scheduler: onChange and conditions

interface/src/project/Scheduler.tsx

@@ -87,7 +87,7 @@ const Scheduler: FC = () => {
 
   const schedule_theme = useTheme({
     Table: `
-      --data-table-library_grid-template-columns: 36px 324px 50px 192px repeat(1, minmax(100px, 1fr)) 160px;
+      --data-table-library_grid-template-columns: 36px 210px 100px 192px repeat(1, minmax(100px, 1fr)) 160px;
     `,
     BaseRow: `
       font-size: 14px;
@@ -198,7 +198,7 @@ const Scheduler: FC = () => {
       active: false,
       deleted: false,
       flags: 0,
-      time: '12:00',
+      time: '',
       cmd: '',
       value: '',
       name: ''
@@ -216,11 +216,21 @@ const Scheduler: FC = () => {
         <Box>
           <Typography
             sx={{ fontSize: 11 }}
-            color={(si.flags & flag) === flag ? 'primary' : 'grey'}
+            color={
+              si.flags >= ScheduleFlag.SCHEDULE_TIMER && si.flags !== flag
+                ? 'gray'
+                : (si.flags & flag) === flag
+                  ? 'primary'
+                  : 'grey'
+            }
           >
             {flag === ScheduleFlag.SCHEDULE_TIMER
               ? LL.TIMER(0)
-              : dow[Math.log(flag) / Math.log(2)]}
+              : flag === ScheduleFlag.SCHEDULE_ONCHANGE
+                ? 'OnChange'
+                : flag === ScheduleFlag.SCHEDULE_CONDITION
+                  ? 'Condition'
+                  : dow[Math.log(flag) / Math.log(2)]}
           </Typography>
         </Box>
         <Divider orientation="vertical" flexItem />
@@ -245,7 +255,7 @@ const Scheduler: FC = () => {
               <HeaderRow>
                 <HeaderCell />
                 <HeaderCell stiff>{LL.SCHEDULE(0)}</HeaderCell>
-                <HeaderCell stiff>{LL.TIME(0)}</HeaderCell>
+                <HeaderCell stiff>{LL.TIME(0)}/Cond.</HeaderCell>
                 <HeaderCell stiff>{LL.COMMAND(0)}</HeaderCell>
                 <HeaderCell stiff>{LL.VALUE(0)}</HeaderCell>
                 <HeaderCell stiff>{LL.NAME(0)}</HeaderCell>
@@ -268,16 +278,25 @@ const Scheduler: FC = () => {
                     )}
                   </Cell>
                   <Cell stiff>
-                    <Stack spacing={1} direction="row">
+                    <Stack spacing={0.5} direction="row">
                       <Divider orientation="vertical" flexItem />
-                      {dayBox(si, ScheduleFlag.SCHEDULE_MON)}
+                      {si.flags < ScheduleFlag.SCHEDULE_TIMER ? (
-                      {dayBox(si, ScheduleFlag.SCHEDULE_TUE)}
+                        <>
-                      {dayBox(si, ScheduleFlag.SCHEDULE_WED)}
+                          {dayBox(si, ScheduleFlag.SCHEDULE_MON)}
-                      {dayBox(si, ScheduleFlag.SCHEDULE_THU)}
+                          {dayBox(si, ScheduleFlag.SCHEDULE_TUE)}
-                      {dayBox(si, ScheduleFlag.SCHEDULE_FRI)}
+                          {dayBox(si, ScheduleFlag.SCHEDULE_WED)}
-                      {dayBox(si, ScheduleFlag.SCHEDULE_SAT)}
+                          {dayBox(si, ScheduleFlag.SCHEDULE_THU)}
-                      {dayBox(si, ScheduleFlag.SCHEDULE_SUN)}
+                          {dayBox(si, ScheduleFlag.SCHEDULE_FRI)}
-                      {dayBox(si, ScheduleFlag.SCHEDULE_TIMER)}
+                          {dayBox(si, ScheduleFlag.SCHEDULE_SAT)}
+                          {dayBox(si, ScheduleFlag.SCHEDULE_SUN)}
+                        </>
+                      ) : (
+                        <>
+                          {dayBox(si, ScheduleFlag.SCHEDULE_TIMER)}
+                          {dayBox(si, ScheduleFlag.SCHEDULE_ONCHANGE)}
+                          {dayBox(si, ScheduleFlag.SCHEDULE_CONDITION)}
+                        </>
+                      )}
                     </Stack>
                   </Cell>
                   <Cell>{si.time}</Cell>
@@ -341,7 +360,7 @@ const Scheduler: FC = () => {
             <Button
               startIcon={<AddIcon />}
               variant="outlined"
-              color="secondary"
+              color="primary"
               onClick={addScheduleItem}
             >
               {LL.ADD(0)}

