rumdl_lib/utils/

fix_utils.rs

//! Utilities for applying fixes consistently between CLI and LSP
//!
//! This module provides shared logic for applying markdown fixes to ensure
//! that both CLI batch fixes and LSP individual fixes produce identical results.

use crate::inline_config::InlineConfig;
use crate::rule::{Fix, LintWarning};
use std::borrow::Cow;
use std::ops::Range;

/// Filter warnings by inline config, removing those on disabled lines.
///
/// Replicates the same filtering logic used in the check/reporting path
/// (`src/lib.rs`) so that fix mode respects inline disable comments.
pub fn filter_warnings_by_inline_config(
    warnings: Vec<LintWarning>,
    inline_config: &InlineConfig,
    rule_name: &str,
) -> Vec<LintWarning> {
    warnings
        .into_iter()
        .filter(|warning| warning_is_enabled(warning, inline_config, rule_name))
        .collect()
}

/// The fix engine's eligibility test, independent of diagnostic presentation.
pub(crate) fn warning_is_enabled(warning: &LintWarning, inline_config: &InlineConfig, rule_name: &str) -> bool {
    let base_rule_name = if let Some(dash_pos) = rule_name.find('-') {
        // Handle sub-rules like "MD029-style" -> "MD029"
        // But only if the prefix looks like a rule ID (starts with "MD")
        let prefix = &rule_name[..dash_pos];
        if prefix.starts_with("MD") { prefix } else { rule_name }
    } else {
        rule_name
    };

    let end = warning.end_line.max(warning.line);
    !(warning.line..=end).any(|line| inline_config.is_rule_disabled(base_rule_name, line))
}

/// Apply a list of warning fixes to content, simulating how the LSP client would apply them
/// This is used for testing consistency between CLI and LSP fix methods
pub fn apply_warning_fixes(content: &str, warnings: &[LintWarning]) -> Result<String, String> {
    apply_edits(content, warnings.iter().filter_map(|warning| warning.fix.as_ref())).map(Cow::into_owned)
}

/// Apply source edits without requiring diagnostics or copying an unchanged
/// document. Warning and engine callers share ordering, overlap, UTF-8 and EOL
/// handling through this one implementation.
pub(crate) fn apply_edits<'a, 'f>(
    content: &'a str,
    edits: impl Iterator<Item = &'f Fix>,
) -> Result<Cow<'a, str>, String> {
    let mut fixes: Vec<(usize, &Fix)> = edits
        .enumerate()
        .flat_map(|(i, fix)| {
            // A logical fix may carry additional edits at separate ranges
            // (e.g. MD054 ref-emit fixes that rewrite a link in place AND
            // append a new ref definition at EOF). Flatten so each edit
            // participates in the same dedup/sort/apply pipeline.
            std::iter::once((i, fix)).chain(fix.additional_edits.iter().map(move |e| (i, e)))
        })
        .collect();

    // No-op fast path: if there are no actual fixes to apply, return the
    // content unchanged. This avoids unnecessary line-ending normalization
    // when all warnings were filtered out (e.g., by inline config) or had
    // no fix attached.
    if fixes.is_empty() {
        return Ok(Cow::Borrowed(content));
    }

    // Sort ascending so the dedup/coalesce pass sees fixes that share a range
    // as adjacent neighbors. Tie-break on warning index so declaration order
    // is preserved when we later concatenate same-offset zero-width inserts.
    fixes.sort_by(|(idx_a, fix_a), (idx_b, fix_b)| {
        let range_cmp = fix_a.range.start.cmp(&fix_b.range.start);
        if range_cmp != std::cmp::Ordering::Equal {
            return range_cmp;
        }
        let end_cmp = fix_a.range.end.cmp(&fix_b.range.end);
        if end_cmp != std::cmp::Ordering::Equal {
            return end_cmp;
        }
        idx_a.cmp(idx_b)
    });

    // Dedup identical (range, replacement) pairs AND coalesce same-offset
    // zero-width inserts into a single logical edit by concatenating their
    // replacements in declaration order.
    //
    // The coalesce step is required because `replace_range(N..N, X)` followed
    // by `replace_range(N..N, Y)` on the *same* document position produces
    // `Y X` — `X` is already at offset N when `Y` inserts, so `Y` lands
    // before it. With per-warning insertion (e.g., several MD054 ref-emit
    // fixes appending different `[label]: url` definitions at EOF), that
    // would reverse declaration order. Concatenating up front gives one
    // `replace_range(N..N, X + Y)` that lands `X` then `Y` in source order.
    let mut applicable: Vec<ApplicableEdit<'_>> = Vec::with_capacity(fixes.len());
    let mut i = 0;
    while i < fixes.len() {
        let (_, current) = fixes[i];
        let mut combined: Option<String> = None;
        let is_zero_width = current.range.start == current.range.end;
        let mut j = i + 1;
        while j < fixes.len() {
            let (_, next) = fixes[j];
            if next.range != current.range {
                break;
            }
            if next.replacement == current.replacement {
                // Pure duplicate — drop and continue scanning siblings.
                j += 1;
                continue;
            }
            if !is_zero_width {
                // Two different replacements competing for the same non-zero
                // range is a rule-authoring bug at the call site, not something
                // we can sensibly merge. Stop here so the apply loop sees only
                // the first replacement (matching prior behavior).
                break;
            }
            // Zero-width inserts at the same offset: concatenate.
            let buf = combined.get_or_insert_with(|| current.replacement.clone());
            buf.push_str(&next.replacement);
            j += 1;
        }

