"""
merged implementation of the cache provider

the name cache was not chosen to ensure pluggy automatically
ignores the external pytest-cache
"""
from __future__ import absolute_import, division, print_function
import py
import pytest
import json
import os
from os.path import sep as _sep, altsep as _altsep


class Cache(object):
    def __init__(self, config):
        self.config = config
        self._cachedir = Cache.cache_dir_from_config(config)
        self.trace = config.trace.root.get("cache")
        if config.getvalue("cacheclear"):
            self.trace("clearing cachedir")
            if self._cachedir.check():
                self._cachedir.remove()
            self._cachedir.mkdir()

    @staticmethod
    def cache_dir_from_config(config):
        cache_dir = config.getini("cache_dir")
        cache_dir = os.path.expanduser(cache_dir)
        cache_dir = os.path.expandvars(cache_dir)
        if os.path.isabs(cache_dir):
            return py.path.local(cache_dir)
        else:
            return config.rootdir.join(cache_dir)

    def makedir(self, name):
        """ return a directory path object with the given name.  If the
        directory does not yet exist, it will be created.  You can use it
        to manage files likes e. g. store/retrieve database
        dumps across test sessions.

        :param name: must be a string not containing a ``/`` separator.
             Make sure the name contains your plugin or application
             identifiers to prevent clashes with other cache users.
        """
        if _sep in name or _altsep is not None and _altsep in name:
            raise ValueError("name is not allowed to contain path separators")
        return self._cachedir.ensure_dir("d", name)

    def _getvaluepath(self, key):
        return self._cachedir.join('v', *key.split('/'))

    def get(self, key, default):
        """ return cached value for the given key.  If no value
        was yet cached or the value cannot be read, the specified
        default is returned.

        :param key: must be a ``/`` separated value. Usually the first
             name is the name of your plugin or your application.
        :param default: must be provided in case of a cache-miss or
             invalid cache values.

        """
        path = self._getvaluepath(key)
        if path.check():
            try:
                with path.open("r") as f:
                    return json.load(f)
            except ValueError:
                self.trace("cache-invalid at %s" % (path,))
        return default

    def set(self, key, value):
        """ save value for the given key.

        :param key: must be a ``/`` separated value. Usually the first
             name is the name of your plugin or your application.
        :param value: must be of any combination of basic
               python types, including nested types
               like e. g. lists of dictionaries.
        """
        path = self._getvaluepath(key)
        try:
            path.dirpath().ensure_dir()
        except (py.error.EEXIST, py.error.EACCES):
            self.config.warn(
                code='I9', message='could not create cache path %s' % (path,)
            )
            return
        try:
            f = path.open('w')
        except py.error.ENOTDIR:
            self.config.warn(
                code='I9', message='cache could not write path %s' % (path,))
        else:
            with f:
                self.trace("cache-write %s: %r" % (key, value,))
                json.dump(value, f, indent=2, sort_keys=True)


class LFPlugin:
    """ Plugin which implements the --lf (run last-failing) option """

    def __init__(self, config):
        self.config = config
        active_keys = 'lf', 'failedfirst'
        self.active = any(config.getvalue(key) for key in active_keys)
        self.lastfailed = config.cache.get("cache/lastfailed", {})
        self._previously_failed_count = None

    def pytest_report_collectionfinish(self):
        if self.active:
            if not self._previously_failed_count:
                mode = "run all (no recorded failures)"
            else:
                noun = 'failure' if self._previously_failed_count == 1 else 'failures'
                suffix = " first" if self.config.getvalue("failedfirst") else ""
                mode = "rerun previous {count} {noun}{suffix}".format(
                    count=self._previously_failed_count, suffix=suffix, noun=noun
                )
            return "run-last-failure: %s" % mode

    def pytest_runtest_logreport(self, report):
        if (report.when == 'call' and report.passed) or report.skipped:
            self.lastfailed.pop(report.nodeid, None)
        elif report.failed:
            self.lastfailed[report.nodeid] = True

