#
# Copyright © 2012–2022 Michal Čihař <michal@cihar.com>
#
# This file is part of Weblate <https://weblate.org/>
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <https://www.gnu.org/licenses/>.
#
"""Translate Toolkit based file-format wrappers."""

import importlib
import inspect
import os
import re
import subprocess
from typing import Callable, List, Optional, Tuple, Union

from django.core.exceptions import ValidationError
from django.utils.functional import cached_property
from django.utils.translation import gettext
from django.utils.translation import gettext_lazy as _
from lxml import etree
from lxml.etree import XMLSyntaxError
from translate.misc import quote
from translate.misc.multistring import multistring
from translate.misc.xml_helpers import setXMLspace
from translate.storage.base import TranslationStore
from translate.storage.csvl10n import csv
from translate.storage.jsonl10n import BaseJsonUnit, JsonFile
from translate.storage.lisa import LISAfile
from translate.storage.po import pofile, pounit
from translate.storage.poxliff import PoXliffFile
from translate.storage.resx import RESXFile
from translate.storage.tbx import tbxfile, tbxunit
from translate.storage.ts2 import tsfile, tsunit
from translate.storage.xliff import ID_SEPARATOR, xlifffile, xliffunit

import weblate.utils.version
from weblate.checks.flags import Flags
from weblate.formats.base import (
    BilingualUpdateMixin,
    TranslationFormat,
    TranslationUnit,
    UpdateError,
)
from weblate.lang.data import FORMULA_WITH_ZERO, ZERO_PLURAL_TYPES
from weblate.trans.util import (
    get_clean_env,
    get_string,
    rich_to_xliff_string,
    xliff_string_to_rich,
)
from weblate.utils.errors import report_error
from weblate.utils.state import STATE_APPROVED, STATE_FUZZY, STATE_TRANSLATED

LOCATIONS_RE = re.compile(r"^([+-]|.*, [+-]|.*:[+-])")
PO_DOCSTRING_LOCATION = re.compile(r":docstring of [a-zA-Z0-9._]+:[0-9]+")
SUPPORTS_FUZZY = (pounit, tsunit)
XLIFF_FUZZY_STATES = {"new", "needs-translation", "needs-adaptation", "needs-l10n"}


class TTKitUnit(TranslationUnit):
    @cached_property
    def locations(self):
        """Return a comma-separated list of locations."""
        return ", ".join(x for x in self.mainunit.getlocations() if x is not None)

    @cached_property
    def source(self):
        """Return source string from a Translate Toolkit unit."""
        if self.template is not None:
            return get_string(self.template.target)
        return get_string(self.unit.source)

    @cached_property
    def target(self):
        """Return target string from a Translate Toolkit unit."""
        if self.unit is None:
            return ""
        return get_string(self.unit.target)

    @cached_property
    def context(self):
        """Return context of message.

        In some cases we have to use ID here to make all the back-ends consistent.
        """
        return self.mainunit.getcontext()

    @cached_property
    def notes(self):
        """Return notes or notes from units."""
        comment = ""

        if self.unit is not None:
            comment = self.unit.getnotes()

        if self.template is not None:
            # Avoid duplication in case template has same notes
            template_comment = self.template.getnotes()
            if template_comment != comment:
                comment = template_comment + "\n" + comment

        return comment

    def is_translated(self):
        """Check whether unit is translated."""
        if self.unit is None:
            return False
        return self.unit.istranslated()

    def is_fuzzy(self, fallback=False):
        """Check whether unit needs editing."""
        if self.unit is None:
            return fallback
        # Most of the formats do not support this, but they
        # happily return False
        if isinstance(self.unit, SUPPORTS_FUZZY):
            return self.unit.isfuzzy()
        return fallback

    def has_content(self):
        """Check whether unit has content."""
        return (
            not self.mainunit.isheader()
            and not self.mainunit.isblank()
            and not self.mainunit.isobsolete()
        )

    def is_readonly(self):
        return not self.mainunit.istranslatable()

    def set_target(self, target):
        """Set translation unit target."""
        self._invalidate_target()
        if isinstance(target, list):
            target = multistring(target)
        self.unit.target = target

    def set_state(self, state):
        """Set fuzzy /approved flag on translated unit."""
        if "flags" in self.__dict__:
            del self.__dict__["flags"]
        self.unit.markfuzzy(state == STATE_FUZZY)
        if hasattr(self.unit, "markapproved"):
            self.unit.markapproved(state == STATE_APPROVED)

    @cached_property
    def flags(self):
        """Return flags from unit.

