1 files changed, 314 insertions, 0 deletions
diff --git a/src/modules/dotnet.rs b/src/modules/dotnet.rs
new file mode 100644
index 000000000..d63256e56
--- /dev/null
+++ b/src/modules/dotnet.rs
@@ -0,0 +1,314 @@
+use std::ffi::OsStr;
+use std::iter::Iterator;
+use std::ops::Deref;
+use std::path::{Path, PathBuf};
+use std::process::{Command, Stdio};
+use std::str;
+
+use super::{Context, Module};
+use crate::config::RootModuleConfig;
+use crate::configs::dotnet::DotnetConfig;
+
+type JValue = serde_json::Value;
+
+const GLOBAL_JSON_FILE: &str = "global.json";
+const PROJECT_JSON_FILE: &str = "project.json";
+
+/// A module which shows the latest (or pinned) version of the dotnet SDK
+///
+/// Will display if any of the following files are present in
+/// the current directory:
+/// global.json, project.json, *.sln, *.csproj, *.fsproj, *.xproj
+pub fn module<'a>(context: &'a Context) -> Option<Module<'a>> {
+    let dotnet_files = get_local_dotnet_files(context).ok()?;
+    if dotnet_files.is_empty() {
+        return None;
+    }
+
+    let mut module = context.new_module("dotnet");
+    let config = DotnetConfig::try_load(module.config);
+
+    // Internally, this module uses its own mechanism for version detection.
+    // Typically it is twice as fast as running `dotnet --version`.
+    let enable_heuristic = config.heuristic;
+    let version = if enable_heuristic {
+        let repo_root = context
+            .get_repo()
+            .ok()
+            .and_then(|r| r.root.as_ref().map(PathBuf::as_path));
+        estimate_dotnet_version(&dotnet_files, &context.current_dir, repo_root)?
+    } else {
+        get_version_from_cli()?
+    };
+
+    module.set_style(config.style);
+    module.create_segment("symbol", &config.symbol);
+    module.create_segment("version", &config.version.with_value(&version.0));
+
+    Some(module)
+}
+
+fn estimate_dotnet_version<'a>(
+    files: &[DotNetFile<'a>],
+    current_dir: &Path,
+    repo_root: Option<&Path>,
+) -> Option<Version> {
+    let get_file_of_type = |t: FileType| files.iter().find(|f| f.file_type == t);
+
+    // It's important to check for a global.json or a solution file first,
+    // but otherwise we can take any relevant file. We'll take whichever is first.
+    let relevant_file = get_file_of_type(FileType::GlobalJson)
+        .or_else(|| get_file_of_type(FileType::SolutionFile))
+        .or_else(|| files.iter().next())?;
+
+    match relevant_file.file_type {
+        FileType::GlobalJson => {
+            get_pinned_sdk_version_from_file(relevant_file.path).or_else(get_latest_sdk_from_cli)
+        }
+        FileType::SolutionFile => {
+            // With this heuristic, we'll assume that a "global.json" won't
+            // be found in any directory above the solution file.
+            get_latest_sdk_from_cli()
+        }
+        _ => {
+            // If we see a dotnet project, we'll check a small number of neighboring
+            // directories to see if we can find a global.json. Otherwise, assume the
+            // latest SDK is in use.
+            try_find_nearby_global_json(current_dir, repo_root).or_else(get_latest_sdk_from_cli)
+        }
+    }
+}
+
+/// Looks for a `global.json` which may exist in one of the parent directories of the current path.
+/// If there is one present, and it contains valid version pinning information, then return that version.
+///
+/// The following places are scanned:
+///     - The parent of the current directory
+///       (Unless there is a git repository, and the parent is above the root of that repository)
+///     - The root of the git repository
+///       (If there is one)
+fn try_find_nearby_global_json(current_dir: &Path, repo_root: Option<&Path>) -> Option<Version> {
+    let current_dir_is_repo_root = repo_root.map(|r| r == current_dir).unwrap_or(false);
+    let parent_dir = if current_dir_is_repo_root {
+        // Don't scan the parent directory if it's above the root of a git repository
+        None
+    } else {
+        current_dir.parent()
+    };
+
+    // Check the parent directory, or otherwise the repository root, for a global.json
+    let mut check_dirs = parent_dir
+        .iter()
+        .chain(repo_root.iter())
+        .copied() // Copies the reference, not the Path itself
+        .collect::<Vec<&Path>>();
+
+    // The parent directory and repository root may be the same directory,
+    // so avoid checking it twice.
+    check_dirs.dedup();
+
+    check_dirs
+        .iter()
+        // repo_root may be the same as the current directory. We don't need to scan it again.