    def pytest_collectreport(self, report):
        passed = report.outcome in ('passed', 'skipped')
        if passed:
            if report.nodeid in self.lastfailed:
                self.lastfailed.pop(report.nodeid)
                self.lastfailed.update(
                    (item.nodeid, True)
                    for item in report.result)
        else:
            self.lastfailed[report.nodeid] = True

    def pytest_collection_modifyitems(self, session, config, items):
        if self.active and self.lastfailed:
            previously_failed = []
            previously_passed = []
            for item in items:
                if item.nodeid in self.lastfailed:
                    previously_failed.append(item)
                else:
                    previously_passed.append(item)
            self._previously_failed_count = len(previously_failed)
            if not previously_failed:
                # running a subset of all tests with recorded failures outside
                # of the set of tests currently executing
                return
            if self.config.getvalue("lf"):
                items[:] = previously_failed
                config.hook.pytest_deselected(items=previously_passed)
            else:
                items[:] = previously_failed + previously_passed

    def pytest_sessionfinish(self, session):
        config = self.config
        if config.getvalue("cacheshow") or hasattr(config, "slaveinput"):
            return

        saved_lastfailed = config.cache.get("cache/lastfailed", {})
        if saved_lastfailed != self.lastfailed:
            config.cache.set("cache/lastfailed", self.lastfailed)


def pytest_addoption(parser):
    group = parser.getgroup("general")
    group.addoption(
        '--lf', '--last-failed', action='store_true', dest="lf",
        help="rerun only the tests that failed "
             "at the last run (or all if none failed)")
    group.addoption(
        '--ff', '--failed-first', action='store_true', dest="failedfirst",
        help="run all tests but run the last failures first.  "
             "This may re-order tests and thus lead to "
             "repeated fixture setup/teardown")
    group.addoption(
        '--cache-show', action='store_true', dest="cacheshow",
        help="show cache contents, don't perform collection or tests")
    group.addoption(
        '--cache-clear', action='store_true', dest="cacheclear",
        help="remove all cache contents at start of test run.")
    parser.addini(
        "cache_dir", default='.cache',
        help="cache directory path.")


def pytest_cmdline_main(config):
    if config.option.cacheshow:
        from _pytest.main import wrap_session
        return wrap_session(config, cacheshow)


@pytest.hookimpl(tryfirst=True)
def pytest_configure(config):
    config.cache = Cache(config)
    config.pluginmanager.register(LFPlugin(config), "lfplugin")


@pytest.fixture
def cache(request):
    """
    Return a cache object that can persist state between testing sessions.

    cache.get(key, default)
    cache.set(key, value)

    Keys must be a ``/`` separated value, where the first part is usually the
    name of your plugin or application to avoid clashes with other cache users.

    Values can be any object handled by the json stdlib module.
    """
    return request.config.cache


def pytest_report_header(config):
    if config.option.verbose:
        relpath = py.path.local().bestrelpath(config.cache._cachedir)
        return "cachedir: %s" % relpath


def cacheshow(config, session):
    from pprint import pprint
    tw = py.io.TerminalWriter()
    tw.line("cachedir: " + str(config.cache._cachedir))
    if not config.cache._cachedir.check():
        tw.line("cache is empty")
        return 0
    dummy = object()
    basedir = config.cache._cachedir
    vdir = basedir.join("v")
    tw.sep("-", "cache values")
    for valpath in sorted(vdir.visit(lambda x: x.isfile())):
        key = valpath.relto(vdir).replace(valpath.sep, "/")
        val = config.cache.get(key, dummy)
        if val is dummy:
            tw.line("%s contains unreadable content, "
                    "will be ignored" % key)
        else:
            tw.line("%s contains:" % key)
            stream = py.io.TextIO()
            pprint(val, stream=stream)
            for line in stream.getvalue().splitlines():
                tw.line("  " + line)

    ddir = basedir.join("d")
    if ddir.isdir() and ddir.listdir():
        tw.sep("-", "cache directories")
        for p in sorted(basedir.join("d").visit()):
            # if p.check(dir=1):
            #    print("%s/" % p.relto(basedir))
            if p.isfile():
                key = p.relto(basedir)
                tw.line("%s is a file of length %d" % (
                        key, p.size()))
    return 0
