from __future__ import print_function
import datetime
import warnings
import re
from itertools import chain, repeat, islice

from .config import Configuration
from .utils import trace, string_types

from pkg_resources import iter_entry_points

from pkg_resources import parse_version as pkg_parse_version

SEMVER_MINOR = 2
SEMVER_PATCH = 3
SEMVER_LEN = 3


def _pad(iterable, size, padding=None):
    padded = chain(iterable, repeat(padding))
    return list(islice(padded, size))


def _parse_version_tag(tag, config):
    tagstring = tag if not isinstance(tag, string_types) else str(tag)
    match = config.tag_regex.match(tagstring)

    result = None
    if match:
        if len(match.groups()) == 1:
            key = 1
        else:
            key = 'version'
        
        result = {
            'version': match.group(key),
            'prefix': match.group(0)[:match.start(key)],
            'suffix': match.group(0)[match.end(key):],
        }

    trace("tag '%s' parsed to %s" % (tag, result))
    return result


def _get_version_class():
    modern_version = pkg_parse_version("1.0")
    if isinstance(modern_version, tuple):
        return None
    else:
        return type(modern_version)


VERSION_CLASS = _get_version_class()


class SetuptoolsOutdatedWarning(Warning):
    pass


# append so integrators can disable the warning
warnings.simplefilter("error", SetuptoolsOutdatedWarning, append=True)


def _warn_if_setuptools_outdated():
    if VERSION_CLASS is None:
        warnings.warn("your setuptools is too old (<12)", SetuptoolsOutdatedWarning)


def callable_or_entrypoint(group, callable_or_name):
    trace("ep", (group, callable_or_name))

    if callable(callable_or_name):
        return callable_or_name

    for ep in iter_entry_points(group, callable_or_name):
        trace("ep found:", ep.name)
        return ep.load()


def tag_to_version(tag, config=None):
    """
    take a tag that might be prefixed with a keyword and return only the version part
    :param config: optional configuration object
    """
    trace("tag", tag)

    if not config:
        config = Configuration()

    tagdict = _parse_version_tag(tag, config)
    if not isinstance(tagdict, dict) or not tagdict.get('version', None):
        warnings.warn("tag %r no version found" % (tag,))
        return None

    version = tagdict['version']
    trace("version pre parse", version)

    if tagdict.get('suffix', ''):
        warnings.warn("tag %r will be stripped of its suffix '%s'" % (tag, tagdict['suffix']))

    if VERSION_CLASS is not None:
        version = pkg_parse_version(version)
        trace("version", repr(version))
    
    return version


def tags_to_versions(tags, config=None):
    """
    take tags that might be prefixed with a keyword and return only the version part
    :param tags: an iterable of tags
    :param config: optional configuration object
    """
    return filter(None, map(lambda tag: tag_to_version(tag, config=config), tags))


class ScmVersion(object):

    def __init__(
        self,
        tag_version,
        distance=None,
        node=None,
        dirty=False,
        preformatted=False,
        branch=None,
        **kw
    ):
        if kw:
            trace("unknown args", kw)
        self.tag = tag_version
        if dirty and distance is None:
            distance = 0
        self.distance = distance
        self.node = node
        self.time = datetime.datetime.now()
        self.extra = kw
        self.dirty = dirty
        self.preformatted = preformatted
        self.branch = branch

    @property
    def exact(self):
        return self.distance is None

    def __repr__(self):
        return self.format_with(
            "<ScmVersion {tag} d={distance}" " n={node} d={dirty} b={branch} x={extra}>"
        )

    def format_with(self, fmt, **kw):
        return fmt.format(
            time=self.time,
            tag=self.tag,
            distance=self.distance,
            node=self.node,
            dirty=self.dirty,
            extra=self.extra,
            branch=self.branch,
            **kw
        )

    def format_choice(self, clean_format, dirty_format, **kw):
        return self.format_with(dirty_format if self.dirty else clean_format, **kw)

    def format_next_version(self, guess_next, fmt="{guessed}.dev{distance}", **kw):
        guessed = guess_next(self.tag, **kw)
        return self.format_with(fmt, guessed=guessed)


def _parse_tag(tag, preformatted, config):
    if preformatted:
        return tag
    if VERSION_CLASS is None or not isinstance(tag, VERSION_CLASS):
        tag = tag_to_version(tag, config)
    return tag


def meta(tag, distance=None, dirty=False, node=None, preformatted=False, config=None, **kw):
    if not config:
        warnings.warn("meta invoked without explicit configuration, will use defaults where required.")
    parsed_version = _parse_tag(tag, preformatted, config)
    trace("version", tag, "->", parsed_version)
    assert parsed_version is not None, "cant parse version %s" % tag
    return ScmVersion(parsed_version, distance, node, dirty, preformatted, **kw)


def guess_next_version(tag_version):
    version = _strip_local(str(tag_version))
    return _bump_dev(version) or _bump_regex(version)


def _strip_local(version_string):
    public, sep, local = version_string.partition("+")
    return public


def _bump_dev(version):
    if ".dev" not in version:
        return

    prefix, tail = version.rsplit(".dev", 1)
    assert tail == "0", "own dev numbers are unsupported"
    return prefix


def _bump_regex(version):
    prefix, tail = re.match(r"(.*?)(\d+)$", version).groups()
    return "%s%d" % (prefix, int(tail) + 1)


def guess_next_dev_version(version):
    if version.exact:
        return version.format_with("{tag}")
    else:
        return version.format_next_version(guess_next_version)


def guess_next_simple_semver(version, retain, increment=True):
    parts = map(int, str(version).split("."))
    parts = _pad(parts, retain, 0)
    if increment:
        parts[-1] += 1
    parts = _pad(parts, SEMVER_LEN, 0)
    return ".".join(map(str, parts))


def simplified_semver_version(version):
    if version.exact:
        return guess_next_simple_semver(version.tag, retain=SEMVER_LEN, increment=False)
    else:
        if version.branch is not None and "feature" in version.branch:
            return version.format_next_version(
                guess_next_simple_semver, retain=SEMVER_MINOR
            )
        else:
            return version.format_next_version(
                guess_next_simple_semver, retain=SEMVER_PATCH
            )


def _format_local_with_time(version, time_format):

    if version.exact or version.node is None:
        return version.format_choice(
            "", "+d{time:{time_format}}", time_format=time_format
        )
    else:
        return version.format_choice(
            "+{node}", "+{node}.d{time:{time_format}}", time_format=time_format
        )


def get_local_node_and_date(version):
    return _format_local_with_time(version, time_format="%Y%m%d")


def get_local_node_and_timestamp(version, fmt="%Y%m%d%H%M%S"):
    return _format_local_with_time(version, time_format=fmt)


def get_local_dirty_tag(version):
    return version.format_choice("", "+dirty")


def postrelease_version(version):
    if version.exact:
        return version.format_with("{tag}")
    else:
        return version.format_with("{tag}.post{distance}")


def format_version(version, **config):
    trace("scm version", version)
    trace("config", config)
    if version.preformatted:
        return version.tag
    version_scheme = callable_or_entrypoint(
        "setuptools_scm.version_scheme", config["version_scheme"]
    )
    local_scheme = callable_or_entrypoint(
        "setuptools_scm.local_scheme", config["local_scheme"]
    )
    main_version = version_scheme(version)
    trace("version", main_version)
    local_version = local_scheme(version)
    trace("local_version", local_version)
    return version_scheme(version) + local_scheme(version)
