Refactor prom client

src/prom.rs

@@ -41,10 +41,19 @@ struct MatrixEntry {
     values: Vec<(f64, String)>,
 }
 
-pub fn current_power(base: &str) -> Result<(f64, f64, f64)> {
+pub struct PromClient {
-    let url = format!("{}{}", base, PROM_QUERY);
+    base: String,
+    power_query_url: String
+}
 
-    let reply: PromReply = ureq::get(&url).call()?.into_json()?;
+impl PromClient {
+    pub fn new(base: String) -> Self {
+        let power_query_url = format!("{}{}", &base, PROM_QUERY);
+        PromClient { base, power_query_url }
+    }
+
+    pub fn current_power(&self) -> Result<(f64, f64, f64)> {
+        let reply: PromReply = ureq::get(&self.power_query_url).call()?.into_json()?;
 
         let PromReply::Success {
             data: PromData::Vector(v),
@@ -71,3 +80,5 @@ pub fn current_power(base: &str) -> Result<(f64, f64, f64)> {
             r.2.ok_or_else(|| anyhow!("Missing phase c"))?,
         ))
 }
+
+}