#!/usr/bin/env python3
"""Python Action Builder
#
# 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.
#
"""

from __future__ import print_function
import os, sys, codecs, shutil
from os.path import abspath, exists, dirname

# write a file creating intermediate directories
def write_file(file, body, executable=False):
    os.makedirs(dirname(file), mode=0o755, exist_ok=True)
    with open(file, mode="w", encoding="utf-8") as f:
        f.write(body)
    if executable:
        os.chmod(file, 0o755)

# copy a file eventually replacing a substring
def copy_replace(src, dst, match=None, replacement=""):
    with codecs.open(src, 'r', 'utf-8') as s:
        body = s.read()
        if match:
            body = body.replace(match, replacement)
        write_file(dst, body)

# assemble sources
def sources(launcher, main, src_dir):  
    # move exec in the right place if exists
    src_file = "%s/exec" % src_dir
    if exists(src_file):
        copy_replace(src_file, "%s/main__.py" % src_dir)

    # move __main__ in the right place if it exists
    src_file = "%s/__main__.py" % src_dir
    if exists(src_file):
        copy_replace(src_file, "%s/main__.py" % src_dir)

    # write the boilerplate in a temp dir
    copy_replace(launcher, "%s/exec__.py" % src_dir,
          "from main__ import main as main",
          "from main__ import %s as main" % main )

# compile sources
def build(src_dir, tgt_dir):
    # in general, compile your program into an executable format
    # for scripting languages, move sources and create a launcher
    # move away the action dir and replace with the new
    shutil.rmtree(tgt_dir)
    shutil.move(src_dir, tgt_dir)
    write_file("%s/exec" % tgt_dir, """#!/bin/sh
cd "$(dirname $0)"
exec /usr/local/bin/python exec__.py
""")

if __name__ == '__main__':
    if len(sys.argv) < 4:
        sys.stdout.write("usage: <main-function> <source-dir> <target-dir>\n")
        sys.stdout.flush()
        sys.exit(1)
    launcher = "%s/lib/launcher.py" % dirname(dirname(sys.argv[0]))
    sources(launcher, sys.argv[1], abspath(sys.argv[2]))
    build(abspath(sys.argv[2]), abspath(sys.argv[3]))
    sys.stdout.flush()
    sys.stderr.flush()