# Copyright 2008 Google Inc.
#
# 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 logging

from google.appengine.ext import db

from codereview import models
from codereview.models import gql

from merge_pb2 import MergeService
from pending_merge_pb2 import *
from post_merge_result_pb2 import *
from post_branch_update_pb2 import *
from util import InternalAPI, automatic_retry

from codereview import email

def _send_once(change, field):
  """Mark the change's boolean field to True exactly once.

     Used below to ensure we only attempt to email once
     about something per submission attempt, even if the
     queues get screwed up and a change goes through more
     than once.
  """
  def trans(key):
    c = db.get(key)
    if getattr(c, field):
      return False
    else:
      setattr(c, field, True)
      c.put()
      return True
  return db.run_in_transaction(trans, change.key())


def _send_clean_merge(http_request, change):
  if _send_once(change, 'emailed_clean_merge'):
    additional_to = []
    settings = models.Settings.get_settings()
    if settings.merge_log_email:
      additional_to.append(settings.merge_log_email)

    msg = email.send_change_message(http_request,
                                    change,
                                    "mails/clean_merge.txt",
                                    None,
                                    None,
                                    additional_to=additional_to)
    if msg:
      msg.put()
  
def _send_missing_dependency(http_request, change):
  if _send_once(change, 'emailed_missing_dependency'):
    msg = email.send_change_message(http_request,
                                    change,
                                    "mails/missing_dependency.txt",
                                    None,
                                    None)
    if msg:
      msg.put()

def _send_path_conflict(http_request, change):
  if _send_once(change, 'emailed_path_conflict'):
    msg = email.send_change_message(http_request,
                                    change,
                                    "mails/path_conflict.txt",
                                    None,
                                    None)
    if msg:
      msg.put()


class InvalidBranchStatusError(Exception):
  """The branch cannot be updated in this way at this time."""

class MergeServiceImp(MergeService, InternalAPI):
  @automatic_retry
  def NextPendingMerge(self, rpc_controller, req, done):

    patchsets = []
    while not patchsets:
      branch = gql(models.Branch,
                  "WHERE status = 'NEEDS_MERGE'"
                  " ORDER BY merge_submitted").get()
      if branch is None:
        break
      patchsets = branch.begin_merge()

    rsp = PendingMergeResponse()
    if patchsets:
      first = patchsets[0].change
      rsp.status_code = PendingMergeResponse.MERGE_READY
      rsp.dest_project_name = str(first.dest_project.name)
      rsp.dest_project_key = str(first.dest_project.key())
      rsp.dest_branch_name = str(first.dest_branch.name)
      rsp.dest_branch_key = str(first.dest_branch.key())
      for ps in patchsets:
        pmi = rsp.change.add()
        pmi.patchset_key = str(ps.key())
        pmi.revision_id = str(ps.revision.id)
    else:
      rsp.status_code = PendingMergeResponse.QUEUE_EMPTY
    done(rsp)

  @automatic_retry
  def PostMergeResult(self, rpc_controller, req, done):
    rsp = PostMergeResultResponse()

    success = []
    fail = []
    defer = []

    for ri in req.change:
      sc = ri.status_code
      ps = db.get(db.Key(ri.patchset_key))

      if ps.change.merged:
        success.append(ps)
        continue

      def chg_trans(key):
        change = db.get(key)
        if change.merge_patchset.key() != ps.key():
          return None

        if sc == MergeResultItem.CLEAN_MERGE:
          pass

        elif sc == MergeResultItem.ALREADY_MERGED:
          change.merged = True
          change.closed = True
          change.put()

        elif sc == MergeResultItem.MISSING_DEPENDENCY:
          pass

        elif sc == MergeResultItem.PATH_CONFLICT:
          change.unsubmit_merge()
          change.put()

        return change

      change = db.run_in_transaction(chg_trans, ps.change.key())
      if change:
        if sc == MergeResultItem.CLEAN_MERGE:
          _send_clean_merge(self.http_request, change)

        elif sc == MergeResultItem.ALREADY_MERGED:
          success.append(ps)

        elif sc == MergeResultItem.MISSING_DEPENDENCY:
          _send_missing_dependency(self.http_request, change)
          defer.append(ps)

        elif sc == MergeResultItem.PATH_CONFLICT:
          _send_path_conflict(self.http_request, change)
          fail.append(ps)
      else:
        fail.append(ps)

    branch = db.get(db.Key(req.dest_branch_key))
    branch.finish_merge(success, fail, defer)

    done(rsp)

  @automatic_retry
  def PostBranchUpdate(self, rpc_controller, req, done):
    rsp = PostBranchUpdateResponse()

    branch = db.get(db.Key(req.branch_key))
    merged = [db.get(db.Key(c_key)) for c_key in req.new_change]

    branch.merged(merged)

    for ps in merged:
      def trans(key):
        change = db.get(key)
        if change.merge_patchset.key() == ps.key():
          change.merged = True
          change.closed = True
          change.put()
      db.run_in_transaction(trans, ps.change.key())

    done(rsp)