Added git commands

- gitpython added as a prod requirement
- GitError raised when git command fails
- added functions encompassing key functionality

cookie_composer/composition.py

@@ -234,6 +234,21 @@ def write_composition(layers: List[LayerConfig], destination: Union[str, Path]):
         yaml.dump_all(dict_layers, f)
 
 
+def write_rendered_composition(composition: RenderedComposition):
+    """
+    Write the composition file using the rendered layers to the appropriate.
+
+    Args:
+        composition: The rendered composition object to export
+    """
+    layers = []
+    for rendered_layer in composition.layers:
+        layers.append(rendered_layer.layer)
+
+    composition_file = composition.render_dir / composition.rendered_name / ".composition.yaml"
+    write_composition(layers, composition_file)
+
+
 def get_merge_strategy(path: Path, merge_strategies: Dict[str, str]) -> str:
     """
     Return the merge strategy of the path based on the layer configured rules.
@@ -261,18 +276,3 @@ def get_merge_strategy(path: Path, merge_strategies: Dict[str, str]) -> str:
             break
 
     return strategy
-
-
-def write_rendered_composition(composition: RenderedComposition):
-    """
-    Write the composition file using the rendered layers to the appropriate.
-
-    Args:
-        composition: The rendered composition object to export
-    """
-    layers = []
-    for rendered_layer in composition.layers:
-        layers.append(rendered_layer.layer)
-
-    composition_file = composition.render_dir / composition.rendered_name / ".composition.yaml"
-    write_composition(layers, composition_file)

cookie_composer/exceptions.py

@@ -24,3 +24,9 @@ def __init__(
             msg = f"There was a problem merging {origin} and {destination} using {strategy}: {error_message}"
             super().__init__(msg)
         super().__init__(error_message)
+
+
+class GitError(Exception):
+    """There was a problem doing git operations."""
+
+    pass

cookie_composer/git_commands.py

@@ -0,0 +1,82 @@
+"""Functions for using git."""
+from ctypes import Union
+from pathlib import Path
+
+from git import InvalidGitRepositoryError, Repo
+
+from cookie_composer.exceptions import GitError
+
+
+def get_repo(project_dir: Union[str, Path]) -> Repo:
+    """
+    Get the git Repo object for a directory.
+
+    Args:
+        project_dir: The directory containing the .git folder
+
+    Raises:
+        GitError: If the directory is not a git repo
+
+    Returns:
+        The GitPython Repo object
+    """
+    try:
+        return Repo(str(project_dir))
+    except InvalidGitRepositoryError as e:
+        raise GitError("Some cookie composer commands only work on git repositories.") from e
+
+
+def branch_exists(repo: Repo, branch_name: str) -> bool:
+    """
+    Does the branch exist in the repo?
+
+    Args:
+        repo: The repository to check
+        branch_name: The name of the branch to check for
+
+    Returns:
+        ``True`` if the branch exists
+    """
+    return branch_name in repo.refs
+
+
+def remote_branch_exists(repo: Repo, branch_name: str, remote_name: str = "origin") -> bool:
+    """
+    Does the branch exist in the remote repo?
+
+    Args:
+        repo: The repository to check
+        branch_name: The name of the branch to check for
+        remote_name: The name of the remote reference. Defaults to ``origin``
+
+    Returns:
+        ``True`` if the branch exists in the remote repository
+    """
+    return branch_name in repo.remotes[remote_name].refs
+
+
+def checkout_branch(repo: Repo, branch_name: str, remote_name: str = "origin"):
+    """Checkout a local or remote branch."""
+    if repo.is_dirty():
+        raise GitError(
+            "Cookie composer cannot apply updates on an unclean git project."
+            " Please make sure your git working tree is clean before proceeding."
+        )
+    repo.remotes[0].fetch()
+    if branch_exists(repo, branch_name):
+        repo.heads[branch_name].checkout()
+    elif remote_branch_exists(repo, branch_name, remote_name):
+        repo.create_head(branch_name, f"origin/{branch_name}")
+        repo.heads[branch_name].checkout()
+
+
+def branch_from_first_commit(repo: Repo, branch_name: str):
+    """Create and checkout a branch from the repo's first commit."""
+    if repo.is_dirty():
+        raise GitError(
+            "Cookie composer cannot apply updates on an unclean git project."
+            " Please make sure your git working tree is clean before proceeding."
+        )
+    first_commit = list(repo.iter_commits("HEAD", max_parents=0, max_count=1))[0]
+    repo.create_head(branch_name, first_commit.hexsha)
+    repo.heads[branch_name].checkout()

requirements/cookiecutter.txt

@@ -32,7 +32,7 @@ python-slugify==6.1.2
     # via -r cookiecutter.in
 pyyaml==6.0
     # via -r cookiecutter.in
-requests==2.27.1
+requests==2.28.0
     # via -r cookiecutter.in
 six==1.16.0
     # via python-dateutil

