feat(hg_branch): Add support for mercurial topics and find hg root dir (#4771)

* feat(hg_branch): Add support for mercurial topics and find hg root dir

* Fix clippy errors

* Use crate::utils::read_file

* Update config-schema.json

* Extend PathExt to retrieve device ID of Path

* Break hg root search when switching to another device

* Fix clippy and formatting errors

* Update docs/config/README.md

Co-authored-by: David Knaack <davidkna@users.noreply.github.com>

* Update src/modules/utils/path.rs

Co-authored-by: David Knaack <davidkna@users.noreply.github.com>

* Update src/configs/hg_branch.rs

Co-authored-by: David Knaack <davidkna@users.noreply.github.com>

* Update hg_branch description

* Revert to lazy loading, use truncate_text from utils and use fake topic

* Format code and fix clippy error

* Revert to previous test string as topic is optional in the config

* Fix doc formatting

* Stub device_id for windows

* Update config-schema.json

* Update src/modules/hg_branch.rs

Co-authored-by: David Knaack <davidkna@users.noreply.github.com>

* Do not use unwrap in device_id

* Fix formatter error

* Use dev under non linux unixes

Co-authored-by: David Knaack <davidkna@users.noreply.github.com>

6 files changed, 100 insertions, 48 deletions

diff --git a/.github/config-schema.json b/.github/config-schema.json
index 7924c0cea..e4111cbc3 100644
--- a/.github/config-schema.json
+++ b/.github/config-schema.json
@@ -750,7 +750,7 @@
     "hg_branch": {
       "default": {
         "disabled": true,
-        "format": "on [$symbol$branch]($style) ",
+        "format": "on [$symbol$branch(:$topic)]($style) ",
         "style": "bold purple",
         "symbol": " ",
         "truncation_length": 9223372036854775807,
@@ -3537,7 +3537,7 @@
           "type": "string"
         },
         "format": {
-          "default": "on [$symbol$branch]($style) ",
+          "default": "on [$symbol$branch(:$topic)]($style) ",
           "type": "string"
         },
         "truncation_length": {
diff --git a/docs/config/README.md b/docs/config/README.md
index f8b27bfd1..1fc4968fe 100644
--- a/docs/config/README.md
+++ b/docs/config/README.md
@@ -2643,26 +2643,27 @@ style = 'bold dimmed green'
 
 ## Mercurial Branch
 
-The `hg_branch` module shows the active branch of the repo in your current directory.
+The `hg_branch` module shows the active branch and topic of the repo in your current directory.
 
 ### Options
 
-| Option              | Default                          | Description                                                                                  |
-| ------------------- | -------------------------------- | -------------------------------------------------------------------------------------------- |
-| `symbol`            | `' '`                           | The symbol used before the hg bookmark or branch name of the repo in your current directory. |
-| `style`             | `'bold purple'`                  | The style for the module.                                                                    |
-| `format`            | `'on [$symbol$branch]($style) '` | The format for the module.                                                                   |
-| `truncation_length` | `2^63 - 1`                       | Truncates the hg branch name to `N` graphemes                                                |
-| `truncation_symbol` | `'…'`                            | The symbol used to indicate a branch name was truncated.                                     |
-| `disabled`          | `true`                           | Disables the `hg_branch` module.                                                             |
+| Option              | Default                                   | Description                                                                                  |
+| ------------------- | ----------------------------------------- | -------------------------------------------------------------------------------------------- |
+| `symbol`            | `' '`                                    | The symbol used before the hg bookmark or branch name of the repo in your current directory. |
+| `style`             | `'bold purple'`                           | The style for the module.                                                                    |
+| `format`            | `'on [$symbol$branch(:$topic)]($style) '` | The format for the module.                                                                   |
+| `truncation_length` | `2^63 - 1`                                | Truncates the hg branch / topic name to `N` graphemes                                        |
+| `truncation_symbol` | `'…'`                                     | The symbol used to indicate a branch name was truncated.                                     |
+| `disabled`          | `true`                                    | Disables the `hg_branch` module.                                                             |
 
 ### Variables
 
-| Variable | Example  | Description                          |
-| -------- | -------- | ------------------------------------ |
-| branch   | `master` | The active mercurial branch          |
-| symbol   |          | Mirrors the value of option `symbol` |
-| style\*  |          | Mirrors the value of option `style`  |
+| Variable | Example   | Description                          |
+| -------- | --------- | ------------------------------------ |
+| branch   | `master`  | The active mercurial branch          |
+| topic    | `feature` | The active mercurial topic           |
+| symbol   |           | Mirrors the value of option `symbol` |
+| style\*  |           | Mirrors the value of option `style`  |
 
