#!/usr/bin/env python
# License: GPLv3 Copyright: 2021, Kovid Goyal <kovid at kovidgoyal.net>

import importlib
import os
import re
import shlex
import shutil
import subprocess
import sys
import unittest
from contextlib import contextmanager
from functools import lru_cache
from tempfile import TemporaryDirectory
from typing import (
    Any, Callable, Dict, Generator, Iterator, List, NoReturn, Optional, Sequence, Set,
    Tuple,
)


def contents(package: str) -> Iterator[str]:
    try:
        if sys.version_info[:2] < (3, 10):
            raise ImportError('importlib.resources.files() doesnt work with frozen builds on python 3.9')
        from importlib.resources import files
    except ImportError:
        from importlib.resources import contents
        return iter(contents(package))
    return (path.name for path in files(package).iterdir())


def itertests(suite: unittest.TestSuite) -> Generator[unittest.TestCase, None, None]:
    stack = [suite]
    while stack:
        suite = stack.pop()
        for test in suite:
            if isinstance(test, unittest.TestSuite):
                stack.append(test)
                continue
            if test.__class__.__name__ == 'ModuleImportFailure':
                raise Exception('Failed to import a test module: %s' % test)
            yield test


def find_all_tests(package: str = '', excludes: Sequence[str] = ('main', 'gr')) -> unittest.TestSuite:
    suits = []
    if not package:
        package = __name__.rpartition('.')[0] if '.' in __name__ else 'kitty_tests'
    for x in contents(package):
        name, ext = os.path.splitext(x)
        if ext in ('.py', '.pyc') and name not in excludes:
            m = importlib.import_module(package + '.' + x.partition('.')[0])
            suits.append(unittest.defaultTestLoader.loadTestsFromModule(m))
    return unittest.TestSuite(suits)


def filter_tests(suite: unittest.TestSuite, test_ok: Callable[[unittest.TestCase], bool]) -> unittest.TestSuite:
    ans = unittest.TestSuite()
    added: Set[unittest.TestCase] = set()
    for test in itertests(suite):
        if test_ok(test) and test not in added:
            ans.addTest(test)
            added.add(test)
    return ans


def filter_tests_by_name(suite: unittest.TestSuite, *names: str) -> unittest.TestSuite:
    names_ = {x if x.startswith('test_') else 'test_' + x for x in names}

    def q(test: unittest.TestCase) -> bool:
        return test._testMethodName in names_

    return filter_tests(suite, q)


def filter_tests_by_module(suite: unittest.TestSuite, *names: str) -> unittest.TestSuite:
    names_ = frozenset(names)

    def q(test: unittest.TestCase) -> bool:
        m = test.__class__.__module__.rpartition('.')[-1]
        return m in names_

    return filter_tests(suite, q)


@lru_cache
def python_for_type_check() -> str:
    return shutil.which('python') or shutil.which('python3') or 'python'


def type_check() -> NoReturn:
    from kitty.cli_stub import generate_stub  # type:ignore

    generate_stub()
    from kittens.tui.operations_stub import generate_stub  # type: ignore

    generate_stub()
    py = python_for_type_check()
    os.execlp(py, py, '-m', 'mypy', '--pretty')


def run_cli(suite: unittest.TestSuite, verbosity: int = 4) -> bool:
    r = unittest.TextTestRunner
    r.resultclass = unittest.TextTestResult
    runner = r(verbosity=verbosity)
    runner.tb_locals = True  # type: ignore
    result = runner.run(suite)
    return result.wasSuccessful()


def find_testable_go_packages() -> Tuple[Set[str], Dict[str, List[str]]]:
    test_functions: Dict[str, List[str]] = {}
    ans = set()
    base = os.getcwd()
    pat = re.compile(r'^func Test([A-Z]\w+)', re.MULTILINE)
    for (dirpath, dirnames, filenames) in os.walk(base):
        for f in filenames:
            if f.endswith('_test.go'):
                q = os.path.relpath(dirpath, base)
                ans.add(q)
                with open(os.path.join(dirpath, f)) as s:
                    raw = s.read()
                for m in pat.finditer(raw):
                    test_functions.setdefault(m.group(1), []).append(q)
    return ans, test_functions


