agent-file-tools 0.43.1

//! Apply parsed update chunks to file content.
//!
//! This ports `applyUpdateChunks` and its diagnostics from
//! `packages/opencode-plugin/src/patch-parser.ts`.

use crate::patch::matcher::{
    normalize_indent, normalize_unicode, seek_sequence_tiered, SequenceMatch,
};
use crate::patch::parser::UpdateFileChunk;

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub struct ClosestPartialMatch {
    pub line_number: usize,
    pub matched_lines: usize,
    pub first_divergence: usize,
}

/// Return only the matched line index for diagnostics that do not need the full tiered match details.
pub fn seek_sequence(
    lines: &[&str],
    pattern: &[&str],
    start_index: usize,
    eof: bool,
) -> Option<usize> {
    seek_sequence_tiered(lines, pattern, start_index, eof)
        .map(|sequence_match| sequence_match.found)
}

fn line_refs(lines: &[String]) -> Vec<&str> {
    lines.iter().map(String::as_str).collect()
}

fn compare_any(a: &str, b: &str) -> bool {
    if a == b || a.trim_end() == b.trim_end() || a.trim() == b.trim() {
        return true;
    }

    let normalized_a_indent = normalize_indent(a);
    let normalized_b_indent = normalize_indent(b);
    if normalized_a_indent.trim_end() == normalized_b_indent.trim_end() {
        return true;
    }

    normalize_unicode(a.trim()) == normalize_unicode(b.trim())
}

/// Find the closest partial match and report where the candidate first diverges for failure diagnostics.
pub fn find_closest_partial_match(lines: &[&str], pattern: &[&str]) -> Option<ClosestPartialMatch> {
    if pattern.is_empty() || lines.is_empty() {
        return None;
    }

    let mut candidates = Vec::new();
    for (index, line) in lines.iter().enumerate() {
        if compare_any(line, pattern[0]) {
            candidates.push(index);
            if candidates.len() >= 16 {
                break;
            }
        }
    }
    if candidates.is_empty() {
        return None;
    }

    let mut best: Option<ClosestPartialMatch> = None;
    for start in candidates {
        let mut matched = 0;
        for (offset, expected) in pattern.iter().enumerate() {
            let Some(actual) = lines.get(start + offset) else {
                break;
            };
            if !compare_any(actual, expected) {
                break;
            }
            matched += 1;
        }

        if best.is_none_or(|current| matched > current.matched_lines) {
            best = Some(ClosestPartialMatch {
                line_number: start + 1,
                matched_lines: matched,
                first_divergence: matched,
            });
        }
    }

    best
}

fn seek_sequence_tiered_strings(
    lines: &[String],
    pattern: &[String],
    start_index: usize,
    eof: bool,
) -> Option<SequenceMatch> {
    let line_refs = line_refs(lines);
    let pattern_refs: Vec<&str> = pattern.iter().map(String::as_str).collect();
    seek_sequence_tiered(&line_refs, &pattern_refs, start_index, eof)
}

fn seek_sequence_strings(
    lines: &[String],
    pattern: &[String],
    start_index: usize,
    eof: bool,
) -> Option<usize> {
    let line_refs = line_refs(lines);
    let pattern_refs: Vec<&str> = pattern.iter().map(String::as_str).collect();
    seek_sequence(&line_refs, &pattern_refs, start_index, eof)
}

fn json_string(value: &str) -> String {
    serde_json::to_string(value).expect("serializing a string to JSON should not fail")
}

