Choose URL matching the hash of the local artifact

src/main/java/com/fzakaria/mvn2nix/cmd/Maven2nix.java

@@ -6,7 +6,8 @@
 import com.fzakaria.mvn2nix.model.MavenNixInformation;
 import com.fzakaria.mvn2nix.model.URLAdapter;
 import com.google.common.hash.Hashing;
-import com.google.common.io.Files;
+import com.google.common.hash.HashingInputStream;
+import com.google.common.io.ByteStreams;
 import com.squareup.moshi.JsonAdapter;
 import com.squareup.moshi.Moshi;
 import org.slf4j.Logger;
@@ -25,8 +26,10 @@
 import java.net.MalformedURLException;
 import java.net.URL;
 import java.net.URLConnection;
+import java.util.Arrays;
 import java.util.Collection;
 import java.util.Map;
+import java.util.Optional;
 import java.util.concurrent.Callable;
 import java.util.stream.Collectors;
 
@@ -63,43 +66,70 @@ public class Maven2nix implements Callable<Integer> {
             defaultValue = "${java.home}")
     private File javaHome;
 
+    private ArtifactResolver resolver;
+
+    private ArtifactAnalysis analysis;
+
     public Maven2nix() {
+        this.resolver = Maven2nix::sha256OfUrl;
+        this.analysis = this::collectArtifactsFromTempLocalRepository;
+    }
+
+    public Maven2nix(ArtifactResolver resolver, ArtifactAnalysis analysis) {
+        this.resolver = resolver;
+        this.analysis = analysis;
     }
 
     @Override
-    public Integer call() throws Exception {
+    public Integer call() {
         LOGGER.info("Reading {}", file);
+        spec.commandLine().getOut().println(toPrettyJson(mavenNixInformation(resolver, analysis, repositories)));
+        return 0;
+    }
 
-        final Maven maven = Maven.withTemporaryLocalRepository();
-        maven.executeGoals(file, javaHome, goals);
-
-        Collection<Artifact> artifacts = maven.collectAllArtifactsInLocalRepository();
+    static MavenNixInformation mavenNixInformation(
+            ArtifactResolver resolver,
+            ArtifactAnalysis analysis,
+            String[] repositories
+    ) {
+        Collection<Artifact> artifacts = analysis.analyze();
         Map<String, MavenArtifact> dependencies = artifacts.parallelStream()
                 .collect(Collectors.toMap(
-                            Artifact::getCanonicalName,
-                            artifact -> {
-                                for (String repository : repositories) {
-                                    URL url = getRepositoryArtifactUrl(artifact, repository);
-                                    if (!doesUrlExist(url)) {
-                                        LOGGER.info("URL does not exist: {}", url);
-                                        continue;
-                                    }
+                        Artifact::getCanonicalName,
+                        artifact -> new MavenArtifact(artifactUrl(resolver, repositories, artifact), artifact.getLayout(), artifact.getSha256())));
+        return new MavenNixInformation(dependencies);
+    }
 
-                                    File localArtifact = maven.findArtifactInLocalRepository(artifact)
-                                            .orElseThrow(() -> new IllegalStateException("Should never happen"));
+    private static URL artifactUrl(ArtifactResolver resolver, String[] repositories, Artifact artifact) {
+        return Arrays.stream(repositories)
+                .map(r -> getRepositoryArtifactUrl(artifact, r))
+                .filter(u -> resolver.sha256(u).map(artifact.getSha256()::equals).orElse(false))
+                .findFirst()
+                .orElseThrow(() -> new RuntimeException(String.format("Could not find artifact %s in any repository", artifact)));
+    }
 
-                                    String sha256 = calculateSha256OfFile(localArtifact);
-                                    return new MavenArtifact(url, artifact.getLayout(), sha256);
-                                }
-                                throw new RuntimeException(String.format("Could not find artifact %s in any repository", artifact));
-                            }
-                        ));
+    @FunctionalInterface
+    interface ArtifactAnalysis {
+        /**
+         * @return The artifacts needed to run the goals on the given pom.
+         */
+        Collection<Artifact> analyze();
+    }
 
+    @FunctionalInterface
+    public interface ArtifactResolver {
+        /**
+         * @return The sha256 of the file referred to by the given URL or
+         * {@link Optional#empty()} if the URL does not exist.
+         */
+        Optional<String> sha256(URL artifact);
+    }
 
