#!/usr/bin/env python
#
# Copyright 2014  Lars Wirzenius
#
# This program 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.
#
# This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.


import json
import os
import platform
import shutil
import stat
import sys
import tempfile
import time

import cliapp
import Crypto.Cipher.ARC4
import larch
import ttystatus


class BinaryJunkGenerator(object):

    key = b'obnam-benchmark'
    data = b'fake live data' * 1024

    def __init__(self):
        self.cipher = Crypto.Cipher.ARC4.new(self.key)
        self.buffer = ''

    def get(self, num_bytes):
        n = 0
        result = []
        while n < num_bytes:
            if not self.buffer:
                self.buffer = self.cipher.encrypt(self.data)

            part = self.buffer[:num_bytes - n]
            result.append(part)
            n += len(part)
            self.buffer = self.buffer[len(part):]

        return ''.join(result)


class StepInfo(object):

    def __init__(self, label):
        self.label = label
        self.info = {
            'step': label,
            }

    def add_info(self, key, value):
        self.info[key] = value

    def stop_timer(self):
        self.end = time.time()

    def __enter__(self):
        self.start = time.time()
        self.end = None
        return self

    def __exit__(self, exc_type, exc_val, exc_tb):
        if exc_type is None:
            if self.end is None:
                self.end = time.time()
            self.info['duration'] = self.end - self.start
        return False


class ObnamBenchmark(object):

    def __init__(self, settings, results_dir, srctree, junk_generator):
        self.settings = settings
        self.results_dir = results_dir
        self.srctree = srctree
        self.junk_generator = junk_generator

    @classmethod
    def add_settings(self, settings):
        pass

    @property
    def benchmark_name(self):
        s = self.__class__.__name__
        if s.endswith('Benchmark'):
            s = s[:-len('Benchmark')]
        return s

    def result_filename(self, label, suffix):
        return os.path.join(
            self.results_dir,
            '%s-%s%s' % (self.benchmark_name, label, suffix))

    def run(self):
        self.tempdir = tempfile.mkdtemp()
        self.live_data = self.create_live_data_dir()
        self.repo = self.create_repo()
        step_infos = []

        steps = [
            ('create-live-data', self.create_live_data),
            ('initial-backup', self.backup),
            ('no-op-backup', self.backup),
            ('obnam-verify', self.obnam_verify),
            ('obnam-mount', self.obnam_mount),
            ('cleanup',
             lambda si:
                 self.cleanup(si) if self.settings['cleanup'] else None),
            ]

        for label, method in steps:
            print '  %s' % label
            with StepInfo(label) as step_info:
                method(step_info)
            step_infos.append(step_info)

        return {
            'steps': [step_info.info for step_info in step_infos],
            }

    def create_live_data_dir(self):
        live_data = os.path.join(self.tempdir, 'live-data')
        os.mkdir(live_data)
        return live_data

    def create_repo(self):
        repo = os.path.join(self.tempdir, 'repo')
        os.mkdir(repo)
        return repo

    def create_live_data(self, step_info):
        # Subclasses MUST override this.
        raise NotImplementedError()

    def backup(self, step_info):
        self.run_obnam(
            ['backup', '-r', self.repo, self.live_data], step_info.label)
        step_info.stop_timer()
        step_info.add_info('repo-size', self.sum_of_file_sizes(self.repo))
        step_info.add_info(
            'live-data-size', self.sum_of_file_sizes(self.live_data))

    def obnam_verify(self, step_info):
        self.run_obnam(
            ['verify', '-r', self.repo],
            step_info.label)

    def obnam_mount(self, step_info):
        mount = os.path.join(self.tempdir, 'mount')
        os.mkdir(mount)

        self.run_obnam(
            ['mount', '-r', self.repo, '--to', mount],
            step_info.label)

        cliapp.runcmd(['tar', '-cf', '/dev/null', mount + '/.'])

        try:
            cliapp.runcmd(['fusermount', '-u', mount])
        except cliapp.AppException as e:
            print 'ERROR from fusermount: %s' % str(e)

    def cleanup(self, step_info):
        shutil.rmtree(self.tempdir)

    def run_obnam(self, args, label):
        base_command = [
            self.settings['obnam-cmd'],
            '--no-default-config',
            '--log', self.result_filename(label, '.log'),
            '--log-level', 'debug',
            ]
        env = dict(os.environ)
        env['OBNAM_PROFILE'] = self.result_filename(label, '.prof')
        cliapp.runcmd(base_command + args, env=env, cwd=self.srctree)

    def sum_of_file_sizes(self, root_dir):
        total = 0
        for dirname, subdirs, basenames in os.walk(root_dir):
            for basename in basenames:
                pathname = os.path.join(dirname, basename)
                st = os.lstat(pathname)
                if stat.S_ISREG(st.st_mode):
                    total += st.st_size
        return total


class EmptyFilesBenchmark(ObnamBenchmark):

    files_per_dir = 1000

    @classmethod
    def add_settings(self, settings):
        settings.integer(
            ['empty-files-count'],
            'number of empty files for %s' % self.__class__.__name__,
            default=10**6)