/// Apply parsed update chunks to original file content, returning the patched text or an error string.
pub fn apply_update_chunks(
    original_content: &str,
    file_path: &str,
    chunks: &[UpdateFileChunk],
) -> Result<String, String> {
    let mut original_lines: Vec<String> = original_content
        .split('\n')
        .map(ToOwned::to_owned)
        .collect();

    if original_lines.last().is_some_and(String::is_empty) {
        original_lines.pop();
    }

    let mut replacements: Vec<(usize, usize, Vec<String>)> = Vec::new();
    let mut line_index = 0;

    for chunk in chunks {
        let change_context = chunk
            .change_context
            .as_ref()
            .filter(|context| !context.is_empty());
        if let Some(context) = change_context {
            let line_refs = line_refs(&original_lines);
            let context_pattern = [context.as_str()];
            let Some(context_match) =
                seek_sequence_tiered(&line_refs, &context_pattern, line_index, false)
            else {
                return Err(format!("Failed to find context '{context}' in {file_path}"));
            };
            line_index = context_match.found + context_match.line_count;
        }

        if chunk.old_lines.is_empty() {
            let insertion_idx = if change_context.is_some() {
                line_index
            } else if original_lines.last().is_some_and(String::is_empty) {
                original_lines.len() - 1
            } else {
                original_lines.len()
            };
            replacements.push((insertion_idx, 0, chunk.new_lines.clone()));
            continue;
        }

        let mut pattern = chunk.old_lines.clone();
        let mut new_slice = chunk.new_lines.clone();
        let mut matched = seek_sequence_tiered_strings(
            &original_lines,
            &pattern,
            line_index,
            chunk.is_end_of_file,
        );

        if matched.is_none() && pattern.last().is_some_and(String::is_empty) {
            pattern.pop();
            if new_slice.last().is_some_and(String::is_empty) {
                new_slice.pop();
            }
            matched = seek_sequence_tiered_strings(
                &original_lines,
                &pattern,
                line_index,
                chunk.is_end_of_file,
            );
        }

        if let Some(sequence_match) = matched {
            replacements.push((sequence_match.found, sequence_match.line_count, new_slice));
            line_index = sequence_match.found + sequence_match.line_count;
        } else {
            let new_slice_trimmed: Vec<String> = new_slice
                .iter()
                .filter(|line| !line.trim().is_empty())
                .cloned()
                .collect();
            let already_applied = !new_slice_trimmed.is_empty()
                && seek_sequence_strings(
                    &original_lines,
                    &new_slice_trimmed,
                    0,
                    chunk.is_end_of_file,
                )
                .is_some();

            let line_refs = line_refs(&original_lines);
            let pattern_refs: Vec<&str> = pattern.iter().map(String::as_str).collect();
            let closest = find_closest_partial_match(&line_refs, &pattern_refs);
            let mut closest_hint = String::new();
            if let Some(closest) = closest.filter(|closest| closest.matched_lines > 0) {
                let file_line_no = closest.line_number + closest.first_divergence;
                let expected_line = pattern.get(closest.first_divergence).map(String::as_str);
                let expected_json =
                    expected_line.map_or_else(|| "undefined".to_owned(), json_string);
                let actual_line = original_lines
                    .get(file_line_no.saturating_sub(1))
                    .map(String::as_str)
                    .unwrap_or("<EOF>");
                closest_hint = format!(
                    "\n\nClosest match starts at line {} ({} of {} lines matched).\n\
                     First divergence at line {file_line_no}:\n  expected: {}\n  actual:   {}",
                    closest.line_number,
                    closest.matched_lines,
                    pattern.len(),
                    expected_json,
                    json_string(actual_line)
                );
            }

            let tried_tiers =
                "exact, trimEnd, trim, indent (tab/space), unicode, reflow (whitespace-normalized)";
            let already_applied_hint = if already_applied {
                "\n\nHint: the replacement content for this hunk already appears in the file. \
                 The patch may have been partially applied in a prior turn — re-read the file \
                 to confirm which hunks still need to apply."
            } else {
                ""
            };

            return Err(format!(
                "Failed to find expected lines in {file_path}:\n{}\n\n\
                 Tried match tiers: {tried_tiers}.{closest_hint}{already_applied_hint}",
                chunk.old_lines.join("\n")
            ));
        }
    }

    replacements.sort_by(|left, right| left.0.cmp(&right.0));

    let mut result = original_lines;
    for (start_idx, old_len, new_segment) in replacements.into_iter().rev() {
        result.splice(start_idx..start_idx + old_len, new_segment);
    }

    if result.last().is_none_or(|line| !line.is_empty()) {
        result.push(String::new());
    }

