From 90fdc8cf6094a5cfafacca2a160e19233b7d9e77 Mon Sep 17 00:00:00 2001
From: Jan-Piet Mens <jpmens@gmail.com>
Date: Fri, 23 Oct 2015 15:32:52 +0200
Subject: [PATCH] support /last with fields

---
 README.md |  6 +++++-
 http.c    | 24 +++++++++++++++++-------
 ocat.c    |  2 +-
 storage.c | 34 ++++++++++++++++++++++++++++++++--
 storage.h |  2 +-
 5 files changed, 56 insertions(+), 12 deletions(-)

diff --git a/README.md b/README.md
index f27434a..0e8f2ff 100644
--- a/README.md
+++ b/README.md
@@ -398,12 +398,16 @@ curl 'http://127.0.0.1:8083/api/0/monitor'
 
 #### `last`
 
-Returns a list of last users' positions. (Can be limited by _user_ and _device_.)
+Returns a list of last users' positions. (Can be limited by _user_, _device_, and _fields_, a comma-separated list of fields which should be returned instead of the default of all fields.)
 
 ```
 curl http://127.0.0.1:8083/api/0/last [-d user=jjolie [-d device=phone]]
 ```
 
+```
+curl 'http://127.0.0.1:8083/api/0/last?fields=tst,tid,addr,topic,isotst'
+```
+
 #### `list`
 
 List users. If _user_ is specified, lists that user's devices. If both _user_ and _device_ are specified, lists that device's `.rec` files.
diff --git a/http.c b/http.c
index 2970946..e7e0b87 100644
--- a/http.c
+++ b/http.c
@@ -38,6 +38,8 @@
 
 #ifdef WITH_HTTP
 
+#define MAXPARTS 40
+
 /* A transparent 40x40 PNG image with a black border */
 static unsigned char border40x40png[] = {
 	0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A, 0x00, 0x00,
@@ -202,7 +204,7 @@ static void send_last(struct mg_connection *conn)
 	u	  = field(conn, "user");
 	d	  = field(conn, "device");
 
-	if ((user_array = last_users(u, d)) != NULL) {
+	if ((user_array = last_users(u, d, NULL)) != NULL) {
 
 		json_foreach(one, user_array) {
 			JsonNode *f;
@@ -282,7 +284,6 @@ static int xml_response(struct mg_connection *conn, JsonNode *obj)
  * /users/ or /list
  */
 
-#define MAXPARTS 40
 
 #define CLEANUP do {\
 		int k; \
@@ -347,12 +348,21 @@ static int dispatch(struct mg_connection *conn, const char *uri)
 #endif /* WITH_KILL */
 
 	if (nparts == 1 && !strcmp(uparts[0], "last")) {
-                JsonNode *user_array;
+		JsonNode *user_array, *fields = NULL;
+		char *flds = field(conn, "fields");
 
-                if ((user_array = last_users(u, d)) != NULL) {
+		if (flds != NULL) {
+			fields = json_splitter(flds, ",");
+			free(flds);
+		}
+
+		if ((user_array = last_users(u, d, fields)) != NULL) {
 			CLEANUP;
+			json_delete(fields);
+
 			return (json_response(conn, user_array));
-                }
+		}
+		json_delete(fields);
 	}
 
 	if ((ret = mg_get_var(conn, "limit", buf, sizeof(buf))) > 0) {
@@ -396,11 +406,11 @@ static int dispatch(struct mg_connection *conn, const char *uri)
 	/* /locations			[<username>[<device>]] */
 
 	if (nparts == 1 && !strcmp(uparts[0], "locations")) {
-                /*
+		/*
 		 * Obtain a list of .rec files from lister(), possibly limited
 		 * by s_lo/s_hi times, process each and build the JSON `obj'
 		 * with an array of locations.
-                 */
+		 */
 
 		obj = json_mkobject();
 		locs = json_mkarray();
diff --git a/ocat.c b/ocat.c
index cc468ef..9d6250e 100644
--- a/ocat.c
+++ b/ocat.c
@@ -433,7 +433,7 @@ int main(int argc, char **argv)
 	if (last) {
 		JsonNode *user_array;
 
-		if ((user_array = last_users(username, device)) != NULL) {
+		if ((user_array = last_users(username, device, fields)) != NULL) {
 
 			if (otype == JSON) {
 				char *js;
diff --git a/storage.c b/storage.c
index 8ebbefc..08abfd0 100644
--- a/storage.c
+++ b/storage.c
@@ -181,10 +181,11 @@ void append_device_details(JsonNode *userlist, char *user, char *device)
 /*
  * Return an array of users gleaned from LAST with merged details.
  * If user and device are specified, limit to those; either may be
- * NULL.
+ * NULL. If `fields' is not NULL, it's a JSON array of fields to
+ * be returned.
  */
 
-JsonNode *last_users(char *in_user, char *in_device)
+JsonNode *last_users(char *in_user, char *in_device, JsonNode *fields)
 {
 	JsonNode *obj = json_mkobject();
 	JsonNode *un, *dn, *userlist = json_mkarray();
@@ -225,6 +226,35 @@ JsonNode *last_users(char *in_user, char *in_device)
 	}
 	json_delete(obj);
 
+	/*
+	 * userlist now is an array of user objects. If fields were
+	 * specified, re-create that array with object which have
+	 * only the requested fields. It's a shame we have to re-do
+	 * this here, but I can't think of an alternative way at
+	 * the moment.
+	 */
+
+	if (fields) {
+		JsonNode *new_userlist = json_mkarray(), *user;
+
+		json_foreach(user, userlist) {
+			JsonNode *o = json_mkobject(), *f, *j;
+
+			json_foreach(f, fields) {
+				char *field_name = f->string_;
+
+				if ((j = json_find_member(user, field_name)) != NULL) {
+					json_copy_element_to_object(o, field_name, j);
+				}
+			}
+			json_append_element(new_userlist, o);
+		}
+
+
+		json_delete(userlist);
+		return (new_userlist);
+	}
+
 	return (userlist);
 }
 
diff --git a/storage.h b/storage.h
index 7849d93..ab9d532 100644
--- a/storage.h
+++ b/storage.h
@@ -43,7 +43,7 @@ int make_times(char *time_from, time_t *s_lo, char *time_to, time_t *s_to);
 JsonNode *geo_json(JsonNode *json);
 JsonNode *geo_linestring(JsonNode *location_array);
 JsonNode *kill_datastore(char *username, char *device);
-JsonNode *last_users(char *user, char *device);
+JsonNode *last_users(char *user, char *device, JsonNode *fields);
 char *gpx_string(JsonNode *json);
 void storage_init(int revgeo);
 void storage_gcache_dump(char *lmdbname);