+        .filter(|&&d| d != current_dir)
+        .filter_map(|d| check_directory_for_global_json(d))
+        // This will lazily evaluate the first directory with a global.json
+        .next()
+}
+
+fn check_directory_for_global_json(path: &Path) -> Option<Version> {
+    let global_json_path = path.join(GLOBAL_JSON_FILE);
+    log::debug!(
+        "Checking if global.json exists at: {}",
+        &global_json_path.display()
+    );
+    if global_json_path.exists() {
+        get_pinned_sdk_version_from_file(&global_json_path)
+    } else {
+        None
+    }
+}
+
+fn get_pinned_sdk_version_from_file(path: &Path) -> Option<Version> {
+    let json_text = crate::utils::read_file(path).ok()?;
+    log::debug!(
+        "Checking if .NET SDK version is pinned in: {}",
+        path.display()
+    );
+    get_pinned_sdk_version(&json_text)
+}
+
+fn get_pinned_sdk_version(json: &str) -> Option<Version> {
+    let parsed_json: JValue = serde_json::from_str(json).ok()?;
+
+    match parsed_json {
+        JValue::Object(root) => {
+            let sdk = root.get("sdk")?;
+            match sdk {
+                JValue::Object(sdk) => {
+                    let version = sdk.get("version")?;
+                    match version {
+                        JValue::String(version_string) => {
+                            let mut buffer = String::with_capacity(version_string.len() + 1);
+                            buffer.push('v');
+                            buffer.push_str(version_string);
+                            Some(Version(buffer))
+                        }
+                        _ => None,
+                    }
+                }
+                _ => None,
+            }
+        }
+        _ => None,
+    }
+}
+
+fn get_local_dotnet_files<'a>(context: &'a Context) -> Result<Vec<DotNetFile<'a>>, std::io::Error> {
+    Ok(context
+        .get_dir_files()?
+        .iter()
+        .filter_map(|p| {
+            get_dotnet_file_type(p).map(|t| DotNetFile {
+                path: p.as_ref(),
+                file_type: t,
+            })
+        })
+        .collect())
+}
+
+fn get_dotnet_file_type(path: &Path) -> Option<FileType> {
+    let file_name_lower = map_str_to_lower(path.file_name());
+
+    match file_name_lower.as_ref().map(|f| f.as_ref()) {
+        Some(GLOBAL_JSON_FILE) => return Some(FileType::GlobalJson),
+        Some(PROJECT_JSON_FILE) => return Some(FileType::ProjectJson),
+        _ => (),
+    };
+
+    let extension_lower = map_str_to_lower(path.extension());
+
+    match extension_lower.as_ref().map(|f| f.as_ref()) {
+        Some("sln") => return Some(FileType::SolutionFile),
+        Some("csproj") | Some("fsproj") | Some("xproj") => return Some(FileType::ProjectFile),
+        _ => (),
+    };
+
+    None
+}
+
+fn map_str_to_lower(value: Option<&OsStr>) -> Option<String> {
+    Some(value?.to_str()?.to_ascii_lowercase())
+}
+
+fn get_version_from_cli() -> Option<Version> {
+    let version_output = match Command::new("dotnet").arg("--version").output() {
+        Ok(output) => output,
+        Err(e) => {
+            log::warn!("Failed to execute `dotnet --version`. {}", e);
+            return None;
+        }
+    };
+    let version = str::from_utf8(version_output.stdout.as_slice())
+        .ok()?
+        .trim();
+
+    let mut buffer = String::with_capacity(version.len() + 1);
+    buffer.push('v');
+    buffer.push_str(version);
+
+    Some(Version(buffer))
+}
+
+fn get_latest_sdk_from_cli() -> Option<Version> {
+    let mut cmd = Command::new("dotnet");
+    cmd.arg("--list-sdks")
+        .stdout(Stdio::piped())
+        .stderr(Stdio::null())
+        .stdin(Stdio::null());
+
+    let exit_code = match cmd.status() {
+        Ok(status) => status,
+        Err(e) => {
+            log::warn!("Failed to execute `dotnet --list-sdks`. {}", e);
+            return None;
+        }
+    };
+
+    if exit_code.success() {
+        let sdks_output = cmd.output().ok()?;
+        fn parse_failed<T>() -> Option<T> {
+            log::warn!("Unable to parse the output from `dotnet --list-sdks`.");
+            None
+        };
+        let latest_sdk = str::from_utf8(sdks_output.stdout.as_slice())
+            .ok()?
+            .lines()
+            .map(str::trim)
+            .filter(|l| !l.is_empty())
+            .last()
+            .or_else(parse_failed)?;
+        let take_until = latest_sdk.find('[').or_else(parse_failed)? - 1;
+        if take_until > 1 {
+            let version = &latest_sdk[..take_until];
+            let mut buffer = String::with_capacity(version.len() + 1);
+            buffer.push('v');
+            buffer.push_str(version);
+            Some(Version(buffer))
+        } else {
+            parse_failed()
+        }
+    } else {
+        // Older versions of the dotnet cli do not support the --list-sdks command
+        // So, if the status code indicates failure, fall back to `dotnet --version`
+        log::warn!(
+            "Received a non-success exit code from `dotnet --list-sdks`. \
+             Falling back to `dotnet --version`.",
+        );
+        get_version_from_cli()
+    }
+}
+
+struct DotNetFile<'a> {
+    path: &'a Path,
+    file_type: FileType,
+}
+
+#[derive(PartialEq)]
+enum FileType {
+    ProjectJson,
+    ProjectFile,
+    GlobalJson,
+    SolutionFile,
+}
+
+struct Version(String);
+
+impl Deref for Version {
+    type Target = String;
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+
+#[test]
+fn should_parse_version_from_global_json() {
+    let json_text = r#"
+        {
+            "sdk": {
+                "version": "1.2.3"
+            }
+        }
+    "#;
+
+    let version = get_pinned_sdk_version(json_text).unwrap();
+    assert_eq!("v1.2.3", version.0);
+}
+
+#[test]
+fn should_ignore_empty_global_json() {
+    let json_text = "{}";
+
+    let version = get_pinned_sdk_version(json_text);
+    assert!(version.is_none());
+}