fix: allow online-npm-install if prefer-offline fails

This resolves diffplug#1750

Author: simschla

lib/src/main/java/com/diffplug/spotless/npm/NodeApp.java

@@ -15,13 +15,18 @@
  */
 package com.diffplug.spotless.npm;
 
+import static com.diffplug.spotless.npm.NpmProcessFactory.OnlinePreferrence.PREFER_OFFLINE;
+import static com.diffplug.spotless.npm.NpmProcessFactory.OnlinePreferrence.PREFER_ONLINE;
+
 import java.util.Objects;
 
 import javax.annotation.Nonnull;
 
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
+import com.diffplug.spotless.ProcessRunner;
+
 public class NodeApp {
 
 	private static final Logger logger = LoggerFactory.getLogger(NodeApp.class);
@@ -83,6 +88,28 @@ void prepareNodeAppLayout() {
 
 	void npmInstall() {
 		timedLogger.withInfo("Installing npm dependencies for {} with {}.", this.nodeServerLayout, this.npmProcessFactory.describe())
-				.run(() -> npmProcessFactory.createNpmInstallProcess(nodeServerLayout, formatterStepLocations).waitFor());
+				.run(this::optimizedNpmInstall);
+	}
+
+	private void optimizedNpmInstall() {
+		try {
+			npmProcessFactory.createNpmInstallProcess(nodeServerLayout, formatterStepLocations, PREFER_OFFLINE).waitFor();
+		} catch (NpmProcessException e) {
+			if (!offlineInstallFailed(e.getResult())) {
+				throw e; // pass through
+			}
+			// if the npm install fails with message "No matching version found for <package>@<version>", we try again without the offline flag
+			npmProcessFactory.createNpmInstallProcess(nodeServerLayout, formatterStepLocations, PREFER_ONLINE).waitFor();
+		}
+	}
+
+	private boolean offlineInstallFailed(ProcessRunner.Result result) {
+		if (result == null) {
+			return false; // no result, something else must have happened
+		}
+		if (result.exitCode() == 0) {
+			return false; // all is well
+		}
+		return result.stdOutUtf8().contains("code ETARGET") && result.stdOutUtf8().contains("No matching version found for"); // offline install failed, needs online install
 	}
 }

lib/src/main/java/com/diffplug/spotless/npm/NodeModulesCachingNpmProcessFactory.java

@@ -58,8 +58,8 @@ public static NodeModulesCachingNpmProcessFactory create(@Nonnull File cacheDir)
 	}
 
 	@Override
-	public NpmProcess createNpmInstallProcess(NodeServerLayout nodeServerLayout, NpmFormatterStepLocations formatterStepLocations) {
-		NpmProcess actualNpmInstallProcess = StandardNpmProcessFactory.INSTANCE.createNpmInstallProcess(nodeServerLayout, formatterStepLocations);
+	public NpmProcess createNpmInstallProcess(NodeServerLayout nodeServerLayout, NpmFormatterStepLocations formatterStepLocations, OnlinePreferrence onlinePreferrence) {
+		NpmProcess actualNpmInstallProcess = StandardNpmProcessFactory.INSTANCE.createNpmInstallProcess(nodeServerLayout, formatterStepLocations, onlinePreferrence);
 		return new CachingNmpInstall(actualNpmInstallProcess, nodeServerLayout);
 	}
 

lib/src/main/java/com/diffplug/spotless/npm/NpmProcessException.java

@@ -15,14 +15,26 @@
  */
 package com.diffplug.spotless.npm;
 
+import javax.annotation.CheckForNull;
+
+import com.diffplug.spotless.ProcessRunner;
+
 public class NpmProcessException extends RuntimeException {
 	private static final long serialVersionUID = 6424331316676759525L;
+	private final ProcessRunner.Result result;
 
-	public NpmProcessException(String message) {
+	public NpmProcessException(String message, ProcessRunner.Result result) {
 		super(message);
+		this.result = result;
 	}
 
 	public NpmProcessException(String message, Throwable cause) {
 		super(message, cause);
+		this.result = null;
+	}
+
+	@CheckForNull
+	public ProcessRunner.Result getResult() {
+		return result;
 	}
 }

lib/src/main/java/com/diffplug/spotless/npm/NpmProcessFactory.java

@@ -16,7 +16,22 @@
 package com.diffplug.spotless.npm;
 
 public interface NpmProcessFactory {
-	NpmProcess createNpmInstallProcess(NodeServerLayout nodeServerLayout, NpmFormatterStepLocations formatterStepLocations);
+
+	enum OnlinePreferrence {
+		PREFER_OFFLINE("--prefer-offline"), PREFER_ONLINE("--prefer-online");
+
+		private final String option;
+
+		OnlinePreferrence(String option) {
+			this.option = option;
+		}
+
+		public String option() {
+			return option;
+		}
+	}
+
+	NpmProcess createNpmInstallProcess(NodeServerLayout nodeServerLayout, NpmFormatterStepLocations formatterStepLocations, OnlinePreferrence onlinePreferrence);
 
 	NpmLongRunningProcess createNpmServeProcess(NodeServerLayout nodeServerLayout, NpmFormatterStepLocations formatterStepLocations);
 

lib/src/main/java/com/diffplug/spotless/npm/StandardNpmProcessFactory.java

@@ -32,8 +32,8 @@ private StandardNpmProcessFactory() {
 	}
 
 	@Override
-	public NpmProcess createNpmInstallProcess(NodeServerLayout nodeServerLayout, NpmFormatterStepLocations formatterStepLocations) {
-		return new NpmInstall(nodeServerLayout.nodeModulesDir(), formatterStepLocations);
+	public NpmProcess createNpmInstallProcess(NodeServerLayout nodeServerLayout, NpmFormatterStepLocations formatterStepLocations, OnlinePreferrence onlinePreferrence) {
+		return new NpmInstall(nodeServerLayout.nodeModulesDir(), formatterStepLocations, onlinePreferrence);
 	}
 
 	@Override
@@ -80,8 +80,11 @@ public String doDescribe() {
 
 	private static class NpmInstall extends AbstractStandardNpmProcess implements NpmProcess {
 
-		public NpmInstall(File workingDir, NpmFormatterStepLocations formatterStepLocations) {
+		private final OnlinePreferrence onlinePreferrence;
+
+		public NpmInstall(File workingDir, NpmFormatterStepLocations formatterStepLocations, OnlinePreferrence onlinePreferrence) {
 			super(workingDir, formatterStepLocations);
+			this.onlinePreferrence = onlinePreferrence;
 		}
 
 		@Override
@@ -91,7 +94,7 @@ protected List<String> commandLine() {
 					"install",
 					"--no-audit",
 					"--no-fund",
-					"--prefer-offline");
+					onlinePreferrence.option());
 		}
 
 		@Override
@@ -103,7 +106,7 @@ public String describe() {
 		public ProcessRunner.Result waitFor() {
 			try (ProcessRunner.LongRunningProcess npmProcess = doStart()) {
 				if (npmProcess.waitFor() != 0) {
-					throw new NpmProcessException("Running npm command '" + describe() + "' failed with exit code: " + npmProcess.exitValue() + "\n\n" + npmProcess.result());
+					throw new NpmProcessException("Running npm command '" + describe() + "' failed with exit code: " + npmProcess.exitValue() + "\n\n" + npmProcess.result(), npmProcess.result());
 				}
 				return npmProcess.result();
 			} catch (InterruptedException e) {