"""Disassembler of Python byte code into mnemonics."""

import sys
import types
import collections
import io

from opcode import *
from opcode import __all__ as _opcodes_all

__all__ = ["code_info", "dis", "disassemble", "distb", "disco",
 "findlinestarts", "findlabels", "show_code",
 "get_instructions", "Instruction", "Bytecode"] + _opcodes_all
del _opcodes_all

_have_code = (types.MethodType, types.FunctionType, types.CodeType,
 classmethod, staticmethod, type)

FORMAT_VALUE = opmap['FORMAT_VALUE']
FORMAT_VALUE_CONVERTERS = (
 (None, ''),
 (str, 'str'),
 (repr, 'repr'),
 (ascii, 'ascii'),
)
MAKE_FUNCTION = opmap['MAKE_FUNCTION']
MAKE_FUNCTION_FLAGS = ('defaults', 'kwdefaults', 'annotations', 'closure')


def _try_compile(source, name):
 """Attempts to compile the given source, first as an expression and
 then as a statement if the first approach fails.

 Utility function to accept strings in functions that otherwise
 expect code objects
 """
 try:
 c = compile(source, name, 'eval')
 except SyntaxError:
 c = compile(source, name, 'exec')
 return c

def dis(x=None, *, file=None, depth=None):
 """Disassemble classes, methods, functions, and other compiled objects.

 With no argument, disassemble the last traceback.

 Compiled objects currently include generator objects, async generator
 objects, and coroutine objects, all of which store their code object
 in a special attribute.
 """
 if x is None:
 distb(file=file)
 return
 # Extract functions from methods.
 if hasattr(x, '__func__'):
 x = x.__func__
 # Extract compiled code objects from...
 if hasattr(x, '__code__'): # ...a function, or
 x = x.__code__
 elif hasattr(x, 'gi_code'): #...a generator object, or
 x = x.gi_code
 elif hasattr(x, 'ag_code'): #...an asynchronous generator object, or
 x = x.ag_code
 elif hasattr(x, 'cr_code'): #...a coroutine.
 x = x.cr_code
 # Perform the disassembly.
 if hasattr(x, '__dict__'): # Class or module
 items = sorted(x.__dict__.items())
 for name, x1 in items:
 if isinstance(x1, _have_code):
 print("Disassembly of %s:" % name, file=file)
 try:
 dis(x1, file=file, depth=depth)
 except TypeError as msg:
 print("Sorry:", msg, file=file)
 print(file=file)
 elif hasattr(x, 'co_code'): # Code object
 _disassemble_recursive(x, file=file, depth=depth)
 elif isinstance(x, (bytes, bytearray)): # Raw bytecode
 _disassemble_bytes(x, file=file)
 elif isinstance(x, str): # Source code
 _disassemble_str(x, file=file, depth=depth)
 else:
 raise TypeError("don't know how to disassemble %s objects" %
 type(x).__name__)

def distb(tb=None, *, file=None):
 """Disassemble a traceback (default: last traceback)."""
 if tb is None:
 try:
 tb = sys.last_traceback
 except AttributeError:
 raise RuntimeError("no last traceback to disassemble") from None
 while tb.tb_next: tb = tb.tb_next
 disassemble(tb.tb_frame.f_code, tb.tb_lasti, file=file)

# The inspect module interrogates this dictionary to build its
# list of CO_* constants. It is also used by pretty_flags to
# turn the co_flags field into a human readable list.
COMPILER_FLAG_NAMES = {
 1: "OPTIMIZED",
 2: "NEWLOCALS",
 4: "VARARGS",
 8: "VARKEYWORDS",
 16: "NESTED",
 32: "GENERATOR",
 64: "NOFREE",
 128: "COROUTINE",
 256: "ITERABLE_COROUTINE",
 512: "ASYNC_GENERATOR",
}

def pretty_flags(flags):
 """Return pretty representation of code flags."""
 names = []
 for i in range(32):
 flag = 1<<i
 if flags & flag:
 names.append(COMPILER_FLAG_NAMES.get(flag, hex(flag)))
 flags ^= flag
 if not flags:
 break
 else:
 names.append(hex(flags))
 return ", ".join(names)

def _get_code_object(x):
 """Helper to handle methods, compiled or raw code objects, and strings."""
 # Extract functions from methods.
 if hasattr(x, '__func__'):
 x = x.__func__
 # Extract compiled code objects from...
 if hasattr(x, '__code__'): # ...a function, or
 x = x.__code__
 elif hasattr(x, 'gi_code'): #...a generator object, or
 x = x.gi_code
 elif hasattr(x, 'ag_code'): #...an asynchronous generator object, or
 x = x.ag_code
 elif hasattr(x, 'cr_code'): #...a coroutine.
 x = x.cr_code
 # Handle source code.
 if isinstance(x, str):
 x = _try_compile(x, "<disassembly>")
 # By now, if we don't have a code object, we can't disassemble x.
 if hasattr(x, 'co_code'):
 return x
 raise TypeError("don't know how to disassemble %s objects" %
 type(x).__name__)

