# -*- coding: utf-8 -*-
#
# Copyright (C) 2012 The Python Software Foundation.
# See LICENSE.txt and CONTRIBUTORS.txt.
#
"""Implementation of the Metadata for Python packages PEPs.

Supports all metadata formats (1.0, 1.1, 1.2, and 2.0 experimental).
"""
from __future__ import unicode_literals

import codecs
from email import message_from_file
import json
import logging
import re


from . import DistlibException, __version__
from .compat import StringIO, string_types, text_type
from .markers import interpret
from .util import extract_by_key, get_extras
from .version import get_scheme, PEP440_VERSION_RE

logger = logging.getLogger(__name__)


class MetadataMissingError(DistlibException):
    """A required metadata is missing"""


class MetadataConflictError(DistlibException):
    """Attempt to read or write metadata fields that are conflictual."""


class MetadataUnrecognizedVersionError(DistlibException):
    """Unknown metadata version number."""


class MetadataInvalidError(DistlibException):
    """A metadata value is invalid"""

# public API of this module
__all__ = ['Metadata', 'PKG_INFO_ENCODING', 'PKG_INFO_PREFERRED_VERSION']

# Encoding used for the PKG-INFO files
PKG_INFO_ENCODING = 'utf-8'

# preferred version. Hopefully will be changed
# to 1.2 once PEP 345 is supported everywhere
PKG_INFO_PREFERRED_VERSION = '1.1'

_LINE_PREFIX_1_2 = re.compile('\n       \\|')
_LINE_PREFIX_PRE_1_2 = re.compile('\n        ')
_241_FIELDS = ('Metadata-Version', 'Name', 'Version', 'Platform',
               'Summary', 'Description',
               'Keywords', 'Home-page', 'Author', 'Author-email',
               'License')

_314_FIELDS = ('Metadata-Version', 'Name', 'Version', 'Platform',
               'Supported-Platform', 'Summary', 'Description',
               'Keywords', 'Home-page', 'Author', 'Author-email',
               'License', 'Classifier', 'Download-URL', 'Obsoletes',
               'Provides', 'Requires')

_314_MARKERS = ('Obsoletes', 'Provides', 'Requires', 'Classifier',
                'Download-URL')

_345_FIELDS = ('Metadata-Version', 'Name', 'Version', 'Platform',
               'Supported-Platform', 'Summary', 'Description',
               'Keywords', 'Home-page', 'Author', 'Author-email',
               'Maintainer', 'Maintainer-email', 'License',
               'Classifier', 'Download-URL', 'Obsoletes-Dist',
               'Project-URL', 'Provides-Dist', 'Requires-Dist',
               'Requires-Python', 'Requires-External')

_345_MARKERS = ('Provides-Dist', 'Requires-Dist', 'Requires-Python',
                'Obsoletes-Dist', 'Requires-External', 'Maintainer',
                'Maintainer-email', 'Project-URL')

_426_FIELDS = ('Metadata-Version', 'Name', 'Version', 'Platform',
               'Supported-Platform', 'Summary', 'Description',
               'Keywords', 'Home-page', 'Author', 'Author-email',
               'Maintainer', 'Maintainer-email', 'License',
               'Classifier', 'Download-URL', 'Obsoletes-Dist',
               'Project-URL', 'Provides-Dist', 'Requires-Dist',
               'Requires-Python', 'Requires-External', 'Private-Version',
               'Obsoleted-By', 'Setup-Requires-Dist', 'Extension',
               'Provides-Extra')

_426_MARKERS = ('Private-Version', 'Provides-Extra', 'Obsoleted-By',
                'Setup-Requires-Dist', 'Extension')

_566_FIELDS = _426_FIELDS + ('Description-Content-Type',)

_566_MARKERS = ('Description-Content-Type',)

_ALL_FIELDS = set()
_ALL_FIELDS.update(_241_FIELDS)
_ALL_FIELDS.update(_314_FIELDS)
_ALL_FIELDS.update(_345_FIELDS)
_ALL_FIELDS.update(_426_FIELDS)
_ALL_FIELDS.update(_566_FIELDS)