    @property
    def num_files(self):
        return self.settings['empty-files-count']

    def create_live_data(self, step_info):
        step_info.add_info('empty-files-count', self.num_files)
        for i in range(self.num_files):
            subdir = os.path.join(
                self.live_data, 'dir-%d' % (i / self.files_per_dir))
            if (i % self.files_per_dir) == 0:
                os.mkdir(subdir)
            filename = os.path.join(subdir, 'file-%d' % i)
            with open(filename, 'w'):
                pass


class SingleLargeFileBenchmark(ObnamBenchmark):

    @classmethod
    def add_settings(self, settings):
        settings.bytesize(
            ['single-large-file-size'],
            'size of file to create for %s' % self.__class__.__name__,
            default='1TB')

    @property
    def file_size(self):
        return self.settings['single-large-file-size']

    def create_live_data(self, step_info):
        step_info.add_info('single-large-file-size', self.file_size)
        filename = os.path.join(self.live_data, 'file.dat')
        with open(filename, 'w') as f:
            n = 0
            max_chunk_size = 2**10
            ts = ttystatus.TerminalStatus()
            ts['written'] = 0
            ts['total'] = self.file_size
            ts.format(
                '%ElapsedTime() '
                'writing live data: %ByteSize(written) of %ByteSize(total) '
                'at %ByteSpeed(written) '
                '(%PercentDone(written,total))')
            while n < self.file_size:
                num_bytes = min(max_chunk_size, self.file_size - n)
                data = self.junk_generator.get(num_bytes)
                f.write(data)
                n += len(data)
                ts['written'] = n
            ts.clear()
            ts.finish()


class ObnamBenchmarkRunner(cliapp.Application):

    benchmark_classes = [
        EmptyFilesBenchmark,
        SingleLargeFileBenchmark,
        ]

    def add_settings(self):
        self.settings.string(
            ['obnam-cmd'],
            'use CMD as the argv[0] to invoke obnam',
            metavar='CMD',
            default='./obnam')

        self.settings.string(
            ['obnam-treeish'],
            'run Obnam from TREEISH in its git repository',
            metavar='TREEISH',
            default='HEAD')

        self.settings.string(
            ['results-dir'],
            'put results in DIR',
            metavar='DIR',
            default='.')

        self.settings.boolean(
            ['cleanup'],
            'clean up after each benchmark?',
            default=True)

        for benchmark_class in self.benchmark_classes:
            benchmark_class.add_settings(self.settings)

    def process_args(self, args):
        results_dir = self.create_results_dir()
        self.store_settings_in_results(results_dir)
        result_obj = {
            'system-info': self.get_system_info_dict(),
            'versions': self.get_version_info_dict(),
            }

        srctree = self.prepare_source_tree()

        junk_generator = BinaryJunkGenerator()
        benchmark_infos = {}
        for benchmark_class in self.benchmark_classes:
            print 'Benchmark %s' % benchmark_class.__name__
            benchmark = benchmark_class(
                self.settings, results_dir, srctree, junk_generator)
            benchmark_info = benchmark.run()
            benchmark_infos[benchmark.benchmark_name] = benchmark_info
        result_obj['benchmarks'] = benchmark_infos

        self.save_result_obj(results_dir, result_obj)

        shutil.rmtree(srctree)

    def create_results_dir(self):
        results = os.path.abspath(self.settings['results-dir'])
        if not os.path.exists(results):
            os.mkdir(results)
        return results

    def store_settings_in_results(self, results):
        cp = self.settings.as_cp()
        filename = os.path.join(results, 'obnam-benchmark.conf')
        with open(filename, 'w') as f:
            cp.write(f)

    def get_system_info_dict(self):
        return {
            'hostname': platform.node(),
            'machine': platform.machine(),
            'architecture': platform.architecture(),
            'uname': platform.uname(),
            }

    def get_version_info_dict(self):
        treeish = self.settings['obnam-treeish']
        describe = cliapp.runcmd(['git', 'describe', treeish]).strip()
        return {
            'obnam-treeish': treeish,
            'obnam-version': describe,
            'larch-version': larch.__version__,
            }

    def prepare_source_tree(self):
        srctree = tempfile.mkdtemp()
        self.extract_sources_from_git(srctree)
        self.build_obnam(srctree)
        return srctree

    def extract_sources_from_git(self, srctree):
        cliapp.runcmd(
            ['git', 'archive', self.settings['obnam-treeish']],
            ['tar', '-C', srctree, '-xf', '-'])

    def build_obnam(self, srctree):
        cliapp.runcmd(
            ['python', 'setup.py', 'build_ext', '-i'],
            cwd=srctree)

    def save_result_obj(self, results_dir, result_obj):
        filename = os.path.join(results_dir, 'benchmark.json')
        with open(filename, 'w') as f:
            json.dump(result_obj, f, indent=4)


if __name__ == '__main__':
    ObnamBenchmarkRunner().run()