rigsql-rules 0.7.0

use rigsql_core::{Segment, SegmentType};

use crate::rule::{CrawlType, Rule, RuleContext, RuleGroup};
use crate::utils::first_non_trivia;
use crate::violation::{LintViolation, SourceEdit};

/// CV02: Use COALESCE instead of IFNULL or NVL.
///
/// COALESCE is ANSI standard and portable across databases.
#[derive(Debug, Default)]
pub struct RuleCV02;

impl Rule for RuleCV02 {
    fn code(&self) -> &'static str {
        "CV02"
    }
    fn name(&self) -> &'static str {
        "convention.coalesce"
    }
    fn description(&self) -> &'static str {
        "Use COALESCE instead of IFNULL or NVL."
    }
    fn explanation(&self) -> &'static str {
        "COALESCE is the ANSI SQL standard function for handling NULL values. \
         IFNULL (MySQL) and NVL (Oracle) are database-specific alternatives. \
         Using COALESCE improves portability and consistency."
    }
    fn groups(&self) -> &[RuleGroup] {
        &[RuleGroup::Convention]
    }
    fn is_fixable(&self) -> bool {
        true
    }

    fn crawl_type(&self) -> CrawlType {
        CrawlType::Segment(vec![SegmentType::FunctionCall])
    }

    fn eval(&self, ctx: &RuleContext) -> Vec<LintViolation> {
        let children = ctx.segment.children();

        // First non-trivia child should be the function name
        let func_name = first_non_trivia(children);

        if let Some(Segment::Token(t)) = func_name {
            let name = t.token.text.as_str();
            if name.eq_ignore_ascii_case("IFNULL") || name.eq_ignore_ascii_case("NVL") {
                return vec![LintViolation::with_fix_and_msg_key(
                    self.code(),
                    format!("Use COALESCE instead of '{}'.", name),
                    t.token.span,
                    vec![SourceEdit::replace(t.token.span, "COALESCE")],
                    "rules.CV02.msg",
                    vec![("name".to_string(), name.to_string())],
                )];
            }
        }

        vec![]
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::test_utils::lint_sql;

    #[test]
    fn test_cv02_flags_ifnull() {
        let violations = lint_sql("SELECT IFNULL(a, 0) FROM t", RuleCV02);
        assert_eq!(violations.len(), 1);
        assert_eq!(violations[0].fixes.len(), 1);
        assert_eq!(violations[0].fixes[0].new_text, "COALESCE");
    }

    #[test]
    fn test_cv02_flags_nvl() {
        let violations = lint_sql("SELECT NVL(a, 0) FROM t", RuleCV02);
        assert_eq!(violations.len(), 1);
        assert_eq!(violations[0].fixes[0].new_text, "COALESCE");
    }

    #[test]
    fn test_cv02_accepts_coalesce() {
        let violations = lint_sql("SELECT COALESCE(a, 0) FROM t", RuleCV02);
        assert_eq!(violations.len(), 0);
    }
}