badness 0.5.0

//! `duplicate-label`: a `\label{key}` defined more than once in the same label
//! namespace — within one file, or across files that share a document (the
//! cross-file branch, when a [`ResolvedLabels`] is available).
//!
//! LaTeX itself only *warns* on multiply-defined labels (and silently uses the
//! last), so this is a [`Severity::Warning`], not an error. The cross-file branch
//! needs no closed/rooted gate: a key defined in two analyzed files is a true
//! duplicate regardless of any unanalyzed includes (adding files only reveals
//! *more* duplicates).
//!
//! [`ResolvedLabels`]: crate::project::ResolvedLabels

use std::collections::HashMap;
use std::path::PathBuf;

use crate::linter::diagnostic::{Diagnostic, Severity};

use super::{Rule, RuleContext};

pub struct DuplicateLabel;

impl Rule for DuplicateLabel {
    fn id(&self) -> &'static str {
        "duplicate-label"
    }

    fn default_severity(&self) -> Severity {
        Severity::Warning
    }

    fn check_file(&self, ctx: &RuleContext<'_>, sink: &mut Vec<Diagnostic>) {
        // Count occurrences of each key. Within a file, flag every definition
        // past the first — the first is the "canonical" one LaTeX would keep.
        // On a key's *first* occurrence in this file, the cross-file branch
        // instead checks whether another file in the namespace defines it (the
        // intra-file branch already owns the 2nd+ occurrences, so no overlap).
        let mut seen: HashMap<&str, usize> = HashMap::new();
        for label in ctx.model.labels() {
            let count = seen.entry(label.name.as_str()).or_insert(0);
            *count += 1;
            let message = if *count > 1 {
                Some(format!("label `{}` is defined more than once", label.name))
            } else {
                ctx.resolution
                    .and_then(|resolution| cross_file_message(ctx, resolution, &label.name))
            };
            if let Some(message) = message {
                sink.push(Diagnostic {
                    rule: self.id(),
                    severity: self.default_severity(),
                    path: PathBuf::new(),
                    start: usize::from(label.range.start()),
                    end: usize::from(label.range.end()),
                    message,
                    fix: None,
                });
            }
        }
    }
}

/// The "also defined in …" message when `name` is defined in another file of
/// `ctx.path`'s namespace, or `None` when it is unique across files. Other
/// definers are sorted (from [`ResolvedLabels`]) so the message is deterministic.
fn cross_file_message(
    ctx: &RuleContext<'_>,
    resolution: &crate::project::ResolvedLabels,
    name: &str,
) -> Option<String> {
    let others: Vec<String> = resolution
        .definers(ctx.path, name)
        .iter()
        .filter(|definer| definer.as_path() != ctx.path)
        .map(|definer| format!("`{}`", definer.display()))
        .collect();
    if others.is_empty() {
        return None;
    }
    Some(format!(
        "label `{name}` is also defined in {}",
        others.join(", ")
    ))
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::parser::parse;
    use crate::semantic::SemanticModel;
    use crate::syntax::SyntaxNode;

    fn findings(src: &str) -> Vec<Diagnostic> {
        let root = SyntaxNode::new_root(parse(src).green);
        let model = SemanticModel::build(&root);
        let ctx = RuleContext {
            path: std::path::Path::new("x.tex"),
            root: &root,
            model: &model,
            resolution: None,
            citations: None,
        };
        let mut out = Vec::new();
        DuplicateLabel.check_file(&ctx, &mut out);
        out
    }

    #[test]
    fn flags_only_the_second_definition() {
        let src = "\\label{a}\\label{a}\n";
        let out = findings(src);
        assert_eq!(out.len(), 1);
        assert_eq!(out[0].rule, "duplicate-label");
        // Points tightly at the second `\label{a}` (bytes 9..18), not beyond.
        assert_eq!((out[0].start, out[0].end), (9, 18));
    }

    #[test]
    fn caret_excludes_an_over_attached_second_group() {
        // The greedy parser attaches `{x}` as a spurious second arg to the
        // duplicate `\label{a}`; the caret must still stop at the key group.
        let out = findings("\\label{a}\\label{a}\n{x}\n");
        assert_eq!(out.len(), 1);
        assert_eq!((out[0].start, out[0].end), (9, 18));
    }

    #[test]
    fn distinct_keys_are_fine() {
        assert!(findings("\\label{a}\\label{b}\n").is_empty());
    }

    #[test]
    fn three_definitions_flag_two() {
        assert_eq!(findings("\\label{a}\\label{a}\\label{a}\n").len(), 2);
    }

    // --- Cross-file branch (needs a `ResolvedLabels`) -----------------------

    use crate::project::ResolvedLabels;
    use crate::project::graph::{FileFacts, IncludeGraph};
    use smol_str::SmolStr;

    /// A two-file namespace (`main.tex` `\input`s `other.tex`), each defining the
    /// labels given. Both share one component, so a key in both is a cross-file
    /// duplicate.
    fn two_file_resolution(main_labels: &[&str], other_labels: &[&str]) -> ResolvedLabels {
        let graph = IncludeGraph::build(
            &[
                FileFacts {
                    path: PathBuf::from("main.tex"),
                    include_edges: vec![crate::project::IncludeEdgeKey {
                        kind: crate::project::IncludeKind::Input,
                        target: crate::project::IncludeTarget::Path(PathBuf::from("other.tex")),
                    }],
                },
                FileFacts {
                    path: PathBuf::from("other.tex"),
                    include_edges: Vec::new(),
                },
            ],
            None,
        );
        let names = |list: &[&str]| list.iter().map(SmolStr::new).collect::<Vec<_>>();
        ResolvedLabels::build(
            &[
                (PathBuf::from("main.tex"), names(main_labels), true),
                (PathBuf::from("other.tex"), names(other_labels), false),
            ],
            &graph,
        )
    }

    fn cross_findings(src: &str, path: &str, resolution: &ResolvedLabels) -> Vec<Diagnostic> {
        let root = SyntaxNode::new_root(parse(src).green);
        let model = SemanticModel::build(&root);
        let ctx = RuleContext {
            path: std::path::Path::new(path),
            root: &root,
            model: &model,
            resolution: Some(resolution),
            citations: None,
        };
        let mut out = Vec::new();
        DuplicateLabel.check_file(&ctx, &mut out);
        out
    }

    #[test]
    fn cross_file_duplicate_names_the_other_file() {
        let r = two_file_resolution(&["shared"], &["shared"]);
        let out = cross_findings("\\label{shared}\n", "main.tex", &r);
        assert_eq!(out.len(), 1);
        assert_eq!(out[0].rule, "duplicate-label");
        assert!(
            out[0].message.contains("also defined in `other.tex`"),
            "got: {}",
            out[0].message
        );
    }

    #[test]
    fn cross_file_unique_key_is_fine() {
        let r = two_file_resolution(&["only-main"], &["only-other"]);
        assert!(cross_findings("\\label{only-main}\n", "main.tex", &r).is_empty());
    }

    #[test]
    fn intra_and_cross_file_do_not_double_report_first_occurrence() {
        // `dup` appears twice in main AND once in other. The first occurrence is
        // flagged cross-file ("also defined in other"); the second intra-file
        // ("defined more than once"). Two findings, distinct messages.
        let r = two_file_resolution(&["dup"], &["dup"]);
        let out = cross_findings("\\label{dup}\\label{dup}\n", "main.tex", &r);
        assert_eq!(out.len(), 2);
        assert!(out[0].message.contains("also defined in"));
        assert!(out[1].message.contains("defined more than once"));
    }
}