@lru_cache
def go_exe() -> str:
    return shutil.which('go') or ''


def run_go(packages: Set[str], names: str) -> 'subprocess.Popen[bytes]':
    go = go_exe()
    go_pkg_args = [f'kitty/{x}' for x in packages]
    cmd = [go, 'test', '-v']
    for name in names:
        cmd.extend(('-run', name))
    cmd += go_pkg_args
    print(shlex.join(cmd), flush=True)
    return subprocess.Popen(cmd, stdout=subprocess.PIPE, stderr=subprocess.STDOUT)


def reduce_go_pkgs(module: str, names: Sequence[str]) -> Set[str]:
    if not go_exe():
        raise SystemExit('go executable not found, current path: ' + repr(os.environ.get('PATH', '')))
    go_packages, go_functions = find_testable_go_packages()
    if module:
        go_packages &= {module}
    if names:
        pkgs = set()
        for name in names:
            pkgs |= set(go_functions.get(name, []))
        go_packages &= pkgs
    return go_packages


def run_python_tests(args: Any, go_proc: 'Optional[subprocess.Popen[bytes]]' = None) -> None:
    tests = find_all_tests()

    def print_go() -> None:
        try:
            print(go_proc.stdout.read().decode(), end='', flush=True)
        except KeyboardInterrupt:
            go_proc.terminate()
            if go_proc.wait(0.1) is None:
                go_proc.kill()
        go_proc.stdout.close()
        go_proc.wait()

    if args.module:
        tests = filter_tests_by_module(tests, args.module)
        if not tests._tests:
            if go_proc:
                print_go()
                raise SystemExit(go_proc.returncode)
            raise SystemExit('No test module named %s found' % args.module)

    if args.name:
        tests = filter_tests_by_name(tests, *args.name)
        if not tests._tests and not go_proc:
            raise SystemExit('No test named %s found' % args.name)
    python_tests_ok = run_cli(tests, args.verbosity)
    exit_code = 0 if python_tests_ok else 1
    if go_proc:
        print_go()
        if exit_code == 0:
            exit_code = go_proc.returncode
    if exit_code != 0:
        print("\x1b[31mError\x1b[39m: Some tests failed!")
    raise SystemExit(exit_code)


def run_tests(report_env: bool = False) -> None:
    import argparse

    parser = argparse.ArgumentParser()
    parser.add_argument(
        'name',
        nargs='*',
        default=[],
        help='The name of the test to run, for e.g. linebuf corresponds to test_linebuf. Can be specified multiple times.'
        ' For go tests Something corresponds to TestSometing.',
    )
    parser.add_argument('--verbosity', default=4, type=int, help='Test verbosity')
    parser.add_argument(
        '--module',
        default='',
        help='Name of a test module to restrict to. For example: ssh.' ' For Go tests this is the name of a package, for example: tools/cli',
    )
    args = parser.parse_args()
    if args.name and args.name[0] in ('type-check', 'type_check', 'mypy'):
        type_check()
    go_pkgs = reduce_go_pkgs(args.module, args.name)
    if go_pkgs:
        go_proc: 'Optional[subprocess.Popen[bytes]]' = run_go(go_pkgs, args.name)
    else:
        go_proc = None
    with env_for_python_tests(report_env):
        run_python_tests(args, go_proc)


@contextmanager
def env_vars(**kw: str) -> Iterator[None]:
    originals = {k: os.environ.get(k) for k in kw}
    os.environ.update(kw)
    try:
        yield
    finally:
        for k, v in originals.items():
            if v is None:
                os.environ.pop(k, None)
            else:
                os.environ[k] = v


@contextmanager
def env_for_python_tests(report_env: bool = False) -> Iterator[None]:
    gohome = os.path.expanduser('~/go')
    current_home = os.path.expanduser('~') + os.sep
    paths = os.environ.get('PATH', '/usr/local/sbin:/usr/local/bin:/usr/bin').split(os.pathsep)
    path = os.pathsep.join(x for x in paths if not x.startswith(current_home))
    launcher_dir = os.path.join(os.path.dirname(os.path.abspath(__file__)), 'kitty', 'launcher')
    path = f'{launcher_dir}{os.pathsep}{path}'
    python_for_type_check()
    if os.environ.get('CI') == 'true' or report_env:
        print('Using PATH in test environment:', path)
        print('Python:', python_for_type_check())

    with TemporaryDirectory() as tdir, env_vars(
        HOME=tdir,
        USERPROFILE=tdir,
        PATH=path,
        XDG_CONFIG_HOME=os.path.join(tdir, '.config'),
        XDG_CONFIG_DIRS=os.path.join(tdir, '.config'),
        XDG_DATA_DIRS=os.path.join(tdir, '.local', 'xdg'),
        XDG_CACHE_HOME=os.path.join(tdir, '.cache'),
        XDG_RUNTIME_DIR=os.path.join(tdir, '.cache', 'run'),
        PYTHONWARNINGS='error',
    ):
        if os.path.isdir(gohome):
            os.symlink(gohome, os.path.join(tdir, os.path.basename(gohome)))
        yield


def main() -> None:
    import warnings

    warnings.simplefilter('error')
    run_tests()