import difflib
import os
import re
import shlex
import shutil
import subprocess
import sys
import tempfile
import time
from pathlib import Path
from typing import Callable, Iterable, Iterator, List, Optional, Tuple

import pexpect  # type: ignore[import]
import pytest

PS1 = "/@"
MAGIC_MARK = "__MaGiC-maRKz!__"


def find_unique_completion_pair(
    items: Iterable[str],
) -> Optional[Tuple[str, str]]:
    result = None
    bestscore = 0
    sitems = sorted(set(items))
    for i in range(len(sitems)):
        cur = sitems[i]
        curlen = len(cur)
        prv = sitems[i - 1] if i != 0 else ""
        prvlen = len(prv)
        nxt = sitems[i + 1] if i < len(sitems) - 1 else ""
        nxtlen = len(nxt)
        diffprv = prv == ""
        diffnxt = nxt == ""
        # Analyse each item of the list and look for the minimum length of the
        # partial prefix which is distinct from both nxt and prv. The list
        # is sorted so the prefix will be unique in the entire list.
        for j in range(curlen):
            curchar = cur[j]
            if not diffprv and (j >= prvlen or prv[j] != curchar):
                diffprv = True
            if not diffnxt and (j >= nxtlen or nxt[j] != curchar):
                diffnxt = True
            if diffprv and diffnxt:
                break
        # At the end of the loop, j is the index of last character of
        # the unique partial prefix. The length is one plus that.
        parlen = j + 1
        if parlen >= curlen:
            continue
        # Try to find the most "readable pair"; look for a long pair where
        # part is about half of full.
        if parlen < curlen / 2:
            parlen = int(curlen / 2)
        score = curlen - parlen
        if score > bestscore:
            bestscore = score
            result = (cur[:parlen], cur)
    return result


@pytest.fixture(scope="class")
def output_sort_uniq(bash: pexpect.spawn) -> Callable[[str], List[str]]:
    def _output_sort_uniq(command: str) -> List[str]:
        return sorted(
            set(  # weed out possible duplicates
                assert_bash_exec(bash, command, want_output=True).split()
            )
        )

    return _output_sort_uniq


@pytest.fixture(scope="class")
def part_full_user(
    bash: pexpect.spawn, output_sort_uniq: Callable[[str], List[str]]
) -> Optional[Tuple[str, str]]:
    res = output_sort_uniq("compgen -u")
    pair = find_unique_completion_pair(res)
    if not pair:
        pytest.skip("No suitable test user found")
    return pair


@pytest.fixture(scope="class")
def part_full_group(
    bash: pexpect.spawn, output_sort_uniq: Callable[[str], List[str]]
) -> Optional[Tuple[str, str]]:
    res = output_sort_uniq("compgen -g")
    pair = find_unique_completion_pair(res)
    if not pair:
        pytest.skip("No suitable test user found")
    return pair


@pytest.fixture(scope="class")
def hosts(bash: pexpect.spawn) -> List[str]:
    output = assert_bash_exec(bash, "compgen -A hostname", want_output=True)
    return sorted(set(output.split() + _avahi_hosts(bash)))


@pytest.fixture(scope="class")
def avahi_hosts(bash: pexpect.spawn) -> List[str]:
    return _avahi_hosts(bash)


def _avahi_hosts(bash: pexpect.spawn) -> List[str]:
    output = assert_bash_exec(
        bash,
        "! type avahi-browse &>/dev/null || "
        "avahi-browse -cpr _workstation._tcp 2>/dev/null "
        "| command grep ^= | cut -d';' -f7",
        want_output=None,
    )
    return sorted(set(output.split()))


@pytest.fixture(scope="class")
def known_hosts(bash: pexpect.spawn) -> List[str]:
    output = assert_bash_exec(
        bash,
        '_known_hosts_real ""; '
        r'printf "%s\n" "${COMPREPLY[@]}"; unset COMPREPLY',
        want_output=True,
    )
    return sorted(set(output.split()))


@pytest.fixture(scope="class")
def user_home(bash: pexpect.spawn) -> Tuple[str, str]:
    user = assert_bash_exec(
        bash, 'id -un 2>/dev/null || echo "$USER"', want_output=True
    ).strip()
    # We used to echo $HOME here, but we expect that it will be consistent with
    # ~user as far as bash is concerned which may not hold.
    home = assert_bash_exec(bash, "echo ~%s" % user, want_output=True).strip()
    return (user, home)


def partialize(
    bash: pexpect.spawn, items: Iterable[str]
) -> Tuple[str, List[str]]:
    """
    Get list of items starting with the first char of first of items.

