Check if matching version is already downloaded

get_jreleaser.java

@@ -1,10 +1,15 @@
 //JAVA 11+
+
 import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.net.URL;
 import java.nio.file.Files;
 import java.nio.file.Path;
-import java.nio.file.StandardCopyOption;
+
+import static java.nio.file.StandardCopyOption.REPLACE_EXISTING;
+import static java.nio.file.StandardOpenOption.CREATE;
+import static java.nio.file.StandardOpenOption.TRUNCATE_EXISTING;
+import static java.nio.file.StandardOpenOption.WRITE;
 
 class get_jreleaser {
     public static void main(String... args) throws Exception {
@@ -27,15 +32,27 @@ public static void main(String... args) throws Exception {
             System.exit(1);
         }
 
+        var versionFile = Path.of("JRELEASER_VERSION");
+
+        var cachedVersion = "";
+        if (Files.exists(versionFile)) {
+            try {
+                cachedVersion = Files.readString(versionFile).trim();
+            } catch (IOException e) {
+                System.out.printf("☠️  JReleaser %s could not be resolved%n", version);
+                e.printStackTrace();
+                System.exit(1);
+            }
+        }
+
         // resolve latest to a tagged release
         if ("latest".equalsIgnoreCase(version)) {
             var url = "https://jreleaser.org/releases/latest/download/VERSION";
-            var file = Path.of("JRELEASER_VERSION");
 
             try (var stream = new URL(url).openStream()) {
                 System.out.printf("✅ Located version marker%n");
-                Files.copy(stream, file, StandardCopyOption.REPLACE_EXISTING);
-                version = new String(Files.readAllBytes(file)).trim();
+                Files.copy(stream, versionFile, REPLACE_EXISTING);
+                version = new String(Files.readAllBytes(versionFile)).trim();
                 System.out.printf("✅ JReleaser latest resolves to %s%n", version);
             } catch (FileNotFoundException e) {
                 System.out.printf("❌ JReleaser %s not found%n", version);
@@ -46,18 +63,32 @@ public static void main(String... args) throws Exception {
                 e.printStackTrace();
                 System.exit(1);
             }
+        } else {
+            try {
+                Files.writeString(versionFile, version, CREATE, TRUNCATE_EXISTING, WRITE);
+            } catch (IOException e) {
+                System.out.printf("☠️  JReleaser %s could not be resolved%n", version);
+                e.printStackTrace();
+                System.exit(1);
+            }
+        }
+
+        var jreleaserJar = Path.of("jreleaser-cli.jar");
+        if (version.equals(cachedVersion) && Files.exists(jreleaserJar)) {
+            // assume jreleaserJar has the expected version for now
+            System.out.printf("✅ JReleaser %s already downloaded%n", version);
+            System.exit(0);
         }
 
         // setup the actual download
         var tag = !"early-access".equals(version) ? "v" + version : version;
         var url = "https://github.com/jreleaser/jreleaser/releases/download/" + tag + "/jreleaser-tool-provider-" + version + ".jar";
-        var file = Path.of("jreleaser-cli.jar");
 
         try (var stream = new URL(url).openStream()) {
             System.out.printf("✅ Located JReleaser %s%n", version);
             System.out.printf("⬇️  Downloading %s%n", url);
-            var size = Files.copy(stream, file, StandardCopyOption.REPLACE_EXISTING);
-            System.out.printf("%s << copied %d bytes%n", file, size);
+            var size = Files.copy(stream, jreleaserJar, REPLACE_EXISTING);
+            System.out.printf("%s << copied %d bytes%n", jreleaserJar, size);
             System.out.printf("✅ JReleaser installed successfully%n");
         } catch (FileNotFoundException e) {
             System.out.printf("❌ JReleaser %s not found%n", version);