feature: Detect coursier if it's available locally

src/fetchMetals.ts

@@ -1,56 +1,90 @@
 import * as semver from "semver";
+import path from "path";
+import fs from "fs";
 import { ChildProcessPromise, spawn } from "promisify-child-process";
 import { JavaConfig } from "./getJavaConfig";
+import { OutputChannel } from "./interfaces/OutputChannel";
 
 interface FetchMetalsOptions {
   serverVersion: string;
   serverProperties: string[];
   javaConfig: JavaConfig;
 }
 
-export function fetchMetals({
-  serverVersion,
-  serverProperties,
-  javaConfig: { javaPath, javaOptions, extraEnv, coursierPath },
-}: FetchMetalsOptions): ChildProcessPromise {
+export function fetchMetals(
+  {
+    serverVersion,
+    serverProperties,
+    javaConfig: { javaPath, javaOptions, extraEnv, coursierPath },
+  }: FetchMetalsOptions,
+  output: OutputChannel
+): ChildProcessPromise {
   const fetchProperties = serverProperties.filter(
     (p) => !p.startsWith("-agentlib")
   );
-
   const serverDependency = calcServerDependency(serverVersion);
-  return spawn(
-    javaPath,
-    [
-      ...javaOptions,
-      ...fetchProperties,
-      "-Dfile.encoding=UTF-8",
-      "-jar",
-      coursierPath,
-      "fetch",
-      "-p",
-      "--ttl",
-      // Use infinite ttl to avoid redunant "Checking..." logs when using SNAPSHOT
-      // versions. Metals SNAPSHOT releases are effectively immutable since we
-      // never publish the same version twice.
-      "Inf",
-      serverDependency,
-      "-r",
-      "bintray:scalacenter/releases",
-      "-r",
-      "sonatype:public",
-      "-r",
-      "sonatype:snapshots",
-      "-p",
-    ],
-    {
-      env: {
-        COURSIER_NO_TERM: "true",
-        ...extraEnv,
-        ...process.env,
-      },
-      stdio: ["ignore"], // Due to Issue: #219
-    }
-  );
+
+  const coursierArgs = [
+    "fetch",
+    "-p",
+    "--ttl",
+    // Use infinite ttl to avoid redunant "Checking..." logs when using SNAPSHOT
+    // versions. Metals SNAPSHOT releases are effectively immutable since we
+    // never publish the same version twice.
+    "Inf",
+    serverDependency,
+    "-r",
+    "bintray:scalacenter/releases",
+    "-r",
+    "sonatype:public",
+    "-r",
+    "sonatype:snapshots",
+    "-p",
+  ];
+
+  let possibleCoursier = process.env["PATH"]
+    ?.split(path.delimiter)
+    .flatMap((p) => {
+      if (fs.statSync(p).isDirectory()) {
+        return fs.readdirSync(p).map((sub) => path.resolve(p, sub));
+      } else return [p];
+    })
+    .find(
+      (p) => p.endsWith(path.sep + "cs") || p.endsWith(path.sep + "coursier")
+    );
+
+  function spawnDefault(): ChildProcessPromise {
+    return spawn(
+      javaPath,
+      [
+        ...javaOptions,
+        ...fetchProperties,
+        "-Dfile.encoding=UTF-8",
+        "-jar",
+        coursierPath,
+      ].concat(coursierArgs),
+      {
+        env: {
+          COURSIER_NO_TERM: "true",
+          ...extraEnv,
+          ...process.env,
+        },
+      }
+    );
+  }
+  if (possibleCoursier) {
+    let coursier: string = possibleCoursier;
+    console.debug(`Using coursier located at ${coursier}`);
+    output.appendLine(`Using coursier located at ${coursier}`);
+    spawn(coursier, ["version"])
+      .then((_out) => spawn(coursier, coursierArgs))
+      .catch((err: Error) => {
+        output.appendLine(err.message);
+        console.debug(err);
+        return spawnDefault();
+      });
+  }
+  return spawnDefault();
 }
 
 export function calcServerDependency(serverVersion: string): string {