    Disregard items starting with a COMP_WORDBREAKS character
    (e.g. a colon ~ IPv6 address), they are special cases requiring
    special tests.
    """
    first_char = None
    comp_wordbreaks = assert_bash_exec(
        bash,
        'printf "%s" "$COMP_WORDBREAKS"',
        want_output=True,
        want_newline=False,
    )
    partial_items = []
    for item in sorted(items):
        if first_char is None:
            if item[0] not in comp_wordbreaks:
                first_char = item[0]
                partial_items.append(item)
        elif item.startswith(first_char):
            partial_items.append(item)
        else:
            break
    if first_char is None:
        pytest.skip("Could not generate partial items list from %s" % items)
        # superfluous/dead code to assist mypy; pytest.skip always raises
        assert first_char is not None
    return first_char, partial_items


@pytest.fixture(scope="class")
def bash(request) -> pexpect.spawn:

    logfile = None
    if os.environ.get("BASHCOMP_TEST_LOGFILE"):
        logfile = open(os.environ["BASHCOMP_TEST_LOGFILE"], "w")
    elif os.environ.get("CI"):
        logfile = sys.stdout
    testdir = os.path.abspath(
        os.path.join(os.path.dirname(__file__), os.pardir)
    )
    env = os.environ.copy()
    env.update(
        dict(
            SRCDIR=testdir,  # TODO needed at least by bashrc
            SRCDIRABS=testdir,  # TODO needed?
            PS1=PS1,
            INPUTRC="%s/config/inputrc" % testdir,
            TERM="dumb",
            LC_COLLATE="C",  # to match Python's default locale unaware sort
        )
    )

    fixturesdir = os.path.join(testdir, "fixtures")
    os.chdir(fixturesdir)

    # Start bash
    bash = pexpect.spawn(
        "%s --norc" % os.environ.get("BASHCOMP_TEST_BASH", "bash"),
        maxread=os.environ.get("BASHCOMP_TEST_PEXPECT_MAXREAD", 20000),
        logfile=logfile,
        cwd=fixturesdir,
        env=env,
        encoding="utf-8",  # TODO? or native or...?
        # FIXME: Tests shouldn't depend on dimensions, but it's difficult to
        # expect robustly enough for Bash to wrap lines anywhere (e.g. inside
        # MAGIC_MARK).  Increase window width to reduce wrapping.
        dimensions=(24, 160),
        # TODO? codec_errors="replace",
    )
    bash.expect_exact(PS1)

    # Load bashrc and bash_completion
    assert_bash_exec(bash, "source '%s/config/bashrc'" % testdir)
    assert_bash_exec(bash, "source '%s/../bash_completion'" % testdir)

    # Use command name from marker if set, or grab from test filename
    cmd = None  # type: Optional[str]
    cmd_found = False
    marker = request.node.get_closest_marker("bashcomp")
    if marker:
        cmd = marker.kwargs.get("cmd")
        cmd_found = "cmd" in marker.kwargs
        # Run pre-test commands, early so they're usable in skipif
        for pre_cmd in marker.kwargs.get("pre_cmds", []):
            assert_bash_exec(bash, pre_cmd, want_output=None)
        # Process skip and xfail conditions
        skipif = marker.kwargs.get("skipif")
        if skipif:
            try:
                assert_bash_exec(bash, skipif, want_output=None)
            except AssertionError:
                pass
            else:
                bash.close()
                pytest.skip(skipif)
        xfail = marker.kwargs.get("xfail")
        if xfail:
            try:
                assert_bash_exec(bash, xfail, want_output=None)
            except AssertionError:
                pass
            else:
                pytest.xfail(xfail)
    if not cmd_found:
        match = re.search(
            r"^test_(.+)\.py$", os.path.basename(str(request.fspath))
        )
        if match:
            cmd = match.group(1)

    request.cls.cmd = cmd

    if (cmd_found and cmd is None) or is_testable(bash, cmd):
        before_env = get_env(bash)
        yield bash
        # Not exactly sure why, but some errors leave bash in state where
        # getting the env here would fail and trash our test output. So
        # reset to a good state first (Ctrl+C, expect prompt).
        bash.sendintr()
        bash.expect_exact(PS1)
        diff_env(
            before_env,
            get_env(bash),
            marker.kwargs.get("ignore_env") if marker else "",
        )

    if marker:
        for post_cmd in marker.kwargs.get("post_cmds", []):
            assert_bash_exec(bash, post_cmd, want_output=None)