def code_info(x):
 """Formatted details of methods, functions, or code."""
 return _format_code_info(_get_code_object(x))

def _format_code_info(co):
 lines = []
 lines.append("Name: %s" % co.co_name)
 lines.append("Filename: %s" % co.co_filename)
 lines.append("Argument count: %s" % co.co_argcount)
 lines.append("Positional-only arguments: %s" % co.co_posonlyargcount)
 lines.append("Kw-only arguments: %s" % co.co_kwonlyargcount)
 lines.append("Number of locals: %s" % co.co_nlocals)
 lines.append("Stack size: %s" % co.co_stacksize)
 lines.append("Flags: %s" % pretty_flags(co.co_flags))
 if co.co_consts:
 lines.append("Constants:")
 for i_c in enumerate(co.co_consts):
 lines.append("%4d: %r" % i_c)
 if co.co_names:
 lines.append("Names:")
 for i_n in enumerate(co.co_names):
 lines.append("%4d: %s" % i_n)
 if co.co_varnames:
 lines.append("Variable names:")
 for i_n in enumerate(co.co_varnames):
 lines.append("%4d: %s" % i_n)
 if co.co_freevars:
 lines.append("Free variables:")
 for i_n in enumerate(co.co_freevars):
 lines.append("%4d: %s" % i_n)
 if co.co_cellvars:
 lines.append("Cell variables:")
 for i_n in enumerate(co.co_cellvars):
 lines.append("%4d: %s" % i_n)
 return "\n".join(lines)

def show_code(co, *, file=None):
 """Print details of methods, functions, or code to *file*.

 If *file* is not provided, the output is printed on stdout.
 """
 print(code_info(co), file=file)

_Instruction = collections.namedtuple("_Instruction",
 "opname opcode arg argval argrepr offset starts_line is_jump_target")

_Instruction.opname.__doc__ = "Human readable name for operation"
_Instruction.opcode.__doc__ = "Numeric code for operation"
_Instruction.arg.__doc__ = "Numeric argument to operation (if any), otherwise None"
_Instruction.argval.__doc__ = "Resolved arg value (if known), otherwise same as arg"
_Instruction.argrepr.__doc__ = "Human readable description of operation argument"
_Instruction.offset.__doc__ = "Start index of operation within bytecode sequence"
_Instruction.starts_line.__doc__ = "Line started by this opcode (if any), otherwise None"
_Instruction.is_jump_target.__doc__ = "True if other code jumps to here, otherwise False"

_OPNAME_WIDTH = 20
_OPARG_WIDTH = 5

class Instruction(_Instruction):
 """Details for a bytecode operation

 Defined fields:
 opname - human readable name for operation
 opcode - numeric code for operation
 arg - numeric argument to operation (if any), otherwise None
 argval - resolved arg value (if known), otherwise same as arg
 argrepr - human readable description of operation argument
 offset - start index of operation within bytecode sequence
 starts_line - line started by this opcode (if any), otherwise None
 is_jump_target - True if other code jumps to here, otherwise False
 """

 def _disassemble(self, lineno_width=3, mark_as_current=False, offset_width=4):
 """Format instruction details for inclusion in disassembly output

 *lineno_width* sets the width of the line number field (0 omits it)
 *mark_as_current* inserts a '-->' marker arrow as part of the line
 *offset_width* sets the width of the instruction offset field
 """
 fields = []
 # Column: Source code line number
 if lineno_width:
 if self.starts_line is not None:
 lineno_fmt = "%%%dd" % lineno_width
 fields.append(lineno_fmt % self.starts_line)
 else:
 fields.append(' ' * lineno_width)
 # Column: Current instruction indicator
 if mark_as_current:
 fields.append('-->')
 else:
 fields.append(' ')
 # Column: Jump target marker
 if self.is_jump_target:
 fields.append('>>')
 else:
 fields.append(' ')
 # Column: Instruction offset from start of code sequence
 fields.append(repr(self.offset).rjust(offset_width))
 # Column: Opcode name
 fields.append(self.opname.ljust(_OPNAME_WIDTH))
 # Column: Opcode argument
 if self.arg is not None:
 fields.append(repr(self.arg).rjust(_OPARG_WIDTH))
 # Column: Opcode argument details
 if self.argrepr:
 fields.append('(' + self.argrepr + ')')
 return ' '.join(fields).rstrip()


def get_instructions(x, *, first_line=None):
 """Iterator for the opcodes in methods, functions or code

 Generates a series of Instruction named tuples giving the details of
 each operations in the supplied code.