        applicable.push(ApplicableEdit {
            range: current.range.clone(),
            replacement: match combined {
                Some(owned) => Cow::Owned(owned),
                None => Cow::Borrowed(current.replacement.as_str()),
            },
        });
        i = j;
    }

    // Reverse-sort by range start so earlier-offset edits stay valid as later
    // ones mutate the buffer. Coalescing collapsed the previous tertiary
    // tiebreak case, so a simple two-key sort is enough.
    applicable.sort_by(|a, b| {
        let cmp = b.range.start.cmp(&a.range.start);
        if cmp != std::cmp::Ordering::Equal {
            return cmp;
        }
        b.range.end.cmp(&a.range.end)
    });

    // The edits that survive, collected last to first and assembled in one
    // forward pass, so applying many fixes costs one copy of the document
    // rather than a shift of its tail per edit.
    let mut kept: Vec<ApplicableEdit<'_>> = Vec::with_capacity(applicable.len());

    // Track the lowest byte offset touched by an already-applied fix.
    // Since fixes are sorted in reverse order (highest start first),
    // any subsequent fix whose range.end > min_applied_start would
    // overlap with an already-applied fix and corrupt the result.
    let mut min_applied_start = usize::MAX;

    for edit in applicable {
        // Every range addresses the content as the rule saw it, so validate against
        // that and not the buffer edits have already shrunk. Measuring the mutated
        // buffer rejected ranges that were merely about to be skipped as
        // overlapping, and the whole document's fix failed instead: MD039 declined
        // to fix `[ a ![ x ](i.png) b ](t.md)` at all, and whether it did depended
        // on how much unrelated text the document held after that line.
        if edit.range.end > content.len() {
            return Err(format!(
                "Fix range end {} exceeds content length {}",
                edit.range.end,
                content.len()
            ));
        }

        if edit.range.start > edit.range.end {
            return Err(format!(
                "Invalid fix range: start {} > end {}",
                edit.range.start, edit.range.end
            ));
        }

        // Reject ranges that do not lie on UTF-8 char boundaries. replace_range
        // would panic on such a range; a rule emitting one is a bug, so surface
        // it as an error rather than corrupting or crashing on the document.
        if !content.is_char_boundary(edit.range.start) || !content.is_char_boundary(edit.range.end) {
            return Err(format!(
                "Fix range {}..{} does not lie on UTF-8 char boundaries",
                edit.range.start, edit.range.end
            ));
        }

        // Skip fixes that overlap with an already-applied fix to prevent
        // offset corruption (e.g., nested link/image constructs in MD039).
        if edit.range.end > min_applied_start {
            continue;
        }

        min_applied_start = edit.range.start;
        kept.push(edit);
    }

    let growth: usize = kept.iter().map(|edit| edit.replacement.len()).sum();
    let mut result = String::with_capacity(content.len() + growth);
    let mut copied = 0;
    for edit in kept.iter().rev() {
        result.push_str(&content[copied..edit.range.start]);
        result.push_str(&edit.replacement);
        copied = edit.range.end;
    }
    result.push_str(&content[copied..]);

    // Ensure line endings are consistent with the original document
    let result = super::line_ending::LineEndingPolicy::new(content).apply_owned(result);
    Ok(Cow::Owned(result))
}

/// One physical edit ready to apply. Either passes through a single `Fix`'s
/// replacement borrow or holds the concatenation of several same-offset
/// zero-width inserts.
struct ApplicableEdit<'a> {
    range: Range<usize>,
    replacement: Cow<'a, str>,
}

/// Convert a single warning fix to a text edit-style representation
/// This helps validate that individual warning fixes are correctly structured
pub fn warning_fix_to_edit(content: &str, warning: &LintWarning) -> Result<(usize, usize, String), String> {
    if let Some(fix) = &warning.fix {
        // Validate the fix range against content
        if fix.range.end > content.len() {
            return Err(format!(
                "Fix range end {} exceeds content length {}",
                fix.range.end,
                content.len()
            ));
        }

        Ok((fix.range.start, fix.range.end, fix.replacement.clone()))
    } else {
        Err("Warning has no fix".to_string())
    }
}