    # Clean up
    bash.close()
    if logfile:
        logfile.close()


def is_testable(bash: pexpect.spawn, cmd: Optional[str]) -> bool:
    if not cmd:
        pytest.fail("Could not resolve name of command to test")
        return False
    if not load_completion_for(bash, cmd):
        pytest.skip("No completion for command %s" % cmd)
    return True


def is_bash_type(bash: pexpect.spawn, cmd: Optional[str]) -> bool:
    if not cmd:
        return False
    typecmd = "type %s &>/dev/null && echo -n 0 || echo -n 1" % cmd
    bash.sendline(typecmd)
    bash.expect_exact(typecmd + "\r\n")
    result = bash.expect_exact(["0", "1"]) == 0
    bash.expect_exact(PS1)
    return result


def load_completion_for(bash: pexpect.spawn, cmd: str) -> bool:
    try:
        # Allow __load_completion to fail so we can test completions
        # that are directly loaded in bash_completion without a separate file.
        assert_bash_exec(bash, "__load_completion %s || :" % cmd)
        assert_bash_exec(bash, "complete -p %s &>/dev/null" % cmd)
    except AssertionError:
        return False
    return True


def assert_bash_exec(
    bash: pexpect.spawn,
    cmd: str,
    want_output: Optional[bool] = False,
    want_newline=True,
) -> str:
    """
    :param want_output: if None, don't care if got output or not
    """

    # Send command
    bash.sendline(cmd)
    bash.expect_exact(cmd)

    # Find prompt, output is before it
    bash.expect_exact("%s%s" % ("\r\n" if want_newline else "", PS1))
    output = bash.before

    # Retrieve exit status
    echo = "echo $?"
    bash.sendline(echo)
    got = bash.expect(
        [
            r"^%s\r\n(\d+)\r\n%s" % (re.escape(echo), re.escape(PS1)),
            PS1,
            pexpect.EOF,
            pexpect.TIMEOUT,
        ]
    )
    status = bash.match.group(1) if got == 0 else "unknown"

    assert status == "0", 'Error running "%s": exit status=%s, output="%s"' % (
        cmd,
        status,
        output,
    )
    if want_output is not None:
        if output:
            assert (
                want_output
            ), 'Unexpected output from "%s": exit status=%s, output="%s"' % (
                cmd,
                status,
                output,
            )
        else:
            assert (
                not want_output
            ), 'Expected output from "%s": exit status=%s, output="%s"' % (
                cmd,
                status,
                output,
            )

    return output


def get_env(bash: pexpect.spawn) -> List[str]:
    return (
        assert_bash_exec(
            bash,
            "{ (set -o posix ; set); declare -F; shopt -p; set -o; }",
            want_output=True,
        )
        .strip()
        .splitlines()
    )


def diff_env(before: List[str], after: List[str], ignore: str):
    diff = [
        x
        for x in difflib.unified_diff(before, after, n=0, lineterm="")
        # Remove unified diff markers:
        if not re.search(r"^(---|\+\+\+|@@ )", x)
        # Ignore variables expected to change:
        and not re.search("^[-+](_|PPID|BASH_REMATCH|OLDPWD)=", x)
        # Ignore likely completion functions added by us:
        and not re.search(r"^\+declare -f _.+", x)
        # ...and additional specified things:
        and not re.search(ignore or "^$", x)
    ]
    # For some reason, COMP_WORDBREAKS gets added to the list after
    # saving. Remove its changes, and note that it may take two lines.
    for i in range(0, len(diff)):
        if re.match("^[-+]COMP_WORDBREAKS=", diff[i]):
            if i < len(diff) and not re.match(r"^\+[\w]+=", diff[i + 1]):
                del diff[i + 1]
            del diff[i]
            break
    assert not diff, "Environment should not be modified"


class CompletionResult(Iterable[str]):
    """
    Class to hold completion results.
    """

    def __init__(self, output: Optional[str] = None):
        """
        :param output: All completion output as-is.
        """
        self.output = output or ""

    def endswith(self, suffix: str) -> bool:
        return self.output.endswith(suffix)

    def startswith(self, prefix: str) -> bool:
        return self.output.startswith(prefix)

    def _items(self) -> List[str]:
        return [x.strip() for x in self.output.strip().splitlines()]

    def __eq__(self, expected: object) -> bool:
        """
        Returns True if completion contains expected items, and no others.

