1 files changed, 76 insertions, 0 deletions
diff --git a/pre_commit/languages/coursier.py b/pre_commit/languages/coursier.py
new file mode 100644
index 0000000..6558bf6
--- /dev/null
+++ b/pre_commit/languages/coursier.py
@@ -0,0 +1,76 @@
+from __future__ import annotations
+
+import contextlib
+import os.path
+from collections.abc import Generator
+from collections.abc import Sequence
+
+from pre_commit import lang_base
+from pre_commit.envcontext import envcontext
+from pre_commit.envcontext import PatchesT
+from pre_commit.envcontext import Var
+from pre_commit.errors import FatalError
+from pre_commit.parse_shebang import find_executable
+from pre_commit.prefix import Prefix
+
+ENVIRONMENT_DIR = 'coursier'
+
+get_default_version = lang_base.basic_get_default_version
+health_check = lang_base.basic_health_check
+run_hook = lang_base.basic_run_hook
+
+
+def install_environment(
+        prefix: Prefix,
+        version: str,
+        additional_dependencies: Sequence[str],
+) -> None:
+    lang_base.assert_version_default('coursier', version)
+
+    # Support both possible executable names (either "cs" or "coursier")
+    cs = find_executable('cs') or find_executable('coursier')
+    if cs is None:
+        raise AssertionError(
+            'pre-commit requires system-installed "cs" or "coursier" '
+            'executables in the application search path',
+        )
+
+    envdir = lang_base.environment_dir(prefix, ENVIRONMENT_DIR, version)
+
+    def _install(*opts: str) -> None:
+        assert cs is not None
+        lang_base.setup_cmd(prefix, (cs, 'fetch', *opts))
+        lang_base.setup_cmd(prefix, (cs, 'install', '--dir', envdir, *opts))
+
+    with in_env(prefix, version):
+        channel = prefix.path('.pre-commit-channel')
+        if os.path.isdir(channel):
+            for app_descriptor in os.listdir(channel):
+                _, app_file = os.path.split(app_descriptor)
+                app, _ = os.path.splitext(app_file)
+                _install(
+                    '--default-channels=false',
+                    '--channel', channel,
+                    app,
+                )
+        elif not additional_dependencies:
+            raise FatalError(
+                'expected .pre-commit-channel dir or additional_dependencies',
+            )
+
+        if additional_dependencies:
+            _install(*additional_dependencies)
+
+
+def get_env_patch(target_dir: str) -> PatchesT:
+    return (
+        ('PATH', (target_dir, os.pathsep, Var('PATH'))),
+        ('COURSIER_CACHE', os.path.join(target_dir, '.cs-cache')),
+    )
+
+
+@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