use oxc_ast::ast::Program;
use oxc_ast_visit::Visit;
use oxc_ast_visit::walk::walk_statement;
use oxc_semantic::Semantic;
use oxc_span::GetSpan;
use crate::rules::{Rule, RuleFinding, RuleMeta, Severity};
pub struct NoDeepNesting;
const RULE_META: RuleMeta = RuleMeta {
id: "no-deep-nesting",
default_severity: Severity::Warning,
category: "quality",
description: "Avoid nesting deeper than 4 levels",
};
const MAX_DEPTH: usize = 4;
impl Rule for NoDeepNesting {
fn meta(&self) -> &RuleMeta {
&RULE_META
}
fn run(&self, program: &Program, _semantic: &Semantic, source_text: &str) -> Vec<RuleFinding> {
let mut collector = NestingCollector {
findings: Vec::new(),
source: source_text,
depth: 0,
};
collector.visit_program(program);
collector.findings
}
}
struct NestingCollector<'a> {
findings: Vec<RuleFinding>,
source: &'a str,
depth: usize,
}
impl<'a> Visit<'a> for NestingCollector<'a> {
fn visit_statement(&mut self, stmt: &oxc_ast::ast::Statement<'a>) {
let is_nesting = matches!(
stmt,
oxc_ast::ast::Statement::IfStatement(_)
| oxc_ast::ast::Statement::ForStatement(_)
| oxc_ast::ast::Statement::ForInStatement(_)
| oxc_ast::ast::Statement::ForOfStatement(_)
| oxc_ast::ast::Statement::WhileStatement(_)
| oxc_ast::ast::Statement::DoWhileStatement(_)
| oxc_ast::ast::Statement::SwitchStatement(_)
);
if is_nesting {
self.depth += 1;
if self.depth > MAX_DEPTH {
let start = stmt.span().start as usize;
let line = self.source[..start].lines().count().max(1);
let col = start - self.source[..start].rfind('\n').map(|i| i + 1).unwrap_or(0);
self.findings.push(RuleFinding {
line,
column: col + 1,
message: format!(
"Nesting depth {depth} exceeds max {MAX_DEPTH}",
depth = self.depth
),
});
}
walk_statement(self, stmt);
self.depth -= 1;
} else {
walk_statement(self, stmt);
}
}
}