interface/src/project/SchedulerDialog.tsx

@@ -91,10 +91,10 @@ const SchedulerDialog = ({
 
   const getFlagString = (f: number) => {
     const new_flags: string[] = [];
-    if ((f & 1) === 1) {
+    if ((f & 129) === 1) {
       new_flags.push('1');
     }
-    if ((f & 2) === 2) {
+    if ((f & 130) === 2) {
       new_flags.push('2');
     }
     if ((f & 4) === 4) {
@@ -112,26 +112,45 @@ const SchedulerDialog = ({
     if ((f & 64) === 64) {
       new_flags.push('64');
     }
-    if ((f & 128) === 128) {
+    if ((f & 131) === 128) {
       new_flags.push('128');
     }
+    if ((f & 131) === 129) {
+      new_flags.push('129');
+    }
+    if ((f & 131) === 130) {
+      new_flags.push('130');
+    }
     return new_flags;
   };
 
+  const isTimer = editItem.flags === ScheduleFlag.SCHEDULE_TIMER;
+  const isCondition = editItem.flags === ScheduleFlag.SCHEDULE_CONDITION;
+  const isOnChange = editItem.flags === ScheduleFlag.SCHEDULE_ONCHANGE;
+
   const showFlag = (si: ScheduleItem, flag: number) => (
     <Typography
       variant="button"
       sx={{ fontSize: 10 }}
-      color={(si.flags & flag) === flag ? 'primary' : 'grey'}
+      color={
+        (isOnChange && flag !== ScheduleFlag.SCHEDULE_ONCHANGE) ||
+        (isCondition && flag !== ScheduleFlag.SCHEDULE_CONDITION)
+          ? 'grey'
+          : (si.flags & flag) === flag
+            ? 'primary'
+            : 'grey'
+      }
     >
       {flag === ScheduleFlag.SCHEDULE_TIMER
         ? LL.TIMER(0)
-        : dow[Math.log(flag) / Math.log(2)]}
+        : flag === ScheduleFlag.SCHEDULE_ONCHANGE
+          ? 'On Change'
+          : flag === ScheduleFlag.SCHEDULE_CONDITION
+            ? 'Condition'
+            : dow[Math.log(flag) / Math.log(2)]}
     </Typography>
   );
 
-  const isTimer = editItem.flags === ScheduleFlag.SCHEDULE_TIMER;
-
   return (
     <Dialog sx={dialogStyle} open={open} onClose={close}>
       <DialogTitle>
@@ -179,7 +198,7 @@ const SchedulerDialog = ({
                 sx={{ bgcolor: '#334f65' }}
                 variant="contained"
                 onClick={() => {
-                  setEditItem({ ...editItem, flags: 0 });
+                  setEditItem({ ...editItem, flags: ScheduleFlag.SCHEDULE_TIMER });
                 }}
               >
                 {showFlag(editItem, ScheduleFlag.SCHEDULE_TIMER)}
@@ -199,6 +218,66 @@ const SchedulerDialog = ({
               </Button>
             )}
           </Box>
+          <Box>
+            {isOnChange ? (
+              <Button
+                size="large"
+                sx={{ bgcolor: '#334f65' }}
+                variant="contained"
+                onClick={() => {
+                  setEditItem({
+                    ...editItem,
+                    flags: ScheduleFlag.SCHEDULE_ONCHANGE
+                  });
+                }}
+              >
+                {showFlag(editItem, ScheduleFlag.SCHEDULE_ONCHANGE)}
+              </Button>
+            ) : (
+              <Button
+                size="large"
+                variant="outlined"
+                onClick={() => {
+                  setEditItem({
+                    ...editItem,
+                    flags: ScheduleFlag.SCHEDULE_ONCHANGE
+                  });
+                }}
+              >
+                {showFlag(editItem, ScheduleFlag.SCHEDULE_ONCHANGE)}
+              </Button>
+            )}
+          </Box>
+          <Box>
+            {isCondition ? (
+              <Button
+                size="large"
+                sx={{ bgcolor: '#334f65' }}
+                variant="contained"
+                onClick={() => {
+                  setEditItem({
+                    ...editItem,
+                    flags: ScheduleFlag.SCHEDULE_CONDITION
+                  });
+                }}
+              >
+                {showFlag(editItem, ScheduleFlag.SCHEDULE_CONDITION)}
+              </Button>
+            ) : (
+              <Button
+                size="large"
+                variant="outlined"
+                onClick={() => {
+                  setEditItem({
+                    ...editItem,
+                    flags: ScheduleFlag.SCHEDULE_CONDITION
+                  });
+                }}
+              >
+                {showFlag(editItem, ScheduleFlag.SCHEDULE_CONDITION)}
+              </Button>
+            )}
+          </Box>
         </Box>
         <Grid container>
           <BlockFormControlLabel
@@ -213,18 +292,31 @@ const SchedulerDialog = ({
           />
         </Grid>
         <Grid container>
-          <TextField
+          {isCondition || isOnChange ? (
-            name="time"
+            <TextField
-            type="time"
+              name="time"
-            label={isTimer ? LL.TIMER(1) : LL.TIME(1)}
+              label={isCondition ? 'Condition' : 'On Change Value'}
-            value={editItem.time}
+              fullWidth
-            margin="normal"
+              value={editItem.time}
-            onChange={updateFormValue}
+              margin="normal"
-          />
+              onChange={updateFormValue}
-          {isTimer && (
+            />
-            <Box color="warning.main" ml={2} mt={4}>
+          ) : (
-              <Typography variant="body2">{LL.SCHEDULER_HELP_2()}</Typography>
+            <>
-            </Box>
+              <TextField
+                name="time"
+                type="time"
+                label={isTimer ? LL.TIMER(1) : LL.TIME(1)}
+                value={editItem.time}
+                margin="normal"
+                onChange={updateFormValue}
+              />
+              {isTimer && (
+                <Box color="warning.main" ml={2} mt={4}>
+                  <Typography variant="body2">{LL.SCHEDULER_HELP_2()}</Typography>
+                </Box>
+              )}
+            </>
           )}
         </Grid>
         <ValidatedTextField

