from __future__ import absolute_import
import os, traceback, threading, shlex
from . import controller

class ScriptError(Exception):
    pass


class ScriptContext:
    def __init__(self, master):
        self._master = master

    def log(self, message, level="info"):
        """
            Logs an event.

            By default, only events with level "error" get displayed. This can be controlled with the "-v" switch.
            How log messages are handled depends on the front-end. mitmdump will print them to stdout,
            mitmproxy sends output to the eventlog for display ("e" keyboard shortcut).
        """
        self._master.add_event(message, level)

    def duplicate_flow(self, f):
        """
            Returns a duplicate of the specified flow. The flow is also
            injected into the current state, and is ready for editing, replay,
            etc.
        """
        self._master.pause_scripts = True
        f = self._master.duplicate_flow(f)
        self._master.pause_scripts = False
        return f

    def replay_request(self, f):
        """
            Replay the request on the current flow. The response will be added
            to the flow object.
        """
        self._master.replay_request(f)


class Script:
    """
        The instantiator should do something along this vein:

            s = Script(argv, master)
            s.load()
    """
    def __init__(self, command, master):
        self.command = command
        self.argv = self.parse_command(command)
        self.ctx = ScriptContext(master)
        self.ns = None
        self.load()

    @classmethod
    def parse_command(klass, command):
        if os.name == "nt":  # Windows: escape all backslashes in the path.
            backslashes = shlex.split(command, posix=False)[0].count("\\")
            command = command.replace("\\", "\\\\", backslashes)
        args = shlex.split(command)
        args[0] = os.path.expanduser(args[0])
        if not os.path.exists(args[0]):
            raise ScriptError(("Script file not found: %s.\r\n"
                               "If you script path contains spaces, "
                               "make sure to wrap it in additional quotes, e.g. -s \"'./foo bar/baz.py' --args\".") % args[0])
        elif not os.path.isfile(args[0]):
            raise ScriptError("Not a file: %s" % args[0])
        return args

    def load(self):
        """
            Loads a module.

            Raises ScriptError on failure, with argument equal to an error
            message that may be a formatted traceback.
        """
        ns = {}
        try:
            execfile(self.argv[0], ns, ns)
        except Exception, v:
            raise ScriptError(traceback.format_exc(v))
        self.ns = ns
        r = self.run("start", self.argv)
        if not r[0] and r[1]:
            raise ScriptError(r[1][1])

    def unload(self):
        return self.run("done")

    def run(self, name, *args, **kwargs):
        """
            Runs a plugin method.

            Returns:

                (True, retval) on success.
                (False, None) on nonexistent method.
                (False, (exc, traceback string)) if there was an exception.
        """
        f = self.ns.get(name)
        if f:
            try:
                return (True, f(self.ctx, *args, **kwargs))
            except Exception, v:
                return (False, (v, traceback.format_exc(v)))
        else:
            return (False, None)


class ReplyProxy(object):
    def __init__(self, original_reply):
        self._ignore_calls = 1
        self.lock = threading.Lock()
        self.original_reply = original_reply

    def __call__(self, *args, **kwargs):
        with self.lock:
            if self._ignore_calls > 0:
                self._ignore_calls -= 1
                return
        self.original_reply(*args, **kwargs)

    def __getattr__ (self, k):
        return getattr(self.original_reply, k)


def _handle_concurrent_reply(fn, o, *args, **kwargs):
    # Make first call to o.reply a no op

    reply_proxy = ReplyProxy(o.reply)
    o.reply = reply_proxy

    def run():
        fn(*args, **kwargs)
        o.reply()  # If the script did not call .reply(), we have to do it now.
    threading.Thread(target=run, name="ScriptThread").start()


def concurrent(fn):
    if fn.func_name in ("request", "response", "error", "clientconnect", "serverconnect", "clientdisconnect"):
        def _concurrent(ctx, obj):
            _handle_concurrent_reply(fn, obj, ctx, obj)
        return _concurrent
    raise NotImplementedError("Concurrent decorator not supported for this method.")