# vim: ft=python fileencoding=utf-8 sts=4 sw=4 et:

# Copyright 2015-2021 Florian Bruhin (The Compiler) <mail@qutebrowser.org>
#
# This file is part of qutebrowser.
#
# qutebrowser is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# qutebrowser is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with qutebrowser.  If not, see <https://www.gnu.org/licenses/>.

"""Base class for a subprocess run for tests."""

import re
import time
import warnings
import dataclasses

import pytest
import pytestqt.wait_signal
from PyQt5.QtCore import (pyqtSlot, pyqtSignal, QProcess, QObject,
                          QElapsedTimer, QProcessEnvironment)
from PyQt5.QtTest import QSignalSpy

from helpers import testutils

from qutebrowser.utils import utils as quteutils


class InvalidLine(Exception):

    """Raised when the process prints a line which is not parsable."""


class ProcessExited(Exception):

    """Raised when the child process did exit."""


class WaitForTimeout(Exception):

    """Raised when wait_for didn't get the expected message."""


class BlacklistedMessageError(Exception):

    """Raised when ensure_not_logged found a message."""


@dataclasses.dataclass
class Line:

    """Container for a line of data the process emits.

    Attributes:
        data: The raw data passed to the constructor.
        waited_for: If Process.wait_for was used on this line already.
    """

    data: str
    waited_for: bool = False


def _render_log(data, *, verbose, threshold=100):
    """Shorten the given log without -v and convert to a string."""
    data = [str(d) for d in data]
    is_exception = any('Traceback (most recent call last):' in line or
                       'Uncaught exception' in line for line in data)
    if (len(data) > threshold and
            not verbose and
            not is_exception and
            not testutils.ON_CI):
        msg = '[{} lines suppressed, use -v to show]'.format(
            len(data) - threshold)
        data = [msg] + data[-threshold:]

    if testutils.ON_CI:
        data = [testutils.gha_group_begin('Log')] + data + [testutils.gha_group_end()]

    return '\n'.join(data)


@pytest.hookimpl(hookwrapper=True)
def pytest_runtest_makereport(item, call):
    """Add qutebrowser/server sections to captured output if a test failed."""
    outcome = yield
    if call.when not in ['call', 'teardown']:
        return
    report = outcome.get_result()

    if report.passed:
        return

    quteproc_log = getattr(item, '_quteproc_log', None)
    server_logs = getattr(item, '_server_logs', [])

    if not hasattr(report.longrepr, 'addsection'):
        # In some conditions (on macOS and Windows it seems), report.longrepr
        # is actually a tuple. This is handled similarly in pytest-qt too.
        return

    if item.config.getoption('--capture') == 'no':
        # Already printed live
        return

    verbose = item.config.getoption('--verbose')
    if quteproc_log is not None:
        report.longrepr.addsection(
            "qutebrowser output", _render_log(quteproc_log, verbose=verbose))
    for name, content in server_logs:
        report.longrepr.addsection(
            f"{name} output", _render_log(content, verbose=verbose))


class Process(QObject):

    """Abstraction over a running test subprocess process.

    Reads the log from its stdout and parses it.

    Attributes:
        _invalid: A list of lines which could not be parsed.
        _data: A list of parsed lines.
        _started: Whether the process was ever started.
        proc: The QProcess for the underlying process.
        exit_expected: Whether the process is expected to quit.
        request: The request object for the current test.

    Signals:
        ready: Emitted when the server finished starting up.
        new_data: Emitted when a new line was parsed.
    """

    ready = pyqtSignal()
    new_data = pyqtSignal(object)
    KEYS = ['data']

    def __init__(self, request, parent=None):
        super().__init__(parent)
        self.request = request
        self.captured_log = []
        self._started = False
        self._invalid = []
        self._data = []
        self.proc = QProcess()
        self.proc.setReadChannel(QProcess.StandardError)
        self.exit_expected = None  # Not started at all yet

    def _log(self, line):
        """Add the given line to the captured log output."""
        if self.request.config.getoption('--capture') == 'no':
            print(line)
        self.captured_log.append(line)

    def log_summary(self, text):
        """Log the given line as summary/title."""
        text = '\n{line} {text} {line}\n'.format(line='='*30, text=text)
        self._log(text)

    def _parse_line(self, line):
        """Parse the given line from the log.

        Return:
            A self.ParseResult member.
        """
        raise NotImplementedError

    def _executable_args(self):
        """Get the executable and necessary arguments as a tuple."""
        raise NotImplementedError

    def _default_args(self):
        """Get the default arguments to use if none were passed to start()."""
        raise NotImplementedError

    def _get_data(self):
        """Get the parsed data for this test.

        Also waits for 0.5s to make sure any new data is received.

