1 files changed, 110 insertions, 0 deletions
diff --git a/pre_commit/languages/node.py b/pre_commit/languages/node.py
new file mode 100644
index 0000000..d49c0e3
--- /dev/null
+++ b/pre_commit/languages/node.py
@@ -0,0 +1,110 @@
+from __future__ import annotations
+
+import contextlib
+import functools
+import os
+import sys
+from collections.abc import Generator
+from collections.abc import Sequence
+
+import pre_commit.constants as C
+from pre_commit import lang_base
+from pre_commit.envcontext import envcontext
+from pre_commit.envcontext import PatchesT
+from pre_commit.envcontext import UNSET
+from pre_commit.envcontext import Var
+from pre_commit.languages.python import bin_dir
+from pre_commit.prefix import Prefix
+from pre_commit.util import cmd_output
+from pre_commit.util import cmd_output_b
+from pre_commit.util import rmtree
+
+ENVIRONMENT_DIR = 'node_env'
+run_hook = lang_base.basic_run_hook
+
+
+@functools.lru_cache(maxsize=1)
+def get_default_version() -> str:
+    # nodeenv does not yet support `-n system` on windows
+    if sys.platform == 'win32':
+        return C.DEFAULT
+    # if node is already installed, we can save a bunch of setup time by
+    # using the installed version
+    elif all(lang_base.exe_exists(exe) for exe in ('node', 'npm')):
+        return 'system'
+    else:
+        return C.DEFAULT
+
+
+def get_env_patch(venv: str) -> PatchesT:
+    if sys.platform == 'cygwin':  # pragma: no cover
+        _, win_venv, _ = cmd_output('cygpath', '-w', venv)
+        install_prefix = fr'{win_venv.strip()}\bin'
+        lib_dir = 'lib'
+    elif sys.platform == 'win32':  # pragma: no cover
+        install_prefix = bin_dir(venv)
+        lib_dir = 'Scripts'
+    else:  # pragma: win32 no cover
+        install_prefix = venv
+        lib_dir = 'lib'
+    return (
+        ('NODE_VIRTUAL_ENV', venv),
+        ('NPM_CONFIG_PREFIX', install_prefix),
+        ('npm_config_prefix', install_prefix),
+        ('NPM_CONFIG_USERCONFIG', UNSET),
+        ('npm_config_userconfig', UNSET),
+        ('NODE_PATH', os.path.join(venv, lib_dir, 'node_modules')),
+        ('PATH', (bin_dir(venv), os.pathsep, Var('PATH'))),
+    )
+
+
+@contextlib.contextmanager
+def in_env(prefix: Prefix, version: str) -> Generator[None, None, None]:
+    envdir = lang_base.environment_dir(prefix, ENVIRONMENT_DIR, version)
+    with envcontext(get_env_patch(envdir)):
+        yield
+
+
+def health_check(prefix: Prefix, version: str) -> str | None:
+    with in_env(prefix, version):
+        retcode, _, _ = cmd_output_b('node', '--version', check=False)
+        if retcode != 0:  # pragma: win32 no cover
+            return f'`node --version` returned {retcode}'
+        else:
+            return None
+
+
+def install_environment(
+        prefix: Prefix, version: str, additional_dependencies: Sequence[str],
+) -> None:
+    assert prefix.exists('package.json')
+    envdir = lang_base.environment_dir(prefix, ENVIRONMENT_DIR, version)
+
+    # https://msdn.microsoft.com/en-us/library/windows/desktop/aa365247(v=vs.85).aspx?f=255&MSPPError=-2147217396#maxpath
+    if sys.platform == 'win32':  # pragma: no cover
+        envdir = fr'\\?\{os.path.normpath(envdir)}'
+    cmd = [sys.executable, '-mnodeenv', '--prebuilt', '--clean-src', envdir]
+    if version != C.DEFAULT:
+        cmd.extend(['-n', version])
+    cmd_output_b(*cmd)
+
+    with in_env(prefix, version):
+        # https://npm.community/t/npm-install-g-git-vs-git-clone-cd-npm-install-g/5449
+        # install as if we installed from git
+
+        local_install_cmd = (
+            'npm', 'install', '--include=dev', '--include=prod',
+            '--ignore-prepublish', '--no-progress', '--no-save',
+        )
+        lang_base.setup_cmd(prefix, local_install_cmd)
+
+        _, pkg, _ = cmd_output('npm', 'pack', cwd=prefix.prefix_dir)
+        pkg = prefix.path(pkg.strip())
+
+        install = ('npm', 'install', '-g', pkg, *additional_dependencies)
+        lang_base.setup_cmd(prefix, install)
+
+        # clean these up after installation
+        if prefix.exists('node_modules'):  # pragma: win32 no cover
+            rmtree(prefix.path('node_modules'))
+        os.remove(pkg)