"""
The contents of this file are taken from
[Django-admin](https://github.com/niwinz/django-jinja/blob/master/django_jinja/management/commands/makemessages.py)

Jinja2's i18n functionality is not exactly the same as Django's.
In particular, the tags names and their syntax are different:

  1. The Django ``trans`` tag is replaced by a _() global.
  2. The Django ``blocktrans`` tag is called ``trans``.

(1) isn't an issue, since the whole ``makemessages`` process is based on
converting the template tags to ``_()`` calls. However, (2) means that
those Jinja2 ``trans`` tags will not be picked up by Django's
``makemessages`` command.

There aren't any nice solutions here. While Jinja2's i18n extension does
come with extraction capabilities built in, the code behind ``makemessages``
unfortunately isn't extensible, so we can:

  * Duplicate the command + code behind it.
  * Offer a separate command for Jinja2 extraction.
  * Try to get Django to offer hooks into makemessages().
  * Monkey-patch.

We are currently doing that last thing. It turns out there we are lucky
for once: It's simply a matter of extending two regular expressions.
Credit for the approach goes to:
http://stackoverflow.com/questions/2090717/getting-translation-strings-for-jinja2-templates-integrated-with-django-1-x

"""
from __future__ import absolute_import

from typing import Any, Dict, Iterable, Optional, Mapping, Set, Tuple, Text

from argparse import ArgumentParser
import os
import re
import glob
import json
from six.moves import filter
from six.moves import map
from six.moves import zip

from django.core.management.commands import makemessages
from django.utils.translation import trans_real
from django.template.base import BLOCK_TAG_START, BLOCK_TAG_END
from django.conf import settings

strip_whitespace_right = re.compile(u"(%s-?\\s*(trans|pluralize).*?-%s)\\s+" % (BLOCK_TAG_START, BLOCK_TAG_END), re.U)
strip_whitespace_left = re.compile(u"\\s+(%s-\\s*(endtrans|pluralize).*?-?%s)" % (
                                   BLOCK_TAG_START, BLOCK_TAG_END), re.U)

regexes = ['{{#tr .*?}}(.*?){{/tr}}',
           '{{t "(.*?)"\W*}}',
           "{{t '(.*?)'\W*}}",
           "i18n\.t\('([^\']*?)'\)",
           "i18n\.t\('(.*?)',.*?[^,]\)",
           'i18n\.t\("([^\"]*?)"\)',
           'i18n\.t\("(.*?)",.*?[^,]\)',
           ]

frontend_compiled_regexes = [re.compile(regex) for regex in regexes]
multiline_js_comment = re.compile("/\*.*?\*/", re.DOTALL)
singleline_js_comment = re.compile("//.*?\n")

def strip_whitespaces(src):
    # type: (Text) -> Text
    src = strip_whitespace_left.sub(u'\\1', src)
    src = strip_whitespace_right.sub(u'\\1', src)
    return src

class Command(makemessages.Command):

    def add_arguments(self, parser):
        # type: (ArgumentParser) -> None
        super(Command, self).add_arguments(parser)
        parser.add_argument('--frontend-source', type=str,
                            default='static/templates',
                            help='Name of the Handlebars template directory')
        parser.add_argument('--frontend-output', type=str,
                            default='static/locale',
                            help='Name of the frontend messages output directory')
        parser.add_argument('--frontend-namespace', type=str,
                            default='translations.json',
                            help='Namespace of the frontend locale file')

    def handle(self, *args, **options):
        # type: (*Any, **Any) -> None
        self.handle_django_locales(*args, **options)
        self.handle_frontend_locales(*args, **options)

    def handle_frontend_locales(self, *args, **options):
        # type: (*Any, **Any) -> None
        self.frontend_source = options.get('frontend_source')
        self.frontend_output = options.get('frontend_output')
        self.frontend_namespace = options.get('frontend_namespace')
        self.frontend_locale = options.get('locale')
        self.frontend_exclude = options.get('exclude')
        self.frontend_all = options.get('all')

        translation_strings = self.get_translation_strings()
        self.write_translation_strings(translation_strings)

    def handle_django_locales(self, *args, **options):
        # type: (*Any, **Any) -> None
        old_endblock_re = trans_real.endblock_re
        old_block_re = trans_real.block_re
        old_constant_re = trans_real.constant_re

