[CIT-162] Implement Azure IoT Mapper (#242)

Implement Azure Mapper

Features:
- Azure Mapper takes Thin Edge JSON formatted input and coverts to Thin Edge JSON.
- It adds a timestamp when `azure.mapper.timestamp` is true in the tedge config.

Code changes:
- Add many files in tedge_mapper crate. 
- Now `tedge_mapper` requires one argument, c8y or az. Lauch by `tedge_mapper az`
- Add a key `azure.mapper.timestamp` in tedge config
- Give a temporary solution to add `az` to tedge-mapper systemd service.

5 files changed, 135 insertions, 1 deletions

diff --git a/tedge_config/src/models/flag.rs b/tedge_config/src/models/flag.rs
new file mode 100644
index 00000000..debdbe36
--- /dev/null
+++ b/tedge_config/src/models/flag.rs
@@ -0,0 +1,89 @@
+use std::convert::TryFrom;
+
+/// Represents a boolean type.
+///
+/// We need this newtype in order to implement `TryFrom<String>` and `TryInto<String>`.
+/// The `config_key!` macro uses query_string() and update_string().
+/// Therefore, boolean needs to be converted from/to String.
+#[derive(Debug, Clone, serde::Serialize, serde::Deserialize, Eq, PartialEq)]
+#[serde(transparent)]
+pub struct Flag(pub bool);
+
+#[derive(thiserror::Error, Debug)]
+#[error("Failed to parse flag: {input}. Supported values are: true, false")]
+pub struct InvalidFlag {
+    input: String,
+}
+
+impl TryFrom<String> for Flag {
+    type Error = InvalidFlag;
+
+    fn try_from(input: String) -> Result<Self, Self::Error> {
+        match input.as_str() {
+            "true" => Ok(Flag(true)),
+            "false" => Ok(Flag(false)),
+            _ => Err(InvalidFlag { input }),
+        }
+    }
+}
+
+impl From<Flag> for bool {
+    fn from(value: Flag) -> Self {
+        value.0
+    }
+}
+
+impl From<Flag> for String {
+    fn from(value: Flag) -> Self {
+        match value {
+            Flag(true) => "true".to_string(),
+            Flag(false) => "false".to_string(),
+        }
+    }
+}
+
+impl Flag {
+    pub fn is_set(&self) -> bool {
+        self.0
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use std::convert::TryInto;
+
+    #[test]
+    fn convert_string_true_to_bool_true() {
+        let input = "true".to_string();
+        let output: bool = Flag::try_from(input).unwrap().into();
+        assert_eq!(output, true);
+    }
+
+    #[test]
+    fn convert_string_false_to_bool_false() {
+        let input = "false".to_string();
+        let output: bool = Flag::try_from(input).unwrap().into();
+        assert_eq!(output, false);
+    }
+
+    #[test]
+    fn return_error_for_unexpected_string_input() {
+        let input = "unknown".to_string();
+        assert!(Flag::try_from(input).is_err());
+    }
+
+    #[test]
+    fn convert_bool_true_to_string_true() {
+        let input = true;
+        let output: String = Flag::try_into(Flag(input)).unwrap();
+        assert_eq!(output, "true");
+    }
+
+    #[test]
+    fn convert_bool_false_to_string_false() {
+        let input = false;
+        let output: String = Flag::try_into(Flag(input)).unwrap();
+        assert_eq!(output, "false");
+    }
+}
diff --git a/tedge_config/src/models/mod.rs b/tedge_config/src/models/mod.rs
index ce81e3af..9ea27a70 100644
--- a/tedge_config/src/models/mod.rs
+++ b/tedge_config/src/models/mod.rs
@@ -1,4 +1,5 @@
 pub mod connect_url;
 pub mod file_path;
+pub mod flag;
 
-pub use self::{connect_url::*, file_path::*};
+pub use self::{connect_url::*, file_path::*, flag::*};
diff --git a/tedge_config/src/settings.rs b/tedge_config/src/settings.rs
index f247cfe7..35092393 100644
--- a/tedge_config/src/settings.rs
+++ b/tedge_config/src/settings.rs
@@ -125,3 +125,22 @@ impl ConfigSetting for AzureRootCertPathSetting {
 
     type Value = FilePath;
 }
+
+///
+/// Boolean whether Azure mapper should add timestamp if timestamp is not added in the incoming payload.
+///
+/// Example: true
+///
+#[derive(Debug, Copy, Clone, Eq, PartialEq)]
+pub struct AzureMapperTimestamp;
+
+impl ConfigSetting for AzureMapperTimestamp {
+    const KEY: &'static str = "azure.mapper.timestamp";
+
+    const DESCRIPTION: &'static str = concat!(
+        "Boolean whether Azure mapper should add timestamp or not. ",
+        "Example: true"
+    );
+
+    type Value = Flag;
+}
diff --git a/tedge_config/src/tedge_config.rs b/tedge_config/src/tedge_config.rs
index 29f611f5..d4d2fbbd 100644
--- a/tedge_config/src/tedge_config.rs
+++ b/tedge_config/src/tedge_config.rs
@@ -177,6 +177,27 @@ impl ConfigSettingAccessor<AzureRootCertPathSetting> for TEdgeConfig {
     }
 }
 
+impl ConfigSettingAccessor<AzureMapperTimestamp> for TEdgeConfig {
+    fn query(&self, _setting: AzureMapperTimestamp) -> ConfigSettingResult<Flag> {
+        Ok(self
+            .data
+            .azure
+            .mapper_timestamp
+            .map(Flag)
+            .unwrap_or_else(|| Flag(true)))
+    }
+
+    fn update(&mut self, _setting: AzureMapperTimestamp, value: Flag) -> ConfigSettingResult<()> {
+        self.data.azure.mapper_timestamp = Some(value.into());
+        Ok(())
+    }
+
+    fn unset(&mut self, _setting: AzureMapperTimestamp) -> ConfigSettingResult<()> {
+        self.data.azure.mapper_timestamp = None;
+        Ok(())
+    }
+}
+
 impl ConfigSettingAccessor<C8yRootCertPathSetting> for TEdgeConfig {
     fn query(&self, _setting: C8yRootCertPathSetting) -> ConfigSettingResult<FilePath> {
         Ok(self
diff --git a/tedge_config/src/tedge_config_dto.rs b/tedge_config/src/tedge_config_dto.rs
index 6da6c74c..0d00ffbe 100644
--- a/tedge_config/src/tedge_config_dto.rs
+++ b/tedge_config/src/tedge_config_dto.rs
@@ -50,6 +50,9 @@ pub(crate) struct CumulocityConfigDto {
     /// The path where Cumulocity root certificate(s) are stored.
     /// The value can be a directory path as well as the path of the direct certificate file.
     pub(crate) root_cert_path: Option<FilePath>,
+
+    /// Boolean whether Azure mapper adds timestamp or not.
+    pub(crate) mapper_timestamp: Option<bool>,
 }
 
 #[derive(Debug, Default, Deserialize, Serialize)]
@@ -58,4 +61,5 @@ pub(crate) struct AzureConfigDto {
     pub(crate) connect: Option<String>,
     pub(crate) url: Option<ConnectUrl>,
     pub(crate) root_cert_path: Option<FilePath>,
+    pub(crate) mapper_timestamp: Option<bool>,
 }