/// Helper function to validate that a fix range makes sense in the context
pub fn validate_fix_range(content: &str, fix: &Fix) -> Result<(), String> {
    if fix.range.start > content.len() {
        return Err(format!(
            "Fix range start {} exceeds content length {}",
            fix.range.start,
            content.len()
        ));
    }

    if fix.range.end > content.len() {
        return Err(format!(
            "Fix range end {} exceeds content length {}",
            fix.range.end,
            content.len()
        ));
    }

    if fix.range.start > fix.range.end {
        return Err(format!(
            "Invalid fix range: start {} > end {}",
            fix.range.start, fix.range.end
        ));
    }

    // Mirror apply_warning_fixes: a range that splits a UTF-8 codepoint is
    // invalid and would panic if applied.
    if !content.is_char_boundary(fix.range.start) || !content.is_char_boundary(fix.range.end) {
        return Err(format!(
            "Fix range {}..{} does not lie on UTF-8 char boundaries",
            fix.range.start, fix.range.end
        ));
    }

    Ok(())
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::rule::{Fix, LintWarning, Severity};

    #[test]
    fn test_validate_fix_range_rejects_non_char_boundary() {
        // "é" is 2 bytes (0xC3 0xA9); the range 1..2 splits it.
        let content = "é world";
        let fix = Fix::new(1..2, "x".to_string());
        assert!(
            validate_fix_range(content, &fix).is_err(),
            "validate_fix_range must reject a range that splits a codepoint"
        );
        // A boundary-aligned range is still accepted.
        let ok_fix = Fix::new(0..2, "x".to_string());
        assert!(validate_fix_range(content, &ok_fix).is_ok());
    }

    #[test]
    fn test_apply_single_fix() {
        let content = "1.  Multiple spaces";
        let warning = LintWarning {
            message: "Too many spaces".to_string(),
            line: 1,
            column: 3,
            end_line: 1,
            end_column: 5,
            severity: Severity::Warning,
            fix: Some(Fix::new(2..4, " ".to_string())),
            rule_name: Some("MD030".to_string()),
        };

        let result = apply_warning_fixes(content, &[warning]).unwrap();
        assert_eq!(result, "1. Multiple spaces");
    }

    #[test]
    fn test_apply_fix_with_non_char_boundary_range_does_not_panic() {
        // A buggy rule could emit a fix range that lands inside a multi-byte
        // codepoint. The central apply path must reject it rather than panic
        // in replace_range. "é" is 2 bytes (0xC3 0xA9); 1..2 splits it.
        let content = "é world";
        let warning = LintWarning {
            message: "bad range".to_string(),
            line: 1,
            column: 1,
            end_line: 1,
            end_column: 2,
            severity: Severity::Warning,
            fix: Some(Fix::new(1..2, "x".to_string())),
            rule_name: Some("MDTEST".to_string()),
        };

        let result = apply_warning_fixes(content, &[warning]);
        assert!(
            result.is_err(),
            "non-char-boundary range must be rejected, got {result:?}"
        );
    }

    #[test]
    fn test_apply_multiple_fixes() {
        let content = "1.  First\n*   Second";
        let warnings = vec![
            LintWarning {
                message: "Too many spaces".to_string(),
                line: 1,
                column: 3,
                end_line: 1,
                end_column: 5,
                severity: Severity::Warning,
                fix: Some(Fix::new(2..4, " ".to_string())),
                rule_name: Some("MD030".to_string()),
            },
            LintWarning {
                message: "Too many spaces".to_string(),
                line: 2,
                column: 2,
                end_line: 2,
                end_column: 5,
                severity: Severity::Warning,
                fix: Some(Fix::new(11..14, " ".to_string())),
                rule_name: Some("MD030".to_string()),
            },
        ];

        let result = apply_warning_fixes(content, &warnings).unwrap();
        assert_eq!(result, "1. First\n* Second");
    }

    #[test]
    fn test_apply_non_overlapping_fixes() {
        // "Test  multiple    spaces"
        //  0123456789012345678901234
        //      ^^       ^^^^
        //      4-6      14-18
        let content = "Test  multiple    spaces";
        let warnings = vec![
            LintWarning {
                message: "Too many spaces".to_string(),
                line: 1,
                column: 5,
                end_line: 1,
                end_column: 7,
                severity: Severity::Warning,
                fix: Some(Fix::new(4..6, " ".to_string())),
                rule_name: Some("MD009".to_string()),
            },
            LintWarning {
                message: "Too many spaces".to_string(),
                line: 1,
                column: 15,
                end_line: 1,
                end_column: 19,
                severity: Severity::Warning,
                fix: Some(Fix::new(14..18, " ".to_string())),
                rule_name: Some("MD009".to_string()),
            },
        ];

        let result = apply_warning_fixes(content, &warnings).unwrap();
        assert_eq!(result, "Test multiple spaces");
    }

