#!/usr/bin/env python3
# Copyright 2014-2015, Tresys Technology, LLC
#
# SPDX-License-Identifier: GPL-2.0-only
#

import sys
import argparse
import logging
import signal
import warnings

import networkx as nx
import setools


signal.signal(signal.SIGPIPE, signal.SIG_DFL)

parser = argparse.ArgumentParser(
    description="SELinux policy domain transition analysis tool.",
    epilog="If no analysis is selected, all forward transitions out of the source will be printed.")
parser.add_argument("--version", action="version", version=setools.__version__)
parser.add_argument("-p", "--policy", help="Path to SELinux policy to analyze.")
parser.add_argument("-s", "--source", help="Source type of the analysis.", required=True)
parser.add_argument("-t", "--target", help="Target type of the analysis.")
parser.add_argument("--full", help="Print rule lists for transitions.", action="store_true")
parser.add_argument("--stats", action="store_true",
                    help="Display statistics at the end of the analysis.")
parser.add_argument("-v", "--verbose", action="store_true",
                    help="Print extra informational messages")
parser.add_argument("--debug", action="store_true", dest="debug", help="Enable debugging.")

alg = parser.add_argument_group("Analysis algorithm")
alg.add_argument("-S", "--shortest_path", action="store_true",
                 help="Calculate all shortest paths.")
alg.add_argument("-A", "--all_paths", type=int, metavar="MAX_STEPS",
                 help="Calculate all paths, with the specified maximum path length. (Expensive)")

opts = parser.add_argument_group("Analysis options")
opts.add_argument("-r", "--reverse", action="store_true", default=False,
                  help="Perform a reverse DTA.")
opts.add_argument("-l", "--limit_trans", default=0, type=int,
                  help="Limit to the specified number of transitions.  Default is unlimited.")
opts.add_argument("-o", "--output_file", help="Output file for graphical results, PNG format.")
opts.add_argument("exclude", help="List of excluded types in the analysis.", nargs="*")

args = parser.parse_args()

if not args.target and (args.shortest_path or args.all_paths):
    parser.error("The target type must be specified to determine a path.")

if args.target and not (args.shortest_path or args.all_paths):
    parser.error("An algorithm must be specified to determine a path.")

if args.debug:
    logging.basicConfig(level=logging.DEBUG,
                        format='%(asctime)s|%(levelname)s|%(name)s|%(message)s')
    if not sys.warnoptions:
        warnings.simplefilter("default")
elif args.verbose:
    logging.basicConfig(level=logging.INFO, format='%(message)s')
    if not sys.warnoptions:
        warnings.simplefilter("default")
else:
    logging.basicConfig(level=logging.WARNING, format='%(message)s')
    if not sys.warnoptions:
        warnings.simplefilter("ignore")

try:
    p = setools.SELinuxPolicy(args.policy)
    g = setools.DomainTransitionAnalysis(p, exclude=args.exclude)

    pathnum: int = 0
    path: setools.DTAPath
    stepnum: int = 0
    step: setools.DomainTransition
    if args.shortest_path or args.all_paths:
        g.source = args.source
        g.target = args.target
        g.reverse = args.reverse
        if args.shortest_path:
            g.mode = setools.DomainTransitionAnalysis.Mode.ShortestPaths
        else:
            g.mode = setools.DomainTransitionAnalysis.Mode.AllPaths
            g.depth_limit = args.all_paths

        if args.output_file:
            pgv = nx.nx_agraph.to_agraph(g.graphical_results())
            pgv.draw(path=args.output_file, prog="dot", format="png")
        else:
            for pathnum, path in enumerate(g.results(), start=1):  # type: ignore
                print(f"Domain transition path {pathnum}:")

                for stepnum, step in enumerate(path, start=1):
                    if args.full:
                        print(f"Step {stepnum}: {step:full}\n")
                    else:
                        print(f"Step {stepnum}: {step}")

                if args.limit_trans and pathnum >= args.limit_trans:
                    break

                print()

            print(f"\n{pathnum} domain transition path(s) found.")

    else:  # single transition
        if args.reverse:
            g.mode = setools.DomainTransitionAnalysis.Mode.TransitionsIn
            g.target = args.source
        else:
            g.mode = setools.DomainTransitionAnalysis.Mode.TransitionsOut
            g.source = args.source

        if args.output_file:
            pgv = nx.nx_agraph.to_agraph(g.graphical_results())
            pgv.draw(path=args.output_file, prog="dot", format="png")
        else:
            for pathnum, step in enumerate(g.results(), start=1):  # type: ignore
                if args.full:
                    print(f"Transition {pathnum}: {step:full}\n")
                else:
                    print(f"Transition {pathnum}: {step}")

                if args.limit_trans and pathnum >= args.limit_trans:
                    break

            print(f"\n{pathnum} domain transition(s) found.")

    if args.stats:
        print("\nGraph statistics:")
        print(g.get_stats())

except AssertionError:
    # Always provide a traceback for assertion errors
    raise

except Exception as err:
    if args.debug:
        raise
    else:
        print(err)

    sys.exit(1)