"""
Main program for 2to3.
"""

from __future__ import with_statement, print_function

import sys
import os
import difflib
import logging
import shutil
import optparse

from . import refactor


def diff_texts(a, b, filename):
 """Return a unified diff of two strings."""
 a = a.splitlines()
 b = b.splitlines()
 return difflib.unified_diff(a, b, filename, filename,
 "(original)", "(refactored)",
 lineterm="")


class StdoutRefactoringTool(refactor.MultiprocessRefactoringTool):
 """
 A refactoring tool that can avoid overwriting its input files.
 Prints output to stdout.

 Output files can optionally be written to a different directory and or
 have an extra file suffix appended to their name for use in situations
 where you do not want to replace the input files.
 """

 def __init__(self, fixers, options, explicit, nobackups, show_diffs,
 input_base_dir='', output_dir='', append_suffix=''):
 """
 Args:
 fixers: A list of fixers to import.
 options: A dict with RefactoringTool configuration.
 explicit: A list of fixers to run even if they are explicit.
 nobackups: If true no backup '.bak' files will be created for those
 files that are being refactored.
 show_diffs: Should diffs of the refactoring be printed to stdout?
 input_base_dir: The base directory for all input files. This class
 will strip this path prefix off of filenames before substituting
 it with output_dir. Only meaningful if output_dir is supplied.
 All files processed by refactor() must start with this path.
 output_dir: If supplied, all converted files will be written into
 this directory tree instead of input_base_dir.
 append_suffix: If supplied, all files output by this tool will have
 this appended to their filename. Useful for changing .py to
 .py3 for example by passing append_suffix='3'.
 """
 self.nobackups = nobackups
 self.show_diffs = show_diffs
 if input_base_dir and not input_base_dir.endswith(os.sep):
 input_base_dir += os.sep
 self._input_base_dir = input_base_dir
 self._output_dir = output_dir
 self._append_suffix = append_suffix
 super(StdoutRefactoringTool, self).__init__(fixers, options, explicit)

 def log_error(self, msg, *args, **kwargs):
 self.errors.append((msg, args, kwargs))
 self.logger.error(msg, *args, **kwargs)

 def write_file(self, new_text, filename, old_text, encoding):
 orig_filename = filename
 if self._output_dir:
 if filename.startswith(self._input_base_dir):
 filename = os.path.join(self._output_dir,
 filename[len(self._input_base_dir):])
 else:
 raise ValueError('filename %s does not start with the '
 'input_base_dir %s' % (
 filename, self._input_base_dir))
 if self._append_suffix:
 filename += self._append_suffix
 if orig_filename != filename:
 output_dir = os.path.dirname(filename)
 if not os.path.isdir(output_dir) and output_dir:
 os.makedirs(output_dir)
 self.log_message('Writing converted %s to %s.', orig_filename,
 filename)
 if not self.nobackups:
 # Make backup
 backup = filename + ".bak"
 if os.path.lexists(backup):
 try:
 os.remove(backup)
 except OSError as err:
 self.log_message("Can't remove backup %s", backup)
 try:
 os.rename(filename, backup)
 except OSError as err:
 self.log_message("Can't rename %s to %s", filename, backup)
 # Actually write the new file
 write = super(StdoutRefactoringTool, self).write_file
 write(new_text, filename, old_text, encoding)
 if not self.nobackups:
 shutil.copymode(backup, filename)
 if orig_filename != filename:
 # Preserve the file mode in the new output directory.
 shutil.copymode(orig_filename, filename)

 def print_output(self, old, new, filename, equal):
 if equal:
 self.log_message("No changes to %s", filename)
 else:
 self.log_message("Refactored %s", filename)
 if self.show_diffs:
 diff_lines = diff_texts(old, new, filename)
 try:
 if self.output_lock is not None:
 with self.output_lock:
 for line in diff_lines:
 print(line)
 sys.stdout.flush()
 else:
 for line in diff_lines:
 print(line)
 except UnicodeEncodeError:
 warn("couldn't encode %s's diff for your terminal" %
 (filename,))
 return

def warn(msg):
 print("WARNING: %s" % (msg,), file=sys.stderr)


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

 Args:
 fixer_pkg: the name of a package where the fixers are located.
 args: optional; a list of command line arguments. If omitted,
 sys.argv[1:] is used.

 Returns a suggested exit status (0, 1, 2).
 """
 # Set up option parser
 parser = optparse.OptionParser(usage="2to3 [options] file|dir ...")
 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 transformation 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")
 parser.add_option("-o", "--output-dir", action="store", type="str",
 default="", help="Put output files in this directory "
 "instead of overwriting the input files. Requires -n.")
 parser.add_option("-W", "--write-unchanged-files", action="store_true",
 help="Also write files even if no changes were required"
 " (useful with --output-dir); implies -w.")
 parser.add_option("--add-suffix", action="store", type="str", default="",
 help="Append this string to all output filenames."
 " Requires -n if non-empty. "
 "ex: --add-suffix='3' will generate .py3 files.")

 # Parse command line arguments
 refactor_stdin = False
 flags = {}
 options, args = parser.parse_args(args)
 if options.write_unchanged_files:
 flags["write_unchanged_files"] = True
 if not options.write:
 warn("--write-unchanged-files/-W implies -w.")
 options.write = True
 # If we allowed these, the original files would be renamed to backup names
 # but not replaced.
 if options.output_dir and not options.nobackups:
 parser.error("Can't use --output-dir/-o without -n.")
 if options.add_suffix and not options.nobackups:
 parser.error("Can't use --add-suffix without -n.")

 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 refactor.get_all_fix_names(fixer_pkg):
 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
 if options.print_function:
 flags["print_function"] = True

 # Set up logging handler
 level = logging.DEBUG if options.verbose else logging.INFO
 logging.basicConfig(format='%(name)s: %(message)s', level=level)
 logger = logging.getLogger('lib2to3.main')

 # Initialize the refactoring tool
 avail_fixes = set(refactor.get_fixers_from_package(fixer_pkg))
 unwanted_fixes = set(fixer_pkg + ".fix_" + fix for fix in options.nofix)
 explicit = set()
 if options.fix:
 all_present = False
 for fix in options.fix:
 if fix == "all":
 all_present = True
 else:
 explicit.add(fixer_pkg + ".fix_" + fix)
 requested = avail_fixes.union(explicit) if all_present else explicit
 else:
 requested = avail_fixes.union(explicit)
 fixer_names = requested.difference(unwanted_fixes)
 input_base_dir = os.path.commonprefix(args)
 if (input_base_dir and not input_base_dir.endswith(os.sep)
 and not os.path.isdir(input_base_dir)):
 # One or more similar names were passed, their directory is the base.
 # os.path.commonprefix() is ignorant of path elements, this corrects
 # for that weird API.
 input_base_dir = os.path.dirname(input_base_dir)
 if options.output_dir:
 input_base_dir = input_base_dir.rstrip(os.sep)
 logger.info('Output in %r will mirror the input directory %r layout.',
 options.output_dir, input_base_dir)
 rt = StdoutRefactoringTool(
 sorted(fixer_names), flags, sorted(explicit),
 options.nobackups, not options.no_diffs,
 input_base_dir=input_base_dir,
 output_dir=options.output_dir,
 append_suffix=options.add_suffix)

 # 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))