    #[test]
    fn test_apply_duplicate_fixes() {
        let content = "Test  content";
        let warnings = vec![
            LintWarning {
                message: "Fix 1".to_string(),
                line: 1,
                column: 5,
                end_line: 1,
                end_column: 7,
                severity: Severity::Warning,
                fix: Some(Fix::new(4..6, " ".to_string())),
                rule_name: Some("MD009".to_string()),
            },
            LintWarning {
                message: "Fix 2 (duplicate)".to_string(),
                line: 1,
                column: 5,
                end_line: 1,
                end_column: 7,
                severity: Severity::Warning,
                fix: Some(Fix::new(4..6, " ".to_string())),
                rule_name: Some("MD009".to_string()),
            },
        ];

        // Duplicates should be deduplicated
        let result = apply_warning_fixes(content, &warnings).unwrap();
        assert_eq!(result, "Test content");
    }

    #[test]
    fn test_apply_fixes_with_windows_line_endings() {
        let content = "1.  First\r\n*   Second\r\n";
        let warnings = vec![
            LintWarning {
                message: "Too many spaces".to_string(),
                line: 1,
                column: 3,
                end_line: 1,
                end_column: 5,
                severity: Severity::Warning,
                fix: Some(Fix::new(2..4, " ".to_string())),
                rule_name: Some("MD030".to_string()),
            },
            LintWarning {
                message: "Too many spaces".to_string(),
                line: 2,
                column: 2,
                end_line: 2,
                end_column: 5,
                severity: Severity::Warning,
                fix: Some(Fix::new(12..15, " ".to_string())),
                rule_name: Some("MD030".to_string()),
            },
        ];

        let result = apply_warning_fixes(content, &warnings).unwrap();
        // The implementation normalizes line endings, which may double \r
        // Just test that the fixes were applied correctly
        assert!(result.contains("1. First"));
        assert!(result.contains("* Second"));
    }

    #[test]
    fn test_apply_fix_with_invalid_range() {
        let content = "Short";
        let warning = LintWarning {
            message: "Invalid fix".to_string(),
            line: 1,
            column: 1,
            end_line: 1,
            end_column: 10,
            severity: Severity::Warning,
            fix: Some(Fix::new(0..100, "Replacement".to_string())),
            rule_name: Some("TEST".to_string()),
        };

        let result = apply_warning_fixes(content, &[warning]);
        assert!(result.is_err());
        assert!(result.unwrap_err().contains("exceeds content length"));
    }

    #[test]
    #[allow(clippy::reversed_empty_ranges)]
    fn test_apply_fix_with_reversed_range() {
        let content = "Hello world";
        let warning = LintWarning {
            message: "Invalid fix".to_string(),
            line: 1,
            column: 5,
            end_line: 1,
            end_column: 3,
            severity: Severity::Warning,
            fix: Some(Fix::new(10..5, "Test".to_string())),
            rule_name: Some("TEST".to_string()),
        };

        let result = apply_warning_fixes(content, &[warning]);
        assert!(result.is_err());
        assert!(result.unwrap_err().contains("Invalid fix range"));
    }

    #[test]
    fn test_apply_no_fixes() {
        let content = "No changes needed";
        let warnings = vec![LintWarning {
            message: "Warning without fix".to_string(),
            line: 1,
            column: 1,
            end_line: 1,
            end_column: 5,
            severity: Severity::Warning,
            fix: None,
            rule_name: Some("TEST".to_string()),
        }];

        let result = apply_warning_fixes(content, &warnings).unwrap();
        assert_eq!(result, content);
    }

    #[test]
    fn test_overlapping_fixes_skip_outer() {
        // Simulates nested link/image: [ ![ alt ](img) ](url) suffix
        // Inner fix: range 2..15 (image text)
        // Outer fix: range 0..22 (link text) — overlaps inner
        // Only the inner (higher start) should be applied; outer is skipped.
        let content = "[ ![ alt ](img) ](url) suffix";
        let warnings = vec![
            LintWarning {
                message: "Outer link".to_string(),
                line: 1,
                column: 1,
                end_line: 1,
                end_column: 22,
                severity: Severity::Warning,
                fix: Some(Fix::new(0..22, "[![alt](img)](url)".to_string())),
                rule_name: Some("MD039".to_string()),
            },
            LintWarning {
                message: "Inner image".to_string(),
                line: 1,
                column: 3,
                end_line: 1,
                end_column: 15,
                severity: Severity::Warning,
                fix: Some(Fix::new(2..15, "![alt](img)".to_string())),
                rule_name: Some("MD039".to_string()),
            },
        ];

        let result = apply_warning_fixes(content, &warnings).unwrap();
        // Inner fix applied: "![ alt ](img)" → "![alt](img)"
        // Outer fix skipped (overlaps). Suffix preserved.
        assert_eq!(result, "[ ![alt](img) ](url) suffix");
    }