interface/src/project/types.ts

@@ -334,7 +334,9 @@ export enum ScheduleFlag {
   SCHEDULE_THU = 16,
   SCHEDULE_FRI = 32,
   SCHEDULE_SAT = 64,
-  SCHEDULE_TIMER = 128
+  SCHEDULE_TIMER = 128,
+  SCHEDULE_ONCHANGE = 129,
+  SCHEDULE_CONDITION = 130
 }
 
 export interface EntityItem {

src/analogsensor.cpp

@@ -409,6 +409,9 @@ void AnalogSensor::publish_sensor(const Sensor & sensor) const {
         char payload[10];
         Mqtt::queue_publish(topic, Helpers::render_value(payload, sensor.value(), 2)); // always publish as doubles
     }
+    char cmd[COMMAND_MAX_LENGTH];
+    snprintf(cmd, sizeof(cmd), "%s/%s", F_(analogsensor), sensor.name().c_str());
+    EMSESP::webSchedulerService.onChange(cmd);
 }
 
 // send empty config topic to remove the entry from HA

src/emsdevice.cpp

@@ -105,6 +105,10 @@ const char * EMSdevice::device_type_2_device_name(const uint8_t device_type) {
     switch (device_type) {
     case DeviceType::SYSTEM:
         return F_(system);
+    case DeviceType::TEMPERATURESENSOR:
+        return F_(temperaturesensor);
+    case DeviceType::ANALOGSENSOR:
+        return F_(analogsensor);
     case DeviceType::SCHEDULER:
         return F_(scheduler);
     case DeviceType::CUSTOM:
@@ -113,28 +117,26 @@ const char * EMSdevice::device_type_2_device_name(const uint8_t device_type) {
         return F_(boiler);
     case DeviceType::THERMOSTAT:
         return F_(thermostat);
-    case DeviceType::HEATPUMP:
-        return F_(heatpump);
-    case DeviceType::SOLAR:
-        return F_(solar);
-    case DeviceType::CONNECT:
-        return F_(connect);
     case DeviceType::MIXER:
         return F_(mixer);
-    case DeviceType::TEMPERATURESENSOR:
+    case DeviceType::SOLAR:
-        return F_(temperaturesensor);
+        return F_(solar);
-    case DeviceType::ANALOGSENSOR:
+    case DeviceType::HEATPUMP:
-        return F_(analogsensor);
+        return F_(heatpump);
-    case DeviceType::CONTROLLER:
-        return F_(controller);
-    case DeviceType::SWITCH:
-        return F_(switch);
     case DeviceType::GATEWAY:
         return F_(gateway);
+    case DeviceType::SWITCH:
+        return F_(switch);
+    case DeviceType::CONTROLLER:
+        return F_(controller);
+    case DeviceType::CONNECT:
+        return F_(connect);
     case DeviceType::ALERT:
         return F_(alert);
     case DeviceType::EXTENSION:
         return F_(extension);
+    case DeviceType::GENERIC:
+        return F_(generic);
     case DeviceType::HEATSOURCE:
         return F_(heatsource);
     case DeviceType::VENTILATION:
@@ -752,7 +754,8 @@ void EMSdevice::set_minmax(const void * value_p, int16_t min, uint32_t max) {
 
