# Copyright 2018-2019 Florian Fischer <florian.fl.fischer@fau.de>
#
# This file is part of allocbench.
#
# allocbench 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.
#
# allocbench 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 allocbench.  If not, see <http://www.gnu.org/licenses/>.
"""Collect facts about the benchmark environment"""

import ctypes
import datetime
import errno
import json
import multiprocessing
import os
import platform
import subprocess

import src.globalvars as gv
from src.util import print_error, print_info, run_cmd

FACTS = {}

def collect_facts():
    """Collect general facts about the benchmark environment"""
    # Populate src.globalvars.facts on import
    _uname = platform.uname()
    FACTS["hostname"] = _uname.node
    FACTS["system"] = _uname.system
    FACTS["kernel"] = _uname.release
    FACTS["arch"] = _uname.machine
    FACTS["cpus"] = multiprocessing.cpu_count()
    FACTS["LD_PRELOAD"] = os.environ.get("LD_PRELOAD", None)

    with open(os.path.join(gv.builddir, "ccinfo"), "r") as ccinfo:
        FACTS["cc"] = ccinfo.readlines()[-1][:-1]

    # get commit info from git
    allocbench_version()

    starttime = datetime.datetime.now().isoformat()
    # strip seconds from string
    starttime = starttime[:starttime.rfind(':')]
    FACTS["starttime"] = starttime


def store_facts(path=None):
    """Store facts to file"""
    if not path:
        filename = "facts.json"
    elif os.path.isdir(path):
        filename = os.path.join(path, "facts.json")
    else:
        filename = path

    print_info(f"Saving facts to: {filename}")
    with open(filename, "w") as f:
        json.dump(FACTS, f)


def load_facts(path=None):
    """Load facts from file"""
    if not path:
        filename = "facts"
    else:
        if os.path.isdir(path):
            filename = os.path.join(path, self.name)
        else:
            filename = os.path.splitext(path)[0]

    if os.path.exists(filename + ".json"):
        filename += ".json"
        with open(filename, "r") as f:
            FACTS = json.load(f)
    elif os.path.exists(filename + ".save"):
        import pickle
        filename += ".save"
        with open(filename, "rb") as f:
            FACTS = pickle.load(f)
    else:
        raise FileNotFoundError(errno.ENOENT, os.strerror(errno.ENOENT),
                                filename)

    print_info(f"Loading facts from: {filename}")

def allocbench_version():
    "Store and return allocbench version string."""
    if "allocbench" in FACTS:
        return FACTS["allocbench"]

    commit = run_cmd(["git", "rev-parse", "HEAD"], capture=True).stdout[:-1]

    proc = run_cmd(["git", "status", "--porcelain"], capture=True)
    dirty = "-dirty" if proc.stdout != "" else ""

    FACTS["allocbench"] = f"{commit}{dirty}"
    return FACTS["allocbench"]


# Copied from pip.
# https://github.com/pypa/pip/blob/master/src/pip/_internal/utils/glibc.py
# Licensed under MIT.
def glibc_version_string(executable=None):
    "Returns glibc version string, or None if not using glibc."

    # ctypes.CDLL(None) internally calls dlopen(NULL), and as the dlopen
    # manpage says, "If filename is NULL, then the returned handle is for the
    # main program". This way we can let the linker do the work to figure out
    # which libc our process is actually using.
    try:
        process_namespace = ctypes.CDLL(executable)
    except OSError:
        return None

    try:
        gnu_get_libc_version = process_namespace.gnu_get_libc_version
    except AttributeError:
        # Symbol doesn't exist -> therefore, we are not linked to
        # glibc.
        return None

    # Call gnu_get_libc_version, which returns a string like "2.5"
    gnu_get_libc_version.restype = ctypes.c_char_p
    version_str = gnu_get_libc_version()
    # py2 / py3 compatibility:
    if not isinstance(version_str, str):
        version_str = version_str.decode("ascii")

    return version_str


# platform.libc_ver regularly returns completely nonsensical glibc
# versions. E.g. on my computer, platform says:
#
#   ~$ python2.7 -c 'import platform; print(platform.libc_ver())'
#   ('glibc', '2.7')
#   ~$ python3.5 -c 'import platform; print(platform.libc_ver())'
#   ('glibc', '2.9')
#
# But the truth is:
#
#   ~$ ldd --version
#   ldd (Debian GLIBC 2.22-11) 2.22
#
# This is unfortunate, because it means that the linehaul data on libc
# versions that was generated by pip 8.1.2 and earlier is useless and
# misleading. Solution: instead of using platform, use our code that actually
# works.
def libc_ver(executable=None):
    """Return glibc version or platform.libc_ver as fallback"""
    glibc_version = glibc_version_string(executable)
    if glibc_version is None:
        # For non-glibc platforms, fall back on platform.libc_ver
        return platform.libc_ver(executable)

    return ("glibc", glibc_version)


def exe_version(executable, version_flag="--version"):
    """Return version of executable"""
    proc = subprocess.run([executable, version_flag],
                          universal_newlines=True,
                          stdout=subprocess.PIPE)

    if proc.returncode != 0:
        print_warning(f"failed to get version of {executable}")
        return ""

    return proc.stdout[:-1]