#!/usr/bin/env python
# -*- coding: utf-8 -*-
#
# Finding potential software vulnerabilities from git commit messages
#
# Software is free software released under the "GNU Affero General Public License v3.0"
#
# This software is part of cve-search.org
#
# Copyright (c) 2019-2020 Alexandre Dulaunoy - a@foo.be


import os
import re
import git
import json
import sys
import typing
from langdetect import detect as langdetect


PATTERNS_PATH="./git_vuln_finder/patterns"


def build_pattern(pattern_file):
    fp = open(pattern_file, "r")
    rex = ""
    try:
        prefix_fp = open(pattern_file + ".prefix", "r")
        rex += prefix_fp.read()
        prefix_fp.close()
    except:
        pass

    for line in fp.readlines():
        rex += line.rstrip() + "|"
    rex = rex[:-1] # We remove the extra '|
    fp.close()

    try:
        suffix_fp = open(pattern_file + ".suffix", "r")
        rex += suffix_fp.read()
        suffix_fp.close()
    except:
        pass

    return rex


def get_patterns(patterns_path=PATTERNS_PATH):
    patterns = {}
    for root, dirs, files in os.walk(patterns_path):
        path = root.split(os.sep)
        for f in files:
            if f.endswith(".prefix") or f.endswith(".suffix"):
                continue
            npath = root[len(patterns_path):].split(os.sep)
            try:
                npath.remove('')
            except ValueError:
                pass

            lang = npath[0]
            severity = npath[1]
            pattern_category = f

            try: # FIXME: Is there a better way?
                a = patterns[lang]
            except KeyError:
                patterns[lang] = {}
            try:
                a = patterns[lang][severity]
            except KeyError:
                patterns[lang][severity] = {}
            try:
                a = patterns[lang][severity][pattern_category]
            except KeyError:
                rex = build_pattern(root + os.sep + f)
                patterns[lang][severity][pattern_category] = re.compile(rex)

    return patterns


def find_vuln(commit, pattern, versbose=False):
    m = pattern.search(commit.message)
    if m:
        if versbose:
            print("Match found: {}".format(m.group(0)), file=sys.stderr)
            print(commit.message, file=sys.stderr)
            print("---", file=sys.stderr)
        ret = {}
        ret['commit'] = commit
        ret['match'] = m.groups()
        return ret
    else:
        return None


def summary(commit,
            branch,
            pattern,
            origin=None,
            vuln_match=None,
            tags_matching=False,
            commit_state="under-review"
):
    potential_vulnerabilities = {}
    rcommit = commit
    cve = extract_cve(rcommit.message)
    if origin is not None:
        origin = origin
        if origin.find('github.com'):
            origin_github_api = origin.split(':')[1]
            (org_name, repo_name) = origin_github_api.split('/', 1)
            if repo_name.find('.git$'):
                repo_name = re.sub(r".git$","", repo_name)
            origin_github_api = 'https://api.github.com/repos/{}/{}/commits/{}'.format(org_name, repo_name, rcommit.hexsha)

    else:
        origin = 'git origin unknown'
    # deduplication if similar commits on different branches
    if rcommit.hexsha in potential_vulnerabilities:
       potential_vulnerabilities[rcommit.hexsha]['branches'].append(branch)
    else:
        potential_vulnerabilities[rcommit.hexsha] = {}
        potential_vulnerabilities[rcommit.hexsha]['message'] = rcommit.message
        potential_vulnerabilities[rcommit.hexsha]['language'] = langdetect(rcommit.message)
        potential_vulnerabilities[rcommit.hexsha]['commit-id'] = rcommit.hexsha
        potential_vulnerabilities[rcommit.hexsha]['summary'] = rcommit.summary
        potential_vulnerabilities[rcommit.hexsha]['stats'] = rcommit.stats.total
        potential_vulnerabilities[rcommit.hexsha]['author'] = rcommit.author.name
        potential_vulnerabilities[rcommit.hexsha]['author-email'] = rcommit.author.email
        potential_vulnerabilities[rcommit.hexsha]['authored_date'] = rcommit.authored_date
        potential_vulnerabilities[rcommit.hexsha]['committed_date'] = rcommit.committed_date
        potential_vulnerabilities[rcommit.hexsha]['branches'] = []
        potential_vulnerabilities[rcommit.hexsha]['branches'].append(branch)
        potential_vulnerabilities[rcommit.hexsha]['pattern-selected'] = pattern.pattern
        potential_vulnerabilities[rcommit.hexsha]['pattern-matches'] = vuln_match
        potential_vulnerabilities[rcommit.hexsha]['origin'] = origin
        if origin_github_api:
            potential_vulnerabilities[commit.hexsha]['origin-github-api'] = origin_github_api
        potential_vulnerabilities[rcommit.hexsha]['tags'] = []
        if tags_matching:
            if repo.commit(rcommit).hexsha in tagmap:
                potential_vulnerabilities[rcommit.hexsha]['tags'] = tagmap[repo.commit(rcommit).hexsha]
        if cve: potential_vulnerabilities[rcommit.hexsha]['cve'] = cve
        if cve:
            potential_vulnerabilities[rcommit.hexsha]['state'] = "cve-assigned"
        else:
            potential_vulnerabilities[rcommit.hexsha]['state'] = commit_state

    return rcommit.hexsha, potential_vulnerabilities


def extract_cve(commit):
    cve_found = set()
    cve_find = re.compile(r'CVE-[1-2]\d{1,4}-\d{1,7}', re.IGNORECASE)
    m = cve_find.findall(commit)
    if m:
        for v in m:
            cve_found.add(v)
        return m
    else:
        return None