"""
pasteurize: automatic conversion of Python 3 code to clean 2&3 code
===================================================================

``pasteurize`` attempts to convert existing Python 3 code into source-compatible
Python 2 and 3 code.

Use it like this on Python 3 code:

  $ pasteurize --verbose mypython3script.py

This removes any Py3-only syntax (e.g. new metaclasses) and adds these
import lines:

    from __future__ import absolute_import
    from __future__ import division
    from __future__ import print_function
    from __future__ import unicode_literals
    from future import standard_library
    standard_library.install_hooks()
    from future.builtins import *

To write changes to the files, use the -w flag.

It also adds any other wrappers needed for Py2/3 compatibility.

Note that separate stages are not available (or needed) when converting from
Python 3 with ``pasteurize`` as they are when converting from Python 2 with
``futurize``.

"""

from __future__ import (absolute_import, print_function, unicode_literals)
from future.builtins import *

import sys
import logging
import optparse

from lib2to3.main import main, warn, StdoutRefactoringTool
from lib2to3 import refactor

from libpasteurize.fixes import fix_names


def main(args=None):
    """Main program.

    Returns a suggested exit status (0, 1, 2).
    """
    # Set up option parser
    parser = optparse.OptionParser(usage="futurize [options] file|dir ...")
    parser.add_option("-a", "--all-imports", action="store_true",
                      help="Adds all __future__ and future imports to each module")
    parser.add_option("-d", "--doctests_only", action="store_true",
                      help="Fix up doctests only")
    parser.add_option("-f", "--fix", action="append", default=[],
                      help="Each FIX specifies a transformation; default: all")
    parser.add_option("-j", "--processes", action="store", default=1,
                      type="int", help="Run 2to3 concurrently")
    parser.add_option("-x", "--nofix", action="append", default=[],
                      help="Prevent a fixer from being run.")
    parser.add_option("-l", "--list-fixes", action="store_true",
                      help="List available transformations")
    # parser.add_option("-p", "--print-function", action="store_true",
    #                   help="Modify the grammar so that print() is a function")
    parser.add_option("-v", "--verbose", action="store_true",
                      help="More verbose logging")
    parser.add_option("--no-diffs", action="store_true",
                      help="Don't show diffs of the refactoring")
    parser.add_option("-w", "--write", action="store_true",
                      help="Write back modified files")
    parser.add_option("-n", "--nobackups", action="store_true", default=False,
                      help="Don't write backups for modified files.")

    # Parse command line arguments
    refactor_stdin = False
    flags = {}
    options, args = parser.parse_args(args)
    fixer_pkg = 'libpasteurize.fixes'
    avail_fixes = fix_names
    flags["print_function"] = True

    if not options.write and options.no_diffs:
        warn("not writing files and not printing diffs; that's not very useful")
    if not options.write and options.nobackups:
        parser.error("Can't use -n without -w")
    if options.list_fixes:
        print("Available transformations for the -f/--fix option:")
        for fixname in sorted(avail_fixes):
            print(fixname)
        if not args:
            return 0
    if not args:
        print("At least one file or directory argument required.",
              file=sys.stderr)
        print("Use --help to show usage.", file=sys.stderr)
        return 2
    if "-" in args:
        refactor_stdin = True
        if options.write:
            print("Can't write to stdin.", file=sys.stderr)
            return 2

    # Set up logging handler
    level = logging.DEBUG if options.verbose else logging.INFO
    logging.basicConfig(format='%(name)s: %(message)s', level=level)

    # Initialize the refactoring tool
    unwanted_fixes = set(fixer_pkg + ".fix_" + fix for fix in options.nofix)

    # The 'all-imports' option forces adding all imports __future__ and "from
    # future import standard_library", even if they don't seem necessary for
    # the current state of each module. (This can simplify testing, and can
    # reduce the need to think about Py2 compatibility when editing the code
    # further.)
    extra_fixes = set()
    if options.all_imports:
        prefix = 'libfuturize.fixes.'
        if options.stage1:
            extra_fixes.add(prefix +
                            'fix_add__future__imports_except_unicode_literals')
        else:
            # In case the user hasn't run stage1 for some reason:
            extra_fixes.add(prefix + 'fix_add__future__imports')
            extra_fixes.add(prefix + 'fix_add_future_standard_library_import')
            extra_fixes.add(prefix + 'fix_add_all_future_builtins')

    fixer_names = avail_fixes | extra_fixes - unwanted_fixes

    rt = StdoutRefactoringTool(sorted(fixer_names), flags, set(),
                               options.nobackups, not options.no_diffs)

    # Refactor all files and directories passed as arguments
    if not rt.errors:
        if refactor_stdin:
            rt.refactor_stdin()
        else:
            try:
                rt.refactor(args, options.write, options.doctests_only,
                            options.processes)
            except refactor.MultiprocessingUnsupported:
                assert options.processes > 1
                print("Sorry, -j isn't " \
                      "supported on this platform.", file=sys.stderr)
                return 1
        rt.summarize()

    # Return error status (0 if rt.errors is zero)
    return int(bool(rt.errors))

