import re
import subprocess
from ..utils import RepoStats, ThreadedSegment, get_git_subprocess_env


def parse_git_branch_info(status):
    info = re.search('^## (?P<local>\S+?)''(\.{3}(?P<remote>\S+?)( \[(ahead (?P<ahead>\d+)(, )?)?(behind (?P<behind>\d+))?\])?)?$', status[0])
    return info.groupdict() if info else None


def _get_git_detached_branch():
    p = subprocess.Popen(['git', 'describe', '--tags', '--always'],
                         stdout=subprocess.PIPE, stderr=subprocess.PIPE,
                         env=get_git_subprocess_env())
    detached_ref = p.communicate()[0].decode("utf-8").rstrip('\n')
    if p.returncode == 0:
        branch = u'{} {}'.format(RepoStats.symbols['detached'], detached_ref)
    else:
        branch = 'Big Bang'
    return branch


def parse_git_stats(status):
    stats = RepoStats()
    for statusline in status[1:]:
        code = statusline[:2]
        if code == '??':
            stats.new += 1
        elif code in ('DD', 'AU', 'UD', 'UA', 'DU', 'AA', 'UU'):
            stats.conflicted += 1
        else:
            if code[1] != ' ':
                stats.changed += 1
            if code[0] != ' ':
                stats.staged += 1

    return stats


def build_stats():
    try:
        p = subprocess.Popen(['git', 'status', '--porcelain', '-b'],
                             stdout=subprocess.PIPE, stderr=subprocess.PIPE,
                             env=get_git_subprocess_env())
    except OSError:
        # Popen will throw an OSError if git is not found
        return (None, None)

    pdata = p.communicate()
    if p.returncode != 0:
        return (None, None)

    status = pdata[0].decode("utf-8").splitlines()
    stats = parse_git_stats(status)
    branch_info = parse_git_branch_info(status)

    if branch_info:
        stats.ahead = branch_info["ahead"]
        stats.behind = branch_info["behind"]
        branch = branch_info['local']
    else:
        branch = _get_git_detached_branch()
    return stats, branch


class Segment(ThreadedSegment):
    def run(self):
        self.stats, self.branch = build_stats()

    def add_to_powerline(self):
        self.join()
        if not self.stats:
            return
        bg = self.powerline.theme.REPO_CLEAN_BG
        fg = self.powerline.theme.REPO_CLEAN_FG
        if self.stats.dirty:
            bg = self.powerline.theme.REPO_DIRTY_BG
            fg = self.powerline.theme.REPO_DIRTY_FG
        if self.powerline.segment_conf("vcs", "show_symbol"):
            symbol = RepoStats().symbols["git"] + " "
        else:
            symbol = ""
        self.powerline.append(" " + symbol + self.branch + " ", fg, bg)
        self.stats.add_to_powerline(self.powerline)