#!/usr/bin/env python
#
#
# Licensed to the Apache Software Foundation (ASF) under one
# or more contributor license agreements.  See the NOTICE file
# distributed with this work for additional information
# regarding copyright ownership.  The ASF licenses this file
# to you 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.
#
#
#
# transform_sql.py -- create a header file with the appropriate SQL variables
# from an SQL file
#


import os
import re
import sys


DEFINE_END = '  ""\n\n'


def usage_and_exit(msg):
  if msg:
    sys.stderr.write('%s\n\n' % msg)
  sys.stderr.write(
    'USAGE: %s SQLITE_FILE [OUTPUT_FILE]\n'
    '  stdout will be used if OUTPUT_FILE is not provided.\n'
    % os.path.basename(sys.argv[0]))
  sys.stderr.flush()
  sys.exit(1)


def main(input, output, filename):
  input = input.read()

  var_name = re.sub('[-.]', '_', filename).upper()

  output.write(
    '/* This file is automatically generated from %s.\n'
    ' * Do not edit this file -- edit the source and rerun gen-make.py */\n'
    '\n'
    % (filename,))

  var_printed = False
  stmt_count = 0

  # only used once, but we need the flags. so re.compile it is!
  re_comments = re.compile(r'/\*.*?\*/', re.MULTILINE|re.DOTALL)
  input = re_comments.sub('', input)

  # a couple SQL comments that act as directives for this transform system
  re_format = re.compile('-- *format: *([0-9]+)')
  re_statement = re.compile('-- *STMT_([A-Z_]+)')

  for line in input.split('\n'):
    line = line.replace('"', '\\"')

    if line.strip():
      match = re_format.match(line)
      if match:
        vsn = match.group(1)
        if var_printed:
          # end the previous #define
          output.write(DEFINE_END)
        output.write('#define %s_%s \\\n' % (var_name, match.group(1)))
        var_printed = True

        # no need to put the directive into the file. skip this line.
        continue

      match = re_statement.match(line)
      if match:
        name = match.group(1)
        if var_printed:
          # end the previous #define
          output.write(DEFINE_END)
        output.write('#define STMT_%s %d\n' % (match.group(1), stmt_count))
        output.write('#define STMT_%d \\\n' % (stmt_count,))
        var_printed = True

        stmt_count += 1

        # no need to put the directive into the file. skip this line.
        continue

      if not var_printed:
        output.write('#define %s \\\n' % var_name)
        var_printed = True

      # got something besides whitespace. write it out. include some whitespace
      # to separate the SQL commands. and a backslash to continue the string
      # onto the next line.
      output.write('  "%s " \\\n' % line)

  # previous line had a continuation. end the madness.
  assert var_printed
  output.write(DEFINE_END)

  ### the STMT_%d naming precludes *multiple* transform_sql headers from
  ### being used within the same .c file. for now, that's more than fine.
  ### in the future, we can always add a var_name discriminator or use
  ### the statement name itself (which should hopefully be unique across
  ### all names in use; or can easily be made so)
  if stmt_count > 0:
    output.write('#define %s_DECLARE_STATEMENTS(varname) \\\n' % (var_name,)
                 + '  static const char * const varname[] = { \\\n'
                 + ', \\\n'.join('    STMT_%d' % (i,) for i in range(stmt_count))
                 + ' \\\n  }\n')


if __name__ == '__main__':
  if len(sys.argv) < 2 or len(sys.argv) > 3:
    usage_and_exit('Incorrect number of arguments')

  # Note: we could use stdin, but then we'd have no var_name
  input_file = open(sys.argv[1], 'r')

  if len(sys.argv) > 2:
    output_file = open(sys.argv[2], 'w')
  else:
    output_file = sys.stdout

  main(input_file, output_file, os.path.basename(sys.argv[1]))