 If *first_line* is not None, it indicates the line number that should
 be reported for the first source line in the disassembled code.
 Otherwise, the source line information (if any) is taken directly from
 the disassembled code object.
 """
 co = _get_code_object(x)
 cell_names = co.co_cellvars + co.co_freevars
 linestarts = dict(findlinestarts(co))
 if first_line is not None:
 line_offset = first_line - co.co_firstlineno
 else:
 line_offset = 0
 return _get_instructions_bytes(co.co_code, co.co_varnames, co.co_names,
 co.co_consts, cell_names, linestarts,
 line_offset)

def _get_const_info(const_index, const_list):
 """Helper to get optional details about const references

 Returns the dereferenced constant and its repr if the constant
 list is defined.
 Otherwise returns the constant index and its repr().
 """
 argval = const_index
 if const_list is not None:
 argval = const_list[const_index]
 return argval, repr(argval)

def _get_name_info(name_index, name_list):
 """Helper to get optional details about named references

 Returns the dereferenced name as both value and repr if the name
 list is defined.
 Otherwise returns the name index and its repr().
 """
 argval = name_index
 if name_list is not None:
 argval = name_list[name_index]
 argrepr = argval
 else:
 argrepr = repr(argval)
 return argval, argrepr


def _get_instructions_bytes(code, varnames=None, names=None, constants=None,
 cells=None, linestarts=None, line_offset=0):
 """Iterate over the instructions in a bytecode string.

 Generates a sequence of Instruction namedtuples giving the details of each
 opcode. Additional information about the code's runtime environment
 (e.g. variable names, constants) can be specified using optional
 arguments.

 """
 labels = findlabels(code)
 starts_line = None
 for offset, op, arg in _unpack_opargs(code):
 if linestarts is not None:
 starts_line = linestarts.get(offset, None)
 if starts_line is not None:
 starts_line += line_offset
 is_jump_target = offset in labels
 argval = None
 argrepr = ''
 if arg is not None:
 # Set argval to the dereferenced value of the argument when
 # available, and argrepr to the string representation of argval.
 # _disassemble_bytes needs the string repr of the
 # raw name index for LOAD_GLOBAL, LOAD_CONST, etc.
 argval = arg
 if op in hasconst:
 argval, argrepr = _get_const_info(arg, constants)
 elif op in hasname:
 argval, argrepr = _get_name_info(arg, names)
 elif op in hasjrel:
 argval = offset + 2 + arg
 argrepr = "to " + repr(argval)
 elif op in haslocal:
 argval, argrepr = _get_name_info(arg, varnames)
 elif op in hascompare:
 argval = cmp_op[arg]
 argrepr = argval
 elif op in hasfree:
 argval, argrepr = _get_name_info(arg, cells)
 elif op == FORMAT_VALUE:
 argval, argrepr = FORMAT_VALUE_CONVERTERS[arg & 0x3]
 argval = (argval, bool(arg & 0x4))
 if argval[1]:
 if argrepr:
 argrepr += ', '
 argrepr += 'with format'
 elif op == MAKE_FUNCTION:
 argrepr = ', '.join(s for i, s in enumerate(MAKE_FUNCTION_FLAGS)
 if arg & (1<<i))
 yield Instruction(opname[op], op,
 arg, argval, argrepr,
 offset, starts_line, is_jump_target)

def disassemble(co, lasti=-1, *, file=None):
 """Disassemble a code object."""
 cell_names = co.co_cellvars + co.co_freevars
 linestarts = dict(findlinestarts(co))
 _disassemble_bytes(co.co_code, lasti, co.co_varnames, co.co_names,
 co.co_consts, cell_names, linestarts, file=file)

def _disassemble_recursive(co, *, file=None, depth=None):
 disassemble(co, file=file)
 if depth is None or depth > 0:
 if depth is not None:
 depth = depth - 1
 for x in co.co_consts:
 if hasattr(x, 'co_code'):
 print(file=file)
 print("Disassembly of %r:" % (x,), file=file)
 _disassemble_recursive(x, file=file, depth=depth)