    Ok(result.join("\n"))
}

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

    fn chunk(old_lines: &[&str], new_lines: &[&str]) -> UpdateFileChunk {
        UpdateFileChunk {
            old_lines: old_lines.iter().map(|line| (*line).to_owned()).collect(),
            new_lines: new_lines.iter().map(|line| (*line).to_owned()).collect(),
            change_context: None,
            is_end_of_file: false,
        }
    }

    fn context_chunk(context: &str, old_lines: &[&str], new_lines: &[&str]) -> UpdateFileChunk {
        UpdateFileChunk {
            old_lines: old_lines.iter().map(|line| (*line).to_owned()).collect(),
            new_lines: new_lines.iter().map(|line| (*line).to_owned()).collect(),
            change_context: Some(context.to_owned()),
            is_end_of_file: false,
        }
    }

    fn eof_chunk(old_lines: &[&str], new_lines: &[&str]) -> UpdateFileChunk {
        UpdateFileChunk {
            old_lines: old_lines.iter().map(|line| (*line).to_owned()).collect(),
            new_lines: new_lines.iter().map(|line| (*line).to_owned()).collect(),
            change_context: None,
            is_end_of_file: true,
        }
    }

    fn assert_apply_error(original: &str, file_path: &str, chunks: &[UpdateFileChunk]) -> String {
        apply_update_chunks(original, file_path, chunks).unwrap_err()
    }

    #[test]
    fn missing_change_context_matches_patch_parser_test_60_72() {
        let chunks = [context_chunk("missing line", &["beta"], &["updated beta"])];
        assert_eq!(
            assert_apply_error("alpha\nbeta\n", "src/example.ts", &chunks),
            "Failed to find context 'missing line' in src/example.ts"
        );
    }

    #[test]
    fn missing_old_lines_error_format_matches_patch_parser_test_74_85() {
        let chunks = [chunk(&["missing line"], &["replacement line"])];
        assert_eq!(
            assert_apply_error("alpha\nbeta\n", "src/example.ts", &chunks),
            "Failed to find expected lines in src/example.ts:\nmissing line\n\n\
             Tried match tiers: exact, trimEnd, trim, indent (tab/space), unicode, reflow (whitespace-normalized)."
        );
    }

    #[test]
    fn already_applied_hint_matches_patch_parser_test_87_103() {
        let chunks = [chunk(
            &["const mainQuota = await getFreshMainQuota(auth.access, storage)"],
            &["const mainQuota = await getMainQuotaForRouting(auth.access, storage)"],
        )];
        let file_with_rewrite_already_applied =
            "alpha\nconst mainQuota = await getMainQuotaForRouting(auth.access, storage)\nbeta\n";

        assert!(
            assert_apply_error(file_with_rewrite_already_applied, "src/example.ts", &chunks)
                .contains("already appears in the file")
        );
    }

    #[test]
    fn absent_old_and_new_lines_have_no_already_applied_hint_matches_patch_parser_test_105_122() {
        let chunks = [chunk(&["missing old line"], &["missing new line"])];
        let message = assert_apply_error("unrelated content\n", "src/example.ts", &chunks);
        assert!(message.contains("Failed to find expected lines"));
        assert!(!message.contains("already appears in the file"));
    }

    #[test]
    fn spaces_patch_matches_tab_file_matches_patch_parser_test_124_147() {
        let file = "function foo() {\n\treturn 42;\n}\n";
        let chunks = [chunk(&["    return 42;"], &["    return 43;"])];

        assert_eq!(
            apply_update_chunks(file, "src/foo.ts", &chunks).unwrap(),
            "function foo() {\n    return 43;\n}\n"
        );
    }

    #[test]
    fn tab_patch_matches_spaces_file_matches_patch_parser_test_149_162() {
        let file = "function foo() {\n    return 42;\n}\n";
        let chunks = [chunk(&["\treturn 42;"], &["\treturn 43;"])];

        assert_eq!(
            apply_update_chunks(file, "src/foo.ts", &chunks).unwrap(),
            "function foo() {\n\treturn 43;\n}\n"
        );
    }

