Patch the Python aspect template after server install (#41)

The Python aspect template installed by the BSP server will only add a
load statement for rules_python if the Bazel version is 8+. In our
setup, we need this loaded always.

We have added this upstream PR
(JetBrains/hirschgarten#210), and also currently
have some internal logic that patches this for our users as a
workaround. However, I think the best place for it would be to add it
here for now so it always runs immediately after install. We can remove
this once we resume our own internal server releases.

Author: mnoah1

src/server/install.ts

@@ -106,6 +106,9 @@ export class BazelBSPInstaller {
       this.outputChannel.show()
       return false
     }
+
+    // Temporary: Patch the python_info file to be compatible with rules_py.
+    await this.patchPythonAspect(root)
     return true
   }
 
@@ -235,4 +238,43 @@ export class BazelBSPInstaller {
       bazelBinaryPath: bazelBinaryPath,
     }
   }
+
+  /**
+   * Temporary solution to ensure that the rules_python load statement is always included in the Python aspect.
+   * This is needed for compatibility with targets that no longer include the builtin Python providers (e.g. rules_py).
+   * This will be addressed by https://github.com/JetBrains/hirschgarten/pull/210 once we have a standalone version of the server back in place.
+   * @param root
+   */
+  private async patchPythonAspect(root: string) {
+    // Get the current contents of the Python aspect template, as added by the installer.
+    const targetFile = path.join(
+      root,
+      '.bazelbsp/aspects/rules/python/python_info.bzl.template'
+    )
+
+    let content = ''
+    try {
+      content = await fs.readFile(targetFile, 'utf8')
+    } catch {
+      this.outputChannel.appendLine(
+        `Failed to read file ${targetFile}. Skipping patch.`
+      )
+    }
+
+    // Make rules_python load statement non-conditional for compatibility with rules_py.
+    const regex =
+      /#if\( \$pythonEnabled == "true" && \$bazel8OrAbove == "true" \)[\s\S]*?#end/
+    const replacement =
+      'load("@rules_python//python:defs.bzl", "PyInfo", "PyRuntimeInfo")'
+
+    // Replace the matched block with the replacement.
+    content = content.replace(regex, replacement)
+    try {
+      await fs.writeFile(targetFile, content, 'utf8')
+    } catch (err) {
+      this.outputChannel.appendLine(
+        `Failed to write updated Python aspect to ${targetFile}. Skipping patch.`
+      )
+    }
+  }
 }

src/test/suite/install.test.ts

@@ -72,6 +72,14 @@ suite('BSP Installer', () => {
       .withArgs(settings.SettingName.SERVER_INSTALL_MODE)
       .returns('Prompt')
 
+    sandbox.stub(fs, 'readFile').resolves(
+      `#if( $pythonEnabled == "true" && $bazel8OrAbove == "true" )
+load("@rules_python//python:defs.bzl", "PyInfo", "PyRuntimeInfo")
+#end
+
+load("//aspects:utils/utils.bzl", "create_struct", "file_location", "to_file_location")`
+    )
+
     // Simulated data returned by coursier download request.
     const sampleData = 'sample data'
     sandbox.stub(axios.default, 'get').resolves({data: sampleData} as any)
@@ -89,6 +97,12 @@ suite('BSP Installer', () => {
     assert.ok(spawnStub.getCalls()[0].args[0].includes(coursierPath))
     assert.ok(spawnStub.getCalls()[0].args[0].includes('--jvm openjdk:1.17.0'))
     assert.ok(installResult)
+
+    const updatedContents = writeFileSpy.getCalls()[1].args[1]
+    const expectedContents = `load("@rules_python//python:defs.bzl", "PyInfo", "PyRuntimeInfo")
+
+load("//aspects:utils/utils.bzl", "create_struct", "file_location", "to_file_location")`
+    assert.equal(updatedContents, expectedContents)
   })
 
   test('failed coursier download', async () => {