EXTRA_RE = re.compile(r'''extra\s*==\s*("([^"]+)"|'([^']+)')''')


def _version2fieldlist(version):
    if version == '1.0':
        return _241_FIELDS
    elif version == '1.1':
        return _314_FIELDS
    elif version == '1.2':
        return _345_FIELDS
    elif version in ('1.3', '2.1'):
        return _345_FIELDS + _566_FIELDS
    elif version == '2.0':
        return _426_FIELDS
    raise MetadataUnrecognizedVersionError(version)


def _best_version(fields):
    """Detect the best version depending on the fields used."""
    def _has_marker(keys, markers):
        for marker in markers:
            if marker in keys:
                return True
        return False

    keys = []
    for key, value in fields.items():
        if value in ([], 'UNKNOWN', None):
            continue
        keys.append(key)

    possible_versions = ['1.0', '1.1', '1.2', '1.3', '2.0', '2.1']

    # first let's try to see if a field is not part of one of the version
    for key in keys:
        if key not in _241_FIELDS and '1.0' in possible_versions:
            possible_versions.remove('1.0')
            logger.debug('Removed 1.0 due to %s', key)
        if key not in _314_FIELDS and '1.1' in possible_versions:
            possible_versions.remove('1.1')
            logger.debug('Removed 1.1 due to %s', key)
        if key not in _345_FIELDS and '1.2' in possible_versions:
            possible_versions.remove('1.2')
            logger.debug('Removed 1.2 due to %s', key)
        if key not in _566_FIELDS and '1.3' in possible_versions:
            possible_versions.remove('1.3')
            logger.debug('Removed 1.3 due to %s', key)
        if key not in _566_FIELDS and '2.1' in possible_versions:
            if key != 'Description':  # In 2.1, description allowed after headers
                possible_versions.remove('2.1')
                logger.debug('Removed 2.1 due to %s', key)
        if key not in _426_FIELDS and '2.0' in possible_versions:
            possible_versions.remove('2.0')
            logger.debug('Removed 2.0 due to %s', key)

    # possible_version contains qualified versions
    if len(possible_versions) == 1:
        return possible_versions[0]   # found !
    elif len(possible_versions) == 0:
        logger.debug('Out of options - unknown metadata set: %s', fields)
        raise MetadataConflictError('Unknown metadata set')

    # let's see if one unique marker is found
    is_1_1 = '1.1' in possible_versions and _has_marker(keys, _314_MARKERS)
    is_1_2 = '1.2' in possible_versions and _has_marker(keys, _345_MARKERS)
    is_2_1 = '2.1' in possible_versions and _has_marker(keys, _566_MARKERS)
    is_2_0 = '2.0' in possible_versions and _has_marker(keys, _426_MARKERS)
    if int(is_1_1) + int(is_1_2) + int(is_2_1) + int(is_2_0) > 1:
        raise MetadataConflictError('You used incompatible 1.1/1.2/2.0/2.1 fields')

    # we have the choice, 1.0, or 1.2, or 2.0
    #   - 1.0 has a broken Summary field but works with all tools
    #   - 1.1 is to avoid
    #   - 1.2 fixes Summary but has little adoption
    #   - 2.0 adds more features and is very new
    if not is_1_1 and not is_1_2 and not is_2_1 and not is_2_0:
        # we couldn't find any specific marker
        if PKG_INFO_PREFERRED_VERSION in possible_versions:
            return PKG_INFO_PREFERRED_VERSION
    if is_1_1:
        return '1.1'
    if is_1_2:
        return '1.2'
    if is_2_1:
        return '2.1'

    return '2.0'

_ATTR2FIELD = {
    'metadata_version': 'Metadata-Version',
    'name': 'Name',
    'version': 'Version',
    'platform': 'Platform',
    'supported_platform': 'Supported-Platform',
    'summary': 'Summary',
    'description': 'Description',
    'keywords': 'Keywords',
    'home_page': 'Home-page',
    'author': 'Author',
    'author_email': 'Author-email',
    'maintainer': 'Maintainer',
    'maintainer_email': 'Maintainer-email',
    'license': 'License',
    'classifier': 'Classifier',
    'download_url': 'Download-URL',
    'obsoletes_dist': 'Obsoletes-Dist',
    'provides_dist': 'Provides-Dist',
    'requires_dist': 'Requires-Dist',
    'setup_requires_dist': 'Setup-Requires-Dist',
    'requires_python': 'Requires-Python',
    'requires_external': 'Requires-External',
    'requires': 'Requires',
    'provides': 'Provides',
    'obsoletes': 'Obsoletes',
    'project_url': 'Project-URL',
    'private_version': 'Private-Version',
    'obsoleted_by': 'Obsoleted-By',
    'extension': 'Extension',
    'provides_extra': 'Provides-Extra',
}