        Subprocesses are expected to alias this to a public method with a
        better name.
        """
        self.proc.waitForReadyRead(500)
        self.read_log()
        return self._data

    def _wait_signal(self, signal, timeout=5000, raising=True):
        """Wait for a signal to be emitted.

        Should be used in a contextmanager.
        """
        blocker = pytestqt.wait_signal.SignalBlocker(timeout=timeout, raising=raising)
        blocker.connect(signal)
        return blocker

    @pyqtSlot()
    def read_log(self):
        """Read the log from the process' stdout."""
        if not hasattr(self, 'proc'):
            # I have no idea how this happens, but it does...
            return
        while self.proc.canReadLine():
            line = self.proc.readLine()
            line = bytes(line).decode('utf-8', errors='ignore').rstrip('\r\n')

            try:
                parsed = self._parse_line(line)
            except InvalidLine:
                self._invalid.append(line)
                self._log("INVALID: {}".format(line))
                continue

            if parsed is None:
                if self._invalid:
                    self._log("IGNORED: {}".format(line))
            else:
                self._data.append(parsed)
                self.new_data.emit(parsed)

    def start(self, args=None, *, env=None):
        """Start the process and wait until it started."""
        self._start(args, env=env)
        self._started = True
        verbose = self.request.config.getoption('--verbose')

        timeout = 60 if testutils.ON_CI else 20
        for _ in range(timeout):
            with self._wait_signal(self.ready, timeout=1000,
                                   raising=False) as blocker:
                pass

            if not self.is_running():
                if self.exit_expected:
                    return
                # _start ensures it actually started, but it might quit shortly
                # afterwards
                raise ProcessExited('\n' + _render_log(self.captured_log,
                                                       verbose=verbose))

            if blocker.signal_triggered:
                self._after_start()
                return

        raise WaitForTimeout("Timed out while waiting for process start.\n" +
                             _render_log(self.captured_log, verbose=verbose))

    def _start(self, args, env):
        """Actually start the process."""
        executable, exec_args = self._executable_args()
        if args is None:
            args = self._default_args()

        procenv = QProcessEnvironment.systemEnvironment()
        if env is not None:
            for k, v in env.items():
                procenv.insert(k, v)

        self.proc.readyRead.connect(self.read_log)
        self.proc.setProcessEnvironment(procenv)
        self.proc.start(executable, exec_args + args)
        ok = self.proc.waitForStarted()
        assert ok
        assert self.is_running()

    def _after_start(self):
        """Do things which should be done immediately after starting."""

    def before_test(self):
        """Restart process before a test if it exited before."""
        self._invalid = []
        if not self.is_running():
            self.start()

    def after_test(self):
        """Clean up data after each test.

        Also checks self._invalid so the test counts as failed if there were
        unexpected output lines earlier.
        """
        __tracebackhide__ = lambda e: e.errisinstance(ProcessExited)
        self.captured_log = []
        if self._invalid:
            # Wait for a bit so the full error has a chance to arrive
            time.sleep(1)
            # Exit the process to make sure we're in a defined state again
            self.terminate()
            self.clear_data()
            raise InvalidLine('\n' + '\n'.join(self._invalid))

        self.clear_data()
        if not self.is_running() and not self.exit_expected and self._started:
            raise ProcessExited
        self.exit_expected = False

    def clear_data(self):
        """Clear the collected data."""
        self._data.clear()

    def terminate(self):
        """Clean up and shut down the process."""
        if not self.is_running():
            return

        if quteutils.is_windows:
            self.proc.kill()
        else:
            self.proc.terminate()

        ok = self.proc.waitForFinished(5000)
        if not ok:
            cmdline = ' '.join([self.proc.program()] + self.proc.arguments())
            warnings.warn(f"Test process {cmdline} with PID {self.proc.processId()} "
                          "failed to terminate!")
            self.proc.kill()
            self.proc.waitForFinished()

    def is_running(self):
        """Check if the process is currently running."""
        return self.proc.state() == QProcess.Running

    def _match_data(self, value, expected):
        """Helper for wait_for to match a given value.

        The behavior of this method is slightly different depending on the
        types of the filtered values:

        - If expected is None, the filter always matches.
        - If the value is a string or bytes object and the expected value is
          too, the pattern is treated as a glob pattern (with only * active).
        - If the value is a string or bytes object and the expected value is a
          compiled regex, it is used for matching.
        - If the value is any other type, == is used.

        Return:
            A bool
        """
        regex_type = type(re.compile(''))
        if expected is None:
            return True
        elif isinstance(expected, regex_type):
            return expected.search(value)
        elif isinstance(value, (bytes, str)):
            return testutils.pattern_match(pattern=expected, value=value)
        else:
            return value == expected

    def _wait_for_existing(self, override_waited_for, after, **kwargs):
        """Check if there are any line in the history for wait_for.

