import signal
import os
import sys
import traceback
from log import RED, single_line_delim, double_line_delim
from debug import spawn_gdb
from subprocess import check_output, CalledProcessError


class Hook(object):
    """
    Generic hooks before/after API/CLI calls
    """

    def __init__(self, logger):
        self.logger = logger

    def before_api(self, api_name, api_args):
        """
        Function called before API call
        Emit a debug message describing the API name and arguments

        @param api_name: name of the API
        @param api_args: tuple containing the API arguments
        """
        self.logger.debug("API: %s (%s)" %
                          (api_name, api_args), extra={'color': RED})

    def after_api(self, api_name, api_args):
        """
        Function called after API call

        @param api_name: name of the API
        @param api_args: tuple containing the API arguments
        """
        pass

    def before_cli(self, cli):
        """
        Function called before CLI call
        Emit a debug message describing the CLI

        @param cli: CLI string
        """
        self.logger.debug("CLI: %s" % (cli), extra={'color': RED})

    def after_cli(self, cli):
        """
        Function called after CLI call
        """
        pass


class VppDiedError(Exception):
    pass


class PollHook(Hook):
    """ Hook which checks if the vpp subprocess is alive """

    def __init__(self, testcase):
        self.testcase = testcase
        self.logger = testcase.logger

    def on_crash(self, core_path):
        if self.testcase.debug_core:
            # notify parent process that we're handling a core file
            open('%s/_core_handled' % self.testcase.tempdir, 'a').close()
            spawn_gdb(self.testcase.vpp_bin, core_path, self.logger)
        else:
            self.logger.error("Core file present, debug with: gdb %s %s" %
                              (self.testcase.vpp_bin, core_path))
            self.logger.error("Running `file %s':" % core_path)
            try:
                info = check_output(["file", core_path])
                self.logger.error(info)
            except CalledProcessError as e:
                self.logger.error(
                    "Could not run `file' utility on core-file, "
                    "rc=%s" % e.returncode)
                pass

    def poll_vpp(self):
        """
        Poll the vpp status and throw an exception if it's not running
        :raises VppDiedError: exception if VPP is not running anymore
        """
        if self.testcase.vpp_dead:
            # already dead, nothing to do
            return

        self.testcase.vpp.poll()
        if self.testcase.vpp.returncode is not None:
            signaldict = dict(
                (k, v) for v, k in reversed(sorted(signal.__dict__.items()))
                if v.startswith('SIG') and not v.startswith('SIG_'))

            if self.testcase.vpp.returncode in signaldict:
                s = signaldict[abs(self.testcase.vpp.returncode)]
            else:
                s = "unknown"
            msg = "VPP subprocess died unexpectedly with returncode %d [%s]" %\
                (self.testcase.vpp.returncode, s)
            self.logger.critical(msg)
            core_path = self.testcase.tempdir + '/core'
            if os.path.isfile(core_path):
                self.on_crash(core_path)
            self.testcase.vpp_dead = True
            raise VppDiedError(msg)

    def before_api(self, api_name, api_args):
        """
        Check if VPP died before executing an API

        :param api_name: name of the API
        :param api_args: tuple containing the API arguments
        :raises VppDiedError: exception if VPP is not running anymore

        """
        super(PollHook, self).before_api(api_name, api_args)
        self.poll_vpp()

    def before_cli(self, cli):
        """
        Check if VPP died before executing a CLI

        :param cli: CLI string
        :raises Exception: exception if VPP is not running anymore

        """
        super(PollHook, self).before_cli(cli)
        self.poll_vpp()


class StepHook(PollHook):
    """ Hook which requires user to press ENTER before doing any API/CLI """

    def __init__(self, testcase):
        self.skip_stack = None
        self.skip_num = None
        self.skip_count = 0
        super(StepHook, self).__init__(testcase)

    def skip(self):
        if self.skip_stack is None:
            return False
        stack = traceback.extract_stack()
        counter = 0
        skip = True
        for e in stack:
            if counter > self.skip_num:
                break
            if e[0] != self.skip_stack[counter][0]:
                skip = False
            if e[1] != self.skip_stack[counter][1]:
                skip = False
            counter += 1
        if skip:
            self.skip_count += 1
            return True
        else:
            print("%d API/CLI calls skipped in specified stack "
                  "frame" % self.skip_count)
            self.skip_count = 0
            self.skip_stack = None
            self.skip_num = None
            return False

    def user_input(self):
        print('number\tfunction\tfile\tcode')
        counter = 0
        stack = traceback.extract_stack()
        for e in stack:
            print('%02d.\t%s\t%s:%d\t[%s]' % (counter, e[2], e[0], e[1], e[3]))
            counter += 1
        print(single_line_delim)
        print("You can enter a number of stack frame chosen from above")
        print("Calls in/below that stack frame will be not be stepped anymore")
        print(single_line_delim)
        while True:
            choice = sys.stdin.readline(
                "Enter your choice, if any, and press ENTER to continue "
                "running the testcase...")
            if choice == "":
                choice = None
            try:
                if choice is not None:
                    num = int(choice)
            except TypeError:
                print("Invalid input")
                continue
            if choice is not None and (num < 0 or num >= len(stack)):
                print("Invalid choice")
                continue
            break
        if choice is not None:
            self.skip_stack = stack
            self.skip_num = num

    def before_cli(self, cli):
        """ Wait for ENTER before executing CLI """
        if self.skip():
            print("Skip pause before executing CLI: %s" % cli)
        else:
            print(double_line_delim)
            print("Test paused before executing CLI: %s" % cli)
            print(single_line_delim)
            self.user_input()
        super(StepHook, self).before_cli(cli)

    def before_api(self, api_name, api_args):
        """ Wait for ENTER before executing API """
        if self.skip():
            print("Skip pause before executing API: %s (%s)"
                  % (api_name, api_args))
        else:
            print(double_line_delim)
            print("Test paused before executing API: %s (%s)"
                  % (api_name, api_args))
            print(single_line_delim)
            self.user_input()
        super(StepHook, self).before_api(api_name, api_args)