requirements/dev.txt

@@ -73,7 +73,7 @@ distlib==0.3.4
     # via
     #   -r test.txt
     #   virtualenv
-docutils==0.17.1
+docutils==0.18.1
     # via
     #   -r docs.txt
     #   myst-parser
@@ -96,9 +96,13 @@ ghp-import==2.1.0
 git-fame==1.15.1
     # via -r dev.in
 gitdb==4.0.9
-    # via gitpython
+    # via
+    #   -r test.txt
+    #   gitpython
 gitpython==3.1.27
-    # via generate-changelog
+    # via
+    #   -r test.txt
+    #   generate-changelog
 identify==2.5.1
     # via
     #   -r test.txt
@@ -162,7 +166,7 @@ mypy-extensions==0.4.3
     # via
     #   -r test.txt
     #   black
-myst-parser==0.17.2
+myst-parser==0.18.0
     # via -r docs.txt
 nodeenv==1.6.0
     # via
@@ -249,7 +253,7 @@ pyyaml==6.0
     #   -r test.txt
     #   myst-parser
     #   pre-commit
-requests==2.27.1
+requests==2.28.0
     # via
     #   -r docs.txt
     #   -r test.txt
@@ -277,7 +281,9 @@ six==1.16.0
     #   python-dateutil
     #   virtualenv
 smmap==5.0.0
-    # via gitdb
+    # via
+    #   -r test.txt
+    #   gitdb
 snowballstemmer==2.2.0
     # via
     #   -r docs.txt
@@ -286,7 +292,7 @@ soupsieve==2.3.2.post1
     # via
     #   -r docs.txt
     #   beautifulsoup4
-sphinx==4.5.0
+sphinx==5.0.1
     # via
     #   -r docs.txt
     #   furo
@@ -295,7 +301,7 @@ sphinx==4.5.0
     #   sphinx-basic-ng
     #   sphinx-click
     #   sphinx-copybutton
-sphinx-autodoc-typehints==1.18.2
+sphinx-autodoc-typehints==1.18.3
     # via -r docs.txt
 sphinx-basic-ng==0.0.1a11
     # via

requirements/docs.txt

@@ -22,7 +22,7 @@ click==8.1.3
     # via
     #   -c test.txt
     #   sphinx-click
-docutils==0.17.1
+docutils==0.18.1
     # via
     #   myst-parser
     #   sphinx
@@ -58,7 +58,7 @@ mdit-py-plugins==0.3.0
     # via myst-parser
 mdurl==0.1.1
     # via markdown-it-py
-myst-parser==0.17.2
+myst-parser==0.18.0
     # via -r docs.in
 packaging==21.3
     # via
@@ -83,7 +83,7 @@ pyyaml==6.0
     # via
     #   -c test.txt
     #   myst-parser
-requests==2.27.1
+requests==2.28.0
     # via
     #   -c test.txt
     #   sphinx
@@ -95,7 +95,7 @@ snowballstemmer==2.2.0
     # via sphinx
 soupsieve==2.3.2.post1
     # via beautifulsoup4
-sphinx==4.5.0
+sphinx==5.0.1
     # via
     #   -r docs.in
     #   furo
@@ -104,7 +104,7 @@ sphinx==4.5.0
     #   sphinx-basic-ng
     #   sphinx-click
     #   sphinx-copybutton
-sphinx-autodoc-typehints==1.18.2
+sphinx-autodoc-typehints==1.18.3
     # via -r docs.in
 sphinx-basic-ng==0.0.1a11
     # via furo

requirements/prod.in

@@ -1,6 +1,7 @@
 -r cookiecutter.txt
 
 fsspec
+gitpython
 pydantic
 requests
 rich-click

requirements/prod.txt

@@ -30,6 +30,10 @@ commonmark==0.9.1
     # via rich
 fsspec==2022.5.0
     # via -r prod.in
+gitdb==4.0.9
+    # via gitpython
+gitpython==3.1.27
+    # via -r prod.in
 idna==3.3
     # via
     #   -r cookiecutter.txt
@@ -56,7 +60,7 @@ python-slugify==6.1.2
     # via -r cookiecutter.txt
 pyyaml==6.0
     # via -r cookiecutter.txt
-requests==2.27.1
+requests==2.28.0
     # via
     #   -r cookiecutter.txt
     #   -r prod.in
@@ -72,6 +76,8 @@ six==1.16.0
     # via
     #   -r cookiecutter.txt
     #   python-dateutil
+smmap==5.0.0
+    # via gitdb
 text-unidecode==1.3
     # via
     #   -r cookiecutter.txt

requirements/test.txt

@@ -49,6 +49,12 @@ flake8==4.0.1
     # via -r test.in
 fsspec==2022.5.0
     # via -r prod.txt
+gitdb==4.0.9
+    # via
+    #   -r prod.txt
+    #   gitpython
+gitpython==3.1.27
+    # via -r prod.txt
 identify==2.5.1
     # via pre-commit
 idna==3.3
@@ -118,7 +124,7 @@ pyyaml==6.0
     # via
     #   -r prod.txt
     #   pre-commit
-requests==2.27.1
+requests==2.28.0
     # via -r prod.txt
 rich==12.4.4
     # via
@@ -137,6 +143,10 @@ six==1.16.0
     #   -r prod.txt
     #   python-dateutil
     #   virtualenv
+smmap==5.0.0
+    # via
+    #   -r prod.txt
+    #   gitdb
 text-unidecode==1.3
     # via
     #   -r prod.txt