 // publish a single value on change
 void EMSdevice::publish_value(void * value_p) const {
-    if (!Mqtt::publish_single() || value_p == nullptr) {
+    // if (!Mqtt::publish_single() || value_p == nullptr) {
+    if (value_p == nullptr) {
         return;
     }
 
@@ -820,9 +823,17 @@ void EMSdevice::publish_value(void * value_p) const {
                 break;
             }
 
-            if (payload[0] != '\0') {
+            if (Mqtt::publish_single() && payload[0] != '\0') {
                 Mqtt::queue_publish(topic, payload);
             }
+            // check scheduler for on change
+            char cmd[COMMAND_MAX_LENGTH];
+            if (dv.tag >= DeviceValueTAG::TAG_HC1) {
+                snprintf(cmd, sizeof(cmd), "%s/%s/%s", device_type_2_device_name(device_type_), tag_to_mqtt(dv.tag), dv.short_name);
+            } else {
+                snprintf(cmd, sizeof(cmd), "%s/%s", device_type_2_device_name(device_type_), (dv.short_name));
+            }
+            EMSESP::webSchedulerService.onChange(cmd);
         }
     }
 }

src/temperaturesensor.cpp

@@ -441,6 +441,9 @@ void TemperatureSensor::publish_sensor(const Sensor & sensor) {
         char payload[10];
         Mqtt::queue_publish(topic, Helpers::render_value(payload, sensor.temperature_c, 10, EMSESP::system_.fahrenheit() ? 2 : 0));
     }
+    char cmd[COMMAND_MAX_LENGTH];
+    snprintf(cmd, sizeof(cmd), "%s/%s", F_(temperaturesensor), sensor.name().c_str());
+    EMSESP::webSchedulerService.onChange(cmd);
 }
 
 // send empty config topic to remove the entry from HA

src/web/WebCustomEntityService.cpp

@@ -175,6 +175,9 @@ bool WebCustomEntityService::command_setvalue(const char * value, const std::str
             if (EMSESP::mqtt_.get_publish_onchange(0)) {
                 publish();
             }
+            char cmd[COMMAND_MAX_LENGTH];
+            snprintf(cmd, sizeof(cmd_function_p), "custom/%s", entityItem.name.c_str());
+            EMSESP::webSchedulerService.onChange(cmd);
             return true;
         }
     }
@@ -591,7 +594,7 @@ void WebCustomEntityService::fetch() {
 bool WebCustomEntityService::get_value(std::shared_ptr<const Telegram> telegram) {
     bool has_change = false;
     EMSESP::webCustomEntityService.read([&](WebCustomEntity & webEntity) { customEntityItems = &webEntity.customEntityItems; });
-    // read-length of BOOL, INT, UINT, SHORT, USHORT, ULONG, TIME
+    // read-length of BOOL, INT8, UINT8, INT16, UINT16, UINT24, TIME, UINT32
     const uint8_t len[] = {1, 1, 1, 2, 2, 3, 3, 4};
     for (auto & entity : *customEntityItems) {
         if (entity.value_type == DeviceValueType::STRING && telegram->type_id == entity.type_id && telegram->src == entity.device_id
@@ -604,6 +607,9 @@ bool WebCustomEntityService::get_value(std::shared_ptr<const Telegram> telegram)
                 } else if (EMSESP::mqtt_.get_publish_onchange(0)) {
                     has_change = true;
                 }
+                char cmd[COMMAND_MAX_LENGTH];
+                snprintf(cmd, sizeof(cmd_function_p), "custom/%s", entity.name.c_str());
+                EMSESP::webSchedulerService.onChange(cmd);
             }
         } else if (entity.value_type != DeviceValueType::STRING && telegram->type_id == entity.type_id && telegram->src == entity.device_id
                    && telegram->offset <= entity.offset && (telegram->offset + telegram->message_length) >= (entity.offset + len[entity.value_type])) {
@@ -618,6 +624,9 @@ bool WebCustomEntityService::get_value(std::shared_ptr<const Telegram> telegram)
                 } else if (EMSESP::mqtt_.get_publish_onchange(0)) {
                     has_change = true;
                 }
+                char cmd[COMMAND_MAX_LENGTH];
+                snprintf(cmd, sizeof(cmd_function_p), "%s/%s", "custom", entity.name.c_str());
+                EMSESP::webSchedulerService.onChange(cmd);
             }
             // EMSESP::logger().debug("custom entity %s received with value %d", entity.name.c_str(), (int)entity.val);
         }

src/web/WebSchedulerService.cpp

@@ -367,26 +367,64 @@ bool WebSchedulerService::command(const char * cmd, const char * data) {
     return false;
 }
 