        Defining __eq__ this way is quite ugly, but facilitates concise
        testing code.
        """
        if isinstance(expected, str):
            expiter = [expected]  # type: Iterable
        elif not isinstance(expected, Iterable):
            return False
        else:
            expiter = expected
        return self._items() == expiter

    def __contains__(self, item: str) -> bool:
        return item in self._items()

    def __iter__(self) -> Iterator[str]:
        return iter(self._items())

    def __len__(self) -> int:
        return len(self._items())

    def __repr__(self) -> str:
        return "<CompletionResult %s>" % self._items()


def assert_complete(
    bash: pexpect.spawn, cmd: str, **kwargs
) -> CompletionResult:
    skipif = kwargs.get("skipif")
    if skipif:
        try:
            assert_bash_exec(bash, skipif, want_output=None)
        except AssertionError:
            pass
        else:
            pytest.skip(skipif)
    xfail = kwargs.get("xfail")
    if xfail:
        try:
            assert_bash_exec(bash, xfail, want_output=None)
        except AssertionError:
            pass
        else:
            pytest.xfail(xfail)
    cwd = kwargs.get("cwd")
    if cwd:
        assert_bash_exec(bash, "cd '%s'" % cwd)
    env_prefix = "_BASHCOMP_TEST_"
    env = kwargs.get("env", {})
    if env:
        # Back up environment and apply new one
        assert_bash_exec(
            bash,
            " ".join('%s%s="${%s-}"' % (env_prefix, k, k) for k in env.keys()),
        )
        assert_bash_exec(
            bash,
            "export %s" % " ".join("%s=%s" % (k, v) for k, v in env.items()),
        )
    try:
        bash.send(cmd + "\t")
        # Sleep a bit if requested, to avoid `.*` matching too early
        time.sleep(kwargs.get("sleep_after_tab", 0))
        bash.expect_exact(cmd)
        bash.send(MAGIC_MARK)
        got = bash.expect(
            [
                # 0: multiple lines, result in .before
                r"\r\n" + re.escape(PS1 + cmd) + ".*" + re.escape(MAGIC_MARK),
                # 1: no completion
                r"^" + re.escape(MAGIC_MARK),
                # 2: on same line, result in .match
                r"^([^\r]+)%s$" % re.escape(MAGIC_MARK),
                pexpect.EOF,
                pexpect.TIMEOUT,
            ]
        )
        if got == 0:
            output = bash.before
            if output.endswith(MAGIC_MARK):
                output = bash.before[: -len(MAGIC_MARK)]
            result = CompletionResult(output)
        elif got == 2:
            output = bash.match.group(1)
            result = CompletionResult(output)
        else:
            # TODO: warn about EOF/TIMEOUT?
            result = CompletionResult()
    finally:
        bash.sendintr()
        bash.expect_exact(PS1)
        if env:
            # Restore environment, and clean up backup
            # TODO: Test with declare -p if a var was set, backup only if yes, and
            #       similarly restore only backed up vars. Should remove some need
            #       for ignore_env.
            assert_bash_exec(
                bash,
                "export %s"
                % " ".join(
                    '%s="$%s%s"' % (k, env_prefix, k) for k in env.keys()
                ),
            )
            assert_bash_exec(
                bash,
                "unset -v %s"
                % " ".join("%s%s" % (env_prefix, k) for k in env.keys()),
            )
        if cwd:
            assert_bash_exec(bash, "cd - >/dev/null")
    return result