    #[test]
    fn closest_match_diagnostic_matches_patch_parser_test_164_195() {
        let file =
            "function foo() {\n  const x = 1;\n  const y = 2;\n  const z = 3;\n  return x + y + z;\n}\n";
        let chunks = [chunk(
            &["  const x = 1;", "  const y = 2;", "  const Q = 99;"],
            &["  const x = 1;", "  const y = 2;", "  const Q = 100;"],
        )];

        let message = assert_apply_error(file, "src/foo.ts", &chunks);
        assert!(message.contains("Closest match starts at line 2"));
        assert!(message.contains("2 of 3 lines matched"));
        assert!(message.contains("First divergence at line 4"));
        assert!(message.contains("expected: \"  const Q = 99;\""));
        assert!(message.contains("actual:   \"  const z = 3;\""));
    }

    #[test]
    fn tried_tiers_diagnostic_matches_patch_parser_test_197_221() {
        let chunks = [chunk(&["completely unrelated line"], &["replacement"])];
        let message = assert_apply_error("alpha\nbeta\ngamma\n", "src/foo.ts", &chunks);

        assert!(message.contains("Tried match tiers:"));
        assert!(message.contains("exact"));
        assert!(message.contains("trim"));
        assert!(message.contains("indent"));
        assert!(message.contains("unicode"));
    }

    #[test]
    fn reflow_one_line_to_three_line_split_matches_patch_parser_test_225_240() {
        let original =
            "function demo() {\n  const value = alpha +\n    beta +\n    gamma;\n  return value;\n}\n";
        let chunks = [chunk(
            &["  const value = alpha + beta + gamma;"],
            &["  const value = alpha + beta + delta;"],
        )];

        assert_eq!(
            apply_update_chunks(original, "src/demo.ts", &chunks).unwrap(),
            "function demo() {\n  const value = alpha + beta + delta;\n  return value;\n}\n"
        );
    }

    #[test]
    fn reflow_three_line_to_one_line_join_matches_patch_parser_test_242_254() {
        let original = "function demo() {\n  const value = alpha + beta + gamma;\n}\n";
        let chunks = [chunk(
            &["  const value = alpha +", "    beta +", "    gamma;"],
            &["  const value = alpha +", "    beta +", "    delta;"],
        )];

        assert_eq!(
            apply_update_chunks(original, "src/demo.ts", &chunks).unwrap(),
            "function demo() {\n  const value = alpha +\n    beta +\n    delta;\n}\n"
        );
    }

    #[test]
    fn ambiguous_reflow_rejects_matches_patch_parser_test_256_269() {
        let original =
            "const value = alpha +\n  beta +\n  gamma;\n\nconst value = alpha +\n  beta +\n  gamma;\n";
        let chunks = [chunk(
            &["const value = alpha + beta + gamma;"],
            &["const value = alpha + beta + delta;"],
        )];

        assert!(assert_apply_error(original, "src/demo.ts", &chunks)
            .contains("Failed to find expected lines in src/demo.ts"));
    }

    #[test]
    fn reflow_near_miss_rejects_matches_patch_parser_test_271_282() {
        let chunks = [chunk(
            &["const value = alpha + beta + delta;"],
            &["const value = alpha + beta + epsilon;"],
        )];

        assert!(assert_apply_error(
            "const value = alpha +\n  beta +\n  gamma;\n",
            "src/demo.ts",
            &chunks,
        )
        .contains("Failed to find expected lines in src/demo.ts"));
    }

    #[test]
    fn contiguous_match_wins_before_reflow_matches_patch_parser_test_284_299() {
        let original =
            "const value = alpha +\n  beta +\n  gamma;\nconst value = alpha + beta + gamma;\n";
        let chunks = [chunk(
            &["const value = alpha + beta + gamma;"],
            &["const value = alpha + beta + delta;"],
        )];

        assert_eq!(
            apply_update_chunks(original, "src/demo.ts", &chunks).unwrap(),
            "const value = alpha +\n  beta +\n  gamma;\nconst value = alpha + beta + delta;\n"
        );
    }