 *: This variable can only be used as a part of a style string
 
diff --git a/src/configs/hg_branch.rs b/src/configs/hg_branch.rs
index 9e45fe5ff..fff150c96 100644
--- a/src/configs/hg_branch.rs
+++ b/src/configs/hg_branch.rs
@@ -21,7 +21,7 @@ impl<'a> Default for HgBranchConfig<'a> {
         HgBranchConfig {
             symbol: " ",
             style: "bold purple",
-            format: "on [$symbol$branch]($style) ",
+            format: "on [$symbol$branch(:$topic)]($style) ",
             truncation_length: std::i64::MAX,
             truncation_symbol: "…",
             disabled: true,
diff --git a/src/modules/hg_branch.rs b/src/modules/hg_branch.rs
index 3aefd4b65..cb2adecd9 100644
--- a/src/modules/hg_branch.rs
+++ b/src/modules/hg_branch.rs
@@ -1,20 +1,18 @@
-use unicode_segmentation::UnicodeSegmentation;
+use std::io::{Error, ErrorKind};
+use std::path::Path;
 
+use super::utils::truncate::truncate_text;
 use super::{Context, Module, ModuleConfig};
 
 use crate::configs::hg_branch::HgBranchConfig;
 use crate::formatter::StringFormatter;
+use crate::modules::utils::path::PathExt;
+use crate::utils::read_file;
 
 /// Creates a module with the Hg bookmark or branch in the current directory
 ///
 /// Will display the bookmark or branch name if the current directory is an hg repo
 pub fn module<'a>(context: &'a Context) -> Option<Module<'a>> {
-    let is_hg_repo = context.try_begin_scan()?.set_folders(&[".hg"]).is_match();
-
-    if !is_hg_repo {
-        return None;
-    }
-
     let mut module = context.new_module("hg_branch");
     let config: HgBranchConfig = HgBranchConfig::try_load(module.config);
 
@@ -34,16 +32,16 @@ pub fn module<'a>(context: &'a Context) -> Option<Module<'a>> {
         config.truncation_length as usize
     };
 
-    let branch_name =
-        get_hg_current_bookmark(context).unwrap_or_else(|| get_hg_branch_name(context));
+    let repo_root = get_hg_repo_root(context).ok()?;
+    let branch_name = get_hg_current_bookmark(repo_root).unwrap_or_else(|_| {
+        get_hg_branch_name(repo_root).unwrap_or_else(|_| String::from("default"))
+    });
 
-    let truncated_graphemes = get_graphemes(&branch_name, len);
-    // The truncation symbol should only be added if we truncated
-    let truncated_and_symbol = if len < graphemes_len(&branch_name) {
-        let truncation_symbol = get_graphemes(config.truncation_symbol, 1);
-        truncated_graphemes + truncation_symbol.as_str()
+    let branch_graphemes = truncate_text(&branch_name, len, config.truncation_symbol);
+    let topic_graphemes = if let Ok(topic) = get_hg_topic_name(repo_root) {
+        truncate_text(&topic, len, config.truncation_symbol)
     } else {
-        truncated_graphemes
+        String::from("")
     };
 
     let parsed = StringFormatter::new(config.format).and_then(|formatter| {
@@ -57,7 +55,8 @@ pub fn module<'a>(context: &'a Context) -> Option<Module<'a>> {
                 _ => None,
             })
             .map(|variable| match variable {
-                "branch" => Some(Ok(truncated_and_symbol.as_str())),
+                "branch" => Some(Ok(branch_graphemes.as_str())),
+                "topic" => Some(Ok(topic_graphemes.as_str())),
                 _ => None,
             })
             .parse(None, Some(context))
@@ -74,26 +73,33 @@ pub fn module<'a>(context: &'a Context) -> Option<Module<'a>> {
     Some(module)
 }
 
-fn get_hg_branch_name(ctx: &Context) -> String {
-    std::fs::read_to_string(ctx.current_dir.join(".hg").join("branch"))
-        .map_or_else(|_| "default".to_string(), |s| s.trim().into())
+fn get_hg_repo_root<'a>(ctx: &'a Context) -> Result<&'a Path, Error> {
+    let dir = ctx.current_dir.as_path();
+    let dev_id = dir.device_id();
+    for root_dir in dir.ancestors() {
+        if dev_id != root_dir.device_id() {
+            break;
+        }
+        if root_dir.join(".hg").is_dir() {
+            return Ok(root_dir);
+        }
+    }
+    Err(Error::new(ErrorKind::Other, "No .hg found!"))
 }
 
