1 files changed, 171 insertions, 0 deletions
diff --git a/crates/typologies/src/processor/typology/evaluate_expression.rs b/crates/typologies/src/processor/typology/evaluate_expression.rs
new file mode 100644
index 0000000..844011e
--- /dev/null
+++ b/crates/typologies/src/processor/typology/evaluate_expression.rs
@@ -0,0 +1,171 @@
+use anyhow::Result;
+use tracing::warn;
+use warden_core::{configuration::typology::TypologyConfiguration, message::TypologyResult};
+
+pub(super) fn evaluate_expression(
+    typology_result: &mut TypologyResult,
+    typology_config: &TypologyConfiguration,
+) -> Result<f64> {
+    let mut to_return = 0.0;
+    let expression = typology_config
+        .expression
+        .as_ref()
+        .expect("expression is missing");
+
+    let rule_values = &typology_config.rules;
+
+    for rule in expression.terms.iter() {
+        let rule_result = typology_result
+            .rule_results
+            .iter()
+            .find(|value| value.id.eq(&rule.id) && value.version.eq(&rule.version));
+
+        if rule_result.is_none() {
+            warn!(term = ?rule, "could not find rule result for typology term");
+            return Ok(Default::default());
+        }
+
+        let rule_result = rule_result.expect("checked and is some");
+
+        let weight = rule_values
+            .iter()
+            .filter_map(|rv| {
+                if !(rv.id.eq(&rule_result.id) && rv.version.eq(&rule_result.version)) {
+                    None
+                } else {
+                    rv.wghts.iter().find_map(|value| {
+                        match value.r#ref.eq(&rule_result.sub_rule_ref) {
+                            true => Some(value.wght),
+                            false => None,
+                        }
+                    })
+                }
+            })
+            .next();
+
+        if weight.is_none() {
+            warn!(rule = ?rule, "could not find a weight for the matching rule");
+        }
+        let weight = weight.unwrap_or_default();
+
+        to_return = match expression.operator() {
+            warden_core::configuration::typology::Operator::Add => to_return + weight,
+            warden_core::configuration::typology::Operator::Multiply => to_return * weight,
+            warden_core::configuration::typology::Operator::Subtract => to_return - weight,
+            warden_core::configuration::typology::Operator::Divide => {
+                if weight.ne(&0.0) {
+                    to_return / weight
+                } else {
+                    to_return
+                }
+            }
+        };
+    }
+    Ok(to_return)
+}
+
+#[cfg(test)]
+mod tests {
+    use warden_core::{
+        configuration::typology::{Expression, Operator, Term, TypologyRule, TypologyRuleWeight},
+        message::RuleResult,
+    };
+
+    use super::*;
+
+    fn make_rule_result(id: &str, version: &str, sub_ref: &str) -> RuleResult {
+        RuleResult {
+            id: id.to_string(),
+            version: version.to_string(),
+            sub_rule_ref: sub_ref.to_string(),
+            ..Default::default()
+        }
+    }
+
+    fn make_rule_value(id: &str, version: &str, ref_name: &str, weight: f64) -> TypologyRule {
+        TypologyRule {
+            id: id.to_string(),
+            version: version.to_string(),
+            wghts: vec![TypologyRuleWeight {
+                r#ref: ref_name.to_string(),
+                wght: weight,
+            }],
+        }
+    }
+
+    fn make_expression(terms: Vec<(&str, &str)>, op: Operator) -> Expression {
+        Expression {
+            terms: terms
+                .into_iter()
+                .map(|(id, version)| Term {
+                    id: id.to_string(),
+                    version: version.to_string(),
+                })
+                .collect(),
+            operator: op.into(),
+        }
+    }
+
+    #[test]
+    fn test_add_operator_multiple_terms() {
+        let mut typology_result = TypologyResult {
+            rule_results: vec![
+                make_rule_result("R1", "v1", "sub1"),
+                make_rule_result("R2", "v1", "sub2"),
+            ],
+            ..Default::default()
+        };
+
+        let config = TypologyConfiguration {
+            expression: Some(make_expression(
+                vec![("R1", "v1"), ("R2", "v1")],
+                Operator::Add,
+            )),
+            rules: vec![
+                make_rule_value("R1", "v1", "sub1", 10.0),
+                make_rule_value("R2", "v1", "sub2", 5.0),
+            ],
+            ..Default::default()
+        };
+
+        let result = evaluate_expression(&mut typology_result, &config).unwrap();
+        assert_eq!(result, 15.0);
+    }
+
+    #[test]
+    fn test_missing_rule_result_returns_zero() {
+        let mut typology_result = TypologyResult {
+            rule_results: vec![make_rule_result("R1", "v1", "sub1")],
+            ..Default::default()
+        };
+
+        let config = TypologyConfiguration {
+            expression: Some(make_expression(
+                vec![("R1", "v1"), ("R2", "v1")],
+                Operator::Add,
+            )),
+            rules: vec![make_rule_value("R1", "v1", "sub1", 10.0)],
+            ..Default::default()
+        };
+
+        let result = evaluate_expression(&mut typology_result, &config).unwrap();
+        assert_eq!(result, 0.0);
+    }
+
+    #[test]
+    fn test_missing_weight_defaults_to_zero() {
+        let mut typology_result = TypologyResult {
+            rule_results: vec![make_rule_result("R1", "v1", "subX")], // sub_ref doesn't match
+            ..Default::default()
+        };
+
+        let config = TypologyConfiguration {
+            expression: Some(make_expression(vec![("R1", "v1")], Operator::Add)),
+            rules: vec![make_rule_value("R1", "v1", "sub1", 10.0)], // different ref
+            ..Default::default()
+        };
+
+        let result = evaluate_expression(&mut typology_result, &config).unwrap();
+        assert_eq!(result, 0.0);
+    }
+}