Added HASS specific modules

src/httpserver/hass.c

@@ -2,4 +2,153 @@
 #include "../new_common.h"
 #include "../new_cfg.h"
 
-//This will get populated in a later merge
+/* Sample Hass Discovery JSON
+{
+    "dev":{
+        "ids":["espurna_9de8f9"],
+        "name":"ESPURNA_9DE8F9",
+        "sw":"1.15.0-dev.git0e55397a",
+        "mf":"NODEMCU",
+        "mdl":"LOLIN"
+    },
+    "avty_t":"ESPURNA-9DE8F9/status",
+    "pl_avail":"1",
+    "pl_not_avail":"0",
+    "pl_on":"1",
+    "pl_off":"0",
+    "uniq_id":"espurna_9de8f9_relay_0",
+    "name":"ESPURNA_9DE8F9 0",
+    "stat_t":"ESPURNA-9DE8F9/relay/0",
+    "cmd_t":"ESPURNA-9DE8F9/relay/0/set"
+}
+*/
+
+/// @brief Returns HomeAssistant unique id for the entity. The caller needs to free the returned pointer.
+/// @param type Entity type
+/// @param index Entity index
+/// @return 
+char *hass_build_unique_id(ENTITY_TYPE type, int index){
+    //https://developers.home-assistant.io/docs/entity_registry_index/#unique-id-requirements mentions that mac can be used for
+    //unique_id and I think that longDeviceName should contain that e.g. longDeviceName_relay_1
+
+    const char *longDeviceName = CFG_GetDeviceName();
+
+    //Entity type is `relay` or `light` - 5 char
+    char *uniq_id = (char *)os_malloc(strlen(longDeviceName) + 1 + 5 + 1 + 4);    //4 for index and nul char
+    if (type == ENTITY_LIGHT){
+        sprintf(uniq_id,"%s_%s_%d", longDeviceName, "light", index);
+    }
+    else{
+        sprintf(uniq_id,"%s_%s_%d", longDeviceName, "relay", index);
+    }
+
+    return uniq_id;
+}
+
+/// @brief Returns HomeAssistant device configuration MQTT channel e.g. switch/enbrighten_9de8f9_relay_0/config. The caller needs to free the returned pointer.
+/// @param type Entity type
+/// @param uniq_id Entity unique id
+/// @return 
+char *hass_get_device_config_channel(ENTITY_TYPE type, char *uniq_id){
+    //device_type is `switch` or `light` - 6 char
+    char *channel = (char *)os_malloc(6 + 1 + strlen(uniq_id) + 7 + 1);
+
+    if (type == ENTITY_LIGHT){
+        sprintf(channel, "light/%s/config", uniq_id);
+    }
+    else{
+        sprintf(channel, "switch/%s/config", uniq_id);
+    }
+
+    return channel;
+}
+
+/// @brief Builds HomeAssistant device discovery info. The caller needs to free the returned pointer.
+/// @param baseName 
+/// @param ids 
+cJSON *hass_build_device_node(const char *baseName, cJSON *ids) {
+    cJSON *dev = cJSON_CreateObject();
+    cJSON_AddItemToObject(dev, "ids", ids);     //identifiers
+    cJSON_AddStringToObject(dev, "name", baseName);
+    cJSON_AddStringToObject(dev, "sw", USER_SW_VER);   //sw_version
+    cJSON_AddStringToObject(dev, "mf", MANUFACTURER);   //manufacturer
+    cJSON_AddStringToObject(dev, "mdl", PLATFORM_MCU_NAME);  //Using chipset for model
+    return dev;
+}
+
+/// @brief Populates common values for HomeAssistant device discovery.
+/// @param root 
+/// @param baseName 
+/// @param index 
+/// @param unique_id 
+/// @param payload_on 
+/// @param payload_off 
+void hass_populate_common(cJSON *root, const char *baseName, int index, char *unique_id, char *payload_on, char *payload_off){
+    char tmp[64];  //baseName is g_cfg.shortDeviceName which reserves 32 char so 64 would be enough
+
+    //Using abbreviated node names as per https://www.home-assistant.io/docs/mqtt/discovery/
+    sprintf(tmp,"%s %i",baseName,index);
+    cJSON_AddStringToObject(root, "name", tmp);
+
+    sprintf(tmp,"%s/%i/get",baseName,index);
+    cJSON_AddStringToObject(root, "stat_t", tmp);   //state_topic
+
+    sprintf(tmp,"%s/%i/set",baseName,index);
+    cJSON_AddStringToObject(root, "cmd_t", tmp);    //command_topic
+
+    sprintf(tmp,"%s/connected",baseName);
+    cJSON_AddStringToObject(root, "avty_t", tmp);   //availability_topic
+
+    cJSON_AddStringToObject(root, "pl_on", "1");    //payload_on
+    cJSON_AddStringToObject(root, "pl_off", "0");   //payload_off
+    cJSON_AddStringToObject(root, "uniq_id", unique_id);  //unique_id
+}
+
+/// @brief Initializes HomeAssistant device discovery storage.
+/// @param type 
+/// @param index 
+/// @param payload_on 
+/// @param payload_off 
+/// @return 
+HassDeviceInfo *hass_init_device_info(ENTITY_TYPE type, int index, char *payload_on, char *payload_off){
+    const char *baseName = CFG_GetShortDeviceName();
+    HassDeviceInfo *info = os_malloc(sizeof(HassDeviceInfo));
+
+    info->unique_id = hass_build_unique_id(type, index);
+    info->channel = hass_get_device_config_channel(type, info->unique_id);
+
+    info->ids = cJSON_CreateArray();
+    cJSON_AddItemToArray(info->ids, cJSON_CreateString(CFG_GetDeviceName()));
+
+    info->device = hass_build_device_node(baseName, info->ids);
+
+    info->root = cJSON_CreateObject();
+    cJSON_AddItemToObject(info->root, "dev", info->device);    //device
+    
+    hass_populate_common(info->root, baseName, index, info->unique_id, payload_on, payload_off);
+    return info;
+}
+
+/// @brief Returns the discovery JSON.
+/// @param info 
+/// @return 
+char *hass_build_discovery_json(HassDeviceInfo *info){
+    info->json = cJSON_PrintUnformatted(info->root);
+    return info->json;
+}
+
+/// @brief Release allocated memory.
+/// @param info 
+void hass_free_device_info(HassDeviceInfo *info){
+    if (info == NULL) return;
+
+    os_free(info->unique_id);
+    os_free(info->channel);
+    os_free(info->json);
+    
+    cJSON_Delete(info->root);
+    cJSON_Delete(info->device);
+    cJSON_Delete(info->ids);
+
+    os_free(info);
+}

src/httpserver/hass.h

@@ -1,2 +1,23 @@
 
-//This will get populated in a later merge
+#include "../cJSON/cJSON.h"
+
+typedef enum {
+	ENTITY_RELAY = 0,
+    ENTITY_LIGHT = 1
+} ENTITY_TYPE;
+
+/// @brief HomeAssistant device discovery information
+typedef struct HassDeviceInfo_s{
+    char *unique_id;
+    char *channel;
+    char *json;
+    cJSON *root;
+    cJSON *device;
+    cJSON *ids;
+} HassDeviceInfo;
+
+char *hass_build_unique_id(ENTITY_TYPE type, int index);
+char *hass_build_unique_id(ENTITY_TYPE type, int index);
+char *hass_build_discovery_json(HassDeviceInfo *info);
+HassDeviceInfo *hass_init_device_info(ENTITY_TYPE type, int index, char *payload_on, char *payload_off);
+void hass_free_device_info(HassDeviceInfo *info);