Fix confusion with accel-to-decel/minimum-cruise-ratio config option

As documented in #61 and #62, there are issues with the config being all
wrong when reading this. It appears to be caused by some kind of
internal data race in Config. Refactor to have separate fields for the
two options and recalculate accel_to_decel as appropriate.

lib/src/planner.rs

@@ -734,8 +734,10 @@ impl MoveSequence {
 pub struct PrinterLimits {
     pub max_velocity: f64,
     pub max_acceleration: f64,
-    #[serde(flatten)]
-    pub max_accel_to_decel: AccelToDecel,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub max_accel_to_decel: Option<f64>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub minimum_cruise_ratio: Option<f64>,
     pub square_corner_velocity: f64,
     #[serde(skip)]
     pub junction_deviation: f64,
@@ -749,29 +751,13 @@ pub struct PrinterLimits {
     pub move_checkers: Vec<MoveChecker>,
 }
 
-#[derive(Debug, Copy, Clone, Serialize, Deserialize, PartialEq)]
-pub enum AccelToDecel {
-    #[serde(rename = "max_accel_to_decel")]
-    Static(f64),
-    #[serde(rename = "minimum_cruise_ratio")]
-    CruiseRatio(f64),
-}
-
-impl AccelToDecel {
-    pub fn to_absolute(&self, accel: f64) -> f64 {
-        match self {
-            Self::Static(v) => v.min(accel),
-            Self::CruiseRatio(v) => accel * (1.0 - v.clamp(0.0, 1.0)),
-        }
-    }
-}
-
 impl Default for PrinterLimits {
     fn default() -> Self {
         PrinterLimits {
             max_velocity: 100.0,
             max_acceleration: 100.0,
-            max_accel_to_decel: AccelToDecel::Static(50.0),
+            max_accel_to_decel: Some(50.0),
+            minimum_cruise_ratio: None,
             square_corner_velocity: 5.0,
             junction_deviation: Self::scv_to_jd(5.0, 100000.0),
             accel_to_decel: 50.0,
@@ -796,15 +782,18 @@ impl PrinterLimits {
     pub fn set_max_acceleration(&mut self, v: f64) {
         self.max_acceleration = v;
         self.update_junction_deviation();
+        self.update_accel_to_decel();
     }
 
     pub fn set_max_accel_to_decel(&mut self, v: f64) {
-        self.max_accel_to_decel = AccelToDecel::Static(v);
+        self.max_accel_to_decel = Some(v);
+        self.minimum_cruise_ratio = None;
         self.update_accel_to_decel();
     }
 
     pub fn set_minimum_cruise_ratio(&mut self, v: f64) {
-        self.max_accel_to_decel = AccelToDecel::CruiseRatio(v.clamp(0.0, 1.0));
+        self.max_accel_to_decel = None;
+        self.minimum_cruise_ratio = Some(v.clamp(0.0, 1.0));
         self.update_accel_to_decel();
     }
 
@@ -828,7 +817,11 @@ impl PrinterLimits {
     }
 
     fn update_accel_to_decel(&mut self) {
-        self.accel_to_decel = self.max_accel_to_decel.to_absolute(self.max_acceleration);
+        self.accel_to_decel = match (self.minimum_cruise_ratio, self.max_accel_to_decel) {
+            (Some(v), _) => self.max_acceleration * (1.0 - v.clamp(0.0, 1.0)),
+            (_, Some(v)) => v.min(self.max_acceleration),
+            _ => 50.0f64.min(self.max_acceleration),
+        }
     }
 }
 

tool/src/main.rs

@@ -81,12 +81,7 @@ impl Opts {
     fn load_config(&self) -> anyhow::Result<PrinterLimits> {
         use config::Config;
 
-        let builder = Config::builder()
-            .set_default(
-                "max_accel_to_decel",
-                Value::new(None, ValueKind::Float(50.0)),
-            )
-            .unwrap();
+        let builder = Config::builder();
 
         let builder = if let Some(url) = &self.config_moonraker {
             builder.add_source(MoonrakerSource::new(