"""Test helpers for importing the calibre plugin modules outside of calibre.

The DeDRM and Obok plugins normally run inside calibre's bundled Python and use
intra-package (``from .x import y``) imports. To unit-test the pure logic we:

  * put the plugin source directories on ``sys.path`` (for absolute imports such
    as ``import kgenpids`` / ``import alfcrypto``);
  * provide a minimal ``calibre`` stub for the few modules that import it;
  * register a synthetic ``dedrm`` package whose ``__path__`` points at the
    DeDRM_plugin directory, so modules that use relative imports resolve without
    executing the real (calibre-dependent) ``__init__.py``.

Modules with no relative imports (alfcrypto, argv_utils, obok) are loaded
top-level; modules with ``from .`` imports are loaded as ``dedrm.X``. kgenpids
is a hybrid: it is imported absolutely by other worker modules, so it falls back
to an absolute ``from utilities import ...`` and is still loaded top-level here.
"""

import importlib
import os
import sys
import types

ROOT = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
DEDRM = os.path.join(ROOT, "DeDRM_plugin")
OBOK = os.path.join(ROOT, "Obok_plugin", "obok")


def _ensure_on_path(path):
    if path not in sys.path:
        sys.path.insert(0, path)


def _setup():
    _ensure_on_path(DEDRM)
    _ensure_on_path(OBOK)

    # Minimal calibre stub (only the bits the plugin modules touch at import).
    if "calibre" not in sys.modules:
        sys.modules["calibre"] = types.ModuleType("calibre")
        constants = types.ModuleType("calibre.constants")
        constants.iswindows = sys.platform.startswith("win")
        sys.modules["calibre.constants"] = constants

    # Synthetic package so `from .x import y` works without the real __init__.py.
    if "dedrm" not in sys.modules:
        pkg = types.ModuleType("dedrm")
        pkg.__path__ = [DEDRM]
        pkg.__package__ = "dedrm"
        sys.modules["dedrm"] = pkg


_setup()


def load(module_name, package=None):
    """Import and return a plugin module.

    Pass ``package="dedrm"`` for modules that use relative imports.
    """
    if package:
        return importlib.import_module("{0}.{1}".format(package, module_name))
    return importlib.import_module(module_name)