1 files changed, 141 insertions, 0 deletions

diff --git a/editors/code/src/installation/language_server.ts b/editors/code/src/installation/language_server.ts
new file mode 100644
index 000000000..1ce67b8b2
--- /dev/null
+++ b/editors/code/src/installation/language_server.ts
@@ -0,0 +1,141 @@
+import * as vscode from "vscode";
+import * as path from "path";
+import { strict as assert } from "assert";
+import { promises as fs } from "fs";
+import { promises as dns } from "dns";
+import { spawnSync } from "child_process";
+import { throttle } from "throttle-debounce";
+
+import { BinarySource } from "./interfaces";
+import { fetchLatestArtifactMetadata } from "./fetch_latest_artifact_metadata";
+import { downloadFile } from "./download_file";
+
+export async function downloadLatestLanguageServer(
+    {file: artifactFileName, dir: installationDir, repo}: BinarySource.GithubRelease
+) {
+    const { releaseName, downloadUrl } = (await fetchLatestArtifactMetadata(
+        repo, artifactFileName
+    ))!;
+
+    await fs.mkdir(installationDir).catch(err => assert.strictEqual(
+        err?.code,
+        "EEXIST",
+        `Couldn't create directory "${installationDir}" to download `+
+        `language server binary: ${err.message}`
+    ));
+
+    const installationPath = path.join(installationDir, artifactFileName);
+
+    console.time("Downloading ra_lsp_server");
+    await vscode.window.withProgress(
+        {
+            location: vscode.ProgressLocation.Notification,
+            cancellable: false, // FIXME: add support for canceling download?
+            title: `Downloading language server (${releaseName})`
+        },
+        async (progress, _cancellationToken) => {
+            let lastPrecentage = 0;
+            await downloadFile(downloadUrl, installationPath, throttle(
+                200,
+                /* noTrailing: */ true,
+                (readBytes, totalBytes) => {
+                    const newPercentage = (readBytes / totalBytes) * 100;
+                    progress.report({
+                        message: newPercentage.toFixed(0) + "%",
+                        increment: newPercentage - lastPrecentage
+                    });
+
+                    lastPrecentage = newPercentage;
+                })
+            );
+        }
+    );
+    console.timeEnd("Downloading ra_lsp_server");
+
+    await fs.chmod(installationPath, 0o755); // Set (rwx, r_x, r_x) permissions
+}
+export async function ensureLanguageServerBinary(
+    langServerSource: null | BinarySource
+): Promise<null | string> {
+
+    if (!langServerSource) {
+        vscode.window.showErrorMessage(
+            "Unfortunately we don't ship binaries for your platform yet. " +
+            "You need to manually clone rust-analyzer repository and " +
+            "run `cargo xtask install --server` to build the language server from sources. " +
+            "If you feel that your platform should be supported, please create an issue " +
+            "about that [here](https://github.com/rust-analyzer/rust-analyzer/issues) and we " +
+            "will consider it."
+        );
+        return null;
+    }
+
+    switch (langServerSource.type) {
+        case BinarySource.Type.ExplicitPath: {
+            if (isBinaryAvailable(langServerSource.path)) {
+                return langServerSource.path;
+            }
+
+            vscode.window.showErrorMessage(
+                `Unable to run ${langServerSource.path} binary. ` +
+                `To use the pre-built language server, set "rust-analyzer.raLspServerPath" ` +
+                "value to `null` or remove it from the settings to use it by default."
+            );
+            return null;
+        }
+        case BinarySource.Type.GithubRelease: {
+            const prebuiltBinaryPath = path.join(langServerSource.dir, langServerSource.file);
+
+            if (isBinaryAvailable(prebuiltBinaryPath)) {
+                return prebuiltBinaryPath;
+            }
+
+            const userResponse = await vscode.window.showInformationMessage(
+                "Language server binary for rust-analyzer was not found. " +
+                "Do you want to download it now?",
+                "Download now", "Cancel"
+            );
+            if (userResponse !== "Download now") return null;
+
+            try {
+                await downloadLatestLanguageServer(langServerSource);
+            } catch (err) {
+                await vscode.window.showErrorMessage(
+                    `Failed to download language server from ${langServerSource.repo.name} ` +
+                    `GitHub repository: ${err.message}`
+                );
+
+                await dns.resolve('www.google.com').catch(err => {
+                    console.error("DNS resolution failed, there might be an issue with Internet availability");
+                    console.error(err);
+                });
+
+                return null;
+            }
+
+            if (!isBinaryAvailable(prebuiltBinaryPath)) assert(false,
+                `Downloaded language server binary is not functional.` +
+                `Downloaded from: ${JSON.stringify(langServerSource)}`
+            );
+
+
+            vscode.window.showInformationMessage(
+                "Rust analyzer language server was successfully installed 🦀"
+            );
+
+            return prebuiltBinaryPath;
+        }
+    }
+
+    function isBinaryAvailable(binaryPath: string) {
+        const res = spawnSync(binaryPath, ["--version"]);
+
+        // ACHTUNG! `res` type declaration is inherently wrong, see
+        // https://github.com/DefinitelyTyped/DefinitelyTyped/issues/42221
+
+        console.log("Checked binary availablity via --version", res);
+        console.log(binaryPath, "--version output:", res.output?.map(String));
+
+        return res.status === 0;
+    }
+}