From 4639a79c006bc65a855f950860c0da10c679e844 Mon Sep 17 00:00:00 2001
From: Adrian Malacoda <malacoda@monarch-pass.net>
Date: Wed, 11 Nov 2020 21:50:14 -0600
Subject: [PATCH] java: automatically download and install jdt.ls if not given
 on command line

---
 lsp_proxy/java.py | 41 ++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 40 insertions(+), 1 deletion(-)

diff --git a/lsp_proxy/java.py b/lsp_proxy/java.py
index 1c56ae8..5ea4733 100644
--- a/lsp_proxy/java.py
+++ b/lsp_proxy/java.py
@@ -1,11 +1,21 @@
 import os
 import sys
 
+import tarfile
+from urllib import request
+
 from .lsp import LspServer, command, get_data_home
 
 FILE_URI = "file://"
 
+VERSION = "0.64.0"
+DOWNLOADS_URI = "http://download.eclipse.org/jdtls/milestones/{version}/{file}"
+LATEST = "latest.txt"
+
 def locate_product_directory (jdt_ls_path):
+    if os.path.isdir(os.path.join(jdt_ls_path, "plugins")):
+        return jdt_ls_path
+    
     return os.path.join(jdt_ls_path, "org.eclipse.jdt.ls.product/target/repository")
 
 def locate_launcher_jar (jdt_ls_path):
@@ -15,8 +25,37 @@ def locate_launcher_jar (jdt_ls_path):
 def locate_launcher_configuration (jdt_ls_path):
     return os.path.join(jdt_ls_path, "config_linux")
 
+def log (message, *args, **kwargs):
+    print(message.format(*args, **kwargs), file=sys.stderr)
+
 def download_jdt_ls (destination):
-    raise Exception("download_jdt_ls not implemented")
+    if not os.path.isdir(destination):
+        os.makedirs(destination)
+        
+    current_version = None
+    current_version_file = os.path.join(destination, LATEST)
+    if os.path.isfile(current_version_file):
+        with open(current_version_file) as f:
+            current_version = f.read().strip()
+            log("Currently downloaded version is {version}:", version=current_version)
+    
+    latest_version = None
+    with request.urlopen(DOWNLOADS_URI.format(version=VERSION, file=LATEST)) as f:
+        latest_version = f.read().decode().strip()
+        log("Latest available version is {version}:", version=latest_version)
+        
+    if not latest_version == current_version:
+        latest_uri = DOWNLOADS_URI.format(version=VERSION, file=latest_version)
+        log("Downloading latest version from: {uri}:", uri=latest_uri)
+        with request.urlopen(latest_uri) as f:
+            with tarfile.open(fileobj=f, mode="r|gz") as tar:
+                tar.extractall(destination)
+                print(tar)
+
+        with open(current_version_file, "w") as cvf:
+            cvf.write(latest_version)
+    
+    return destination
 
 # TODO
 def locate_lombok ():