"""
per-test stdout/stderr capturing mechanism.

"""
from __future__ import with_statement

import sys
import os
from tempfile import TemporaryFile
import contextlib

import py
import pytest

from py.io import TextIO
unicode = py.builtin.text

patchsysdict = {0: 'stdin', 1: 'stdout', 2: 'stderr'}


def pytest_addoption(parser):
    group = parser.getgroup("general")
    group._addoption(
        '--capture', action="store", default=None,
        metavar="method", choices=['fd', 'sys', 'no'],
        help="per-test capturing method: one of fd (default)|sys|no.")
    group._addoption(
        '-s', action="store_const", const="no", dest="capture",
        help="shortcut for --capture=no.")


@pytest.mark.tryfirst
def pytest_load_initial_conftests(early_config, parser, args, __multicall__):
    ns = parser.parse_known_args(args)
    method = ns.capture
    if not method:
        method = "fd"
    if method == "fd" and not hasattr(os, "dup"):
        method = "sys"
    pluginmanager = early_config.pluginmanager
    if method != "no":
        dupped_stdout = safe_text_dupfile(sys.stdout, "wb")
        pluginmanager.register(dupped_stdout, "dupped_stdout")
            #pluginmanager.add_shutdown(dupped_stdout.close)
    capman = CaptureManager(method)
    pluginmanager.register(capman, "capturemanager")

    # make sure that capturemanager is properly reset at final shutdown
    def teardown():
        try:
            capman.reset_capturings()
        except ValueError:
            pass

    pluginmanager.add_shutdown(teardown)

    # make sure logging does not raise exceptions at the end
    def silence_logging_at_shutdown():
        if "logging" in sys.modules:
            sys.modules["logging"].raiseExceptions = False
    pluginmanager.add_shutdown(silence_logging_at_shutdown)

    # finally trigger conftest loading but while capturing (issue93)
    capman.resumecapture()
    try:
        try:
            return __multicall__.execute()
        finally:
            out, err = capman.suspendcapture()
    except:
        sys.stdout.write(out)
        sys.stderr.write(err)
        raise



class CaptureManager:
    def __init__(self, defaultmethod=None):
        self._method2capture = {}
        self._defaultmethod = defaultmethod

    def _getcapture(self, method):
        if method == "fd":
            return MultiCapture(out=True, err=True, Capture=FDCapture)
        elif method == "sys":
            return MultiCapture(out=True, err=True, Capture=SysCapture)
        elif method == "no":
            return MultiCapture(out=False, err=False, in_=False)
        else:
            raise ValueError("unknown capturing method: %r" % method)

    def _getmethod(self, config, fspath):
        if config.option.capture:
            method = config.option.capture
        else:
            try:
                method = config._conftest.rget("option_capture", path=fspath)
            except KeyError:
                method = "fd"
        if method == "fd" and not hasattr(os, 'dup'):  # e.g. jython
            method = "sys"
        return method

    def reset_capturings(self):
        for cap in self._method2capture.values():
            cap.pop_outerr_to_orig()
            cap.stop_capturing()
        self._method2capture.clear()

    def resumecapture_item(self, item):
        method = self._getmethod(item.config, item.fspath)
        return self.resumecapture(method)

    def resumecapture(self, method=None):
        if hasattr(self, '_capturing'):
            raise ValueError(
                "cannot resume, already capturing with %r" %
                (self._capturing,))
        if method is None:
            method = self._defaultmethod
        cap = self._method2capture.get(method)
        self._capturing = method
        if cap is None:
            self._method2capture[method] = cap = self._getcapture(method)
            cap.start_capturing()
        else:
            cap.pop_outerr_to_orig()

    def suspendcapture(self, item=None):
        self.deactivate_funcargs()
        method = self.__dict__.pop("_capturing", None)
        if method is not None:
            cap = self._method2capture.get(method)
            if cap is not None:
                return cap.readouterr()
        return "", ""

    def activate_funcargs(self, pyfuncitem):
        capfuncarg = pyfuncitem.__dict__.pop("_capfuncarg", None)
        if capfuncarg is not None:
            capfuncarg._start()
            self._capfuncarg = capfuncarg

    def deactivate_funcargs(self):
        capfuncarg = self.__dict__.pop("_capfuncarg", None)
        if capfuncarg is not None:
            capfuncarg.close()