    #[test]
    fn test_overlapping_outer_fix_is_skipped_without_trailing_slack() {
        // Same nested shape with nothing after the link, which is what MD039
        // actually produces for a whole-line link. Applying the inner fix shrinks
        // the buffer past the outer fix's end, so measuring bounds against the
        // buffer turned a skippable overlap into a hard error and threw away the
        // inner fix along with it. The trailing text in the test above was the
        // only reason it passed.
        let content = "[ a ![ x ](i.png) b ](t.md)\n";
        let warnings = vec![
            LintWarning {
                message: "Outer link".to_string(),
                line: 1,
                column: 1,
                end_line: 1,
                end_column: 28,
                severity: Severity::Warning,
                fix: Some(Fix::new(0..27, "[a ![ x ](i.png) b](t.md)".to_string())),
                rule_name: Some("MD039".to_string()),
            },
            LintWarning {
                message: "Inner image".to_string(),
                line: 1,
                column: 5,
                end_line: 1,
                end_column: 18,
                severity: Severity::Warning,
                fix: Some(Fix::new(4..17, "![x](i.png)".to_string())),
                rule_name: Some("MD039".to_string()),
            },
        ];

        let result = apply_warning_fixes(content, &warnings).unwrap();
        assert_eq!(result, "[ a ![x](i.png) b ](t.md)\n");
    }

    #[test]
    fn test_out_of_bounds_fix_is_still_rejected() {
        // The bounds check still has to catch a rule addressing content that does
        // not exist. Measuring the original rather than the edited buffer must not
        // turn this into a silent no-op.
        let content = "short\n";
        let warnings = vec![LintWarning {
            message: "Past the end".to_string(),
            line: 1,
            column: 1,
            end_line: 1,
            end_column: 1,
            severity: Severity::Warning,
            fix: Some(Fix::new(0..99, "x".to_string())),
            rule_name: Some("MDTEST".to_string()),
        }];

        // Asserting the message, not just an error: the char-boundary check below
        // also rejects an index past the end, so `is_err()` alone would pass with
        // the bounds check deleted and prove nothing about it.
        let err = apply_warning_fixes(content, &warnings).expect_err("out-of-bounds range must be rejected");
        assert_eq!(err, "Fix range end 99 exceeds content length 6");
    }

    #[test]
    fn test_apply_fix_with_additional_edits_atomic() {
        // Models the MD054 ref-emit shape: a single Fix with a primary in-place
        // rewrite of an inline link plus an additional_edit that appends a new
        // reference definition at EOF. apply_warning_fixes must apply both halves
        // — applying only the primary would leave a dangling reference.
        let content = "See [docs](https://example.com) for details.\n";
        let primary_range = content.find("[docs](https://example.com)").unwrap()..content.find(" for details").unwrap();
        let appended = "\n[docs]: https://example.com\n".to_string();
        let warnings = vec![LintWarning {
            message: "Inconsistent link style".to_string(),
            line: 1,
            column: 5,
            end_line: 1,
            end_column: 32,
            severity: Severity::Warning,
            fix: Some(Fix::with_additional_edits(
                primary_range,
                "[docs]".to_string(),
                vec![Fix::new(content.len()..content.len(), appended)],
            )),
            rule_name: Some("MD054".to_string()),
        }];

        let result = apply_warning_fixes(content, &warnings).unwrap();
        assert!(
            result.contains("See [docs] for details."),
            "primary edit must rewrite the inline link in place: {result:?}"
        );
        assert!(
            result.contains("[docs]: https://example.com"),
            "additional edit must append the ref-def at EOF: {result:?}"
        );
        assert!(
            !result.contains("[docs](https://example.com)"),
            "the inline form must be gone after the atomic fix: {result:?}"
        );
    }

