#!/usr/bin/python
#
#  Copyright 2015 Google Inc. All Rights Reserved
#
#  This script takes a set of flags, telling it what cros_pkg_setup.sh changed
#  during the set up process.  Based on the values of the input flags, it
#  generates a cleanup script, named cros_pkg_${BOARD}_cleanup.sh, which will
#  undo the changes made by cros_pkg_setup.sh, returning everything to its
#  original state.
#

import argparse
import os
import sys


def Usage(parser, msg):
    print "ERROR: " + msg
    parser.print_help()
    sys.exit(1)

def Main(argv):
    """
    The script cros_pkg_setup.sh make two main changes that need to be
    undone: 1).  It creates a soft link making /build/${board} point to
    /build/${board}.work, and 2). It saves a copy of the build_image
    script, then updates build_image to not execute 'eclean'.  For the first
    change, it had to see if /build/${board} already existed, and if so, whether
    it was a real tree or a soft link.  If it was soft link, it saved the old
    value of the link, then deleted it and created the new link.  If it was a
    real tree, it renamed the tree to /build/${board}.save, and then created the
    new soft link.  If the /build/${board} did not previously exist, then it just
    created the new soft link.

    This function takes arguments that tell it exactly what cros_pkg_setup.sh
    actually did, then generates a script to undo those exact changes.
    """

    parser = argparse.ArgumentParser()
    parser.add_argument("--board", dest="board", required=True,
                        help="Chromeos board for packages/image.")

    parser.add_argument("--old_tree_missing", dest="tree_existed",
                        action="store_false",
                        help="Did /build/${BOARD} exist.", default=True)

    parser.add_argument("--renamed_tree", dest="renamed_tree",
                        action="store_true",
                        help="Was /build/${BOARD} saved & renamed.",
                        default=False)

    parser.add_argument("--old_link", dest="old_link",
                        help=("The original build tree soft link."))

    options = parser.parse_args(argv[1:])

    if options.old_link or options.renamed_tree:
        if not options.tree_existed:
            Usage(parser, "If --tree_existed is False, cannot have "
                  "--renamed_tree or --old_link")

    if options.old_link and options.renamed_tree:
        Usage(parser, "--old_link and --renamed_tree are incompatible options.")

    if options.tree_existed:
        if not options.old_link and not options.renamed_tree:
            Usage(parser, "If --tree_existed is True, then must have either "
                  "--old_link or --renamed_tree")

    out_filename = "cros_pkg_" + options.board + "_cleanup.sh"

    with open(out_filename, "w") as out_file:
        out_file.write("#!/bin/bash\n\n")
        # First, remove the 'new' soft link.
        out_file.write("sudo rm /build/%s\n" % options.board)
        if options.tree_existed:
            if options.renamed_tree:
                # Old build tree existed and was a real tree, so it got
                # renamed.  Move the renamed tree back to the original tree.
                out_file.write("sudo mv /build/%s.save /build/%s\n"
                               % (options.board, options.board))
            else:
                # Old tree existed and was already a soft link.  Re-create the
                # original soft link.
                original_link = options.old_link
                if original_link[0] == "'":
                    original_link = original_link[1:]
                if original_link[-1] == "'":
                    original_link = original_link[:-1]
                out_file.write("sudo ln -s %s /build/%s\n" % (original_link,
                                                              options.board))
        out_file.write("\n")
        # Restore the original saved version of build_image script.
        out_file.write("mv ~/trunk/src/scripts/build_image.save "
                       "~/trunk/src/scripts/build_image\n\n")
        # Remove cros_pkg_common.sh file
        out_file.write("rm cros_pkg_common.sh\n")

    return 0


if __name__ == "__main__":
    retval = Main(sys.argv)
    sys.exit(retval)