"""
support for presenting detailed information in failing assertions.
"""
import py
import os
import sys

from _pytest.assertion import util
from _pytest.assertion import rewrite


def pytest_addoption(parser):
    group = parser.getgroup("debugconfig")
    group.addoption('--assert',
                    action="store",
                    dest="assertmode",
                    choices=("rewrite", "reinterp", "plain",),
                    default="rewrite",
                    metavar="MODE",
                    help="""control assertion debugging tools.  'plain'
                            performs no assertion debugging.  'reinterp'
                            reinterprets assert statements after they failed
                            to provide assertion expression information.
                            'rewrite' (the default) rewrites assert
                            statements in test modules on import to
                            provide assert expression information. """)


def pytest_namespace():
    return {'register_assert_rewrite': register_assert_rewrite}


def register_assert_rewrite(*names):
    """Register a module name to be rewritten on import.

    This function will make sure that the module will get it's assert
    statements rewritten when it is imported.  Thus you should make
    sure to call this before the module is actually imported, usually
    in your __init__.py if you are a plugin using a package.
    """
    for hook in sys.meta_path:
        if isinstance(hook, rewrite.AssertionRewritingHook):
            importhook = hook
            break
    else:
        importhook = DummyRewriteHook()
    importhook.mark_rewrite(*names)


class DummyRewriteHook(object):
    """A no-op import hook for when rewriting is disabled."""

    def mark_rewrite(self, *names):
        pass


class AssertionState:
    """State for the assertion plugin."""

    def __init__(self, config, mode):
        self.mode = mode
        self.trace = config.trace.root.get("assertion")


def install_importhook(config, mode):
    if mode == "rewrite":
        try:
            import ast  # noqa
        except ImportError:
            mode = "reinterp"
        else:
            # Both Jython and CPython 2.6.0 have AST bugs that make the
            # assertion rewriting hook malfunction.
            if (sys.platform.startswith('java') or
                    sys.version_info[:3] == (2, 6, 0)):
                mode = "reinterp"

    config._assertstate = AssertionState(config, mode)

    _load_modules(mode)
    from _pytest.monkeypatch import MonkeyPatch
    m = MonkeyPatch()
    config._cleanup.append(m.undo)
    m.setattr(py.builtin.builtins, 'AssertionError',
              reinterpret.AssertionError)  # noqa

    hook = None
    if mode == "rewrite":
        hook = rewrite.AssertionRewritingHook(config)  # noqa
        sys.meta_path.insert(0, hook)

    config._assertstate.hook = hook
    config._assertstate.trace("configured with mode set to %r" % (mode,))
    def undo():
        hook = config._assertstate.hook
        if hook is not None and hook in sys.meta_path:
            sys.meta_path.remove(hook)
    config.add_cleanup(undo)
    return hook


def pytest_collection(session):
    # this hook is only called when test modules are collected
    # so for example not in the master process of pytest-xdist
    # (which does not collect test modules)
    assertstate = getattr(session.config, '_assertstate', None)
    if assertstate:
        if assertstate.hook is not None:
            assertstate.hook.set_session(session)


def _running_on_ci():
    """Check if we're currently running on a CI system."""
    env_vars = ['CI', 'BUILD_NUMBER']
    return any(var in os.environ for var in env_vars)


def pytest_runtest_setup(item):
    """Setup the pytest_assertrepr_compare hook

    The newinterpret and rewrite modules will use util._reprcompare if
    it exists to use custom reporting via the
    pytest_assertrepr_compare hook.  This sets up this custom
    comparison for the test.
    """
    def callbinrepr(op, left, right):
        """Call the pytest_assertrepr_compare hook and prepare the result

        This uses the first result from the hook and then ensures the
        following:
        * Overly verbose explanations are dropped unless -vv was used or
          running on a CI.
        * Embedded newlines are escaped to help util.format_explanation()
          later.
        * If the rewrite mode is used embedded %-characters are replaced
          to protect later % formatting.

        The result can be formatted by util.format_explanation() for
        pretty printing.
        """
        hook_result = item.ihook.pytest_assertrepr_compare(
            config=item.config, op=op, left=left, right=right)
        for new_expl in hook_result:
            if new_expl:
                if (sum(len(p) for p in new_expl[1:]) > 80*8 and
                        item.config.option.verbose < 2 and
                        not _running_on_ci()):
                    show_max = 10
                    truncated_lines = len(new_expl) - show_max
                    new_expl[show_max:] = [py.builtin._totext(
                        'Detailed information truncated (%d more lines)'
                        ', use "-vv" to show' % truncated_lines)]
                new_expl = [line.replace("\n", "\\n") for line in new_expl]
                res = py.builtin._totext("\n~").join(new_expl)
                if item.config.getvalue("assertmode") == "rewrite":
                    res = res.replace("%", "%%")
                return res
    util._reprcompare = callbinrepr


def pytest_runtest_teardown(item):
    util._reprcompare = None


def pytest_sessionfinish(session):
    assertstate = getattr(session.config, '_assertstate', None)
    if assertstate:
        if assertstate.hook is not None:
            assertstate.hook.set_session(None)


def _load_modules(mode):
    """Lazily import assertion related code."""
    global rewrite, reinterpret
    from _pytest.assertion import reinterpret  # noqa
    if mode == "rewrite":
        from _pytest.assertion import rewrite  # noqa


# Expose this plugin's implementation for the pytest_assertrepr_compare hook
pytest_assertrepr_compare = util.assertrepr_compare