import importlib
import inspect
import re
import tempfile
from contextlib import contextmanager

from . import desc
from .graph import *  # TODO: remove this

cacheFolder = os.path.join(tempfile.gettempdir(), 'processGraphCache')
nodesDesc = {}


@contextmanager
def add_to_path(p):
    import sys
    old_path = sys.path
    sys.path = sys.path[:]
    sys.path.insert(0, p)
    try:
        yield
    finally:
        sys.path = old_path


def loadNodesDesc(folder, packageName='nodes'):
    """
    """
    global nodesDesc

    nodeTypes = []
    errors = []

    # temporarily add folder to python path
    with add_to_path(folder):
        # import node package
        package = importlib.import_module(packageName)

        pysearchre = re.compile('.py$', re.IGNORECASE)
        pluginFiles = filter(pysearchre.search, os.listdir(os.path.dirname(package.__file__)))
        for pluginFile in pluginFiles:
            if pluginFile.startswith('__'):
                continue

            pluginName = os.path.splitext(pluginFile)[0]
            pluginModule = '.' + pluginName
            try:
                m = importlib.import_module(pluginModule, package=package.__name__)
                p = [a for a in m.__dict__.values() if inspect.isclass(a) and issubclass(a, desc.Node)]
                if not p:
                    raise RuntimeError('No class defined in plugin: %s' % pluginModule)
                nodeTypes.extend(p)
            except Exception as e:
                errors.append('  * Errors while loading "{}".\n    File: {}\n    {}'.format(pluginName, pluginFile, str(e)))

        nodesDesc = dict([(m.__name__, m) for m in nodeTypes])
        print('Plugins loaded: ', ', '.join(nodesDesc.keys()))
        if errors:
            print('== Error while loading the following plugins: ==')
            print('\n'.join(errors))
            print('================================================')

    return nodeTypes


# Load plugins
# TODO: seems "risky" at module level, should be in a registerNodes function in meshroom package
loadNodesDesc(folder=os.path.dirname(os.path.dirname(__file__)))