feat: gix config with section and sub-section filtering. (#331)

Author: Byron

Diff for: gitoxide-core/src/repository/config.rs

@@ -4,15 +4,94 @@ use git_repository as git;
 
 pub fn list(
     repo: git::Repository,
-    _filters: Vec<String>,
+    filters: Vec<String>,
     format: OutputFormat,
-    out: impl std::io::Write,
+    mut out: impl std::io::Write,
 ) -> Result<()> {
     if format != OutputFormat::Human {
         bail!("Only human output format is supported at the moment");
     }
     let config = repo.config_snapshot();
     let config = config.plumbing();
-    config.write_to(out)?;
+    if let Some(frontmatter) = config.frontmatter() {
+        for event in frontmatter {
+            event.write_to(&mut out)?;
+        }
+    }
+    let filters: Vec<_> = filters.into_iter().map(Filter::new).collect();
+    let mut last_meta = None;
+    for (section, matter) in config.sections_and_postmatter() {
+        if !filters.is_empty() && !filters.iter().any(|filter| filter.matches_section(section)) {
+            continue;
+        }
+
+        let meta = section.meta();
+        if last_meta.map_or(true, |last| last != meta) {
+            write_meta(meta, &mut out)?;
+        }
+        last_meta = Some(meta);
+
+        section.write_to(&mut out)?;
+        for event in matter {
+            event.write_to(&mut out)?;
+        }
+        writeln!(&mut out)?;
+    }
     Ok(())
 }
+
+struct Filter {
+    name: String,
+    subsection: Option<String>,
+}
+
+impl Filter {
+    fn new(input: String) -> Self {
+        match git::config::parse::key(&input) {
+            Some(key) => Filter {
+                name: key.section_name.into(),
+                subsection: key.subsection_name.map(ToOwned::to_owned),
+            },
+            None => Filter {
+                name: input,
+                subsection: None,
+            },
+        }
+    }
+
+    fn matches_section(&self, section: &git::config::file::Section<'_>) -> bool {
+        let ignore_case = git::glob::wildmatch::Mode::IGNORE_CASE;
+
+        if !git::glob::wildmatch(self.name.as_bytes().into(), section.header().name(), ignore_case) {
+            return false;
+        }
+        match (self.subsection.as_deref(), section.header().subsection_name()) {
+            (Some(filter), Some(name)) => {
+                if !git::glob::wildmatch(filter.as_bytes().into(), name, ignore_case) {
+                    return false;
+                }
+            }
+            (None, None) | (None, Some(_)) => {}
+            _ => return false,
+        };
+        true
+    }
+}
+
+fn write_meta(meta: &git::config::file::Metadata, out: &mut impl std::io::Write) -> std::io::Result<()> {
+    writeln!(
+        out,
+        "# From '{}' ({:?}{}{})",
+        meta.path
+            .as_deref()
+            .map(|p| p.display().to_string())
+            .unwrap_or_else(|| "memory".into()),
+        meta.source,
+        (meta.level != 0)
+            .then(|| format!(", include level {}", meta.level))
+            .unwrap_or_default(),
+        (meta.trust != git::sec::Trust::Full)
+            .then(|| "untrusted")
+            .unwrap_or_default()
+    )
+}

Diff for: src/plumbing/options.rs

@@ -85,7 +85,10 @@ pub mod config {
     #[derive(Debug, clap::Parser)]
     #[clap(subcommand_required(false))]
     pub struct Platform {
-        /// The filter terms to limit the output to matching sections and values only.
+        /// The filter terms to limit the output to matching sections and subsections only.
+        ///
+        /// Typical filters are `branch` or `remote.origin` or `remote.or*` - git-style globs are supported
+        /// and comparisons are case-insensitive.
         pub filter: Vec<String>,
     }
 }