
+        }
+        if (!json_object_object_get_ex(datum, "details", &datum)) {
+          fprintf(stderr, "'timeseries:[%d] data: instant:' has no 'details:'\n", i);
+          json_object_put(doc);
+          return NULL;
+        }
+        if (!json_object_object_get_ex(datum, "air_temperature", &details)) {
+          fprintf(stderr, "'timeseries:[%d] data: instant: details:' has no 'air_temperature:'\n", i);
+          json_object_put(doc);
+          return NULL;
+        }
+        cur_val = json_object_get_double(details);
+        if (errno) {
+          fprintf(stderr, "'timeseries:[%d] data: instant: details: air_temperature:' is no double\n", i);
+          json_object_put(doc);
+          return NULL;
+        }
+        if (isnan(temp_max) || (cur_val > temp_max))
+          temp_max = cur_val;
+        if (isnan(temp_min) || (cur_val < temp_min))
+          temp_min = cur_val;
+        if (!json_object_object_get_ex(datum, "wind_speed", &details)) {
+          fprintf(stderr, "'timeseries:[%d] data: instant: details:' has no 'wind_speed:'\n", i);
+          json_object_put(doc);
+          return NULL;
+        }
+        cur_val = json_object_get_double(details);
+        if (errno) {
+          fprintf(stderr, "'timeseries:[%d] data: instant: details: wind_speed:' is no double\n", i);
+          json_object_put(doc);
+          return NULL;
+        }
+        if (isnan(wind_max) || (cur_val > wind_max))
+          wind_max = cur_val;
 
-  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 (!json_object_object_get_ex(data_point, "next_1_hours", &datum)) {
+          fprintf(stderr, "'timeseries:[%d] data:' has no 'next_1_hours:'\n", i);
+          json_object_put(doc);
+          return NULL;
         }
-        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");
+        if (!json_object_object_get_ex(datum, "details", &datum)) {
+          fprintf(stderr, "'timeseries:[%d] data: next_1_hours:' has no 'details:'\n", i);
+          json_object_put(doc);
+          return NULL;
+        }
+        if (!json_object_object_get_ex(datum, "precipitation_amount", &datum)) {
+          fprintf(stderr, "'timeseries:[%d] data: next_1_hours: details:' has no 'precipitation_amount:'\n", i);
+          json_object_put(doc);
+          return NULL;
+        }
+        rain_total += json_object_get_double(datum);
+        if (errno) {
+          fprintf(stderr, "'timeseries:[%d] data: next_1_hours: details: precipitation_amount:' is no double\n", i);
+          json_object_put(doc);
+          return NULL;
         }
       }
     }
   }
 
-  xmlFreeDoc(doc);
+  json_object_put(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);
@@ -447,6 +525,10 @@ void *gadgets_watch_weather_forecast(void *param)
   t_input_thread *p = param;
   time_t next_update = 0;
   time_t next_dns_query = 0;
+  MemoryStruct chunk;
+  chunk.memory = malloc(1);
+  chunk.size = 0;
+  time_t expiration = 0;
   p->text_output = malloc(MAX_TEXT_OUTPUT_LEN);
   if (p->text_output == NULL) {
     fprintf(stderr, "malloc failed\n");
@@ -459,6 +541,8 @@ void *gadgets_watch_weather_forecast(void *param)
       next_dns_query = time(NULL) + 30; // 1/2 minute ahead
       memset(p->text_output, 0, MAX_TEXT_OUTPUT_LEN);
       if (gadgets_retrieve_weather_forecast(
+        &chunk,
+        &expiration,
         p->text_output,
         MAX_TEXT_OUTPUT_LEN-1
       )) {
@@ -477,6 +561,7 @@ void *gadgets_watch_weather_forecast(void *param)
     usleep(100000);
   }
   free(p->text_output);
+  free(chunk.memory);
   return NULL;
 }