# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0. If a copy of the MPL was not distributed with this
# file, You can obtain one at http://mozilla.org/MPL/2.0/.

import time
from cProfile import Profile
from pathlib import Path

import six

from .base import MachError

INVALID_COMMAND_CONTEXT = r"""
It looks like you tried to run a mach command from an invalid context. The %s
command failed to meet the following conditions: %s

Run |mach help| to show a list of all commands available to the current context.
""".lstrip()


class MachRegistrar(object):
    """Container for mach command and config providers."""

    def __init__(self):
        self.command_handlers = {}
        self.commands_by_category = {}
        self.settings_providers = set()
        self.categories = {}
        self.require_conditions = False
        self.command_depth = 0

    def register_command_handler(self, handler):
        name = handler.name

        if not handler.category:
            raise MachError(
                "Cannot register a mach command without a " "category: %s" % name
            )

        if handler.category not in self.categories:
            raise MachError(
                "Cannot register a command to an undefined "
                "category: %s -> %s" % (name, handler.category)
            )

        self.command_handlers[name] = handler
        self.commands_by_category[handler.category].add(name)

    def register_settings_provider(self, cls):
        self.settings_providers.add(cls)

    def register_category(self, name, title, description, priority=50):
        self.categories[name] = (title, description, priority)
        self.commands_by_category[name] = set()

    @classmethod
    def _condition_failed_message(cls, name, conditions):
        msg = ["\n"]
        for c in conditions:
            part = ["  %s" % getattr(c, "__name__", c)]
            if c.__doc__ is not None:
                part.append(c.__doc__)
            msg.append(" - ".join(part))
        return INVALID_COMMAND_CONTEXT % (name, "\n".join(msg))

    @classmethod
    def _instance(_, handler, context, **kwargs):
        if context is None:
            raise ValueError("Expected a non-None context.")

        prerun = getattr(context, "pre_dispatch_handler", None)
        if prerun:
            prerun(context, handler, args=kwargs)

        context.handler = handler
        return handler.create_instance(context, handler.virtualenv_name)

    @classmethod
    def _fail_conditions(_, handler, instance):
        fail_conditions = []
        if handler.conditions:
            for c in handler.conditions:
                if not c(instance):
                    fail_conditions.append(c)

        return fail_conditions

    def _run_command_handler(
        self, handler, context, debug_command=False, profile_command=False, **kwargs
    ):
        instance = MachRegistrar._instance(handler, context, **kwargs)
        fail_conditions = MachRegistrar._fail_conditions(handler, instance)
        if fail_conditions:
            print(
                MachRegistrar._condition_failed_message(handler.name, fail_conditions)
            )
            return 1

        self.command_depth += 1
        fn = handler.func
        if handler.virtualenv_name:
            instance.activate_virtualenv()

        profile = None
        if profile_command:
            profile = Profile()
            profile.enable()

        start_time = time.monotonic()

        if debug_command:
            import pdb

            result = pdb.runcall(fn, instance, **kwargs)
        else:
            result = fn(instance, **kwargs)

        end_time = time.monotonic()

        if profile_command:
            profile.disable()
            profile_file = (
                Path(context.topdir) / f"mach_profile_{handler.name}.cProfile"
            )
            profile.dump_stats(profile_file)
            print(
                f'Mach command profile created at "{profile_file}". To visualize, use '
                f"snakeviz:"
            )
            print("python3 -m pip install snakeviz")
            print(f"python3 -m snakeviz {profile_file.name}")

        result = result or 0
        assert isinstance(result, six.integer_types)

        if not debug_command:
            postrun = getattr(context, "post_dispatch_handler", None)
            if postrun:
                postrun(
                    context,
                    handler,
                    instance,
                    not result,
                    start_time,
                    end_time,
                    self.command_depth,
                    args=kwargs,
                )
        self.command_depth -= 1

        return result

    def dispatch(self, name, context, argv=None, subcommand=None, **kwargs):
        """Dispatch/run a command.

        Commands can use this to call other commands.
        """
        handler = self.command_handlers[name]

        if subcommand:
            handler = handler.subcommand_handlers[subcommand]

        if handler.parser:
            parser = handler.parser

            # save and restore existing defaults so **kwargs don't persist across
            # subsequent invocations of Registrar.dispatch()
            old_defaults = parser._defaults.copy()
            parser.set_defaults(**kwargs)
            kwargs, unknown = parser.parse_known_args(argv or [])
            kwargs = vars(kwargs)
            parser._defaults = old_defaults

            if unknown:
                if subcommand:
                    name = "{} {}".format(name, subcommand)
                parser.error(
                    "unrecognized arguments for {}: {}".format(
                        name, ", ".join(["'{}'".format(arg) for arg in unknown])
                    )
                )

        return self._run_command_handler(handler, context, **kwargs)


Registrar = MachRegistrar()