    #[test]
    fn test_apply_two_ref_emit_fixes_preserve_source_order() {
        // Regression for the multi-warning EOF-insert case in MD054.
        //
        // Two distinct inline links each rewrite to a reference-style link
        // and append a fresh `[label]: url` definition at EOF. Each Fix carries
        // its primary in-place rewrite plus a zero-width additional_edit at
        // `content.len()..content.len()` with a *different* replacement.
        //
        // The naive reverse-sort apply pipeline would `replace_range(N..N, B)`
        // after `replace_range(N..N, A)`, which lands B *before* A — reversing
        // declaration order and producing `<orig> + B + A` rather than
        // `<orig> + A + B`. Coalescing same-offset zero-width inserts into a
        // single concatenated replacement preserves source order.
        let content = "See [a](https://a.com) and [b](https://b.com).\n";
        let span_a = content.find("[a](https://a.com)").unwrap()
            ..content.find("](https://a.com)").unwrap() + "](https://a.com)".len();
        let span_b = content.find("[b](https://b.com)").unwrap()
            ..content.find("](https://b.com)").unwrap() + "](https://b.com)".len();
        let warnings = vec![
            LintWarning {
                message: "Inconsistent link style".to_string(),
                line: 1,
                column: 5,
                end_line: 1,
                end_column: 0,
                severity: Severity::Warning,
                fix: Some(Fix::with_additional_edits(
                    span_a,
                    "[a]".to_string(),
                    vec![Fix::new(
                        content.len()..content.len(),
                        "[a]: https://a.com\n".to_string(),
                    )],
                )),
                rule_name: Some("MD054".to_string()),
            },
            LintWarning {
                message: "Inconsistent link style".to_string(),
                line: 1,
                column: 28,
                end_line: 1,
                end_column: 0,
                severity: Severity::Warning,
                fix: Some(Fix::with_additional_edits(
                    span_b,
                    "[b]".to_string(),
                    vec![Fix::new(
                        content.len()..content.len(),
                        "[b]: https://b.com\n".to_string(),
                    )],
                )),
                rule_name: Some("MD054".to_string()),
            },
        ];

        let result = apply_warning_fixes(content, &warnings).unwrap();

        // Both primary rewrites must land.
        assert!(
            result.contains("See [a] and [b]."),
            "primary rewrites missing: {result:?}"
        );
        assert!(!result.contains("[a](https://a.com)"));
        assert!(!result.contains("[b](https://b.com)"));

        // Both ref-defs must land in source order — `[a]` before `[b]`.
        let pos_a = result.find("[a]: https://a.com").expect("ref-def for [a] missing");
        let pos_b = result.find("[b]: https://b.com").expect("ref-def for [b] missing");
        assert!(
            pos_a < pos_b,
            "ref-defs must appear in source order ([a] before [b]); got result:\n{result}"
        );
    }

    #[test]
    fn test_warning_fix_to_edit() {
        let content = "Hello world";
        let warning = LintWarning {
            message: "Test".to_string(),
            line: 1,
            column: 1,
            end_line: 1,
            end_column: 5,
            severity: Severity::Warning,
            fix: Some(Fix::new(0..5, "Hi".to_string())),
            rule_name: Some("TEST".to_string()),
        };

        let edit = warning_fix_to_edit(content, &warning).unwrap();
        assert_eq!(edit, (0, 5, "Hi".to_string()));
    }

    #[test]
    fn test_warning_fix_to_edit_no_fix() {
        let content = "Hello world";
        let warning = LintWarning {
            message: "Test".to_string(),
            line: 1,
            column: 1,
            end_line: 1,
            end_column: 5,
            severity: Severity::Warning,
            fix: None,
            rule_name: Some("TEST".to_string()),
        };

        let result = warning_fix_to_edit(content, &warning);
        assert!(result.is_err());
        assert_eq!(result.unwrap_err(), "Warning has no fix");
    }

    #[test]
    fn test_warning_fix_to_edit_invalid_range() {
        let content = "Short";
        let warning = LintWarning {
            message: "Test".to_string(),
            line: 1,
            column: 1,
            end_line: 1,
            end_column: 10,
            severity: Severity::Warning,
            fix: Some(Fix::new(0..100, "Long replacement".to_string())),
            rule_name: Some("TEST".to_string()),
        };

        let result = warning_fix_to_edit(content, &warning);
        assert!(result.is_err());
        assert!(result.unwrap_err().contains("exceeds content length"));
    }

    #[test]
    fn test_validate_fix_range() {
        let content = "Hello world";

        // Valid range
        let valid_fix = Fix::new(0..5, "Hi".to_string());
        assert!(validate_fix_range(content, &valid_fix).is_ok());

        // Invalid range (end > content length)
        let invalid_fix = Fix::new(0..20, "Hi".to_string());
        assert!(validate_fix_range(content, &invalid_fix).is_err());

        // Invalid range (start > end) - create reversed range
        let start = 5;
        let end = 3;
        let invalid_fix2 = Fix::new(start..end, "Hi".to_string());
        assert!(validate_fix_range(content, &invalid_fix2).is_err());
    }

    #[test]
    fn test_validate_fix_range_edge_cases() {
        let content = "Test";

        // Empty range at start
        let fix1 = Fix::new(0..0, "Insert".to_string());
        assert!(validate_fix_range(content, &fix1).is_ok());

        // Empty range at end
        let fix2 = Fix::new(4..4, " append".to_string());
        assert!(validate_fix_range(content, &fix2).is_ok());

        // Full content replacement
        let fix3 = Fix::new(0..4, "Replace".to_string());
        assert!(validate_fix_range(content, &fix3).is_ok());

        // Start exceeds content
        let fix4 = Fix::new(10..11, "Invalid".to_string());
        let result = validate_fix_range(content, &fix4);
        assert!(result.is_err());
        assert!(result.unwrap_err().contains("start 10 exceeds"));
    }

