Improve search from maven local repository (#452)

Author: tony-sol

shared/src/main/kotlin/org/javacs/kt/classpath/BackupClassPathResolver.kt

@@ -80,7 +80,7 @@ private fun Path.existsOrNull() =
     if (Files.exists(this)) this else null
 
 private fun findLocalArtifactDirUsingMaven(group: String, artifact: String) =
-    LocalArtifactDirectoryResolution(mavenHome.resolve("repository")
+    LocalArtifactDirectoryResolution(mavenRepository
         ?.resolve(group.replace('.', File.separatorChar))
         ?.resolve(artifact)
         ?.existsOrNull(), "Maven")
@@ -118,4 +118,3 @@ private fun compareVersions(left: Path, right: Path): Int {
 private fun extractVersion(artifactVersionDir: Path): List<String> {
     return artifactVersionDir.toString().split(".")
 }
-

shared/src/main/kotlin/org/javacs/kt/classpath/Home.kt

@@ -3,6 +3,16 @@ package org.javacs.kt.classpath
 import org.javacs.kt.util.userHome
 import java.nio.file.Paths
 
-internal val gradleHome = System.getenv("GRADLE_USER_HOME")?.let { Paths.get(it) } ?: userHome.resolve(".gradle")
-// TODO: try and figure out if mavenHome is in non-default position (requires finding and parsing settings.xml)
-internal val mavenHome = userHome.resolve(".m2")
+
+internal val gradleHome =
+    System.getenv("GRADLE_USER_HOME")?.let { Paths.get(it) }
+        ?: userHome.resolve(".gradle")
+
+internal val mavenHome =
+    System.getenv("MAVEN_HOME")?.let { Paths.get(it) }
+        ?: System.getenv("M2_HOME")?.let { Paths.get(it) }
+        ?: userHome.resolve(".m2")
+
+internal val mavenRepository =
+    System.getenv("MAVEN_REPOSITORY")?.let { Paths.get(it) }
+        ?: mavenHome.resolve("repository")

shared/src/main/kotlin/org/javacs/kt/classpath/MavenClassPathResolver.kt

@@ -84,7 +84,7 @@ private fun readMavenDependencyListWithSources(artifacts: Set<Artifact>, sources
 }
 
 private fun findMavenArtifact(a: Artifact, source: Boolean): Path? {
-    val result = mavenHome.resolve("repository")
+    val result = mavenRepository
         .resolve(a.group.replace('.', File.separatorChar))
         .resolve(a.artifact)
         .resolve(a.version)