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"""Util module for Japanese postal(ZIP) code."""

import codecs


def ReadCSV(file_name):
  """Read CSV file."""
  # Do not use csv reader module because it does not support unicode
  return [
      GetCells(line)
      for line in codecs.open(file_name, 'r', 'cp932', errors='replace')
  ]


def GetCells(line):
  """Get cells."""
  # [A, B, C, ..] from "A","B ",C,..
  return [column.strip('"').strip() for column in line.strip().split(',')]


def MergeCSV(csv_lines):
  """Merge CSV."""
  # When the flag says a zip code have no multiple entry while we can see
  # multiple line for that zip code, we have to merge them.
  zip_count = {}
  ret = []
  for entry in csv_lines:
    zip_code = entry[2]
    zip_count[zip_code] = zip_count.get(zip_code, 0) + 1
    if not ShouldMerge(zip_count, entry):
      ret.append(entry)
    else:
      last_entry = ret[-1]
      last_entry[5] += entry[5]  # reading of '町域'
      last_entry[8] += entry[8]  # '町域'
  return ret


def ShouldMerge(zip_count, entry):
  """Return true if this entry should be merged to the previous entry."""
  zip_code = entry[2]
  flag_multi = (entry[12] == '1')
  should_merge = (zip_count[zip_code] > 1 and not flag_multi)
  should_merge_special = ShouldMergeSpecial(entry)
  return should_merge or should_merge_special


class SpecialMergeZip(object):
  """Container class for special zip code entry to be merged."""

  def __init__(self, zip_code, pref, city, towns):
    self.zip_code = zip_code
    self.pref = pref
    self.city = city
    self.towns = towns


_SPECIAL_CASES = [
    SpecialMergeZip(u'5900111', u'大阪府', u'堺市中区', [u'三原台']),
    SpecialMergeZip(u'8710046', u'大分県', u'中津市',
                    [u'金谷', u'西堀端', u'東堀端', u'古金谷']),
    SpecialMergeZip(u'9218046', u'石川県', u'金沢市',
                    [u'大桑町', u'三小牛町']),
    ]


def ShouldMergeSpecial(entry):
  """Return true for special cases to be merged."""
  zip_code = entry[2]
  level1 = entry[6]
  level2 = entry[7]
  level3 = entry[8]
  for special_case in _SPECIAL_CASES:
    if (zip_code == special_case.zip_code and
        level1 == special_case.pref and
        level2 == special_case.city and
        ContinuedLine(level3, special_case.towns)):
      return True
  return False


def ContinuedLine(level3, towns):
  """Return true if this seems continued line."""
  for town in towns:
    if level3.startswith(town):
      return False
  return True