From 25fb288016645120ebdacce4bafd9d2016e86324 Mon Sep 17 00:00:00 2001
From: Trent Houliston <trent@houliston.me>
Date: Thu, 16 Mar 2023 09:20:18 +1100
Subject: [PATCH] Update the delta filter to take a percentage value as well as
 an absolute value (#4391)

---
 esphome/components/sensor/__init__.py | 16 ++++++++++++++--
 esphome/components/sensor/filter.cpp  | 14 +++++++++-----
 esphome/components/sensor/filter.h    |  6 ++++--
 esphome/config_validation.py          |  2 +-
 tests/test1.yaml                      |  1 +
 5 files changed, 29 insertions(+), 10 deletions(-)

diff --git a/esphome/components/sensor/__init__.py b/esphome/components/sensor/__init__.py
index d3cb39c2f6..821e0afac0 100644
--- a/esphome/components/sensor/__init__.py
+++ b/esphome/components/sensor/__init__.py
@@ -466,9 +466,21 @@ async def lambda_filter_to_code(config, filter_id):
     return cg.new_Pvariable(filter_id, lambda_)
 
 
-@FILTER_REGISTRY.register("delta", DeltaFilter, cv.float_)
+def validate_delta(config):
+    try:
+        return (cv.positive_float(config), False)
+    except cv.Invalid:
+        pass
+    try:
+        return (cv.percentage(config), True)
+    except cv.Invalid:
+        pass
+    raise cv.Invalid("Delta filter requires a positive number or percentage value.")
+
+
+@FILTER_REGISTRY.register("delta", DeltaFilter, validate_delta)
 async def delta_filter_to_code(config, filter_id):
-    return cg.new_Pvariable(filter_id, config)
+    return cg.new_Pvariable(filter_id, *config)
 
 
 @FILTER_REGISTRY.register("or", OrFilter, validate_filters)
diff --git a/esphome/components/sensor/filter.cpp b/esphome/components/sensor/filter.cpp
index 7a2c98109c..bf65ac590f 100644
--- a/esphome/components/sensor/filter.cpp
+++ b/esphome/components/sensor/filter.cpp
@@ -315,19 +315,23 @@ optional<float> ThrottleFilter::new_value(float value) {
 }
 
 // DeltaFilter
-DeltaFilter::DeltaFilter(float min_delta) : min_delta_(min_delta), last_value_(NAN) {}
+DeltaFilter::DeltaFilter(float delta, bool percentage_mode)
+    : delta_(delta), current_delta_(delta), percentage_mode_(percentage_mode), last_value_(NAN) {}
 optional<float> DeltaFilter::new_value(float value) {
   if (std::isnan(value)) {
     if (std::isnan(this->last_value_)) {
       return {};
     } else {
+      if (this->percentage_mode_) {
+        this->current_delta_ = fabsf(value * this->delta_);
+      }
       return this->last_value_ = value;
     }
   }
-  if (std::isnan(this->last_value_)) {
-    return this->last_value_ = value;
-  }
-  if (fabsf(value - this->last_value_) >= this->min_delta_) {
+  if (std::isnan(this->last_value_) || fabsf(value - this->last_value_) >= this->current_delta_) {
+    if (this->percentage_mode_) {
+      this->current_delta_ = fabsf(value * this->delta_);
+    }
     return this->last_value_ = value;
   }
   return {};
diff --git a/esphome/components/sensor/filter.h b/esphome/components/sensor/filter.h
index c17d14583b..b560545b76 100644
--- a/esphome/components/sensor/filter.h
+++ b/esphome/components/sensor/filter.h
@@ -325,12 +325,14 @@ class HeartbeatFilter : public Filter, public Component {
 
 class DeltaFilter : public Filter {
  public:
-  explicit DeltaFilter(float min_delta);
+  explicit DeltaFilter(float delta, bool percentage_mode);
 
   optional<float> new_value(float value) override;
 
  protected:
-  float min_delta_;
+  float delta_;
+  float current_delta_;
+  bool percentage_mode_;
   float last_value_{NAN};
 };
 
diff --git a/esphome/config_validation.py b/esphome/config_validation.py
index a46d14053b..469b7031f6 100644
--- a/esphome/config_validation.py
+++ b/esphome/config_validation.py
@@ -1097,7 +1097,7 @@ def possibly_negative_percentage(value):
     if isinstance(value, str):
         try:
             if value.endswith("%"):
-                has_percent_sign = False
+                has_percent_sign = True
                 value = float(value[:-1].rstrip()) / 100.0
             else:
                 value = float(value)
diff --git a/tests/test1.yaml b/tests/test1.yaml
index ef389ea712..0ff8b60ea2 100644
--- a/tests/test1.yaml
+++ b/tests/test1.yaml
@@ -392,6 +392,7 @@ sensor:
       - heartbeat: 5s
       - debounce: 0.1s
       - delta: 5.0
+      - delta: 1%
       - or:
           - throttle: 1s
           - delta: 5.0