#
# Copyright (C) 2008 The Android Open Source Project
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#      http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

import os
import re
import sys
from error import GitError
from git_command import GitCommand

R_HEADS = 'refs/heads/'
R_TAGS  = 'refs/tags/'
ID_RE = re.compile('^[0-9a-f]{40}$')

def IsId(rev):
  return ID_RE.match(rev)


class GitConfig(object):
  @classmethod
  def ForUser(cls):
    return cls(file = os.path.expanduser('~/.gitconfig'))

  @classmethod
  def ForRepository(cls, gitdir, defaults=None):
    return cls(file = os.path.join(gitdir, 'config'),
               defaults = defaults)

  def __init__(self, file, defaults=None):
    self.file = file
    self.defaults = defaults
    self._cache_dict = None
    self._remotes = {}
    self._branches = {}

  def Has(self, name, include_defaults = True):
    """Return true if this configuration file has the key.
    """
    name = name.lower()
    if name in self._cache:
      return True
    if include_defaults and self.defaults:
      return self.defaults.Has(name, include_defaults = True)
    return False

  def GetBoolean(self, name):
    """Returns a boolean from the configuration file.
       None : The value was not defined, or is not a boolean.
       True : The value was set to true or yes.
       False: The value was set to false or no.
    """
    v = self.GetString(name)
    if v is None:
      return None
    v = v.lower()
    if v in ('true', 'yes'):
      return True
    if v in ('false', 'no'):
      return False
    return None

  def GetString(self, name, all=False):
    """Get the first value for a key, or None if it is not defined.

       This configuration file is used first, if the key is not
       defined or all = True then the defaults are also searched.
    """
    name = name.lower()

    try:
      v = self._cache[name]
    except KeyError:
      if self.defaults:
        return self.defaults.GetString(name, all = all)
      v = []

    if not all:
      if v:
        return v[0]
      return None

    r = []
    r.extend(v)
    if self.defaults:
      r.extend(self.defaults.GetString(name, all = True))
    return r

  def SetString(self, name, value):
    """Set the value(s) for a key.
       Only this configuration file is modified.

       The supplied value should be either a string,
       or a list of strings (to store multiple values).
    """
    name = name.lower()

    try:
      old = self._cache[name]
    except KeyError:
      old = []

    if value is None:
      if old:
        del self._cache[name]
        self._do('--unset-all', name)

    elif isinstance(value, list):
      if len(value) == 0:
        self.SetString(name, None)

      elif len(value) == 1:
        self.SetString(name, value[0])

      elif old != value:
        self._cache[name] = list(value)
        self._do('--replace-all', name, value[0])
        for i in xrange(1, len(value)):
          self._do('--add', name, value[i])

    elif len(old) != 1 or old[0] != value:
      self._cache[name] = [value]
      self._do('--replace-all', name, value)

  def GetRemote(self, name):
    """Get the remote.$name.* configuration values as an object.
    """
    try:
      r = self._remotes[name]
    except KeyError:
      r = Remote(self, name)
      self._remotes[r.name] = r
    return r

  def GetBranch(self, name):
    """Get the branch.$name.* configuration values as an object.
    """
    try:
      b = self._branches[name]
    except KeyError:
      b = Branch(self, name)
      self._branches[b.name] = b
    return b

  @property
  def _cache(self):
    if self._cache_dict is None:
      self._cache_dict = self._Read()
    return self._cache_dict

  def _Read(self):
    d = self._do('--null', '--list')
    c = {}
    while d:
      lf = d.index('\n')
      nul = d.index('\0', lf + 1)

      key = d[0:lf]
      val = d[lf + 1:nul]

      if key in c:
        c[key].append(val)
      else:
        c[key] = [val]

      d = d[nul + 1:]
    return c

  def _do(self, *args):
    command = ['config', '--file', self.file]
    command.extend(args)

    p = GitCommand(None,
                   command,
                   capture_stdout = True,
                   capture_stderr = True)
    if p.Wait() == 0:
      return p.stdout
    else:
      GitError('git config %s: %s' % (str(args), p.stderr))


class RefSpec(object):
  """A Git refspec line, split into its components:

      forced:  True if the line starts with '+'
      src:     Left side of the line
      dst:     Right side of the line
  """

