Prepare for fixing double-parsing (#2477)

Currently we parse the lockfile in both the extension and the repo rule
(so we can generate all the bzl/BUILD file). The plan to fix that is to
move the file generation into the module extension and reuse the parse
state. To do that, we must decouple the generation from the side effects
(dumping files to disk).

While here, I changed the args to `generate` to enforce it becomes pure.

---

### Changes are visible to end-users: no

### Test plan
- Covered by existing test cases

Author: dzbarsky

npm/private/npm_translate_lock.bzl

@@ -155,8 +155,9 @@ See https://github.com/aspect-build/rules_js/issues/1445
 
     rctx.report_progress("Generating starlark for npm dependencies")
 
-    generate_repository_files(
-        rctx,
+    files = generate_repository_files(
+        rctx.name,
+        rctx.attr,
         importers,
         packages,
         state.patched_dependencies(),
@@ -167,6 +168,9 @@ See https://github.com/aspect-build/rules_js/issues/1445
         state.npm_auth(),
     )
 
+    for filename, contents in files.items():
+        rctx.file(filename, contents)
+
     # Support bazel <v8.3 by returning None if repo_metadata is not defined
     if not hasattr(rctx, "repo_metadata"):
         return None

npm/private/npm_translate_lock_generate.bzl

@@ -50,11 +50,13 @@ _PACKAGE_JSON_BZL_FILENAME = "package_json.bzl"
 _RESOLVED_JSON_FILENAME = "resolved.json"
 
 # buildifier: disable=function-docstring
-def generate_repository_files(rctx, importers, packages, patched_dependencies, only_built_dependencies, root_package, default_registry, npm_registries, npm_auth):
+def generate_repository_files(rctx_name, attr, importers, packages, patched_dependencies, only_built_dependencies, root_package, default_registry, npm_registries, npm_auth):
     # empty line after bzl docstring since buildifier expects this if this file is vendored in
-    generated_by_prefix = "\"\"\"@generated by npm_translate_lock(name = \"{}\", pnpm_lock = \"{}\")\"\"\"\n".format(helpers.to_apparent_repo_name(rctx.name), str(rctx.attr.pnpm_lock))
+    generated_by_prefix = "\"\"\"@generated by npm_translate_lock(name = \"{}\", pnpm_lock = \"{}\")\"\"\"\n".format(helpers.to_apparent_repo_name(rctx_name), str(attr.pnpm_lock))
 
-    npm_imports = helpers.get_npm_imports(importers, packages, rctx.attr.replace_packages, patched_dependencies, only_built_dependencies, root_package, rctx.name, rctx.attr, rctx.attr.lifecycle_hooks, rctx.attr.lifecycle_hooks_execution_requirements, rctx.attr.lifecycle_hooks_use_default_shell_env, npm_registries, default_registry, npm_auth)
+    npm_imports = helpers.get_npm_imports(importers, packages, attr.replace_packages, patched_dependencies, only_built_dependencies, root_package, rctx_name, attr, attr.lifecycle_hooks, attr.lifecycle_hooks_execution_requirements, attr.lifecycle_hooks_use_default_shell_env, npm_registries, default_registry, npm_auth)
+
+    final_rctx_files = {}
 
     rctx_files = {
         "BUILD.bazel": [
@@ -186,10 +188,10 @@ js_binary(name = "sync", entry_point = "noop.js")
     )
 
     # Generate visibility configuration first to check if it's actually non-empty
-    npm_visibility_config_generated = _generate_npm_visibility_config(rctx.attr.package_visibility)
+    npm_visibility_config_generated = _generate_npm_visibility_config(attr.package_visibility)
 
     # Check if the generated visibility config is actually non-empty
-    has_package_visibility = rctx.attr.package_visibility != None and npm_visibility_config_generated != None
+    has_package_visibility = attr.package_visibility != None and npm_visibility_config_generated != None
 