    #[test]
    fn strict_tiers_stay_ahead_of_reflow_matches_patch_parser_test_301_342() {
        let cases = [
            (
                "src/rstrip.ts",
                "const value = alpha +\n  beta +\n  gamma;\nconst value = alpha + beta + gamma;   \n",
                vec!["const value = alpha + beta + gamma;"],
                "const value = alpha +\n  beta +\n  gamma;\nconst value = alpha + beta + delta;\n",
            ),
            (
                "src/trim.ts",
                "const value = alpha +\n  beta +\n  gamma;\n  const value = alpha + beta + gamma;\n",
                vec!["const value = alpha + beta + gamma;"],
                "const value = alpha +\n  beta +\n  gamma;\nconst value = alpha + beta + delta;\n",
            ),
            (
                "src/unicode.ts",
                "const label =\n  \"alpha\";\nconst label = “alpha”;\n",
                vec!["const label = \"alpha\";"],
                "const label =\n  \"alpha\";\nconst value = alpha + beta + delta;\n",
            ),
        ];

        for (file_path, original, old_lines, expected) in cases {
            let chunks = [chunk(&old_lines, &["const value = alpha + beta + delta;"])];
            assert_eq!(
                apply_update_chunks(original, file_path, &chunks).unwrap(),
                expected
            );
        }
    }

    #[test]
    fn pure_insertion_with_context_matches_patch_parser_test_345_367() {
        let original = "function foo() {\n  return 1;\n}\n\nfunction bar() {\n  return 2;\n}\n";
        let chunks = [context_chunk("function foo() {", &[], &["  const x = 42;"])];

        let result = apply_update_chunks(original, "src/example.ts", &chunks).unwrap();
        assert_eq!(
            result,
            "function foo() {\n  const x = 42;\n  return 1;\n}\n\nfunction bar() {\n  return 2;\n}\n"
        );
        assert!(!result.contains("  return 2;\n  const x = 42;"));
    }

    #[test]
    fn pure_insertion_without_context_matches_patch_parser_test_369_380() {
        let original = "alpha\nbeta\n";
        let chunks = [chunk(&[], &["gamma"])];

        assert_eq!(
            apply_update_chunks(original, "src/example.ts", &chunks).unwrap(),
            "alpha\nbeta\ngamma\n"
        );
    }

    #[test]
    fn pure_insertion_does_not_short_circuit_matches_patch_parser_test_382_397() {
        let original = "import a;\nimport b;\n\nconst x = 1;\n";
        let chunks = [context_chunk("import a;", &[], &["import inserted;"])];

        assert_eq!(
            apply_update_chunks(original, "src/example.ts", &chunks).unwrap(),
            "import a;\nimport inserted;\nimport b;\n\nconst x = 1;\n"
        );
    }

    #[test]
    fn eof_hunk_applies_final_occurrence_matches_patch_parser_test_400_414() {
        let original = "header\nmarker\nold\nmiddle\nmarker\nold\n";
        let chunks = [eof_chunk(&["marker", "old"], &["marker", "new"])];

        assert_eq!(
            apply_update_chunks(original, "src/eof.ts", &chunks).unwrap(),
            "header\nmarker\nold\nmiddle\nmarker\nnew\n"
        );
    }

    #[test]
    fn eof_hunk_rejects_forward_scan_matches_patch_parser_test_416_429() {
        let original = "header\nmarker\nold\nmiddle\nmarker\nchanged\n";
        let chunks = [eof_chunk(&["marker", "old"], &["marker", "new"])];

        assert!(assert_apply_error(original, "src/eof.ts", &chunks)
            .contains("Failed to find expected lines in src/eof.ts"));
    }

    #[test]
    fn trailing_empty_line_retry_matches_patch_parser_source_514_519() {
        let chunks = [chunk(&["alpha", ""], &["beta", ""])];

        assert_eq!(
            apply_update_chunks("alpha\n", "src/trailing.ts", &chunks).unwrap(),
            "beta\n"
        );
    }
}