  @classmethod
  def FromString(cls, rs):
    lhs, rhs = rs.split(':', 2)
    if lhs.startswith('+'):
      lhs = lhs[1:]
      forced = True
    else:
      forced = False
    return cls(forced, lhs, rhs)

  def __init__(self, forced, lhs, rhs):
    self.forced = forced
    self.src = lhs
    self.dst = rhs

  def SourceMatches(self, rev):
    if self.src:
      if rev == self.src:
        return True
      if self.src.endswith('/*') and rev.startswith(self.src[:-1]):
        return True
    return False

  def DestMatches(self, ref):
    if self.dst:
      if ref == self.dst:
        return True
      if self.dst.endswith('/*') and ref.startswith(self.dst[:-1]):
        return True
    return False

  def MapSource(self, rev):
    if self.src.endswith('/*'):
      return self.dst[:-1] + rev[len(self.src) - 1:]
    return self.dst

  def __str__(self):
    s = ''
    if self.forced:
      s += '+'
    if self.src:
      s += self.src
    if self.dst:
      s += ':'
      s += self.dst
    return s


class Remote(object):
  """Configuration options related to a remote.
  """
  def __init__(self, config, name):
    self._config = config
    self.name = name
    self.url = self._Get('url')
    self.review = self._Get('review')
    self.fetch = map(lambda x: RefSpec.FromString(x),
                     self._Get('fetch', all=True))

  def ToLocal(self, rev):
    """Convert a remote revision string to something we have locally.
    """
    if IsId(rev):
      return rev
    if rev.startswith(R_TAGS):
      return rev

    if not rev.startswith('refs/'):
      rev = R_HEADS + rev

    for spec in self.fetch:
      if spec.SourceMatches(rev):
        return spec.MapSource(rev)
    raise GitError('remote %s does not have %s' % (self.name, rev))

  def WritesTo(self, ref):
    """True if the remote stores to the tracking ref.
    """
    for spec in self.fetch:
      if spec.DestMatches(ref):
        return True
    return False

  def ResetFetch(self):
    """Set the fetch refspec to its default value.
    """
    self.fetch = [RefSpec(True,
                          'refs/heads/*',
                          'refs/remotes/%s/*' % self.name)]

  def Save(self):
    """Save this remote to the configuration.
    """
    self._Set('url', self.url)
    self._Set('review', self.review)
    self._Set('fetch', map(lambda x: str(x), self.fetch))

  def _Set(self, key, value):
    key = 'remote.%s.%s' % (self.name, key)
    return self._config.SetString(key, value)

  def _Get(self, key, all=False):
    key = 'remote.%s.%s' % (self.name, key)
    return self._config.GetString(key, all = all)


class Branch(object):
  """Configuration options related to a single branch.
  """
  def __init__(self, config, name):
    self._config = config
    self.name = name
    self.merge = self._Get('merge')

    r = self._Get('remote')
    if r:
      self.remote = self._config.GetRemote(r)
    else:
      self.remote = None

  @property
  def LocalMerge(self):
    """Convert the merge spec to a local name.
    """
    if self.remote and self.merge:
      return self.remote.ToLocal(self.merge)
    return None

  def Save(self):
    """Save this branch back into the configuration.
    """
    self._Set('merge', self.merge)
    if self.remote:
      self._Set('remote', self.remote.name)
    else:
      self._Set('remote', None)

  def _Set(self, key, value):
    key = 'branch.%s.%s' % (self.name, key)
    return self._config.SetString(key, value)

  def _Get(self, key, all=False):
    key = 'branch.%s.%s' % (self.name, key)
    return self._config.GetString(key, all = all)