cha-core 0.6.5

Core analysis engine for Cha — pluggable code smell detection
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use crate::{AnalysisContext, Finding, Location, Plugin, Severity, SmellCategory};

const PRIMITIVE_TYPES: &[&str] = &[
    "i8", "i16", "i32", "i64", "i128", "isize", "u8", "u16", "u32", "u64", "u128", "usize", "f32",
    "f64", "bool", "char", "String", "&str", "string", "number", "boolean", "any",
];

/// Detect functions where most parameters are primitive types.
pub struct PrimitiveObsessionAnalyzer {
    pub min_params: usize,
    pub primitive_ratio: f64,
}

impl Default for PrimitiveObsessionAnalyzer {
    fn default() -> Self {
        Self {
            min_params: 3,
            primitive_ratio: 0.8,
        }
    }
}

impl Plugin for PrimitiveObsessionAnalyzer {
    fn name(&self) -> &str {
        "primitive_obsession"
    }

    fn description(&self) -> &str {
        "Too many primitive parameter types"
    }

    fn analyze(&self, ctx: &AnalysisContext) -> Vec<Finding> {
        ctx.model
            .functions
            .iter()
            .filter(|f| {
                let total = f.parameter_types.len();
                if total < self.min_params {
                    return false;
                }
                let prim_count = f.parameter_types.iter().filter(|t| is_primitive(t)).count();
                (prim_count as f64 / total as f64) >= self.primitive_ratio
            })
            .map(|f| Finding {
                smell_name: "primitive_obsession".into(),
                category: SmellCategory::Bloaters,
                severity: Severity::Hint,
                location: Location {
                    path: ctx.file.path.clone(),
                    start_line: f.start_line,
                    end_line: f.end_line,
                    name: Some(f.name.clone()),
                },
                message: format!(
                    "Function `{}` uses mostly primitive parameter types",
                    f.name
                ),
                suggested_refactorings: vec![
                    "Replace Data Value with Object".into(),
                    "Replace Type Code with Class".into(),
                ],
            })
            .collect()
    }
}

fn is_primitive(ty: &str) -> bool {
    let base = ty.trim_start_matches('&').trim_start_matches("mut ").trim();
    // Strip generic parameters: Vec<String> → Vec
    let base = base.split('<').next().unwrap_or(base);
    PRIMITIVE_TYPES.contains(&base)
}