    @pytest.mark.hookwrapper
    def pytest_make_collect_report(self, __multicall__, collector):
        method = self._getmethod(collector.config, collector.fspath)
        try:
            self.resumecapture(method)
        except ValueError:
            yield
            # recursive collect, XXX refactor capturing
            # to allow for more lightweight recursive capturing
            return
        yield
        out, err = self.suspendcapture()
        # XXX getting the report from the ongoing hook call is a bit
        # of a hack.  We need to think about capturing during collection
        # and find out if it's really needed fine-grained (per
        # collector).
        if __multicall__.results:
            rep = __multicall__.results[0]
            if out:
                rep.sections.append(("Captured stdout", out))
            if err:
                rep.sections.append(("Captured stderr", err))

    @pytest.mark.hookwrapper
    def pytest_runtest_setup(self, item):
        with self.item_capture_wrapper(item, "setup"):
            yield

    @pytest.mark.hookwrapper
    def pytest_runtest_call(self, item):
        with self.item_capture_wrapper(item, "call"):
            self.activate_funcargs(item)
            yield
            #self.deactivate_funcargs() called from ctx's suspendcapture()

    @pytest.mark.hookwrapper
    def pytest_runtest_teardown(self, item):
        with self.item_capture_wrapper(item, "teardown"):
            yield

    @pytest.mark.tryfirst
    def pytest_keyboard_interrupt(self, excinfo):
        self.reset_capturings()

    @pytest.mark.tryfirst
    def pytest_internalerror(self, excinfo):
        self.reset_capturings()

    @contextlib.contextmanager
    def item_capture_wrapper(self, item, when):
        self.resumecapture_item(item)
        yield
        out, err = self.suspendcapture(item)
        item.add_report_section(when, "out", out)
        item.add_report_section(when, "err", err)

error_capsysfderror = "cannot use capsys and capfd at the same time"


@pytest.fixture
def capsys(request):
    """enables capturing of writes to sys.stdout/sys.stderr and makes
    captured output available via ``capsys.readouterr()`` method calls
    which return a ``(out, err)`` tuple.
    """
    if "capfd" in request._funcargs:
        raise request.raiseerror(error_capsysfderror)
    request.node._capfuncarg = c = CaptureFixture(SysCapture)
    return c

@pytest.fixture
def capfd(request):
    """enables capturing of writes to file descriptors 1 and 2 and makes
    captured output available via ``capsys.readouterr()`` method calls
    which return a ``(out, err)`` tuple.
    """
    if "capsys" in request._funcargs:
        request.raiseerror(error_capsysfderror)
    if not hasattr(os, 'dup'):
        pytest.skip("capfd funcarg needs os.dup")
    request.node._capfuncarg = c = CaptureFixture(FDCapture)
    return c


class CaptureFixture:
    def __init__(self, captureclass):
        self.captureclass = captureclass

    def _start(self):
        self._capture = MultiCapture(out=True, err=True, in_=False,
                                       Capture=self.captureclass)
        self._capture.start_capturing()

    def close(self):
        cap = self.__dict__.pop("_capture", None)
        if cap is not None:
            cap.pop_outerr_to_orig()
            cap.stop_capturing()

    def readouterr(self):
        try:
            return self._capture.readouterr()
        except AttributeError:
            return "", ""


def safe_text_dupfile(f, mode, default_encoding="UTF8"):
    """ return a open text file object that's a duplicate of f on the
        FD-level if possible.
    """
    encoding = getattr(f, "encoding", None)
    try:
        fd = f.fileno()
    except Exception:
        if "b" not in getattr(f, "mode", "") and hasattr(f, "encoding"):
            # we seem to have a text stream, let's just use it
            return f
    else:
        newfd = os.dup(fd)
        if "b" not in mode:
            mode += "b"
        f = os.fdopen(newfd, mode, 0)  # no buffering
    return EncodedFile(f, encoding or default_encoding)


class EncodedFile(object):
    def __init__(self, buffer, encoding):
        self.buffer = buffer
        self.encoding = encoding

    def write(self, obj):
        if isinstance(obj, unicode):
            obj = obj.encode(self.encoding, "replace")
        self.buffer.write(obj)

    def writelines(self, linelist):
        data = ''.join(linelist)
        self.write(data)

    def __getattr__(self, name):
        return getattr(self.buffer, name)


class MultiCapture(object):
    out = err = in_ = None

    def __init__(self, out=True, err=True, in_=True, Capture=None):
        if in_:
            self.in_ = Capture(0)
        if out:
            self.out = Capture(1)
        if err:
            self.err = Capture(2)

    def start_capturing(self):
        if self.in_:
            self.in_.start()
        if self.out:
            self.out.start()
        if self.err:
            self.err.start()