        We currently extract maxwidth attribute.
        """
        flags = Flags()
        if hasattr(self.unit, "xmlelement"):
            flags.merge(self.unit.xmlelement)
        if hasattr(self.template, "xmlelement"):
            flags.merge(self.template.xmlelement)
        return flags.format()


class KeyValueUnit(TTKitUnit):
    @cached_property
    def source(self):
        """Return source string from a Translate Toolkit unit."""
        if self.template is not None:
            return get_string(self.template.source)
        return get_string(self.unit.name)

    @cached_property
    def target(self):
        """Return target string from a Translate Toolkit unit."""
        if self.unit is None:
            return ""
        return get_string(self.unit.source)

    @cached_property
    def context(self):
        """Return context of message.

        In some cases we have to use ID here to make all the back-ends consistent.
        """
        context = super().context
        if not context:
            return self.mainunit.getid()
        return context

    def is_translated(self):
        """Check whether unit is translated."""
        if self.unit is None:
            return False
        # The hasattr check here is needed for merged storages
        # where template is different kind than translations
        if hasattr(self.unit, "value"):
            return not self.unit.isfuzzy() and self.unit.value != ""
        return self.unit.istranslated()

    def set_target(self, target):
        """Set translation unit target."""
        super().set_target(target)
        # Propagate to value so that searializing of empty values works correctly
        self.unit.value = self.unit.target


class TTKitFormat(TranslationFormat):
    unit_class = TTKitUnit
    loader = ("", "")
    set_context_bilingual = True
    # Use settarget/setsource to set language as well
    use_settarget = False

    def __init__(
        self,
        storefile,
        template_store=None,
        language_code: Optional[str] = None,
        source_language: Optional[str] = None,
        is_template: bool = False,
    ):
        super().__init__(
            storefile,
            template_store=template_store,
            language_code=language_code,
            is_template=is_template,
            source_language=source_language,
        )
        # Set language (needed for some which do not include this)
        if language_code is not None and self.store.gettargetlanguage() is None:
            # This gets already native language code, so no conversion is needed
            self.store.settargetlanguage(language_code)
        if source_language is not None and self.store.getsourcelanguage() is None:
            # This gets already native language code, so no conversion is needed
            self.store.setsourcelanguage(source_language)

    @staticmethod
    def serialize(store):
        """Serialize given Translate Toolkit store."""
        return bytes(store)

    def fixup(self, store):
        """Perform optional fixups on store."""
        return

    def load(self, storefile, template_store):
        """Load file using defined loader."""
        if isinstance(storefile, TranslationStore):
            # Used by XLSX writer
            return storefile

        return self.parse_store(storefile)

    @classmethod
    def get_class(cls):
        """Return class for handling this module."""
        # Direct class
        if inspect.isclass(cls.loader):
            return cls.loader
        # Tuple style loader, import from translate toolkit
        module_name, class_name = cls.loader
        if "." not in module_name:
            module_name = f"translate.storage.{module_name}"
        module = importlib.import_module(module_name)

        # Get the class
        return getattr(module, class_name)

    @staticmethod
    def get_class_kwargs():
        return {}

    def parse_store(self, storefile):
        """Parse the store."""
        store = self.get_class()(**self.get_class_kwargs())

        # Apply possible fixups
        self.fixup(store)

        # Read the content
        if isinstance(storefile, str):
            with open(storefile, "rb") as handle:
                content = handle.read()
        else:
            content = storefile.read()

        # Parse the content
        store.parse(content)

        return store

    def add_unit(self, ttkit_unit):
        """Add new unit to underlaying store."""
        if isinstance(self.store, LISAfile):
            # LISA based stores need to know this
            self.store.addunit(ttkit_unit, new=True)
        else:
            self.store.addunit(ttkit_unit)

    def save_content(self, handle):
        """Store content to file."""
        self.store.serialize(handle)

    def save(self):
        """Save underlaying store to disk."""
        self.save_atomic(self.storefile, self.save_content)

    @classmethod
    def mimetype(cls):
        """Return most common media type for format."""
        return cls.get_class().Mimetypes[0]

    @classmethod
    def extension(cls):
        """Return most common file extension for format."""
        return cls.get_class().Extensions[0]

    def is_valid(self):
        """Check whether store seems to be valid.