@pytest.fixture
def completion(request, bash: pexpect.spawn) -> CompletionResult:
    marker = request.node.get_closest_marker("complete")
    if not marker:
        return CompletionResult()
    for pre_cmd in marker.kwargs.get("pre_cmds", []):
        assert_bash_exec(bash, pre_cmd, want_output=None)
    cmd = getattr(request.cls, "cmd", None)
    if marker.kwargs.get("require_longopt"):
        # longopt completions require both command presence and that it
        # responds something useful to --help
        if "require_cmd" not in marker.kwargs:
            marker.kwargs["require_cmd"] = True
        if "xfail" not in marker.kwargs:
            marker.kwargs["xfail"] = (
                "! %s --help &>/dev/null || "
                "! %s --help 2>&1 | command grep -qF -- --help"
            ) % ((cmd,) * 2)
    if marker.kwargs.get("require_cmd") and not is_bash_type(bash, cmd):
        pytest.skip("Command not found")

    if "trail" in marker.kwargs:
        return assert_complete_at_point(
            bash, cmd=marker.args[0], trail=marker.kwargs["trail"]
        )

    return assert_complete(bash, marker.args[0], **marker.kwargs)


def assert_complete_at_point(
    bash: pexpect.spawn, cmd: str, trail: str
) -> CompletionResult:
    # TODO: merge to assert_complete
    fullcmd = "%s%s%s" % (
        cmd,
        trail,
        "\002" * len(trail),
    )  # \002 = ^B = cursor left
    bash.send(fullcmd + "\t")
    bash.send(MAGIC_MARK)
    bash.expect_exact(fullcmd.replace("\002", "\b"))

    got = bash.expect_exact(
        [
            # 0: multiple lines, result in .before
            PS1 + fullcmd.replace("\002", "\b"),
            # 1: no completion
            MAGIC_MARK,
            pexpect.EOF,
            pexpect.TIMEOUT,
        ]
    )
    if got == 0:
        output = bash.before
        result = CompletionResult(output)

        # At this point, something weird happens. For most test setups, as
        # expected (pun intended!), MAGIC_MARK follows as is. But for some
        # others (e.g. CentOS 6, Ubuntu 14 test containers), we get MAGIC_MARK
        # one character a time, followed each time by trail and the corresponding
        # number of \b's. Don't know why, but accept it until/if someone finds out.
        # Or just be fine with it indefinitely, the visible and practical end
        # result on a terminal is the same anyway.
        repeat = "(%s%s)?" % (re.escape(trail), "\b" * len(trail))
        fullexpected = "".join(
            "%s%s" % (re.escape(x), repeat) for x in MAGIC_MARK
        )
        bash.expect(fullexpected)
    else:
        # TODO: warn about EOF/TIMEOUT?
        result = CompletionResult()

    return result


def in_container() -> bool:
    try:
        container = subprocess.check_output(
            "virt-what || systemd-detect-virt --container",
            stderr=subprocess.DEVNULL,
            shell=True,
        ).strip()
    except subprocess.CalledProcessError:
        container = b""
    if container and container != b"none":
        return True
    if os.path.exists("/.dockerenv"):
        return True
    try:
        with open("/proc/1/environ", "rb") as f:
            # LXC, others?
            if any(
                x.startswith(b"container=") for x in f.readline().split(b"\0")
            ):
                return True
    except OSError:
        pass
    return False


def prepare_fixture_dir(
    request, files: Iterable[str], dirs: Iterable[str]
) -> Tuple[Path, List[str], List[str]]:
    """
    Fixture to prepare a test dir with dummy contents on the fly.

    Tests that contain filenames differing only by case should use this to
    prepare a dir on the fly rather than including their fixtures in git and
    the tarball. This is to work better with case insensitive file systems.
    """
    tempdir = Path(tempfile.mkdtemp(prefix="bash-completion-fixture-dir"))
    request.addfinalizer(lambda: shutil.rmtree(str(tempdir)))

    new_files = []
    new_dirs = []

    for file_ in files:
        path = tempdir / file_
        if not path.exists():
            path.touch()
            new_files.append(file_)
    for dir_ in dirs:
        path = tempdir / dir_
        if not path.exists():
            path.mkdir()
            new_dirs.append(dir_)

    return tempdir, sorted(new_files), sorted(new_dirs)


class TestUnitBase:
    def _test_unit(
        self, func, bash, comp_words, comp_cword, comp_line, comp_point, arg=""
    ):
        assert_bash_exec(
            bash,
            "COMP_WORDS=%s COMP_CWORD=%d COMP_LINE=%s COMP_POINT=%d"
            % (comp_words, comp_cword, shlex.quote(comp_line), comp_point),
        )
        output = assert_bash_exec(bash, func % arg, want_output=True)
        return output.strip()
