Flipdot-display/src/esp32/net/ha_api.cpp

#include "net/ha_api.h"

#include <ArduinoJson.h>
#include <HTTPClient.h>
#include <WiFi.h>
#include <vector>

#include "config.h"
#include "credentials.h"

struct Entry
{
	String entity;
	String attribute;
	String value;
	bool known;
	bool watched;
	uint32_t next_poll;
};

static String base_url;
static String token;
static std::vector<Entry> entries;
// Kept for the editor's previews, besides the watched ones
static const size_t MAX_ENTRIES = 16;

void haApiSetSettings(const HomeAssistantSettings &settings)
{
	if (settings.api_url[0])
		base_url = settings.api_url;
	else
		base_url = String("http://") + (settings.host[0] ? String(settings.host) : BROKER_ADDR.toString()) + ":8123";
	while (base_url.endsWith("/"))
		base_url.remove(base_url.length() - 1);
	token = settings.token;
	for (Entry &e : entries)
		e.next_poll = millis(); // read again with the new settings
}

static Entry *find(const char *entity, const char *attribute)
{
	for (Entry &e : entries)
		if (e.entity == entity && e.attribute == attribute)
			return &e;
	return nullptr;
}

static Entry &add(const char *entity, const char *attribute)
{
	Entry *e = find(entity, attribute);
	if (e)
		return *e;
	if (entries.size() >= MAX_ENTRIES)
		for (auto it = entries.begin(); it != entries.end(); ++it)
			if (!it->watched)
			{
				entries.erase(it);
				break;
			}
	entries.push_back({entity, attribute, "", false, false, millis()});
	return entries.back();
}

void haApiWatch(const DynamicPage *page)
{
	for (Entry &e : entries)
		e.watched = false;
	if (!page)
		return;
	for (int i = 0; i < page->element_count; i++)
	{
		const PageElement &element = page->elements[i];
		bool uses_state = element.type == ElementType::HaValue || element.type == ElementType::Image;
		if (!uses_state || !validEntityId(element.entity))
			continue;
		Entry &e = add(element.entity, element.attribute);
		if (!e.watched)
			e.next_poll = millis();
		e.watched = true;
	}
}

// Blocks at most about 2 x HA_HTTP_TIMEOUT (connect, then the answer)
static const char *fetch(const String &entity, const String &attribute, String &value)
{
	if (!token.length())
		return "No Home Assistant token set (Home Assistant tab)";
	if (!WiFi.isConnected())
		return "No WiFi";

	HTTPClient http;
	http.setConnectTimeout(HA_HTTP_TIMEOUT);
	http.setTimeout(HA_HTTP_TIMEOUT);
	if (!http.begin(base_url + "/api/states/" + entity))
		return "Invalid Home Assistant URL";
	http.addHeader("Authorization", "Bearer " + token);
	int code = http.GET();
	if (code != 200)
	{
		http.end();
		if (code == 401)
			return "Home Assistant refused the token";
		if (code == 404)
			return "Unknown entity";
		return code < 0 ? "Home Assistant not reachable" : "Unexpected answer from Home Assistant";
	}

	JsonDocument filter;
	if (attribute.length())
		filter["attributes"][attribute] = true;
	else
		filter["state"] = true;
	JsonDocument doc;
	DeserializationError error = deserializeJson(doc, http.getString(), DeserializationOption::Filter(filter));
	http.end();
	if (error)
		return "Invalid answer from Home Assistant";

	JsonVariantConst v = doc["state"];
	if (attribute.length())
		v = doc["attributes"][attribute];
	if (v.isNull())
		return "Unknown attribute";
	if (v.is<const char *>())
		value = v.as<const char *>();
	else
	{
		value = "";
		serializeJson(v, value); // numbers, true/false
	}
	value.replace("\xC2\xB0", String(DEGREE_SIGN)); // UTF-8 degree sign: the fonts have it as 127
	return nullptr;
}

bool haApiLoop(bool wifi_connected)
{
	if (!wifi_connected || !token.length())
		return false;
	uint32_t now = millis();
	for (Entry &e : entries)
	{
		if (!e.watched || (int32_t)(now - e.next_poll) < 0)
			continue;
		e.next_poll = now + HA_POLL_INTERVAL;
		String value;
		const char *error = fetch(e.entity, e.attribute, value);
		if (error)
		{
			// Shown as "--" until it can be read again
			Serial.printf("Home Assistant %s: %s\n", e.entity.c_str(), error);
			bool changed = e.known;
			e.known = false;
			return changed;
		}
		bool changed = !e.known || e.value != value;
		e.value = value;
		e.known = true;
		return changed; // one entity per loop()
	}
	return false;
}

const char *haApiValue(const char *entity, const char *attribute)
{
	Entry *e = find(entity, attribute);
	return e && e->known ? e->value.c_str() : nullptr;
}

const char *haApiFetchNow(const char *entity, const char *attribute, String &value)
{
	if (!validEntityId(entity))
		return "Invalid entity id";
	const char *error = fetch(entity, attribute, value);
	if (error)
		return error;
	Entry &e = add(entity, attribute);
	e.value = value;
	e.known = true;
	return nullptr;
}