"""
managing loading and interacting with pytest plugins. 
"""
import py
import inspect
from py._plugin import hookspec

default_plugins = (
    "default runner capture mark terminal skipping tmpdir monkeypatch "
    "recwarn pdb pastebin unittest helpconfig nose assertion genscript "
    "junitxml doctest").split()

def check_old_use(mod, modname):
    clsname = modname[len('pytest_'):].capitalize() + "Plugin" 
    assert not hasattr(mod, clsname), (mod, clsname)

class PluginManager(object):
    def __init__(self):
        self.registry = Registry()
        self._name2plugin = {}
        self._hints = []
        self.hook = HookRelay([hookspec], registry=self.registry) 
        self.register(self)
        for spec in default_plugins:
            self.import_plugin(spec)

    def _getpluginname(self, plugin, name):
        if name is None:
            if hasattr(plugin, '__name__'):
                name = plugin.__name__.split(".")[-1]
            else:
                name = id(plugin) 
        return name 

    def register(self, plugin, name=None):
        assert not self.isregistered(plugin), plugin
        assert not self.registry.isregistered(plugin), plugin
        name = self._getpluginname(plugin, name)
        if name in self._name2plugin:
            return False
        self._name2plugin[name] = plugin
        self.call_plugin(plugin, "pytest_addhooks", {'pluginmanager': self})
        self.hook.pytest_plugin_registered(manager=self, plugin=plugin)
        self.registry.register(plugin)
        return True

    def unregister(self, plugin):
        self.hook.pytest_plugin_unregistered(plugin=plugin)
        self.registry.unregister(plugin)
        for name, value in list(self._name2plugin.items()):
            if value == plugin:
                del self._name2plugin[name]

    def isregistered(self, plugin, name=None):
        if self._getpluginname(plugin, name) in self._name2plugin:
            return True
        for val in self._name2plugin.values():
            if plugin == val:
                return True

    def addhooks(self, spec):
        self.hook._addhooks(spec, prefix="pytest_")

    def getplugins(self):
        return list(self.registry)

    def skipifmissing(self, name):
        if not self.hasplugin(name):
            py.test.skip("plugin %r is missing" % name)

    def hasplugin(self, name):
        try:
            self.getplugin(name)
        except KeyError:
            return False
        else:
            return True

    def getplugin(self, name):
        try:
            return self._name2plugin[name]
        except KeyError:
            impname = canonical_importname(name)
            return self._name2plugin[impname]

    # API for bootstrapping 
    #
    def _envlist(self, varname):
        val = py.std.os.environ.get(varname, None)
        if val is not None:
            return val.split(',')
        return ()
    
    def consider_env(self):
        for spec in self._envlist("PYTEST_PLUGINS"):
            self.import_plugin(spec)

    def consider_setuptools_entrypoints(self):
        try:
            from pkg_resources import iter_entry_points
        except ImportError:
            return # XXX issue a warning 
        for ep in iter_entry_points('pytest11'):
            name = canonical_importname(ep.name)
            if name in self._name2plugin:
                continue
            plugin = ep.load()
            self.register(plugin, name=name)

    def consider_preparse(self, args):
        for opt1,opt2 in zip(args, args[1:]):
            if opt1 == "-p": 
                self.import_plugin(opt2)

    def consider_conftest(self, conftestmodule):
        cls = getattr(conftestmodule, 'ConftestPlugin', None)
        if cls is not None:
            raise ValueError("%r: 'ConftestPlugins' only existed till 1.0.0b1, "
                "were removed in 1.0.0b2" % (cls,))
        if self.register(conftestmodule, name=conftestmodule.__file__):
            self.consider_module(conftestmodule)

    def consider_module(self, mod):
        attr = getattr(mod, "pytest_plugins", ())
        if attr:
            if not isinstance(attr, (list, tuple)):
                attr = (attr,)
            for spec in attr:
                self.import_plugin(spec) 

    def import_plugin(self, spec):
        assert isinstance(spec, str)
        modname = canonical_importname(spec)
        if modname in self._name2plugin:
            return
        try:
            mod = importplugin(modname)
        except KeyboardInterrupt:
            raise
        except py.test.skip.Exception:
            e = py.std.sys.exc_info()[1]
            self._hints.append("skipped plugin %r: %s" %((modname, e.msg)))
        else:
            check_old_use(mod, modname) 
            self.register(mod)
            self.consider_module(mod)

    def pytest_terminal_summary(self, terminalreporter):
        tw = terminalreporter._tw
        if terminalreporter.config.option.traceconfig:
            for hint in self._hints:
                tw.line("hint: %s" % hint)