    def pop_outerr_to_orig(self):
        """ pop current snapshot out/err capture and flush to orig streams. """
        out, err = self.readouterr()
        if out:
            self.out.writeorg(out)
        if err:
            self.err.writeorg(err)

    def stop_capturing(self):
        """ stop capturing and reset capturing streams """
        if hasattr(self, '_reset'):
            raise ValueError("was already stopped")
        self._reset = True
        if self.out:
            self.out.done()
        if self.err:
            self.err.done()
        if self.in_:
            self.in_.done()

    def readouterr(self):
        """ return snapshot unicode value of stdout/stderr capturings. """
        return (self.out.snap() if self.out is not None else "",
                self.err.snap() if self.err is not None else "")

class NoCapture:
    __init__ = start = done = lambda *args: None

class FDCapture:
    """ Capture IO to/from a given os-level filedescriptor. """

    def __init__(self, targetfd, tmpfile=None):
        self.targetfd = targetfd
        try:
            self.targetfd_save = os.dup(self.targetfd)
        except OSError:
            self.start = lambda: None
            self.done = lambda: None
        else:
            if targetfd == 0:
                assert not tmpfile, "cannot set tmpfile with stdin"
                tmpfile = open(os.devnull, "r")
                self.syscapture = SysCapture(targetfd)
            else:
                if tmpfile is None:
                    f = TemporaryFile()
                    with f:
                        tmpfile = safe_text_dupfile(f, mode="wb+")
                if targetfd in patchsysdict:
                    self.syscapture = SysCapture(targetfd, tmpfile)
                else:
                    self.syscapture = NoCapture()
            self.tmpfile = tmpfile
            self.tmpfile_fd = tmpfile.fileno()

    def __repr__(self):
        return "<FDCapture %s oldfd=%s>" % (self.targetfd, self.targetfd_save)

    def start(self):
        """ Start capturing on targetfd using memorized tmpfile. """
        try:
            os.fstat(self.targetfd_save)
        except (AttributeError, OSError):
            raise ValueError("saved filedescriptor not valid anymore")
        os.dup2(self.tmpfile_fd, self.targetfd)
        self.syscapture.start()

    def snap(self):
        f = self.tmpfile
        f.seek(0)
        res = f.read()
        if res:
            enc = getattr(f, "encoding", None)
            if enc and isinstance(res, bytes):
                res = py.builtin._totext(res, enc, "replace")
            f.truncate(0)
            f.seek(0)
        return res

    def done(self):
        """ stop capturing, restore streams, return original capture file,
        seeked to position zero. """
        targetfd_save = self.__dict__.pop("targetfd_save")
        os.dup2(targetfd_save, self.targetfd)
        os.close(targetfd_save)
        self.syscapture.done()
        self.tmpfile.close()

    def suspend(self):
        self.syscapture.suspend()
        os.dup2(self.targetfd_save, self.targetfd)

    def resume(self):
        self.syscapture.resume()
        os.dup2(self.tmpfile_fd, self.targetfd)

    def writeorg(self, data):
        """ write to original file descriptor. """
        if py.builtin._istext(data):
            data = data.encode("utf8") # XXX use encoding of original stream
        os.write(self.targetfd_save, data)


class SysCapture:
    def __init__(self, fd, tmpfile=None):
        name = patchsysdict[fd]
        self._old = getattr(sys, name)
        self.name = name
        if tmpfile is None:
            if name == "stdin":
                tmpfile = DontReadFromInput()
            else:
                tmpfile = TextIO()
        self.tmpfile = tmpfile

    def start(self):
        setattr(sys, self.name, self.tmpfile)

    def snap(self):
        f = self.tmpfile
        res = f.getvalue()
        f.truncate(0)
        f.seek(0)
        return res

    def done(self):
        setattr(sys, self.name, self._old)
        del self._old
        self.tmpfile.close()

    def suspend(self):
        setattr(sys, self.name, self._old)

    def resume(self):
        setattr(sys, self.name, self.tmpfile)

    def writeorg(self, data):
        self._old.write(data)
        self._old.flush()


class DontReadFromInput:
    """Temporary stub class.  Ideally when stdin is accessed, the
    capturing should be turned off, with possibly all data captured
    so far sent to the screen.  This should be configurable, though,
    because in automated test runs it is better to crash than
    hang indefinitely.
    """
    def read(self, *args):
        raise IOError("reading from stdin while output is captured")
    readline = read
    readlines = read
    __iter__ = read

    def fileno(self):
        raise ValueError("redirected Stdin is pseudofile, has no fileno()")

    def isatty(self):
        return False

    def close(self):
        pass