-        final MavenNixInformation information = new MavenNixInformation(dependencies);
-        spec.commandLine().getOut().println(toPrettyJson(information));
 
-        return 0;
+    private Collection<Artifact> collectArtifactsFromTempLocalRepository() {
+        final Maven maven = Maven.withTemporaryLocalRepository();
+        maven.executeGoals(file, javaHome, goals);
+        return maven.collectAllArtifactsInLocalRepository();
     }
 
     /**
@@ -130,40 +160,28 @@ public static URL getRepositoryArtifactUrl(Artifact artifact, String repository)
         }
     }
 
-    public static String calculateSha256OfFile(File file) {
-        try {
-            return Files.asByteSource(file).hash(Hashing.sha256()).toString();
-        } catch (IOException e) {
-            throw new UncheckedIOException(e);
-        }
-    }
-
-    /**
-     * Check whether a given URL
-     *
-     * @param url The URL for the pom file.
-     * @return
-     */
-    public static boolean doesUrlExist(URL url) {
+    public static Optional<String> sha256OfUrl(URL url) {
         try {
             URLConnection urlConnection = url.openConnection();
             if (!(urlConnection instanceof HttpURLConnection)) {
-                return false;
+                throw new RuntimeException("The url is not of type http provided.");
             }
 
             HttpURLConnection connection = (HttpURLConnection) urlConnection;
-            connection.setRequestMethod("HEAD");
+            connection.setRequestMethod("GET");
             connection.setInstanceFollowRedirects(true);
             connection.connect();
 
             int code = connection.getResponseCode();
-            if (code == 200) {
-                return true;
+            if (code >= 400) {
+                throw new RuntimeException("Fetching the url failed with status code: " + code);
             }
+            var inputStream = new HashingInputStream(Hashing.sha256(), connection.getInputStream());
+            ByteStreams.exhaust(inputStream);
+            return Optional.of(inputStream.hash().toString());
         } catch (IOException e) {
-            throw new UncheckedIOException(e);
+            return Optional.empty();
         }
-        return false;
     }
 
 }

src/main/java/com/fzakaria/mvn2nix/maven/Artifact.java

@@ -14,32 +14,23 @@ public class Artifact {
     private final String classifier;
     private final String extension;
 
-    public Artifact(String group, String name, String version, String classifier, String extension) {
+    private final String sha256;
+
+    public Artifact(String group, String name, String version, String classifier, String extension, String sha256) {
         this.group = group;
         this.name = name;
         this.version = version;
         this.classifier = classifier;
         this.extension = extension;
-    }
-
-    public String getGroup() {
-        return group;
+        this.sha256 = sha256;
     }
 
     public String getName() {
         return name;
     }
 
-    public String getVersion() {
-        return version;
-    }
-
-    public String getClassifier() {
-        return classifier;
-    }
-
-    public String getExtension() {
-        return extension;
+    public String getSha256() {
+        return sha256;
     }
 
     @Override
@@ -51,7 +42,8 @@ public boolean equals(Object o) {
                 Objects.equals(name, artifact.name) &&
                 Objects.equals(version, artifact.version) &&
                 Objects.equals(classifier, artifact.classifier) &&
-                Objects.equals(extension, artifact.extension);
+                Objects.equals(extension, artifact.extension) &&
+                Objects.equals(sha256, artifact.sha256);
     }
 
     /**
@@ -87,7 +79,7 @@ public String getCanonicalName() {
 
     @Override
     public int hashCode() {
-        return Objects.hash(group, name, version, classifier, extension);
+        return Objects.hash(group, name, version, classifier, extension, sha256);
     }
 
     @Override
@@ -139,6 +131,8 @@ public static class Builder {
         private String classifier;
         private String extension;
 
+        private String sha256;
+
         public Builder setGroup(String group) {
             this.group = group;
             return this;
@@ -164,8 +158,13 @@ public Builder setExtension(String extension) {
             return this;
         }
 
