import os
import re
from subprocess import Popen, PIPE, STDOUT

from method import Method, Argument
from method.vc import VcBlame

try:
    from mercurial import hg, ui
    from mercurial import commands as hgc
    has_hg = True
except ImportError:
    has_hg = False

class HgBase(object):
    def _hg_check(self, w):
        if not has_hg:
            w.set_error("Mercurial is not installed")
            return False
        elif not hasattr(w.buffer, 'path'):
            w.set_error("Buffer has no corresponding file")
            return False
        else:
            return True
    def _hg_init(self, **kwargs):
        ui_imp = ui.ui(**kwargs)
        ui_imp.pushbuffer()
        repo = hg.repository(ui=ui_imp, path='.')
        return ui_imp, repo

class HgBlame(VcBlame, HgBase):
    """Show buffer annotated with hg metadata"""
    num_fields = 3
    # user, rev, [changeset], date, content
    line_re    = re.compile(r'^ *([^ ]+) +(\d+) +[^ ]+ +(\d{4}-\d{2}-\d{2}): (.*)\n$')
    prefix_fmt = '[g:d:*]%*s [c:d:*]%*s [b:d:*]%*s[d:d:*]'
    _is_method = True
    def _open_pipe(self, w, **vargs):
        cmd = ("hg", 'blame', '-cnudq', w.buffer.path)
        return Popen(cmd, stdin=PIPE, stdout=PIPE, stderr=PIPE)

class HgLog(Method, HgBase):
    """Show hg log for this buffer"""
    def _execute(self, w, **vargs):
        if not self._hg_check(w):
            return
        ui_imp, repo = self._hg_init()
        hgc.log(ui_imp, repo, user=None, rev=None, date=None)
        s = ''.join(ui_imp.popbuffer())
        w.application.data_buffer('*Log*', s, switch_to=True)

class HgDiff(Method, HgBase):
    """Diff the current file with the version in Mercurial"""
    def _execute(self, w, **vargs):
        if not self._hg_check(w):
            return
        ui_imp, repo = self._hg_init()
        hgc.diff(ui_imp, repo, w.buffer.path)
        s = ''.join(ui_imp.popbuffer())
        w.application.data_buffer("*Diff*", s, switch_to=True, modename='diff')