# Copyright (C) 2021 Free Software Foundation, Inc.

# 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/>.

import gdb
from gdb.unwinder import Unwinder


class FrameId(object):
    def __init__(self, sp, pc):
        self._sp = sp
        self._pc = pc

    @property
    def sp(self):
        return self._sp

    @property
    def pc(self):
        return self._pc


class TestUnwinder(Unwinder):
    def __init__(self, use_descriptors):
        if use_descriptors:
            tag = "using descriptors"
        else:
            tag = "using strings"

        Unwinder.__init__(self, "break unwinding %s" % tag)
        self._use_descriptors = use_descriptors

    def __call__(self, pending_frame):
        pc_desc = pending_frame.architecture().registers().find("pc")
        pc = pending_frame.read_register(pc_desc)

        sp_desc = pending_frame.architecture().registers().find("sp")
        sp = pending_frame.read_register(sp_desc)

        block = gdb.block_for_pc(int(pc))
        if block is None:
            return None
        func = block.function
        if func is None:
            return None
        if str(func) != "bar":
            return None

        fid = FrameId(pc, sp)
        unwinder = pending_frame.create_unwind_info(fid)
        if self._use_descriptors:
            unwinder.add_saved_register(pc_desc, pc)
            unwinder.add_saved_register(sp_desc, sp)
        else:
            unwinder.add_saved_register("pc", pc)
            unwinder.add_saved_register("sp", sp)
        return unwinder


gdb.unwinder.register_unwinder(None, TestUnwinder(True), True)
gdb.unwinder.register_unwinder(None, TestUnwinder(False), True)