    # 
    #
    # API for interacting with registered and instantiated plugin objects 
    #
    # 
    def listattr(self, attrname, plugins=None):
        return self.registry.listattr(attrname, plugins=plugins)

    def notify_exception(self, excinfo=None):
        if excinfo is None:
            excinfo = py.code.ExceptionInfo()
        excrepr = excinfo.getrepr(funcargs=True, showlocals=True)
        return self.hook.pytest_internalerror(excrepr=excrepr)

    def do_addoption(self, parser):
        mname = "pytest_addoption"
        methods = self.registry.listattr(mname, reverse=True)
        mc = MultiCall(methods, {'parser': parser})
        mc.execute()

    def pytest_plugin_registered(self, plugin):
        dic = self.call_plugin(plugin, "pytest_namespace", {}) or {}
        for name, value in dic.items():
            setattr(py.test, name, value)
            py.test.__all__.append(name)
        if hasattr(self, '_config'):
            self.call_plugin(plugin, "pytest_addoption", 
                {'parser': self._config._parser})
            self.call_plugin(plugin, "pytest_configure", 
                {'config': self._config})

    def call_plugin(self, plugin, methname, kwargs):
        return MultiCall(
                methods=self.listattr(methname, plugins=[plugin]), 
                kwargs=kwargs, firstresult=True).execute()

    def do_configure(self, config):
        assert not hasattr(self, '_config')
        self._config = config
        config.hook.pytest_configure(config=self._config)

    def do_unconfigure(self, config):
        config = self._config 
        del self._config 
        config.hook.pytest_unconfigure(config=config)
        config.pluginmanager.unregister(self)

def canonical_importname(name):
    name = name.lower()
    modprefix = "pytest_"
    if not name.startswith(modprefix):
        name = modprefix + name 
    return name 

def importplugin(importspec):
    try:
        return __import__(importspec) 
    except ImportError:
        e = py.std.sys.exc_info()[1]
        if str(e).find(importspec) == -1:
            raise
        try:
            return __import__("py._plugin.%s" %(importspec), 
                None, None, '__doc__')
        except ImportError:
            e = py.std.sys.exc_info()[1]
            if str(e).find(importspec) == -1:
                raise
            # show the original exception, not the failing internal one
            return __import__(importspec)  


class MultiCall:
    """ execute a call into multiple python functions/methods.  """

    def __init__(self, methods, kwargs, firstresult=False):
        self.methods = methods[:]
        self.kwargs = kwargs.copy()
        self.kwargs['__multicall__'] = self
        self.results = []
        self.firstresult = firstresult

    def __repr__(self):
        status = "%d results, %d meths" % (len(self.results), len(self.methods))
        return "<MultiCall %s, kwargs=%r>" %(status, self.kwargs)

    def execute(self):
        while self.methods:
            method = self.methods.pop()
            kwargs = self.getkwargs(method)
            res = method(**kwargs)
            if res is not None:
                self.results.append(res) 
                if self.firstresult:
                    return res
        if not self.firstresult:
            return self.results 

    def getkwargs(self, method):
        kwargs = {}
        for argname in varnames(method):
            try:
                kwargs[argname] = self.kwargs[argname]
            except KeyError:
                pass # might be optional param
        return kwargs 

def varnames(func):
    ismethod = inspect.ismethod(func)
    rawcode = py.code.getrawcode(func)
    try:
        return rawcode.co_varnames[ismethod:]
    except AttributeError:
        return ()

class Registry:
    """
        Manage Plugins: register/unregister call calls to plugins. 
    """
    def __init__(self, plugins=None):
        if plugins is None:
            plugins = []
        self._plugins = plugins

    def register(self, plugin):
        assert not isinstance(plugin, str)
        assert not plugin in self._plugins
        self._plugins.append(plugin)

    def unregister(self, plugin):
        self._plugins.remove(plugin)

    def isregistered(self, plugin):
        return plugin in self._plugins 

    def __iter__(self):
        return iter(self._plugins)

    def listattr(self, attrname, plugins=None, reverse=False):
        l = []
        if plugins is None:
            plugins = self._plugins
        for plugin in plugins:
            try:
                l.append(getattr(plugin, attrname))
            except AttributeError:
                continue 
        if reverse:
            l.reverse()
        return l

class HookRelay: 
    def __init__(self, hookspecs, registry, prefix="pytest_"):
        if not isinstance(hookspecs, list):
            hookspecs = [hookspecs]
        self._hookspecs = []
        self._registry = registry
        for hookspec in hookspecs:
            self._addhooks(hookspec, prefix)

    def _addhooks(self, hookspecs, prefix):
        self._hookspecs.append(hookspecs)
        added = False
        for name, method in vars(hookspecs).items():
            if name.startswith(prefix):
                if not method.__doc__:
                    raise ValueError("docstring required for hook %r, in %r"
                        % (method, hookspecs))
                firstresult = getattr(method, 'firstresult', False)
                hc = HookCaller(self, name, firstresult=firstresult)
                setattr(self, name, hc)
                added = True
                #print ("setting new hook", name)
        if not added:
            raise ValueError("did not find new %r hooks in %r" %(
                prefix, hookspecs,))
            

    def _performcall(self, name, multicall):
        return multicall.execute()
        
class HookCaller:
    def __init__(self, hookrelay, name, firstresult):
        self.hookrelay = hookrelay 
        self.name = name 
        self.firstresult = firstresult 

    def __repr__(self):
        return "<HookCaller %r>" %(self.name,)

    def __call__(self, **kwargs):
        methods = self.hookrelay._registry.listattr(self.name)
        mc = MultiCall(methods, kwargs, firstresult=self.firstresult)
        return self.hookrelay._performcall(self.name, mc)

    def pcall(self, plugins, **kwargs):
        methods = self.hookrelay._registry.listattr(self.name, plugins=plugins)
        mc = MultiCall(methods, kwargs, firstresult=self.firstresult)
        return self.hookrelay._performcall(self.name, mc)