_PREDICATE_FIELDS = ('Requires-Dist', 'Obsoletes-Dist', 'Provides-Dist')
_VERSIONS_FIELDS = ('Requires-Python',)
_VERSION_FIELDS = ('Version',)
_LISTFIELDS = ('Platform', 'Classifier', 'Obsoletes',
               'Requires', 'Provides', 'Obsoletes-Dist',
               'Provides-Dist', 'Requires-Dist', 'Requires-External',
               'Project-URL', 'Supported-Platform', 'Setup-Requires-Dist',
               'Provides-Extra', 'Extension')
_LISTTUPLEFIELDS = ('Project-URL',)

_ELEMENTSFIELD = ('Keywords',)

_UNICODEFIELDS = ('Author', 'Maintainer', 'Summary', 'Description')

_MISSING = object()

_FILESAFE = re.compile('[^A-Za-z0-9.]+')


def _get_name_and_version(name, version, for_filename=False):
    """Return the distribution name with version.

    If for_filename is true, return a filename-escaped form."""
    if for_filename:
        # For both name and version any runs of non-alphanumeric or '.'
        # characters are replaced with a single '-'.  Additionally any
        # spaces in the version string become '.'
        name = _FILESAFE.sub('-', name)
        version = _FILESAFE.sub('-', version.replace(' ', '.'))
    return '%s-%s' % (name, version)


class LegacyMetadata(object):
    """The legacy metadata of a release.

    Supports versions 1.0, 1.1 and 1.2 (auto-detected). You can
    instantiate the class with one of these arguments (or none):
    - *path*, the path to a metadata file
    - *fileobj* give a file-like object with metadata as content
    - *mapping* is a dict-like object
    - *scheme* is a version scheme name
    """
    # TODO document the mapping API and UNKNOWN default key

    def __init__(self, path=None, fileobj=None, mapping=None,
                 scheme='default'):
        if [path, fileobj, mapping].count(None) < 2:
            raise TypeError('path, fileobj and mapping are exclusive')
        self._fields = {}
        self.requires_files = []
        self._dependencies = None
        self.scheme = scheme
        if path is not None:
            self.read(path)
        elif fileobj is not None:
            self.read_file(fileobj)
        elif mapping is not None:
            self.update(mapping)
            self.set_metadata_version()

    def set_metadata_version(self):
        self._fields['Metadata-Version'] = _best_version(self._fields)

    def _write_field(self, fileobj, name, value):
        fileobj.write('%s: %s\n' % (name, value))

    def __getitem__(self, name):
        return self.get(name)

    def __setitem__(self, name, value):
        return self.set(name, value)

    def __delitem__(self, name):
        field_name = self._convert_name(name)
        try:
            del self._fields[field_name]
        except KeyError:
            raise KeyError(name)

    def __contains__(self, name):
        return (name in self._fields or
                self._convert_name(name) in self._fields)

    def _convert_name(self, name):
        if name in _ALL_FIELDS:
            return name
        name = name.replace('-', '_').lower()
        return _ATTR2FIELD.get(name, name)

    def _default_value(self, name):
        if name in _LISTFIELDS or name in _ELEMENTSFIELD:
            return []
        return 'UNKNOWN'

    def _remove_line_prefix(self, value):
        if self.metadata_version in ('1.0', '1.1'):
            return _LINE_PREFIX_PRE_1_2.sub('\n', value)
        else:
            return _LINE_PREFIX_1_2.sub('\n', value)

    def __getattr__(self, name):
        if name in _ATTR2FIELD:
            return self[name]
        raise AttributeError(name)

    #
    # Public API
    #

#    dependencies = property(_get_dependencies, _set_dependencies)

    def get_fullname(self, filesafe=False):
        """Return the distribution name with version.

        If filesafe is true, return a filename-escaped form."""
        return _get_name_and_version(self['Name'], self['Version'], filesafe)

    def is_field(self, name):
        """return True if name is a valid metadata key"""
        name = self._convert_name(name)