        old_templatize = trans_real.templatize
        # Extend the regular expressions that are used to detect
        # translation blocks with an "OR jinja-syntax" clause.
        trans_real.endblock_re = re.compile(
            trans_real.endblock_re.pattern + '|' + r"""^-?\s*endtrans\s*-?$""")
        trans_real.block_re = re.compile(
            trans_real.block_re.pattern + '|' + r"""^-?\s*trans(?:\s+(?!'|")(?=.*?=.*?)|\s*-?$)""")
        trans_real.plural_re = re.compile(
            trans_real.plural_re.pattern + '|' + r"""^-?\s*pluralize(?:\s+.+|-?$)""")
        trans_real.constant_re = re.compile(r"""_\(((?:".*?")|(?:'.*?')).*\)""")

        def my_templatize(src, origin=None):
            # type: (Text, Optional[Text]) -> Text
            new_src = strip_whitespaces(src)
            return old_templatize(new_src, origin)

        trans_real.templatize = my_templatize

        try:
            ignore_patterns = options.get('ignore_patterns', [])
            ignore_patterns.append('docs/*')
            options['ignore_patterns'] = ignore_patterns
            super(Command, self).handle(*args, **options)
        finally:
            trans_real.endblock_re = old_endblock_re
            trans_real.block_re = old_block_re
            trans_real.templatize = old_templatize
            trans_real.constant_re = old_constant_re

    def extract_strings(self, data):
        # type: (str) -> Dict[str, str]
        data = self.ignore_javascript_comments(data)
        translation_strings = {} # type: Dict[str, str]
        for regex in frontend_compiled_regexes:
            for match in regex.findall(data):
                translation_strings[match] = ""

        return translation_strings

    def ignore_javascript_comments(self, data):
        # type: (str) -> str

        # Removes multi line comments.
        data = re.sub(multiline_js_comment, "", data)
        # Removes single line (//) comments.
        data = re.sub(singleline_js_comment, "", data)
        return data

    def get_translation_strings(self):
        # type: () -> Dict[str, str]
        translation_strings = {} # type: Dict[str, str]
        dirname = self.get_template_dir()

        for dirpath, dirnames, filenames in os.walk(dirname):
            for filename in [f for f in filenames if f.endswith(".handlebars")]:
                with open(os.path.join(dirpath, filename), 'r') as reader:
                    data = reader.read()
                    data = data.replace('\n', '\\n')
                    translation_strings.update(self.extract_strings(data))

        dirname = os.path.join(settings.DEPLOY_ROOT, 'static/js')
        for filename in os.listdir(dirname):
            if filename.endswith('.js'):
                with open(os.path.join(dirname, filename)) as reader:
                    data = reader.read()
                    translation_strings.update(self.extract_strings(data))

        return translation_strings

    def get_template_dir(self):
        # type: () -> str
        return self.frontend_source

    def get_namespace(self):
        # type: () -> str
        return self.frontend_namespace

    def get_locales(self):
        # type: () -> Iterable[str]
        locale = self.frontend_locale
        exclude = self.frontend_exclude
        process_all = self.frontend_all

        paths = glob.glob('%s/*' % self.default_locale_path,)
        all_locales = [os.path.basename(path) for path in paths if os.path.isdir(path)]

        # Account for excluded locales
        if process_all:
            return all_locales
        else:
            locales = locale or all_locales
            return set(locales) - set(exclude)

    def get_base_path(self):
        # type: () -> str
        return self.frontend_output

    def get_output_paths(self):
        # type: () -> Iterable[str]
        base_path = self.get_base_path()
        locales = self.get_locales()
        for path in [os.path.join(base_path, locale) for locale in locales]:
            if not os.path.exists(path):
                os.makedirs(path)

            yield os.path.join(path, self.get_namespace())

    def get_new_strings(self, old_strings, translation_strings):
        # type: (Mapping[str, str], Iterable[str]) -> Dict[str, str]
        """
        Missing strings are removed, new strings are added and already
        translated strings are not touched.
        """
        new_strings = {} # Dict[str, str]
        for k in translation_strings:
            k = k.replace('\\n', '\n')
            new_strings[k] = old_strings.get(k, k)

        plurals = {k: v for k, v in old_strings.items() if k.endswith('_plural')}
        for plural_key, value in plurals.items():
            components = plural_key.split('_')
            singular_key = '_'.join(components[:-1])
            if singular_key in new_strings:
                new_strings[plural_key] = value

        return new_strings

    def write_translation_strings(self, translation_strings):
        # type: (Iterable[str]) -> None
        for locale, output_path in zip(self.get_locales(), self.get_output_paths()):
            self.stdout.write("[frontend] processing locale {}".format(locale))
            try:
                with open(output_path, 'r') as reader:
                    old_strings = json.load(reader)
            except (IOError, ValueError):
                old_strings = {}

            new_strings = self.get_new_strings(old_strings, translation_strings)
            with open(output_path, 'w') as writer:
                json.dump(new_strings, writer, indent=2)