#
# diffoscope: in-depth comparison of files, archives, and directories
#
# Copyright © 2016-2017, 2019-2022 Chris Lamb <lamby@debian.org>
#
# diffoscope is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# diffoscope is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with diffoscope.  If not, see <https://www.gnu.org/licenses/>.

import sys
import time
import contextlib
import collections

from .utils import format_class
from .logging import setup_logging

_ENABLED = False


@contextlib.contextmanager
def profile(namespace, key):
    start = time.time()
    yield

    if _ENABLED:
        ProfileManager().increment(start, namespace, key)


class ProfileManager:
    _singleton = {}

    def __init__(self):
        self.__dict__ = self._singleton

        if not self._singleton:
            self.data = collections.defaultdict(
                lambda: collections.defaultdict(
                    lambda: {"time": 0.0, "count": 0}
                )
            )

    def setup(self, parsed_args):
        global _ENABLED
        _ENABLED = parsed_args.profile_output is not None or parsed_args.debug

    def increment(self, start, namespace, key):
        if not isinstance(key, str):
            key = format_class(key.__class__)

        self.data[namespace][key]["time"] += time.time() - start
        self.data[namespace][key]["count"] += 1

    def finish(self, parsed_args=None):
        from .presenters.utils import make_printer

        # We are being called in the TERM handler so we don't have access to
        # parsed_args. Print the profiling output to stderr if we have been
        # collecting it.
        if parsed_args is None:
            if _ENABLED:
                self.output(lambda x: print(x, file=sys.stderr))
            return

        # Include profiling in --debug output if --profile is not set.
        if parsed_args.profile_output is None:
            with setup_logging(parsed_args.debug, None) as logger:
                self.output(lambda x: logger.debug(x.strip("\n")))
            return

        with make_printer(parsed_args.profile_output) as fn:
            self.output(fn)

    def output(self, print_fn):
        title = "# Profiling output for: {}".format(" ".join(sys.argv))

        print_fn(title)

        def key(x):
            return x[1]["time"]

        for namespace, keys in sorted(self.data.items(), key=lambda x: x[0]):
            print_fn(
                "\n## {} (total time: {:.3f}s)".format(
                    namespace, sum(x["time"] for x in keys.values())
                )
            )

            for value, totals in sorted(keys.items(), key=key, reverse=True):
                print_fn(
                    "  {:10.3f}s {:6d} call{}    {}".format(
                        totals["time"],
                        totals["count"],
                        " " if totals["count"] == 1 else "s",
                        value,
                    )
                )