        In some cases Translate Toolkit happily "parses" the file, even though it really
        did not do so (e.g. gettext parser on a random textfile).
        """
        if self.store is None:
            return False

        return True

    def construct_unit(self, source: str):
        if self.use_settarget and self.source_language:
            # Setting source on LISAunit will make it use default language
            unit = self.store.UnitClass(None)
            unit.setsource(source, self.source_language)
        else:
            unit = self.store.UnitClass(source)
        # Needed by some formats (Android) to set target
        unit._store = self.store
        return unit

    def create_unit_key(
        self, key: str, source: Union[str, List[str], multistring]
    ) -> Union[str, multistring]:
        return key

    def create_unit(
        self,
        key: str,
        source: Union[str, List[str]],
        target: Optional[Union[str, List[str]]] = None,
    ):
        # Make sure target is a string
        if target is None:
            target = ""
        # Process source
        if isinstance(source, list):
            context = source[0]
            if len(source) == 1:
                # Single string passed plain
                source = context
            else:
                # List passed as multistirng
                source = multistring(source)
        else:
            # This is string
            context = source

        # Process target
        if isinstance(target, list):
            if len(target) == 1:
                target = target[0]
            else:
                target = multistring(target)

        # Build the unit
        unit = self.construct_unit(context)

        if self.is_template or self.template_store:
            # Monolingual translation
            unit.setid(key)
            target = source
            source = self.create_unit_key(key, source)
        else:
            # Bilingual translation
            if isinstance(unit, (tbxunit, xliffunit)) and key:
                unit.setid(key)
            elif self.set_context_bilingual and key:
                unit.setcontext(key)
            elif isinstance(unit, BaseJsonUnit):
                unit.setid(context)

        if self.use_settarget and self.source_language:
            unit.setsource(source, self.source_language)
        else:
            unit.source = source

        if self.use_settarget and self.language_code:
            unit.settarget(target, self.language_code)
        else:
            unit.target = target

        return unit

    def untranslate_unit(self, unit, plural, fuzzy: bool):
        if hasattr(unit, "markapproved"):
            # Xliff only
            unit.markapproved(False)
        else:
            unit.markfuzzy(fuzzy)
        if unit.hasplural():
            unit.target = [""] * plural.number
        else:
            unit.target = ""

    def untranslate_store(self, language, fuzzy: bool = False):
        """Remove translations from Translate Toolkit store."""
        self.store.settargetlanguage(self.get_language_code(language.code))
        plural = language.plural

        for unit in self.store.units:
            if unit.istranslatable() and (unit.istranslated() or unit.isfuzzy()):
                self.untranslate_unit(unit, plural, fuzzy)

    @classmethod
    def get_new_file_content(cls):
        result = cls.new_translation
        if isinstance(result, str):
            result = result.encode()
        return result

    @classmethod
    def create_new_file(
        cls,
        filename: str,
        language: str,
        base: str,
        callback: Optional[Callable] = None,
    ):
        """Handle creation of new translation file."""
        if base:
            # Parse file
            store = cls(base)
            if callback:
                callback(store)
            store.untranslate_store(language)
            store.store.savefile(filename)
        elif cls.new_translation is None:
            raise ValueError("Not supported")
        else:
            with open(filename, "wb") as output:
                output.write(cls.get_new_file_content())

    @classmethod
    def is_valid_base_for_new(
        cls,
        base: str,
        monolingual: bool,
        errors: Optional[List] = None,
        fast: bool = False,
    ) -> bool:
        """Check whether base is valid."""
        if not base:
            if cls.create_empty_bilingual:
                return True
            return monolingual and cls.new_translation is not None
        try:
            if not fast:
                cls(base)
            return os.path.exists(base)
        except Exception as exception:
            if errors is not None:
                errors.append(exception)
            report_error(cause="File-parsing error")
            return False

    @property
    def all_store_units(self):
        """Wrapper for all store unit filtering out obsolete."""
        return (unit for unit in self.store.units if not unit.isobsolete())

    def delete_unit(self, ttkit_unit) -> Optional[str]:
        self.store.removeunit(ttkit_unit)


class PropertiesUnit(KeyValueUnit):
    """Wrapper for properties-based units."""