def _disassemble_bytes(code, lasti=-1, varnames=None, names=None,
 constants=None, cells=None, linestarts=None,
 *, file=None, line_offset=0):
 # Omit the line number column entirely if we have no line number info
 show_lineno = linestarts is not None
 if show_lineno:
 maxlineno = max(linestarts.values()) + line_offset
 if maxlineno >= 1000:
 lineno_width = len(str(maxlineno))
 else:
 lineno_width = 3
 else:
 lineno_width = 0
 maxoffset = len(code) - 2
 if maxoffset >= 10000:
 offset_width = len(str(maxoffset))
 else:
 offset_width = 4
 for instr in _get_instructions_bytes(code, varnames, names,
 constants, cells, linestarts,
 line_offset=line_offset):
 new_source_line = (show_lineno and
 instr.starts_line is not None and
 instr.offset > 0)
 if new_source_line:
 print(file=file)
 is_current_instr = instr.offset == lasti
 print(instr._disassemble(lineno_width, is_current_instr, offset_width),
 file=file)

def _disassemble_str(source, **kwargs):
 """Compile the source string, then disassemble the code object."""
 _disassemble_recursive(_try_compile(source, '<dis>'), **kwargs)

disco = disassemble # XXX For backwards compatibility

def _unpack_opargs(code):
 extended_arg = 0
 for i in range(0, len(code), 2):
 op = code[i]
 if op >= HAVE_ARGUMENT:
 arg = code[i+1] | extended_arg
 extended_arg = (arg << 8) if op == EXTENDED_ARG else 0
 else:
 arg = None
 yield (i, op, arg)

def findlabels(code):
 """Detect all offsets in a byte code which are jump targets.

 Return the list of offsets.

 """
 labels = []
 for offset, op, arg in _unpack_opargs(code):
 if arg is not None:
 if op in hasjrel:
 label = offset + 2 + arg
 elif op in hasjabs:
 label = arg
 else:
 continue
 if label not in labels:
 labels.append(label)
 return labels

def findlinestarts(code):
 """Find the offsets in a byte code which are start of lines in the source.

 Generate pairs (offset, lineno) as described in Python/compile.c.

 """
 byte_increments = code.co_lnotab[0::2]
 line_increments = code.co_lnotab[1::2]
 bytecode_len = len(code.co_code)

 lastlineno = None
 lineno = code.co_firstlineno
 addr = 0
 for byte_incr, line_incr in zip(byte_increments, line_increments):
 if byte_incr:
 if lineno != lastlineno:
 yield (addr, lineno)
 lastlineno = lineno
 addr += byte_incr
 if addr >= bytecode_len:
 # The rest of the lnotab byte offsets are past the end of
 # the bytecode, so the lines were optimized away.
 return
 if line_incr >= 0x80:
 # line_increments is an array of 8-bit signed integers
 line_incr -= 0x100
 lineno += line_incr
 if lineno != lastlineno:
 yield (addr, lineno)

class Bytecode:
 """The bytecode operations of a piece of code

 Instantiate this with a function, method, other compiled object, string of
 code, or a code object (as returned by compile()).

 Iterating over this yields the bytecode operations as Instruction instances.
 """
 def __init__(self, x, *, first_line=None, current_offset=None):
 self.codeobj = co = _get_code_object(x)
 if first_line is None:
 self.first_line = co.co_firstlineno
 self._line_offset = 0
 else:
 self.first_line = first_line
 self._line_offset = first_line - co.co_firstlineno
 self._cell_names = co.co_cellvars + co.co_freevars
 self._linestarts = dict(findlinestarts(co))
 self._original_object = x
 self.current_offset = current_offset

 def __iter__(self):
 co = self.codeobj
 return _get_instructions_bytes(co.co_code, co.co_varnames, co.co_names,
 co.co_consts, self._cell_names,
 self._linestarts,
 line_offset=self._line_offset)

 def __repr__(self):
 return "{}({!r})".format(self.__class__.__name__,
 self._original_object)

 @classmethod
 def from_traceback(cls, tb):
 """ Construct a Bytecode from the given traceback """
 while tb.tb_next:
 tb = tb.tb_next
 return cls(tb.tb_frame.f_code, current_offset=tb.tb_lasti)

 def info(self):
 """Return formatted information about the code object."""
 return _format_code_info(self.codeobj)

 def dis(self):
 """Return a formatted view of the bytecode operations."""
 co = self.codeobj
 if self.current_offset is not None:
 offset = self.current_offset
 else:
 offset = -1
 with io.StringIO() as output:
 _disassemble_bytes(co.co_code, varnames=co.co_varnames,
 names=co.co_names, constants=co.co_consts,
 cells=self._cell_names,
 linestarts=self._linestarts,
 line_offset=self._line_offset,
 file=output,
 lasti=offset)
 return output.getvalue()


def _test():
 """Simple test program to disassemble a file."""
 import argparse

 parser = argparse.ArgumentParser()
 parser.add_argument('infile', type=argparse.FileType('rb'), nargs='?', default='-')
 args = parser.parse_args()
 with args.infile as infile:
 source = infile.read()
 code = compile(source, args.infile.name, "exec")
 dis(code)

if __name__ == "__main__":
 _test()