#!/usr/bin/python
# Copyright (C) 2012,2013,2015  Codethink Limited
#
# 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; version 2 of the License.
#
# 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 cliapp
import csv
import os
import shutil
import sys
import tarfile
import tempfile
import time


class SourceStats(cliapp.Application):

    '''Compute some basic statistics about Baserock components.

    * name of component
    * total source lines, excluding blank lines
    * number of commits over last 12 months
    * lines added over 12 months
    * lines removed over 12 months

    Usage: ./source-stat $HOME/baserock/gits/*

    '''

    def add_settings(self):
        self.settings.string(['gitsdir'], 'base directory for git repos')

    def setup(self):
        self.writer = csv.writer(sys.stdout)
        self.cols = ['name', 'lines', 'commits', 'added', 'deleted']
        self.writer.writerow(self.cols)

    def process_input(self, gitdir):
        name = os.path.basename(gitdir)
        stats = self.compute_stats(name, gitdir)
        row = [stats[x] for x in self.cols]
        self.writer.writerow(row)
        sys.stdout.flush()

    def compute_stats(self, name, gitdir):
        stats = {
            'name': name,
        }

        t = time.time() - 365 * 86400
        tt = time.localtime(t)
        start_date = time.strftime('%Y-%m-%d', tt)

        stats['branch'] = self.pick_branch(gitdir)

        self.get_sources(gitdir, stats['branch'])

        stats['lines'] = self.count_source_lines(gitdir)

        start, end = self.find_commit_range(gitdir, start_date)
        stats['commits'] = self.count_commits(gitdir, start, end)
        stats['added'], stats['deleted'] = self.diffstat(gitdir, start, end)

        return stats

    def pick_branch(self, gitdir):
        out = self.runcmd(['git', 'branch', '-r'], cwd=gitdir)
        lines = [x.split()[-1] for x in out.splitlines()]

        candidates = [
            'origin/master',
            'origin/trunk',
            'origin/blead',
        ]

        for x in candidates:
            if x in lines:
                return x
        raise Exception('Cannot decide on branch in %s' % gitdir)

    def get_sources(self, gitdir, branch):
        self.runcmd(['git', 'checkout', branch], cwd=gitdir)

    def count_source_lines(self, tempdir):
        numlines = 0
        for dirname, subdirs, basenames in os.walk(tempdir):
            if '.git' in subdirs:
                subdirs.remove('.git')

            for basename in basenames:
                filename = os.path.join(dirname, basename)
                if os.path.isfile(filename) and not os.path.islink(filename):
                    with open(filename) as f:
                        for line in f:
                            if line.strip():
                                numlines += 1

        return numlines

    def find_commit_range(self, gitdir, start_date):
        out = self.runcmd(['git', 'log', '--format=oneline',
                           '--since=%s' % start_date],
                          cwd=gitdir)
        lines = out.splitlines()
        if len(lines) < 2:
            return 'HEAD', 'HEAD'
        end = lines[0].split()[0]
        start = lines[-1].split()[0]
        return start, end

    def count_commits(self, gitdir, start, end):
        out = self.runcmd(['git', 'log', '--format=oneline',
                           '%s..%s' % (start, end)],
                          cwd=gitdir)
        return len(out.splitlines())

    def diffstat(self, gitdir, start, end):
        out = self.runcmd(['git', 'diff', '--numstat', start, end],
                          cwd=gitdir)
        tuples = [line.split() for line in out.splitlines()]

        def toint(s):
            try:
                return int(s)
            except ValueError:
                return 0
        added = sum(toint(t[0]) for t in tuples)
        deleted = sum(toint(t[1]) for t in tuples)
        return added, deleted

SourceStats().run()