        Return: either the found line or None.
        """
        for line in self._data:
            matches = []

            for key, expected in kwargs.items():
                value = getattr(line, key)
                matches.append(self._match_data(value, expected))

            if after is None:
                too_early = False
            else:
                too_early = ((line.timestamp, line.msecs) <
                             (after.timestamp, after.msecs))

            if (all(matches) and
                    (not line.waited_for or override_waited_for) and
                    not too_early):
                # If we waited for this line, chances are we don't mean the
                # same thing the next time we use wait_for and it matches
                # this line again.
                line.waited_for = True
                self._log("\n----> Already found {!r} in the log: {}".format(
                    kwargs.get('message', 'line'), line))
                return line
        return None

    def _wait_for_new(self, timeout, do_skip, **kwargs):
        """Wait for a log message which doesn't exist yet.

        Called via wait_for.
        """
        __tracebackhide__ = lambda e: e.errisinstance(WaitForTimeout)
        message = kwargs.get('message', None)
        if message is not None:
            elided = quteutils.elide(repr(message), 100)
            self._log("\n----> Waiting for {} in the log".format(elided))

        spy = QSignalSpy(self.new_data)
        elapsed_timer = QElapsedTimer()
        elapsed_timer.start()

        while True:
            # Skip if there are pending messages causing a skip
            self._maybe_skip()
            got_signal = spy.wait(timeout)
            if not got_signal or elapsed_timer.hasExpired(timeout):
                msg = "Timed out after {}ms waiting for {!r}.".format(
                    timeout, kwargs)
                if do_skip:
                    pytest.skip(msg)
                else:
                    raise WaitForTimeout(msg)

            match = self._wait_for_match(spy, kwargs)
            if match is not None:
                if message is not None:
                    self._log("----> found it")
                return match

        raise quteutils.Unreachable

    def _wait_for_match(self, spy, kwargs):
        """Try matching the kwargs with the given QSignalSpy."""
        for args in spy:
            assert len(args) == 1
            line = args[0]

            matches = []

            for key, expected in kwargs.items():
                value = getattr(line, key)
                matches.append(self._match_data(value, expected))

            if all(matches):
                # If we waited for this line, chances are we don't mean the
                # same thing the next time we use wait_for and it matches
                # this line again.
                line.waited_for = True
                return line
        return None

    def _maybe_skip(self):
        """Can be overridden by subclasses to skip on certain log lines.

        We can't run pytest.skip directly while parsing the log, as that would
        lead to a pytest.skip.Exception error in a virtual Qt method, which
        means pytest-qt fails the test.

        Instead, we check for skip messages periodically in
        QuteProc._maybe_skip, and call _maybe_skip after every parsed message
        in wait_for (where it's most likely that new messages arrive).
        """

    def wait_for(self, timeout=None, *, override_waited_for=False,
                 do_skip=False, divisor=1, after=None, **kwargs):
        """Wait until a given value is found in the data.

        Keyword arguments to this function get interpreted as attributes of the
        searched data. Every given argument is treated as a pattern which
        the attribute has to match against.

        Args:
            timeout: How long to wait for the message.
            override_waited_for: If set, gets triggered by previous messages
                                 again.
            do_skip: If set, call pytest.skip on a timeout.
            divisor: A factor to decrease the timeout by.
            after: If it's an existing line, ensure it's after the given one.

        Return:
            The matched line.
        """
        __tracebackhide__ = lambda e: e.errisinstance(WaitForTimeout)

        if timeout is None:
            if do_skip:
                timeout = 2000
            elif testutils.ON_CI:
                timeout = 15000
            else:
                timeout = 5000

        timeout //= divisor

        if not kwargs:
            raise TypeError("No keyword arguments given!")
        for key in kwargs:
            assert key in self.KEYS

        existing = self._wait_for_existing(override_waited_for, after,
                                           **kwargs)
        if existing is not None:
            return existing
        else:
            return self._wait_for_new(timeout=timeout, do_skip=do_skip,
                                      **kwargs)

    def ensure_not_logged(self, delay=500, **kwargs):
        """Make sure the data matching the given arguments is not logged.

        If nothing is found in the log, we wait for delay ms to make sure
        nothing arrives.
        """
        __tracebackhide__ = lambda e: e.errisinstance(BlacklistedMessageError)
        try:
            line = self.wait_for(timeout=delay, override_waited_for=True,
                                 **kwargs)
        except WaitForTimeout:
            return
        else:
            raise BlacklistedMessageError(line)

    def wait_for_quit(self):
        """Wait until the process has quit."""
        self.exit_expected = True
        with self._wait_signal(self.proc.finished, timeout=15000):
            pass
        assert not self.is_running()
