Implement Store. pre-commit now installs files to ~/.pre-commit

pre_commit/store.py

@@ -0,0 +1,97 @@
+from __future__ import unicode_literals
+
+import io
+import logging
+import os
+import os.path
+import tempfile
+from plumbum import local
+
+from pre_commit.prefixed_command_runner import PrefixedCommandRunner
+from pre_commit.util import cached_property
+from pre_commit.util import clean_path_on_failure
+
+
+logger = logging.getLogger('pre_commit')
+
+
+def _get_default_directory():
+    """Returns the default directory for the Store.  This is intentionally
+    underscored to indicate that `Store.get_default_directory` is the intended
+    way to get this information.  This is also done so
+    `Store.get_default_directory` can be mocked in tests and
+    `_get_default_directory` can be tested.
+    """
+    return os.path.join(os.environ['HOME'], '.pre-commit')
+
+
+class Store(object):
+    get_default_directory = staticmethod(_get_default_directory)
+
+    class RepoPathGetter(object):
+        def __init__(self, repo, sha, store):
+            self._repo = repo
+            self._sha = sha
+            self._store = store
+
+        @cached_property
+        def repo_path(self):
+            return self._store.clone(self._repo, self._sha)
+
+    def __init__(self, directory=None):
+        if directory is None:
+            directory = self.get_default_directory()
+
+        self.directory = directory
+        self.__created = False
+
+    def _write_readme(self):
+        with io.open(os.path.join(self.directory, 'README'), 'w') as readme:
+            readme.write(
+                'This directory is maintained by the pre-commit project.\n'
+                'Learn more: https://github.com/pre-commit/pre-commit\n'
+            )
+
+    def _create(self):
+        if os.path.exists(self.directory):
+            return
+        os.makedirs(self.directory)
+        self._write_readme()
+
+    def require_created(self):
+        """Require the pre-commit file store to be created."""
+        if self.__created:
+            return
+
+        self._create()
+        self.__created = True
+
+    def clone(self, url, sha):
+        """Clone the given url and checkout the specific sha."""
+        self.require_created()
+
+        # Check if we already exist
+        sha_path = os.path.join(self.directory, sha)
+        if os.path.exists(sha_path):
+            return os.readlink(sha_path)
+
+        logger.info('Installing environment for {0}.'.format(url))
+        logger.info('Once installed this environment will be reused.')
+        logger.info('This may take a few minutes...')
+
+        dir = tempfile.mkdtemp(prefix='repo', dir=self.directory)
+        with clean_path_on_failure(dir):
+            local['git']('clone', '--no-checkout', url, dir)
+            with local.cwd(dir):
+                local['git']('checkout', sha)
+
+        # Make a symlink from sha->repo
+        os.symlink(dir, sha_path)
+        return dir
+
+    def get_repo_path_getter(self, repo, sha):
+        return self.RepoPathGetter(repo, sha, self)
+
+    @cached_property
+    def cmd_runner(self):
+        return PrefixedCommandRunner(self.directory)