import re
from slither.exceptions import SlitherException
from ..utils.patches import create_patch

# Indicates the recommended versions for replacement
REPLACEMENT_VERSIONS = ["0.4.25", "0.5.3"]

# group:
# 0: ^ > >= < <= (optional)
# 1: ' ' (optional)
# 2: version number
# 3: version number
# 4: version number
PATTERN = re.compile('(\^|>|>=|<|<=)?([ ]+)?(\d+)\.(\d+)\.(\d+)')


def format(slither, patches, elements):
    versions_used = []
    for element in elements:
        versions_used.append(''.join(element['type_specific_fields']['directive'][1:]))
    solc_version_replace = _analyse_versions(versions_used)
    for element in elements:
        _patch(slither, patches, element['source_mapping']['filename_absolute'],
               element['source_mapping']['filename_relative'], solc_version_replace,
               element['source_mapping']['start'],
               element['source_mapping']['start'] + element['source_mapping']['length'])


def _analyse_versions(used_solc_versions):
    replace_solc_versions = list()
    for version in used_solc_versions:
        replace_solc_versions.append(_determine_solc_version_replacement(version))
    if not all(version == replace_solc_versions[0] for version in replace_solc_versions):
        raise SlitherException("Multiple incompatible versions!")
    else:
        return replace_solc_versions[0]


def _determine_solc_version_replacement(used_solc_version):
    versions = PATTERN.findall(used_solc_version)
    if len(versions) == 1:
        version = versions[0]
        minor_version = '.'.join(version[2:])[2]
        if minor_version == '4':
            return "pragma solidity " + REPLACEMENT_VERSIONS[0] + ';'
        elif minor_version == '5':
            return "pragma solidity " + REPLACEMENT_VERSIONS[1] + ';'
        else:
            raise SlitherException("Unknown version!")
    elif len(versions) == 2:
        version_right = versions[1]
        minor_version_right = '.'.join(version_right[2:])[2]
        if minor_version_right == '4':
            # Replace with 0.4.25
            return "pragma solidity " + REPLACEMENT_VERSIONS[0] + ';'
        elif minor_version_right in ['5', '6']:
            # Replace with 0.5.3
            return "pragma solidity " + REPLACEMENT_VERSIONS[1] + ';'


def _patch(slither, patches, in_file, in_file_relative, pragma, modify_loc_start, modify_loc_end):
    in_file_str = slither.source_code[in_file].encode('utf-8')
    old_str_of_interest = in_file_str[modify_loc_start:modify_loc_end]
    create_patch(patches,
                 "pragma",
                 in_file_relative,
                 in_file,
                 int(modify_loc_start),
                 int(modify_loc_end),
                 old_str_of_interest.decode('utf-8'),
                 pragma)