implement hls adapter

crates/zed/src/languages.rs

@@ -202,7 +202,11 @@ pub fn init(
             );
         }
     }
-    language("haskell", tree_sitter_haskell::language(), vec![]);
+    language(
+        "haskell",
+        tree_sitter_haskell::language(),
+        vec![Arc::new(haskell::HaskellLspAdapter)],
+    );
     language(
         "html",
         tree_sitter_html::language(),

crates/zed/src/languages/haskell.rs

@@ -1 +1,135 @@
+use std::env::consts::ARCH;
+use std::{any::Any, path::PathBuf};
 
+use anyhow::{anyhow, Context, Result};
+use async_compression::futures::bufread::XzDecoder;
+use async_tar::Archive;
+use async_trait::async_trait;
+use futures::{io::BufReader, StreamExt};
+use smol::fs;
+
+use language::{LanguageServerName, LspAdapter, LspAdapterDelegate};
+use lsp::LanguageServerBinary;
+use util::async_maybe;
+use util::github::latest_github_release;
+use util::{github::GitHubLspBinaryVersion, ResultExt};
+
+pub struct HaskellLspAdapter;
+
+#[async_trait]
+impl LspAdapter for HaskellLspAdapter {
+    fn name(&self) -> LanguageServerName {
+        LanguageServerName("haskell-language-server".into())
+    }
+
+    fn short_name(&self) -> &'static str {
+        "hls"
+    }
+
+    async fn fetch_latest_server_version(
+        &self,
+        delegate: &dyn LspAdapterDelegate,
+    ) -> Result<Box<dyn 'static + Send + Any>> {
+        // TODO: Release version should be matched against GHC version
+        let release = latest_github_release(
+            "haskell/haskell-language-server",
+            false,
+            delegate.http_client(),
+        )
+        .await?;
+        let asset_name = format!(
+            "haskell-language-server-{}-{}-apple-darwin.tar.xz",
+            release.name, ARCH
+        );
+        let asset = release
+            .assets
+            .iter()
+            .find(|asset| asset.name == asset_name)
+            .ok_or_else(|| anyhow!("no asset found matching {:?}", asset_name))?;
+        let version = GitHubLspBinaryVersion {
+            name: release.name,
+            url: asset.browser_download_url.clone(),
+        };
+        Ok(Box::new(version) as Box<_>)
+    }
+
+    async fn fetch_server_binary(
+        &self,
+        version: Box<dyn 'static + Send + Any>,
+        container_dir: PathBuf,
+        delegate: &dyn LspAdapterDelegate,
+    ) -> Result<LanguageServerBinary> {
+        let version = version.downcast::<GitHubLspBinaryVersion>().unwrap();
+        let destination_path =
+            container_dir.join(format!("haskell-language-server-{}", version.name));
+        if fs::metadata(&destination_path).await.is_err() {
+            let mut response = delegate
+                .http_client()
+                .get(&version.url, Default::default(), true)
+                .await
+                .context("error downloading release")?;
+            let decompressed_bytes = XzDecoder::new(BufReader::new(response.body_mut()));
+            let archive = Archive::new(decompressed_bytes);
+            archive.unpack(&container_dir).await?;
+        }
+        let binary_path = destination_path.join("bin/haskell-language-server-wrapper");
+        fs::set_permissions(
+            &binary_path,
+            <fs::Permissions as fs::unix::PermissionsExt>::from_mode(0o755),
+        )
+        .await?;
+        Ok(LanguageServerBinary {
+            path: binary_path,
+            arguments: vec!["--lsp".into()],
+        })
+    }
+
+    async fn cached_server_binary(
+        &self,
+        container_dir: PathBuf,
+        _: &dyn LspAdapterDelegate,
+    ) -> Option<LanguageServerBinary> {
+        get_cached_server_binary(container_dir).await
+    }
+
+    async fn installation_test_binary(
+        &self,
+        container_dir: PathBuf,
+    ) -> Option<LanguageServerBinary> {
+        get_cached_server_binary(container_dir)
+            .await
+            .map(|mut binary| {
+                binary.arguments = vec!["--help".into()];
+                binary
+            })
+    }
+}
+
+async fn get_cached_server_binary(container_dir: PathBuf) -> Option<LanguageServerBinary> {
+    async_maybe!({
+        let mut last_binary_path = None;
+        let mut entries = fs::read_dir(&container_dir).await?;
+        while let Some(entry) = entries.next().await {
+            let entry = entry?;
+            if entry.file_type().await?.is_file()
+                && entry
+                    .file_name()
+                    .to_str()
+                    .map_or(false, |name| name == "haskell-language-server-wrapper")
+            {
+                last_binary_path = Some(entry.path());
+            }
+        }
+
+        if let Some(path) = last_binary_path {
+            Ok(LanguageServerBinary {
+                path,
+                arguments: Vec::new(),
+            })
+        } else {
+            Err(anyhow!("no cached binary"))
+        }
+    })
+    .await
+    .log_err()
+}