#  Copyright (c) 2015-2016, 2018, 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 3 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, see <http://www.gnu.org/licenses/>.

from collections import deque

from xdis import (
    Bytecode,
    iscode,
    findlinestarts,
    get_opcode,
    offset2line,
    load_file,
    load_module,
)


def line_number_mapping(pyc_filename, src_filename):
    (
        version,
        timestamp,
        magic_int,
        code1,
        is_pypy,
        source_size,
        sip_hash,
    ) = load_module(pyc_filename)
    try:
        code2 = load_file(src_filename)
    except SyntaxError as e:
        return str(e)

    queue = deque([code1, code2])

    mappings = []

    opc = get_opcode(version, is_pypy)
    number_loop(queue, mappings, opc)
    return sorted(mappings, key=lambda x: x[1])


def number_loop(queue, mappings, opc):
    while len(queue) > 0:
        code1 = queue.popleft()
        code2 = queue.popleft()
        assert code1.co_name == code2.co_name
        linestarts_orig = findlinestarts(code1)
        linestarts_uncompiled = list(findlinestarts(code2))
        mappings += [
            [line, offset2line(offset, linestarts_uncompiled)]
            for offset, line in linestarts_orig
        ]
        bytecode1 = Bytecode(code1, opc)
        bytecode2 = Bytecode(code2, opc)
        instr2s = bytecode2.get_instructions(code2)
        seen = set([code1.co_name])
        for instr in bytecode1.get_instructions(code1):
            next_code1 = None
            if iscode(instr.argval):
                next_code1 = instr.argval
            if next_code1:
                next_code2 = None
                while not next_code2:
                    try:
                        instr2 = next(instr2s)
                        if iscode(instr2.argval):
                            next_code2 = instr2.argval
                            pass
                    except StopIteration:
                        break
                    pass
                if next_code2:
                    assert next_code1.co_name == next_code2.co_name
                    if next_code1.co_name not in seen:
                        seen.add(next_code1.co_name)
                        queue.append(next_code1)
                        queue.append(next_code2)
                        pass
                    pass
            pass
        pass
