1 files changed, 143 insertions, 0 deletions
diff --git a/tasks/_setup.py b/tasks/_setup.py
new file mode 100644
index 0000000..9694a68
--- /dev/null
+++ b/tasks/_setup.py
@@ -0,0 +1,143 @@
+# -*- coding: utf-8 -*-
+"""
+Decides if vendor bundles are used or not.
+Setup python path accordingly.
+"""
+
+from __future__ import absolute_import, print_function
+import os.path
+import sys
+
+# -----------------------------------------------------------------------------
+# DEFINES:
+# -----------------------------------------------------------------------------
+HERE = os.path.dirname(__file__)
+TASKS_VENDOR_DIR = os.path.join(HERE, "_vendor")
+INVOKE_BUNDLE = os.path.join(TASKS_VENDOR_DIR, "invoke.zip")
+INVOKE_BUNDLE_VERSION = "1.2.0"
+
+DEBUG_SYSPATH = False
+
+
+# -----------------------------------------------------------------------------
+# EXCEPTIONS:
+# -----------------------------------------------------------------------------
+class VersionRequirementError(SystemExit):
+    pass
+
+
+# -----------------------------------------------------------------------------
+# FUNCTIONS:
+# -----------------------------------------------------------------------------
+def setup_path(invoke_minversion=None):
+    """Setup python search and add ``TASKS_VENDOR_DIR`` (if available)."""
+    # print("INVOKE.tasks: setup_path")
+    if not os.path.isdir(TASKS_VENDOR_DIR):
+        print("SKIP: TASKS_VENDOR_DIR=%s is missing" % TASKS_VENDOR_DIR)
+        return
+    elif os.path.abspath(TASKS_VENDOR_DIR) in sys.path:
+        # -- SETUP ALREADY DONE:
+        # return
+        pass
+
+    use_vendor_bundles = os.environ.get("INVOKE_TASKS_USE_VENDOR_BUNDLES", "no")
+    if need_vendor_bundles(invoke_minversion):
+        use_vendor_bundles = "yes"
+
+    if use_vendor_bundles == "yes":
+        syspath_insert(0, os.path.abspath(TASKS_VENDOR_DIR))
+        if setup_path_for_bundle(INVOKE_BUNDLE, pos=1):
+            import invoke
+            bundle_path = os.path.relpath(INVOKE_BUNDLE, os.getcwd())
+            print("USING: %s (version: %s)" % (bundle_path, invoke.__version__))
+    else:
+        # -- BEST-EFFORT: May rescue something
+        syspath_append(os.path.abspath(TASKS_VENDOR_DIR))
+        setup_path_for_bundle(INVOKE_BUNDLE, pos=len(sys.path))
+
+    if DEBUG_SYSPATH:
+        for index, p in enumerate(sys.path):
+            print("  %d.  %s" % (index, p))
+
+
+def require_invoke_minversion(min_version, verbose=False):
+    """Ensures that :mod:`invoke` has at the least the :param:`min_version`.
+    Otherwise,
+
+    :param min_version: Minimal acceptable invoke version (as string).
+    :param verbose:     Indicates if invoke.version should be shown.
+    :raises: VersionRequirementError=SystemExit if requirement fails.
+    """
+    # -- REQUIRES: sys.path is setup and contains invoke
+    try:
+        import invoke
+        invoke_version = invoke.__version__
+    except ImportError:
+        invoke_version = "__NOT_INSTALLED"
+
+    if invoke_version < min_version:
+        message = "REQUIRE: invoke.version >= %s (but was: %s)" % \
+                  (min_version, invoke_version)
+        message += "\nUSE: pip install invoke>=%s" % min_version
+        raise VersionRequirementError(message)
+
+    # pylint: disable=invalid-name
+    INVOKE_VERSION = os.environ.get("INVOKE_VERSION", None)
+    if verbose and not INVOKE_VERSION:
+        os.environ["INVOKE_VERSION"] = invoke_version
+        print("USING: invoke.version=%s" % invoke_version)
+
+
+def need_vendor_bundles(invoke_minversion=None):
+    invoke_minversion = invoke_minversion or "0.0.0"
+    need_vendor_answers = []
+    need_vendor_answers.append(need_vendor_bundle_invoke(invoke_minversion))
+    # -- REQUIRE: path.py
+    try:
+        import path
+        need_bundle = False
+    except ImportError:
+        need_bundle = True
+    need_vendor_answers.append(need_bundle)
+
+    # -- DIAG: print("INVOKE: need_bundle=%s" % need_bundle1)
+    # return need_bundle1 or need_bundle2
+    return any(need_vendor_answers)
+
+
+def need_vendor_bundle_invoke(invoke_minversion="0.0.0"):
+    # -- REQUIRE: invoke
+    try:
+        import invoke
+        need_bundle = invoke.__version__ < invoke_minversion
+        if need_bundle:
+            del sys.modules["invoke"]
+            del invoke
+    except ImportError:
+        need_bundle = True
+    except Exception:   # pylint: disable=broad-except
+        need_bundle = True
+    return need_bundle
+
+
+# -----------------------------------------------------------------------------
+# UTILITY FUNCTIONS:
+# -----------------------------------------------------------------------------
+def setup_path_for_bundle(bundle_path, pos=0):
+    if os.path.exists(bundle_path):
+        syspath_insert(pos, os.path.abspath(bundle_path))
+        return True
+    return False
+
+
+def syspath_insert(pos, path):
+    if path in sys.path:
+        sys.path.remove(path)
+    sys.path.insert(pos, path)
+
+
+def syspath_append(path):
+    if path in sys.path:
+        sys.path.remove(path)
+    sys.path.append(path)
+