    #[test]
    fn test_fix_ordering_stability() {
        // Test that fixes with identical ranges maintain stable ordering
        let content = "Test content here";
        let warnings = vec![
            LintWarning {
                message: "First warning".to_string(),
                line: 1,
                column: 6,
                end_line: 1,
                end_column: 13,
                severity: Severity::Warning,
                fix: Some(Fix::new(5..12, "stuff".to_string())),
                rule_name: Some("MD001".to_string()),
            },
            LintWarning {
                message: "Second warning".to_string(),
                line: 1,
                column: 6,
                end_line: 1,
                end_column: 13,
                severity: Severity::Warning,
                fix: Some(Fix::new(5..12, "stuff".to_string())),
                rule_name: Some("MD002".to_string()),
            },
        ];

        // Both fixes are identical, so deduplication should leave only one
        let result = apply_warning_fixes(content, &warnings).unwrap();
        assert_eq!(result, "Test stuff here");
    }

    #[test]
    fn test_line_ending_preservation() {
        // Test Unix line endings
        let content_unix = "Line 1\nLine 2\n";
        let warning = LintWarning {
            message: "Add text".to_string(),
            line: 1,
            column: 7,
            end_line: 1,
            end_column: 7,
            severity: Severity::Warning,
            fix: Some(Fix::new(6..6, " added".to_string())),
            rule_name: Some("TEST".to_string()),
        };

        let result = apply_warning_fixes(content_unix, &[warning]).unwrap();
        assert_eq!(result, "Line 1 added\nLine 2\n");

        // Test that Windows line endings work (even if normalization occurs)
        let content_windows = "Line 1\r\nLine 2\r\n";
        let warning_windows = LintWarning {
            message: "Add text".to_string(),
            line: 1,
            column: 7,
            end_line: 1,
            end_column: 7,
            severity: Severity::Warning,
            fix: Some(Fix::new(6..6, " added".to_string())),
            rule_name: Some("TEST".to_string()),
        };

        let result_windows = apply_warning_fixes(content_windows, &[warning_windows]).unwrap();
        // Just verify the fix was applied correctly
        assert!(result_windows.starts_with("Line 1 added"));
        assert!(result_windows.contains("Line 2"));
    }

    fn make_warning(line: usize, end_line: usize, rule_name: &str) -> LintWarning {
        LintWarning {
            message: "test".to_string(),
            line,
            column: 1,
            end_line,
            end_column: 1,
            severity: Severity::Warning,
            fix: Some(Fix::new(0..1, "x".to_string())),
            rule_name: Some(rule_name.to_string()),
        }
    }

    #[test]
    fn test_filter_warnings_disable_enable_block() {
        let content =
            "# Heading\n\n<!-- rumdl-disable MD013 -->\nlong line\n<!-- rumdl-enable MD013 -->\nanother long line\n";
        let inline_config = InlineConfig::from_content(content);

        let warnings = vec![
            make_warning(4, 4, "MD013"), // inside disabled block
            make_warning(6, 6, "MD013"), // outside disabled block
        ];

        let filtered = filter_warnings_by_inline_config(warnings, &inline_config, "MD013");
        assert_eq!(filtered.len(), 1);
        assert_eq!(filtered[0].line, 6);
    }

    #[test]
    fn test_filter_warnings_disable_line() {
        let content = "line one <!-- rumdl-disable-line MD009 -->\nline two\n";
        let inline_config = InlineConfig::from_content(content);

        let warnings = vec![
            make_warning(1, 1, "MD009"), // disabled via disable-line
            make_warning(2, 2, "MD009"), // not disabled
        ];

        let filtered = filter_warnings_by_inline_config(warnings, &inline_config, "MD009");
        assert_eq!(filtered.len(), 1);
        assert_eq!(filtered[0].line, 2);
    }

    #[test]
    fn test_filter_warnings_disable_next_line() {
        let content = "<!-- rumdl-disable-next-line MD034 -->\nhttp://example.com\nhttp://other.com\n";
        let inline_config = InlineConfig::from_content(content);

        let warnings = vec![
            make_warning(2, 2, "MD034"), // disabled via disable-next-line
            make_warning(3, 3, "MD034"), // not disabled
        ];

        let filtered = filter_warnings_by_inline_config(warnings, &inline_config, "MD034");
        assert_eq!(filtered.len(), 1);
        assert_eq!(filtered[0].line, 3);
    }

    #[test]
    fn test_filter_warnings_sub_rule_name() {
        let content = "<!-- rumdl-disable MD029 -->\nline\n<!-- rumdl-enable MD029 -->\nline\n";
        let inline_config = InlineConfig::from_content(content);

