#!/usr/bin/env python
# Mode: -*- python -*-
#
# Copyright (c) 2015 by Rocky Bernstein <rb@dustyfeet.com>
#
"""
Usage: pydisassemble [OPTIONS]... FILE

Examples:
  pydisassemble      foo.pyc
  pydisassemble      foo.py
  pydisassemble -o foo.pydis foo.pyc
  pydisassemble -o /tmp foo.pyc

Options:
  -o <path>     output decompiled files to this path:
                if multiple input files are decompiled, the common prefix
                is stripped from these names and the remainder appended to
                <path>
  --help        show this message

"""

from __future__ import print_function

Usage_short = \
"pydissassemble [--help] [--verify] [--showasm] [--showast] [-o <path>] FILE|DIR..."

import sys, os, getopt, time, types
import os.path
import uncompyle6

def disassemble_code(version, co, out=None):
    """
    diassembles and deparses a given code block 'co'
    """

    assert isinstance(co, types.CodeType)

    # store final output stream for case of error
    __real_out = out or sys.stdout
    print('# Python %s' % version, file=__real_out)
    if co.co_filename:
        print('# Embedded file name: %s' % co.co_filename,
              file=__real_out)

    # Pick up appropriate scanner
    if version == 2.7:
        import uncompyle6.scanners.scanner27 as scan
        scanner = scan.Scanner27()
    elif version == 2.6:
        import uncompyle6.scanners.scanner26 as scan
        scanner = scan.Scanner26()
    elif version == 2.5:
        import uncompyle6.scanners.scanner25 as scan
        scanner = scan.Scanner25()
    elif version == 3.2:
        import uncompyle6.scanners.scanner32 as scan
        scanner = scan.Scanner32()
    elif version == 3.4:
        import uncompyle6.scanners.scanner34 as scan
        scanner = scan.Scanner34()
    scanner.setShowAsm(True, out)
    tokens, customize = scanner.disassemble(co)


def disassemble_file(filename, outstream=None, showasm=False, showast=False):
    """
    disassemble Python byte-code file (.pyc)
    """
    version, co = uncompyle6.load_module(filename)
    if type(co) == list:
        for con in co:
            disassemble_code(version, con, outstream)
    else:
        from trepan.api import debug; debug
        disassemble_code(version, co, outstream)
    co = None

def disassemble_files(in_base, out_base, files, outfile=None):
    """
    in_base	base directory for input files
    out_base	base directory for output files (ignored when
    files	list of filenames to be uncompyled (relative to src_base)
    outfile	write output to this filename (overwrites out_base)

    For redirecting output to
    - <filename>		outfile=<filename> (out_base is ignored)
    - files below out_base	out_base=...
    - stdout			out_base=None, outfile=None
    """
    def _get_outstream(outfile):
        dir = os.path.dirname(outfile)
        failed_file = outfile + '_failed'
        if os.path.exists(failed_file):
            os.remove(failed_file)
        try:
            os.makedirs(dir)
        except OSError:
            pass
        return open(outfile, 'w')

    of = outfile
    if outfile == '-':
        outfile = None # use stdout
    elif outfile and os.path.isdir(outfile):
        out_base = outfile; outfile = None
    elif outfile:
        out_base = outfile; outfile = None


    for filename in files:
        infile = os.path.join(in_base, filename)
        # print (infile, file=sys.stderr)

        if of: # outfile was given as parameter
            outstream = _get_outstream(outfile)
        elif out_base is None:
            outstream = sys.stdout
        else:
            outfile = os.path.join(out_base, file) + '_dis'
            outstream = _get_outstream(outfile)
            # print(outfile, file=sys.stderr)
            pass

        # try to decomyple the input file
        try:
            disassemble_file(infile, outstream, showasm=True, showast=False)
        except KeyboardInterrupt:
            if outfile:
                outstream.close()
                os.remove(outfile)
            raise
        except:
            if outfile:
                outstream.close()
                os.rename(outfile, outfile + '_failed')
            else:
                sys.stderr.write("\n# Can't disassemble %s\n" % infile)
                import traceback
                traceback.print_exc()
        else: # uncompyle successfull
            if outfile:
                outstream.close()
            if not outfile: print('\n# okay decompyling', infile)
            sys.stdout.flush()

        if outfile:
            sys.stdout.write("\n")
            sys.stdout.flush()
        return

if sys.version[:3] != '2.7' and sys.version[:3] != '3.4':
    print('Error:  pydisassemble requires Python 2.7 or 3.4.', file=sys.stderr)
    sys.exit(-1)

outfile = '-'
out_base = None


try:
    opts, files = getopt.getopt(sys.argv[1:], 'ho:', ['help'])
except getopt.GetoptError as e:
    print('%s: %s' % (os.path.basename(sys.argv[0]), e),  file=sys.stderr)
    sys.exit(-1)

for opt, val in opts:
    if opt in ('-h', '--help'):
        print(__doc__)
        sys.exit(0)
    elif opt == '-o':
        outfile = val
    else:
        print(opt)
        print(Usage_short)
        sys.exit(1)

# argl, commonprefix works on strings, not on path parts,
# thus we must handle the case with files in 'some/classes'
# and 'some/cmds'
src_base = os.path.commonprefix(files)
if src_base[-1:] != os.sep:
    src_base = os.path.dirname(src_base)
if src_base:
    sb_len = len( os.path.join(src_base, '') )
    files = [f[sb_len:] for f in files]
    del sb_len

if outfile == '-':
    outfile = None # use stdout
elif outfile and os.path.isdir(outfile):
    out_base = outfile; outfile = None
elif outfile and len(files) > 1:
    out_base = outfile; outfile = None

disassemble_files(src_base, out_base, files, outfile)