+        public Builder setSha256(String sha256) {
+            this.sha256 = sha256;
+            return this;
+        }
+
         public Artifact build() {
-            return new Artifact(group, name, version, classifier, extension);
+            return new Artifact(group, name, version, classifier, extension, sha256);
         }
     }
 }

src/main/java/com/fzakaria/mvn2nix/maven/Maven.java

@@ -3,6 +3,7 @@
 import com.fzakaria.mvn2nix.util.Resources;
 import com.google.common.base.Preconditions;
 import com.google.common.collect.Lists;
+import com.google.common.hash.Hashing;
 import org.apache.logging.log4j.Level;
 import org.apache.logging.log4j.io.IoBuilder;
 import org.apache.maven.shared.invoker.DefaultInvocationRequest;
@@ -21,7 +22,6 @@
 import java.util.Arrays;
 import java.util.Collection;
 import java.util.Objects;
-import java.util.Optional;
 import java.util.stream.Collectors;
 import java.util.stream.StreamSupport;
 
@@ -70,21 +70,7 @@ public static Maven withTemporaryLocalRepository() {
         }
     }
 
-    /**
-     * Return the local File for the provided artifact if it exists.
-     * The ephemeral local repository is checked only.
-     * @param artifact
-     * @return
-     */
-    public Optional<File> findArtifactInLocalRepository(Artifact artifact) {
-        File file = localRepository.toPath().resolve(artifact.getLayout()).toFile();
-        if (!file.exists()) {
-            return Optional.empty();
-        }
-        return Optional.of(file);
-    }
-
-    public void executeGoals(File pom, File javaHome, String... goals) throws MavenInvocationException {
+    public void executeGoals(File pom, File javaHome, String... goals) {
         InvocationRequest request = new DefaultInvocationRequest();
         request.setGoals(Lists.newArrayList(goals));
         request.setBatchMode(true);
@@ -96,13 +82,16 @@ public void executeGoals(File pom, File javaHome, String... goals) throws MavenI
          * This will cut down drastically on the network calls to re-hydrate this temporary local repo.
          */
         request.setGlobalSettingsFile(Resources.export("settings.xml"));
-
-        InvocationResult result = this.invoker.execute(request);
-        if (result.getExitCode() != 0) {
-            throw new MavenInvocationException(
-                    String.format("Failed to execute goals [%s]. Exit code: %s", Arrays.toString(goals), result.getExitCode()),
-                    result.getExecutionException()
-            );
+        try {
+            InvocationResult result = this.invoker.execute(request);
+            if (result.getExitCode() != 0) {
+                throw new MavenInvocationException(
+                        String.format("Failed to execute goals [%s]. Exit code: %s", Arrays.toString(goals), result.getExitCode()),
+                        result.getExecutionException()
+                );
+            }
+        } catch (MavenInvocationException e) {
+            throw new RuntimeException(e);
         }
     }
 
@@ -154,6 +143,7 @@ public Collection<Artifact> collectAllArtifactsInLocalRepository() {
                              .setClassifier(classifier)
                              .setVersion(version)
                              .setExtension(extension)
+                             .setSha256(calculateSha256OfFile(file.toFile()))
                              .build();
                  })
                 .filter(Objects::nonNull)
@@ -163,4 +153,11 @@ public Collection<Artifact> collectAllArtifactsInLocalRepository() {
         }
     }
 
+    private static String calculateSha256OfFile(File file) {
+        try {
+            return com.google.common.io.Files.asByteSource(file).hash(Hashing.sha256()).toString();
+        } catch (IOException e) {
+            throw new UncheckedIOException(e);
+        }
+    }
 }

src/main/java/com/fzakaria/mvn2nix/model/MavenNixInformation.java

@@ -3,14 +3,16 @@
 import com.google.common.base.MoreObjects;
 
 import javax.annotation.concurrent.Immutable;
-import java.util.HashMap;
 import java.util.Map;
 import java.util.Objects;
 import java.util.TreeMap;
 
 @Immutable
 public class MavenNixInformation {
 
+    /**
+     * Maps canonical names to the artifact data.
+     */
     private final Map<String, MavenArtifact> dependencies;
 
     /**
@@ -21,6 +23,10 @@ public MavenNixInformation(Map<String, MavenArtifact> dependencies) {
         this.dependencies = new TreeMap<>(dependencies);
     }
 
+    public MavenArtifact byCanonicalName(String canonicalName) {
+        return dependencies.get(canonicalName);
+    }
+
     @Override
     public boolean equals(Object o) {
         if (this == o) return true;