+#include "shuntingYard.hpp"
+
+bool WebSchedulerService::onChange(const char * cmd) {
+    for (const ScheduleItem & scheduleItem : *scheduleItems_) {
+        if (scheduleItem.active && scheduleItem.flags == SCHEDULEFLAG_SCHEDULE_ONCHANGE && Helpers::toLower(scheduleItem.time) == Helpers::toLower(cmd)) {
+            // emsesp::EMSESP::logger().debug(scheduleItem.cmd.c_str());
+            return command(scheduleItem.cmd.c_str(), compute(scheduleItem.value.c_str()).c_str());
+        }
+    }
+    return false;
+}
+
+void WebSchedulerService::condition() {
+    for (ScheduleItem & scheduleItem : *scheduleItems_) {
+        if (scheduleItem.active && scheduleItem.flags == SCHEDULEFLAG_SCHEDULE_CONDITION) {
+            auto match = compute(scheduleItem.time.c_str());
+#ifdef EMESESP_DEBUG
+            emsesp::EMSESP::logger().debug("condition match: %s", match.c_str());
+#endif
+            if (!match.empty() && match.c_str()[0] == '1') {
+                if (scheduleItem.retry_cnt == 0xFF) { // default unswitched
+                    scheduleItem.retry_cnt = command(scheduleItem.cmd.c_str(), compute(scheduleItem.value.c_str()).c_str()) ? 1 : 0xFF;
+                }
+            } else if (scheduleItem.retry_cnt == 1) {
+                scheduleItem.retry_cnt = 0xFF;
+            }
+        }
+    }
+}
+
 // process any scheduled jobs
 // checks on the minute and at startup
 void WebSchedulerService::loop() {
     // initialize static value on startup
-    static int8_t   last_tm_min     = -1; // invalid value also used for startup commands
+    static int8_t   last_tm_min     = -2; // invalid value also used for startup commands
     static uint32_t last_uptime_min = 0;
+    static uint32_t last_uptime_sec = 0;
 
     // get list of scheduler events and exit if it's empty
     if (scheduleItems_->size() == 0) {
         return;
     }
 
+    // check conditions every 10 seconds
+    uint32_t uptime_sec = uuid::get_uptime_sec() / 10;
+    if (last_uptime_sec != uptime_sec) {
+        condition();
+        last_uptime_sec = uptime_sec;
+    }
+
     // check startup commands
-    if (last_tm_min == -1) {
+    if (last_tm_min == -2) {
         for (ScheduleItem & scheduleItem : *scheduleItems_) {
             if (scheduleItem.active && scheduleItem.flags == SCHEDULEFLAG_SCHEDULE_TIMER && scheduleItem.elapsed_min == 0) {
-                scheduleItem.retry_cnt = command(scheduleItem.cmd.c_str(), scheduleItem.value.c_str()) ? 0xFF : 0;
+                scheduleItem.retry_cnt = command(scheduleItem.cmd.c_str(), compute(scheduleItem.value.c_str()).c_str()) ? 0xFF : 0;
             }
         }
-        last_tm_min = 0; // startup done, now use for RTC
+        last_tm_min = -1; // startup done, now use for RTC
     }
 
     // check timer every minute, sync to EMS-ESP clock
@@ -401,7 +439,7 @@ void WebSchedulerService::loop() {
             // scheduled timer commands
             if (scheduleItem.active && scheduleItem.flags == SCHEDULEFLAG_SCHEDULE_TIMER && scheduleItem.elapsed_min > 0
                 && (uptime_min % scheduleItem.elapsed_min == 0)) {
-                command(scheduleItem.cmd.c_str(), scheduleItem.value.c_str());
+                command(scheduleItem.cmd.c_str(), compute(scheduleItem.value.c_str()).c_str());
             }
         }
         last_uptime_min = uptime_min;
@@ -416,8 +454,9 @@ void WebSchedulerService::loop() {
         uint16_t real_min = tm->tm_hour * 60 + tm->tm_min;
 
         for (const ScheduleItem & scheduleItem : *scheduleItems_) {
-            if (scheduleItem.active && (real_dow & scheduleItem.flags) && real_min == scheduleItem.elapsed_min) {
+            uint8_t dow = scheduleItem.flags & SCHEDULEFLAG_SCHEDULE_TIMER ? 0 : scheduleItem.flags;
-                command(scheduleItem.cmd.c_str(), scheduleItem.value.c_str());
+            if (scheduleItem.active && (real_dow & dow) && real_min == scheduleItem.elapsed_min) {
+                command(scheduleItem.cmd.c_str(), compute(scheduleItem.value.c_str()).c_str());
             }
         }
         last_tm_min = tm->tm_min;

src/web/WebSchedulerService.h

@@ -22,8 +22,10 @@
 #define EMSESP_SCHEDULER_FILE "/config/emsespScheduler.json"
 #define EMSESP_SCHEDULER_SERVICE_PATH "/rest/schedule" // GET and POST
 
