# Copyright 2024 Google LLC
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

import gdb
import re
from collections import defaultdict

INFO_LINE_RE = re.compile(r'(.+\s)*(\S+)\s+(\S+);')
INFO_FILE_RE = re.compile(r'File ([^:]+):$')

def _do_info_line_match(line):
    m = INFO_LINE_RE.match(line)
    if not m:
        return None
    _type = m.group(2)
    if _type.startswith('0x'):
        # This is the address rather than the type
        _type = None
    symbol = m.group(3)
    if symbol.startswith('*'):
        symbol = symbol[1:]
        if _type is not None:
            _type += ' *'

    paren_loc = symbol.find('[')
    if paren_loc > 0:
        symbol = symbol[:paren_loc]
    symbol = "'{}'".format(symbol)
    return (_type, symbol)

def _find_match_for_file(gdb_output, _file):
    matches = []
    in_file = False
    for line in gdb_output.split('\n'):
        if not in_file:
            # matching file
            m = INFO_FILE_RE.match(line)
            if m and m.group(1).endswith(_file):
                in_file = True
        else:
            if not line.strip():
                break # Done the file
            result = _do_info_line_match(line)
            if result is not None:
                matches.append(result)
    if len(matches) == 0:
        return (None, None)
    if len(matches) > 1:
        raise Exception('Error: Multiple statics by same name')
    return matches[0]

def _find_match(gdb_output, _file=None):
    if _file is not None:
        return _find_match_for_file(gdb_output, _file)
    matches = []
    for line in gdb_output.split('\n'):
        result = _do_info_line_match(line)
        if result is not None:
            matches.append(result)
    if len(matches) == 0:
        return (None, None)
    if len(matches) > 1:
        raise Exception('Error: Multiple statics by same name')
    return matches[0]

def _run_info(symbol_name, _type):
    out = gdb.execute('info {} {}\\b'.format(_type, symbol_name), False, True)
    return out

def get_static_variable(variable_name, _file=None, ref=False):
    if get_static_variable.cache[_file][variable_name]:
      return get_static_variable.cache[_file][variable_name]

    out = _run_info(variable_name, 'variables')
    (_type, symbol) = _find_match(out, _file)
    if symbol is None:
        raise Exception('Error: Symbol matching "{}" DNE.'.format(variable_name))
    if ref:
        symbol = '&' + symbol
        if _type is not None:
            _type += ' *'
    if _type:
        ret = '(({}){})'.format(_type, symbol)
    ret = '({})'.format(symbol)
    get_static_variable.cache[_file][variable_name] = ret
    return ret
get_static_variable.cache = defaultdict(lambda: defaultdict(lambda: {}))

def get_static_function(function_name):
    out = _run_info(function_name, 'functions')
    # TODO: Figure out what we need to do to properly find matches here.
    raise Exception('Not yet implemented.')