-fn get_hg_current_bookmark(ctx: &Context) -> Option<String> {
-    std::fs::read_to_string(ctx.current_dir.join(".hg").join("bookmarks.current"))
-        .map(|s| s.trim().into())
-        .ok()
+fn get_hg_branch_name(hg_root: &Path) -> Result<String, Error> {
+    match read_file(hg_root.join(".hg").join("branch")) {
+        Ok(b) => Ok(b.trim().to_string()),
+        Err(e) => Err(e),
+    }
 }
 
-fn get_graphemes(text: &str, length: usize) -> String {
-    UnicodeSegmentation::graphemes(text, true)
-        .take(length)
-        .collect::<Vec<&str>>()
-        .concat()
+fn get_hg_current_bookmark(hg_root: &Path) -> Result<String, Error> {
+    read_file(hg_root.join(".hg").join("bookmarks.current"))
 }
 
-fn graphemes_len(text: &str) -> usize {
-    UnicodeSegmentation::graphemes(text, true).count()
+fn get_hg_topic_name(hg_root: &Path) -> Result<String, Error> {
+    read_file(hg_root.join(".hg").join("topic"))
 }
 
 #[cfg(test)]
@@ -188,6 +194,26 @@ mod tests {
 
     #[test]
     #[ignore]
+    fn test_hg_topic() -> io::Result<()> {
+        let tempdir = fixture_repo(FixtureProvider::Hg)?;
+        let repo_dir = tempdir.path();
+        fs::write(repo_dir.join(".hg").join("topic"), "feature")?;
+
+        let actual = ModuleRenderer::new("hg_branch")
+            .path(repo_dir.to_str().unwrap())
+            .config(toml::toml! {
+                [hg_branch]
+                format = "$topic"
+                disabled = false
+            })
+            .collect();
+
+        assert_eq!(Some(String::from("feature")), actual);
+        tempdir.close()
+    }
+
+    #[test]
+    #[ignore]
     fn test_default_truncation_symbol() -> io::Result<()> {
         let tempdir = fixture_repo(FixtureProvider::Hg)?;
         let repo_dir = tempdir.path();
diff --git a/src/modules/mod.rs b/src/modules/mod.rs
index 64442937f..53c36ec97 100644
--- a/src/modules/mod.rs
+++ b/src/modules/mod.rs
@@ -249,7 +249,7 @@ pub fn description(module: &str) -> &'static str {
         "haskell" => "The selected version of the Haskell toolchain",
         "haxe" => "The currently installed version of Haxe",
         "helm" => "The currently installed version of Helm",
-        "hg_branch" => "The active branch of the repo in your current directory",
+        "hg_branch" => "The active branch and topic of the repo in your current directory",
         "hostname" => "The system hostname",
         "java" => "The currently installed version of Java",
         "jobs" => "The current number of jobs running",
diff --git a/src/modules/utils/path.rs b/src/modules/utils/path.rs
index 2bbb02b51..5f5ad4847 100644
--- a/src/modules/utils/path.rs
+++ b/src/modules/utils/path.rs
@@ -13,6 +13,8 @@ pub trait PathExt {
     /// E.g. `\\?\UNC\server\share\foo` => `\foo`
     /// E.g. `/foo/bar` => `/foo/bar`
     fn without_prefix(&self) -> &Path;
+    /// Get device / volume info
+    fn device_id(&self) -> Option<u64>;
 }
 
 #[cfg(windows)]
@@ -80,6 +82,11 @@ impl PathExt for Path {
         let (_, path) = normalize::normalize_path(self);
         path
     }
+
+    fn device_id(&self) -> Option<u64> {
+        // Maybe it should use unimplemented!
+        Some(42u64)
+    }
 }
 
 // NOTE: Windows path prefixes are only parsed on Windows.
@@ -100,6 +107,24 @@ impl PathExt for Path {
     fn without_prefix(&self) -> &Path {
         self
     }
+
+    #[cfg(target_os = "linux")]
+    fn device_id(&self) -> Option<u64> {
+        use std::os::linux::fs::MetadataExt;
+        match self.metadata() {
+            Ok(m) => Some(m.st_dev()),
+            Err(_) => None,
+        }
+    }
+
+    #[cfg(all(unix, not(target_os = "linux")))]
+    fn device_id(&self) -> Option<u64> {
+        use std::os::unix::fs::MetadataExt;
+        match self.metadata() {
+            Ok(m) => Some(m.dev()),
+            Err(_) => None,
+        }
+    }
 }
 
 #[cfg(test)]