-#define SCHEDULEFLAG_SCHEDULE_TIMER 0x80 // 7th bit for Timer
+#define SCHEDULEFLAG_SCHEDULE_TIMER 0x80     // 7th bit for Timer
-#define MAX_STARTUP_RETRIES 3            // retry the start-up commands x times
+#define SCHEDULEFLAG_SCHEDULE_ONCHANGE 0x81  // 7th+1st bit for OnChange
+#define SCHEDULEFLAG_SCHEDULE_CONDITION 0x82 // 7th+2nd bit for Condition
+#define MAX_STARTUP_RETRIES 3                // retry the start-up commands x times
 
 namespace emsesp {
 
@@ -61,6 +63,7 @@ class WebSchedulerService : public StatefulService<WebScheduler> {
     void ha_reset() {
         ha_registered_ = false;
     }
+    bool onChange(const char * cmd);
 
 #if defined(EMSESP_TEST)
     void test();
@@ -71,6 +74,7 @@ class WebSchedulerService : public StatefulService<WebScheduler> {
   private:
 #endif
     bool command(const char * cmd, const char * data);
+    void condition();
 
     HttpEndpoint<WebScheduler>  _httpEndpoint;
     FSPersistence<WebScheduler> _fsPersistence;

src/web/shuntingYard.hpp

@@ -0,0 +1,404 @@
+// Shunting-yard Algorithm
+// https://en.wikipedia.org/wiki/Shunting-yard_algorithm
+//
+// Implementation notes for unary operators by Austin Taylor
+//  https://stackoverflow.com/a/5240912
+//
+// Example:
+//  https://ideone.com/VocUTq
+//
+// License:
+//  If you use this code in binary / compiled / un-commented (removing all text comments) form,
+//  you can use it under CC0 license.
+//
+//  But if you use this code as source code / readable text, since main content of this code is
+//  their notes, I recommend you to indicate notices which conform CC-BY-SA.  For example,
+//
+//  --- ---
+//  YOUR-CONTENT uses the following materials.
+//  (1) Wikipedia article [Shunting-yard algorithm](https://en.wikipedia.org/wiki/Shunting-yard_algorithm),
+//  which is released under the [Creative Commons Attribution-Share-Alike License 3.0](https://creativecommons.org/licenses/by-sa/3.0/).
+//  (2) [Implementation notes for unary operators in Shunting-Yard algorithm](https://stackoverflow.com/a/5240912) by Austin Taylor
+//  which is released under the [Creative Commons Attribution-Share-Alike License 2.5](https://creativecommons.org/licenses/by-sa/2.5/).
+//  --- ---
+// copy from https://gist.github.com/t-mat/b9f681b7591cdae712f6
+// modified MDvP, 06.2024
+//
+#include <string>
+#include <vector>
+#include <deque>
+#include <math.h>
+
+class Token {
+  public:
+    enum class Type {
+        Unknown,
+        Number,
+        Operator,
+        LeftParen,
+        RightParen,
+    };
+
+    Token(Type type, const std::string & s, int8_t precedence = -1, bool rightAssociative = false, bool unary = false)
+        : type{type}
+        , str(s)
+        , precedence{precedence}
+        , rightAssociative{rightAssociative}
+        , unary{unary} {
+    }
+
+    const Type        type;
+    const std::string str;
+    const int8_t      precedence;
+    const bool        rightAssociative;
+    const bool        unary;
+};
+
+std::deque<Token> exprToTokens(const std::string & expr) {
+    std::deque<Token> tokens;
+
+    for (const auto * p = expr.c_str(); *p; ++p) {
+        if (isblank(*p)) {
+            // do nothing
+        } else if ((*p >= 'a' && *p <= 'z')) {
+            tokens.clear();
+            return tokens;
+        } else if (isdigit(*p)) {
+            const auto * b = p;
+            while (isdigit(*p) || *p == '.') {
+                ++p;
+            }
+            const auto s = std::string(b, p);
+            tokens.push_back(Token{Token::Type::Number, s});
+            --p;
+        } else {
+            Token::Type token            = Token::Type::Operator;
+            int8_t      precedence       = -1;
+            bool        rightAssociative = false;
+            bool        unary            = false;
+            char        c                = *p;
+            switch (c) {
+            default:
+                token = Token::Type::Unknown;
+                break;
+            case '(':
+                token = Token::Type::LeftParen;
+                break;
+            case ')':
+                token = Token::Type::RightParen;
+                break;
+            case '^':
+                precedence       = 4;
+                rightAssociative = true;
+                break;
+            case '*':
+                precedence = 3;
+                break;
+            case '/':
+                precedence = 3;
+                break;
+            case '%':
+                precedence = 3;
+                break;
+            case '+':
+                precedence = 2;
+                break;
+            case '-':
+                // If current token is '-'
+                // and if it is the first token, or preceded by another operator, or left-paren,
+                if (tokens.empty() || tokens.back().type == Token::Type::Operator || tokens.back().type == Token::Type::LeftParen) {
+                    // it's unary '-'
+                    // note#1 : 'm' is a special operator name for unary '-'
