# (C) Copyright 2020 by Rocky Bernstein
#
#  This program is free software; you can redistribute it and/or
#  modify it under the terms of the GNU General Public License
#  as published by the Free Software Foundation; either version 2
#  of the License, or (at your option) any later version.
#
#  This program is distributed in the hope that it will be useful,
#  but WITHOUT ANY WARRANTY; without even the implied warranty of
#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#  GNU General Public License for more details.
#
#  You should have received a copy of the GNU General Public License
#  along with this program; if not, write to the Free Software
#  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.

from xdis.codetype.code13 import Code13, Code13FieldTypes
from copy import deepcopy

# If there is a list of types, then any will work, but the 1st one is the corect one for types.CodeType
Code15FieldTypes = deepcopy(Code13FieldTypes)
Code15FieldTypes.update({
    "co_stacksize": int,
    "co_firstlineno": int,
    "co_lnotab": (str, bytes, dict),
})
# stacksize, co_firstlineno, co_lnotab are new in 1.5

class Code15(Code13):
    """Class for a Python 1.5 code object used for Python interpreters other than 1.5.

    For convenience in generating code objects, fields like
    `co_consts`, co_names which are (immutable) tuples in the end-result can be stored
    instead as (mutable) lists. Likewise the line number table `co_lnotab`
    can be stored as a simple list of offset, line_number tuples.
    """

    def __init__(
        self,
        co_argcount,
        co_nlocals,
        co_stacksize,
        co_flags,
        co_code,
        co_consts,
        co_names,
        co_varnames,
        co_filename,
        co_name,
        co_firstlineno,
        co_lnotab
    ):
        super(Code15, self).__init__(
            co_argcount,
            co_nlocals,
            co_flags,
            co_code,
            co_consts,
            co_names,
            co_varnames,
            co_filename,
            co_name,
        )
        self.co_stacksize = co_stacksize
        self.co_firstlineno = co_firstlineno
        self.co_lnotab = co_lnotab
        # This messes up decompilers somehow.
        # self.decode_lineno_tab()
        self.fieldtypes = Code15FieldTypes
        if type(self) == Code15:
            self.check()
        return

    def decode_lineno_tab(self):
        line_number, line_number_diff = self.co_firstlineno, 0
        offset, offset_diff = 0, 0
        uncompressed_lnotab = {offset: line_number}
        if not hasattr(self.co_lnotab, "__len__"):
            raise TypeError("line number table should have a type with a length; is %s" % type(self.co_lnotab))
        for i in range(0, len(self.co_lnotab), 2):
            offset_diff = self.co_lnotab[i]
            line_number_diff = self.co_lnotab[i+1]
            if not isinstance(offset_diff, int):
                offset_diff = ord(offset_diff)
                line_number_diff = ord(line_number_diff)

            assert offset_diff < 256
            if offset_diff == 255:
                continue
            assert line_number_diff < 256
            if line_number_diff == 255:
                continue
            line_number += line_number_diff
            offset += offset_diff
            line_number_diff, offset_diff = 0, 0
            uncompressed_lnotab[offset] = line_number

        self.co_lnotab = uncompressed_lnotab

    def encode_lineno_tab(self):
        co_lnotab = ""

        prev_line_number = self.co_firstlineno
        prev_offset = 0
        for offset, line_number in self.co_lnotab:
            offset_diff = offset - prev_offset
            line_diff = line_number - prev_line_number
            prev_offset = offset
            prev_line_number = line_number
            while offset_diff >= 256:
                co_lnotab.append(chr(255))
                co_lnotab.append(chr(0))
                offset_diff -= 255
            while line_diff >= 256:
                co_lnotab.append(chr(0))
                co_lnotab.append(chr(255))
                line_diff -= 255
            co_lnotab += chr(offset_diff)
            co_lnotab += chr(line_diff)

        self.co_lnotab = co_lnotab

    def freeze(self):
        for field in "co_consts co_names co_varnames co_freevars co_cellvars".split():
            val = getattr(self, field)
            if isinstance(val, list):
                setattr(self, field, tuple(val))

        if isinstance(self.co_lnotab, dict):
            d = self.co_lnotab
            self.co_lnotab = sorted(zip(d.keys(), d.values()), key=lambda tup: tup[0])
        if isinstance(self.co_lnotab, list):
            # We assume we have a list of tuples:
            # (offset, linenumber) which we convert
            # into the encoded format

            # FIXME: handle PYTHON 3
            self.encode_lineno_tab()

        self.frozen = True
        return self
