plugin_measurement_filter: Make config type self-describing

This patch rewrites the configuration type to be self-describing and
adapts the `PluginBuilder` implementation to implement the
`PluginBuilder::kind_configuration()` interface.

Signed-off-by: Matthias Beyer <matthias.beyer@ifm.com>

4 files changed, 142 insertions, 2 deletions

diff --git a/plugins/plugin_measurement_filter/src/builder.rs b/plugins/plugin_measurement_filter/src/builder.rs
index 24f55759..6f3b2105 100644
--- a/plugins/plugin_measurement_filter/src/builder.rs
+++ b/plugins/plugin_measurement_filter/src/builder.rs
@@ -26,6 +26,10 @@ where
         "measurement_filter"
     }
 
+    fn kind_configuration() -> Option<tedge_api::ConfigDescription> {
+        Some(<MeasurementFilterConfig as tedge_api::AsConfig>::as_config())
+    }
+
     fn kind_message_types() -> HandleTypes
     where
         Self: Sized,
diff --git a/plugins/plugin_measurement_filter/src/config.rs b/plugins/plugin_measurement_filter/src/config.rs
index 46536bd3..f6e973de 100644
--- a/plugins/plugin_measurement_filter/src/config.rs
+++ b/plugins/plugin_measurement_filter/src/config.rs
@@ -1,12 +1,17 @@
-#[derive(Debug, serde::Deserialize)]
+#[derive(Debug, serde::Deserialize, tedge_api::Config)]
 #[serde_with::serde_as]
 pub struct MeasurementFilterConfig {
+    /// The name of the plugin to send the measurements to if the filter did not match its value
     pub(crate) target: String,
+
+    /// The name of the plugin to send measurements to if the filter matched its value
     pub(crate) filtered_target: Option<String>,
 
+    /// A path to find the value inside a measurement
     #[serde_as(as = "TryFromInto<String>")]
     pub(crate) extractor: crate::extractor::Extractor,
 
+    /// The filter to filter the measurements with
     #[serde(flatten)]
     pub(crate) filter: crate::filter::Filter,
 }
diff --git a/plugins/plugin_measurement_filter/src/extractor.rs b/plugins/plugin_measurement_filter/src/extractor.rs
index 08a533ba..a584b6c5 100644
--- a/plugins/plugin_measurement_filter/src/extractor.rs
+++ b/plugins/plugin_measurement_filter/src/extractor.rs
@@ -1,8 +1,30 @@
+use tedge_api::AsConfig;
+use tedge_api::ConfigKind;
 use tracing::trace;
 
 #[derive(Debug, serde_with::DeserializeFromStr)]
 pub struct Extractor(pub(crate) Vec<Token>);
 
+impl AsConfig for Extractor {
+    fn as_config() -> tedge_api::ConfigDescription {
+        tedge_api::ConfigDescription::new(
+            "Extractor".to_string(),
+            ConfigKind::String,
+            Some(indoc::indoc!{r#"
+                A path to extract a value from a measurement
+
+                # Examples
+
+                To extract the member "celcius" from a measurement named "temperature":
+
+                ```
+                temperature.celcius
+                ```
+            "#})
+        )
+    }
+}
+
 impl From<Extractor> for String {
     fn from(e: Extractor) -> String {
         e.0.iter().map(Token::to_string).collect()
diff --git a/plugins/plugin_measurement_filter/src/filter.rs b/plugins/plugin_measurement_filter/src/filter.rs
index 7ccf7341..3b81204e 100644
--- a/plugins/plugin_measurement_filter/src/filter.rs
+++ b/plugins/plugin_measurement_filter/src/filter.rs
@@ -1,3 +1,4 @@
+use tedge_api::AsConfig;
 use tedge_lib::measurement::MeasurementValue;
 use tracing::trace;
 
@@ -20,6 +21,115 @@ pub enum Filter {
     Excludes(String),
 }
 
+impl AsConfig for Filter {
+    fn as_config() -> tedge_api::ConfigDescription {
+        tedge_api::ConfigDescription::new(
+            "Filter".to_string(),
+            tedge_api::ConfigKind::Enum(
+                tedge_api::config::ConfigEnumKind::Untagged,
+                vec![
+                    (
+                        "is",
+                        Some(indoc::indoc!(
+                            r#"
+                            Filter with a boolean comparison
+
+                            ## Example
+
+                            To check whether the measurement value is true:
+
+                            ```
+                            is = true
+                            ```
+                        "#
+                        )),
+                        tedge_api::config::EnumVariantRepresentation::Wrapped(Box::new(
+                            bool::as_config(),
+                        )),
+                    ),
+                    (
+                        "less_than",
+                        Some(indoc::indoc!(
+                            r#"
+                            Filter with a less-than comparison
+
+                            ## Example
+
+                            To check whether the measurement value is less than 5.0:
+
+                            ```
+                            less_than = 5.0
+                            ```
+                        "#
+                        )),
+                        tedge_api::config::EnumVariantRepresentation::Wrapped(Box::new(
+                            f64::as_config(),
+                        )),
+                    ),
+                    (
+                        "more_than",
+                        Some(indoc::indoc!(
+                            r#"
+                            Filter with a more-than comparison
+
+                            ## Example
+
+                            To check whether the measurement value is more than 12.0:
+
+                            ```
+                            more_than = 12.0
+                            ```
+                        "#
+                        )),
+                        tedge_api::config::EnumVariantRepresentation::Wrapped(Box::new(
+                            f64::as_config(),
+                        )),
+                    ),
+                    (
+                        "contains",
+                        Some(indoc::indoc!(
+                            r#"
+                            Filter by checking whether a substring is present in the measurement
+
+                            ## Example
+
+                            To check whether the measurement contains "foo"
+
+                            ```
+                            contains = "foo"
+                            ```
+                        "#
+                        )),
+                        tedge_api::config::EnumVariantRepresentation::Wrapped(Box::new(
+                            String::as_config(),
+                        )),
+                    ),
+                    (
+                        "excludes",
+                        Some(indoc::indoc!(
+                            r#"
+                            Filter by checking whether a substring is absent in the measurement
+
+                            ## Example
+
+                            To check whether the measurement does not contain "bar"
+
+                            ```
+                            excludes = "bar"
+                            ```
+                        "#
+                        )),
+                        tedge_api::config::EnumVariantRepresentation::Wrapped(Box::new(
+                            String::as_config(),
+                        )),
+                    ),
+                ],
+            ),
+            None,
+        )
+    }
+}
+
 pub trait Filterable {
     fn apply_filter(&self, filter: &Filter) -> bool;
 }
@@ -118,5 +228,4 @@ mod tests {
         let filt = Filter::Is(true);
         assert!(!msmt.apply_filter(&filt));
     }
-
 }