+                    // note#2 : It has highest precedence than any of the infix operators
+                    unary      = true;
+                    c          = 'm';
+                    precedence = 5;
+                } else {
+                    // otherwise, it's binary '-'
+                    precedence = 2;
+                }
+                break;
+            case '&':
+                if (p[1] == '&')
+                    ++p;
+                precedence = 0;
+                break;
+            case '|':
+                if (p[1] == '|')
+                    ++p;
+                precedence = 0;
+                break;
+            case '!':
+                unary      = true;
+                precedence = 1;
+                break;
+            case '<':
+                if (p[1] == '=') {
+                    ++p;
+                    c = '{';
+                }
+                precedence = 1;
+                break;
+            case '>':
+                if (p[1] == '=') {
+                    ++p;
+                    c = '}';
+                }
+                precedence = 1;
+                break;
+            case '=':
+                if (p[1] == '=')
+                    ++p;
+                precedence = 1;
+                break;
+            }
+            const auto s = std::string(1, c);
+            tokens.push_back(Token{token, s, precedence, rightAssociative, unary});
+        }
+    }
+
+    return tokens;
+}
+
+
+std::deque<Token> shuntingYard(const std::deque<Token> & tokens) {
+    std::deque<Token>  queue;
+    std::vector<Token> stack;
+
+    // While there are tokens to be read:
+    for (auto token : tokens) {
+        // Read a token
+        switch (token.type) {
+        case Token::Type::Number:
+            // If the token is a number, then add it to the output queue
+            queue.push_back(token);
+            break;
+
+        case Token::Type::Operator: {
+            // If the token is operator, o1, then:
+            const auto o1 = token;
+
+            // while there is an operator token,
+            while (!stack.empty()) {
+                // o2, at the top of stack, and
+                const auto o2 = stack.back();
+
+                // either o1 is left-associative and its precedence is
+                // *less than or equal* to that of o2,
+                // or o1 if right associative, and has precedence
+                // *less than* that of o2,
+                if ((!o1.rightAssociative && o1.precedence <= o2.precedence) || (o1.rightAssociative && o1.precedence < o2.precedence)) {
+                    // then pop o2 off the stack,
+                    stack.pop_back();
+                    // onto the output queue;
+                    queue.push_back(o2);
+
+                    continue;
+                }
+
+                // @@ otherwise, exit.
+                break;
+            }
+
+            // push o1 onto the stack.
+            stack.push_back(o1);
+        } break;
+
+        case Token::Type::LeftParen:
+            // If token is left parenthesis, then push it onto the stack
+            stack.push_back(token);
+            break;
+
+        case Token::Type::RightParen:
+            // If token is right parenthesis:
+            {
+                bool match = false;
+
+                // Until the token at the top of the stack
+                // is a left parenthesis,
+                while (!stack.empty() && stack.back().type != Token::Type::LeftParen) {
+                    // pop operators off the stack
+                    // onto the output queue.
+                    queue.push_back(stack.back());
+                    stack.pop_back();
+                    match = true;
+                }
+
+                if (!match && stack.empty()) {
+                    // If the stack runs out without finding a left parenthesis,
+                    // then there are mismatched parentheses.
+                    return {};
+                }
+
+                // Pop the left parenthesis from the stack,
+                // but not onto the output queue.
+                stack.pop_back();
+            }
+            break;
+
+        default:
+            return {};
+        }
+    }
+
+    // When there are no more tokens to read:
+    //   While there are still operator tokens in the stack:
+    while (!stack.empty()) {
+        // If the operator token on the top of the stack is a parenthesis,
+        // then there are mismatched parentheses.
+        if (stack.back().type == Token::Type::LeftParen) {
+            return {};
+        }
+
+        // Pop the operator onto the output queue.
+        queue.push_back(std::move(stack.back()));
+        stack.pop_back();
+    }
+    return queue;
+}
+
+// replace commands like "<device>/<hc>/<cmd>" with its value"
+std::string commands(std::string & expr) {
+    for (uint8_t device = 0; device < emsesp::EMSdevice::DeviceType::UNKNOWN; device++) {