        // Sub-rule name like "MD029-style" should be stripped to "MD029"
        let warnings = vec![make_warning(2, 2, "MD029"), make_warning(4, 4, "MD029")];

        let filtered = filter_warnings_by_inline_config(warnings, &inline_config, "MD029-style");
        assert_eq!(filtered.len(), 1);
        assert_eq!(filtered[0].line, 4);
    }

    #[test]
    fn test_filter_warnings_multi_line_warning() {
        // A warning spanning lines 3-5 where line 4 is disabled
        let content = "line 1\nline 2\nline 3\n<!-- rumdl-disable-line MD013 -->\nline 5\nline 6\n";
        let inline_config = InlineConfig::from_content(content);

        let warnings = vec![
            make_warning(3, 5, "MD013"), // spans lines 3-5, line 4 is disabled
            make_warning(6, 6, "MD013"), // not disabled
        ];

        let filtered = filter_warnings_by_inline_config(warnings, &inline_config, "MD013");
        // The multi-line warning should be filtered because one of its lines is disabled
        assert_eq!(filtered.len(), 1);
        assert_eq!(filtered[0].line, 6);
    }

    #[test]
    fn test_filter_warnings_empty_input() {
        let inline_config = InlineConfig::from_content("");
        let filtered = filter_warnings_by_inline_config(vec![], &inline_config, "MD013");
        assert!(filtered.is_empty());
    }

    #[test]
    fn test_filter_warnings_none_disabled() {
        let content = "line 1\nline 2\n";
        let inline_config = InlineConfig::from_content(content);

        let warnings = vec![make_warning(1, 1, "MD013"), make_warning(2, 2, "MD013")];

        let filtered = filter_warnings_by_inline_config(warnings, &inline_config, "MD013");
        assert_eq!(filtered.len(), 2);
    }

    #[test]
    fn test_filter_warnings_all_disabled() {
        let content = "<!-- rumdl-disable MD013 -->\nline 1\nline 2\n";
        let inline_config = InlineConfig::from_content(content);

        let warnings = vec![make_warning(2, 2, "MD013"), make_warning(3, 3, "MD013")];

        let filtered = filter_warnings_by_inline_config(warnings, &inline_config, "MD013");
        assert!(filtered.is_empty());
    }

    #[test]
    fn test_filter_warnings_end_line_zero_fallback() {
        // When end_line < line (e.g., end_line=0), should fall back to checking only warning.line
        let content = "<!-- rumdl-disable-line MD013 -->\nline 2\n";
        let inline_config = InlineConfig::from_content(content);

        let warnings = vec![make_warning(1, 0, "MD013")]; // end_line=0 < line=1

        let filtered = filter_warnings_by_inline_config(warnings, &inline_config, "MD013");
        assert!(filtered.is_empty());
    }

    #[test]
    fn test_filter_non_md_rule_name_preserves_dash() {
        // Verify that a non-MD rule name with a dash is NOT split by the helper.
        // The helper should pass "custom-rule" as-is to InlineConfig, not "custom".
        let content = "line 1\nline 2\n";
        let inline_config = InlineConfig::from_content(content);

        let warnings = vec![make_warning(1, 1, "custom-rule")];

        // With nothing disabled, the warning should pass through
        let filtered = filter_warnings_by_inline_config(warnings, &inline_config, "custom-rule");
        assert_eq!(filtered.len(), 1, "Non-MD rule name with dash should not be split");
    }

    #[test]
    fn test_filter_md_sub_rule_name_is_split() {
        // Verify that "MD029-style" is split to "MD029" for inline config lookup
        let content = "<!-- rumdl-disable MD029 -->\nline\n<!-- rumdl-enable MD029 -->\nline\n";
        let inline_config = InlineConfig::from_content(content);

        let warnings = vec![
            make_warning(2, 2, "MD029"), // disabled
            make_warning(4, 4, "MD029"), // not disabled
        ];

        // Passing "MD029-style" as rule_name should still match "MD029" in inline config
        let filtered = filter_warnings_by_inline_config(warnings, &inline_config, "MD029-style");
        assert_eq!(filtered.len(), 1);
        assert_eq!(filtered[0].line, 4);
    }

    #[test]
    fn test_filter_warnings_capture_restore() {
        let content = "<!-- rumdl-disable MD013 -->\nline 1\n<!-- rumdl-capture -->\n<!-- rumdl-enable MD013 -->\nline 4\n<!-- rumdl-restore -->\nline 6\n";
        let inline_config = InlineConfig::from_content(content);

        let warnings = vec![
            make_warning(2, 2, "MD013"), // disabled by initial disable
            make_warning(5, 5, "MD013"), // re-enabled between capture/restore
            make_warning(7, 7, "MD013"), // after restore, back to disabled state
        ];

        let filtered = filter_warnings_by_inline_config(warnings, &inline_config, "MD013");
        assert_eq!(filtered.len(), 1);
        assert_eq!(filtered[0].line, 5);
    }
}