magi-code 0.63.4

use super::{DisplayLine, DisplayRole};

pub(crate) fn render_diff(input: &str) -> Vec<DisplayLine> {
    if input.is_empty() {
        return vec![DisplayLine::from_span("", DisplayRole::DiffContext)];
    }
    input
        .split('\n')
        .map(|line| DisplayLine::from_span(line, classify_diff_line(line)))
        .collect()
}

fn classify_diff_line(line: &str) -> DisplayRole {
    if line.starts_with("diff --git ")
        || line.starts_with("index ")
        || line.starts_with("--- ")
        || line.starts_with("+++ ")
    {
        DisplayRole::DiffFileHeader
    } else if line.starts_with("@@") {
        DisplayRole::DiffHunkHeader
    } else if line.starts_with("\\ No newline at end of file") {
        DisplayRole::DiffMetadata
    } else if line.starts_with('+') {
        DisplayRole::DiffInserted
    } else if line.starts_with('-') {
        DisplayRole::DiffRemoved
    } else if line.starts_with('!') {
        DisplayRole::DiffChanged
    } else {
        DisplayRole::DiffContext
    }
}

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

    #[test]
    fn classifies_git_diff_roles() {
        let lines = render_diff(
            "diff --git a/x b/x\n@@ -1 +1 @@\n-old\n+new\n context\n\\ No newline at end of file",
        );
        let roles: Vec<_> = lines.iter().map(|line| line.spans[0].role).collect();
        assert_eq!(
            roles,
            vec![
                DisplayRole::DiffFileHeader,
                DisplayRole::DiffHunkHeader,
                DisplayRole::DiffRemoved,
                DisplayRole::DiffInserted,
                DisplayRole::DiffContext,
                DisplayRole::DiffMetadata,
            ]
        );
    }

    #[test]
    fn context_diff_changed_lines_classify_as_changed() {
        let lines = render_diff("! old line\n! new line");
        let roles: Vec<_> = lines.iter().map(|line| line.spans[0].role).collect();
        assert_eq!(
            roles,
            vec![DisplayRole::DiffChanged, DisplayRole::DiffChanged]
        );
    }
}