     # Only keep the generated config if it's non-empty
     npm_visibility_config = npm_visibility_config_generated if has_package_visibility else None
@@ -223,10 +225,10 @@ def npm_link_all_packages(name = "node_modules", imported_links = [], prod = Tru
         fail(msg)
 {validation_call}
 """.format(
-            defs_bzl_file = "@{}//:{}".format(rctx.name, _DEFS_BZL_FILENAME),
+            defs_bzl_file = "@{}//:{}".format(rctx_name, _DEFS_BZL_FILENAME),
             link_packages_comma_separated = "\"'\" + \"', '\".join(_IMPORTER_PACKAGES) + \"'\"" if package_to_importer else "\"\"",
             root_package = root_package,
-            pnpm_lock_label = rctx.attr.pnpm_lock,
+            pnpm_lock_label = attr.pnpm_lock,
             validation_call = validation_call,
         ),
     ]
@@ -311,17 +313,17 @@ def npm_link_all_packages(name = "node_modules", imported_links = [], prod = Tru
                 resolved_json_rel_path = "{}/{}".format(link_alias, _RESOLVED_JSON_FILENAME)
                 resolved_json_file_path = "{}/{}".format(link_package, resolved_json_rel_path) if link_package else resolved_json_rel_path
 
-                rctx.file(resolved_json_file_path, json.encode({
+                final_rctx_files[resolved_json_file_path] = json.encode({
                     # Allow consumers to auto-detect this filetype
                     "$schema": "https://docs.aspect.build/rules/aspect_rules_js/docs/npm_translate_lock",
                     "version": _import.version,
                     "integrity": _import.integrity,
-                }))
+                })
                 rctx_files[build_file].append("exports_files([\"{}\"])".format(resolved_json_rel_path))
 
             # the package_json.bzl for this package
             if _import.package_info["has_bin"]:
-                if rctx.attr.generate_bzl_library_targets:
+                if attr.generate_bzl_library_targets:
                     rctx_files[build_file].append("""load("@bazel_skylib//:bzl_library.bzl", "bzl_library")""")
 
                     for link_alias in link_aliases:
@@ -342,12 +344,9 @@ def npm_link_all_packages(name = "node_modules", imported_links = [], prod = Tru
                         link_package = link_package,
                         package_json_bzl = _PACKAGE_JSON_BZL_FILENAME,
                     )
-                    rctx.file(
-                        package_json_bzl_file_path,
-                        _BIN_TMPL.format(
-                            repo_package_json_bzl = repo_package_json_bzl,
-                        ),
-                    )
+                    rctx_files[package_json_bzl_file_path] = [_BIN_TMPL.format(
+                        repo_package_json_bzl = repo_package_json_bzl,
+                    )]
 
     # Generate the first-party package stores and linking of first-party packages
     for i, fp_link in enumerate(fp_links.values()):
@@ -357,7 +356,7 @@ def npm_link_all_packages(name = "node_modules", imported_links = [], prod = Tru
         fp_deps = fp_link["deps"]
         fp_target = "//{}:{}".format(
             fp_path,
-            rctx.attr.npm_package_target_name.replace("{dirname}", paths.basename(fp_path)),
+            attr.npm_package_target_name.replace("{dirname}", paths.basename(fp_path)),
         )
         fp_package_store_name = utils.package_store_name(fp_package, fp_version)
 
@@ -390,7 +389,7 @@ def npm_link_all_packages(name = "node_modules", imported_links = [], prod = Tru
 
         # Generate a single _FP_DIRECT_TMPL block with all link packages
         if fp_link["link_packages"]:
-            package_visibility, _ = helpers.gather_values_from_matching_names(True, rctx.attr.package_visibility, "*", fp_package)
+            package_visibility, _ = helpers.gather_values_from_matching_names(True, attr.package_visibility, "*", fp_package)
             if not package_visibility:
                 package_visibility = None
 
@@ -521,7 +520,7 @@ def npm_link_all_packages(name = "node_modules", imported_links = [], prod = Tru
 
     rctx_files[_DEFS_BZL_FILENAME] = defs_bzl_contents
 
-    for filename, contents in rctx.attr.additional_file_contents.items():
+    for filename, contents in attr.additional_file_contents.items():
         if not rctx_files.get(filename, False):
             rctx_files[filename] = contents
         elif filename.endswith(".bzl"):
@@ -537,8 +536,10 @@ def npm_link_all_packages(name = "node_modules", imported_links = [], prod = Tru
         else:
             rctx_files[filename].extend(contents)
 
-    for filename, contents in rctx_files.items():
-        rctx.file(filename, generated_by_prefix + "\n" + "\n".join(contents).rstrip() + "\n")
+    return final_rctx_files | {
+        filename: generated_by_prefix + "\n" + "\n".join(contents).rstrip() + "\n"
+        for filename, contents in rctx_files.items()
+    }
 
 def _generate_npm_link_targets(links_targets):
     """Generate the npm_link_targets() macro given the links_targets struct"""