+        const char * d = emsesp::EMSdevice::device_type_2_device_name(device);
+        auto         f = expr.find(d);
+        while (f != std::string::npos) {
+            auto e = expr.find_first_of(" )=<>|&+-*\0", f);
+            if (e == std::string::npos) {
+                e = expr.length();
+            }
+            char   cmd[COMMAND_MAX_LENGTH];
+            size_t l = e - f;
+            if (l >= sizeof(cmd) - 1) {
+                break;
+            }
+            expr.copy(cmd, l, f);
+            cmd[l] = '\0';
+            if (strstr(cmd, "/value") == nullptr) {
+                strlcat(cmd, "/value", sizeof(cmd) - 6);
+            }
+            JsonDocument doc_out, doc_in;
+            JsonObject   output = doc_out.to<JsonObject>();
+            JsonObject   input  = doc_in.to<JsonObject>();
+            std::string  cmd_s  = "api/" + std::string(cmd);
+            emsesp::Command::process(cmd_s.c_str(), true, input, output);
+            if (output.containsKey("api_data")) {
+                std::string data = output["api_data"].as<std::string>();
+                if (data == "true" || data == "ON" || data == "on") {
+                    data = "1";
+                }
+                if (data == "false" || data == "OFF" || data == "off") {
+                    data = "0";
+                }
+                expr.replace(f, l, data);
+                e = f + data.length();
+            }
+            f = expr.find(d, e);
+        }
+    }
+    return expr;
+}
+
+std::string compute(const std::string & expr) {
+    auto expr_new = emsesp::Helpers::toLower(expr);
+#ifdef EMESESP_DEBUG
+    emsesp::EMSESP::logger().debug("calculate: %s", expr_new.c_str());
+#endif
+    commands(expr_new);
+#ifdef EMESESP_DEBUG
+    emsesp::EMSESP::logger().debug("calculate: %s", expr_new.c_str());
+#endif
+    const auto tokens = exprToTokens(expr_new);
+    if (tokens.empty()) {
+        return "Error: no tokens";
+    }
+    auto                queue = shuntingYard(tokens);
+    std::vector<double> stack;
+
+    while (!queue.empty()) {
+        const auto token = queue.front();
+        queue.pop_front();
+        switch (token.type) {
+        case Token::Type::Number:
+            stack.push_back(std::stod(token.str));
+            break;
+
+        case Token::Type::Operator: {
+            if (token.unary) {
+                // unray operators
+                const auto rhs = stack.back();
+                stack.pop_back();
+                switch (token.str[0]) {
+                default:
+                    return "";
+                    break;
+                case 'm': // Special operator name for unary '-'
+                    stack.push_back(-rhs);
+                    break;
+                case '!':
+                    stack.push_back(!(int)rhs);
+                    break;
+                }
+            } else {
+                // binary operators
+                const auto rhs = stack.back();
+                stack.pop_back();
+                const auto lhs = stack.back();
+                stack.pop_back();
+
+                switch (token.str[0]) {
+                default:
+                    return "";
+                    break;
+                case '^':
+                    stack.push_back(static_cast<int>(pow(lhs, rhs)));
+                    break;
+                case '*':
+                    stack.push_back(lhs * rhs);
+                    break;
+                case '/':
+                    stack.push_back(lhs / rhs);
+                    break;
+                case '%':
+                    stack.push_back((int)lhs % (int)rhs);
+                    break;
+                case '+':
+                    stack.push_back(lhs + rhs);
+                    break;
+                case '-':
+                    stack.push_back(lhs - rhs);
+                    break;
+                case '&':
+                    stack.push_back(((int)lhs && (int)rhs) ? 1 : 0);
+                    break;
+                case '|':
+                    stack.push_back(((int)lhs || (int)rhs) ? 1 : 0);
+                    break;
+                case '<':
+                    stack.push_back(((int)lhs < (int)rhs) ? 1 : 0);
+                    break;
+                case '{':
+                    stack.push_back(((int)lhs <= (int)rhs) ? 1 : 0);
+                    break;
+                case '>':
+                    stack.push_back(((int)lhs > (int)rhs) ? 1 : 0);
+                    break;
+                case '}':
+                    stack.push_back(((int)lhs >= (int)rhs) ? 1 : 0);
+                    break;
+                case '=':
+                    stack.push_back(((int)lhs == (int)rhs) ? 1 : 0);
+                    break;
+                }
+            }
+        } break;
+
+        default:
+            return "";
+        }
+    }
+    if (stack.back() == (int)stack.back()) {
+        return (std::to_string((int)stack.back()));
+    }
+    return std::to_string(stack.back());
+}