    @cached_property
    def locations(self):
        """Return a comma-separated list of locations."""
        return ""

    @cached_property
    def source(self):
        """Return source string from a Translate Toolkit unit."""
        if self.template is not None:
            return get_string(self.template.source)
        # Need to decode property encoded string
        return get_string(quote.propertiesdecode(self.unit.name))

    @cached_property
    def target(self):
        """Return target string from a Translate Toolkit unit."""
        if self.unit is None:
            return ""
        return get_string(self.unit.target or self.unit.source)


class PoUnit(TTKitUnit):
    """Wrapper for gettext PO unit."""

    def set_state(self, state):
        """Set fuzzy /approved flag on translated unit."""
        super().set_state(state)
        if state != STATE_FUZZY:
            self.unit.prev_msgid = []
            self.unit.prev_msgid_plural = []
            self.unit.prev_msgctxt = []

    @cached_property
    def flags(self):
        """Return flags or typecomments from units."""
        flags = Flags(*self.mainunit.typecomments)
        flags.remove({"fuzzy"})
        return flags.format()

    @cached_property
    def previous_source(self):
        """Return previous message source if there was any."""
        if not self.is_fuzzy():
            return ""
        return get_string(self.unit.prev_source)

    @cached_property
    def locations(self):
        """
        Return comma separated list of locations.

        Here we clean up Sphinx-generated "docstring of ..." part.
        """
        locations = " ".join(self.mainunit.getlocations())
        locations = PO_DOCSTRING_LOCATION.sub("", locations)
        return ", ".join(locations.split())


class PoMonoUnit(PoUnit):
    @cached_property
    def context(self):
        """Return context of message.

        In some cases we have to use ID here to make all the backends consistent.
        """
        # Monolingual PO files
        if self.template is not None:
            context = self.template.getcontext()
            source = self.template.source
            if source and context:
                return f"{context}.{source}"
            return source or context
        return super().context

    @cached_property
    def notes(self):
        result = []
        notes = super().notes
        if notes:
            result.append(notes)
        # Use unit context as note only in case source is present, otherwise
        # it is used as a context (see above)
        if self.template is not None and self.template.source:
            context = self.template.getcontext()
            if context:
                result.append(context)
        return "\n".join(result)

    def set_target(self, target):
        """Set translation unit target."""
        # Add blank msgid_plural to store plural
        if isinstance(target, (list, multistring)) and not self.unit.hasplural():
            self.unit.msgid_plural = ['""']

        super().set_target(target)


class XliffUnit(TTKitUnit):
    """Wrapper unit for XLIFF.

    XLIFF is special in Translate Toolkit — it uses locations for what
    is context in other formats.
    """

    @cached_property
    def source(self):
        """Return source string from a Translate Toolkit unit."""
        if self.template is not None:
            # Use target if set, otherwise fall back to source
            if self.template.target:
                return rich_to_xliff_string(self.template.rich_target)
            return rich_to_xliff_string(self.template.rich_source)
        return rich_to_xliff_string(self.unit.rich_source)

    @cached_property
    def target(self):
        """Return target string from a Translate Toolkit unit."""
        if self.unit is None:
            return ""

        # Use source for monolingual base if target is not set
        if self.unit.target is None:
            if self.parent.is_template:
                return rich_to_xliff_string(self.unit.rich_source)
            return ""

        return rich_to_xliff_string(self.unit.rich_target)

    @cached_property
    def flags(self):
        flags = Flags(super().flags)
        flags.merge("xml-text")
        return flags.format()

    def _invalidate_target(self):
        """Invalidate target cache."""
        super()._invalidate_target()
        if "xliff_node" in self.__dict__:
            del self.__dict__["xliff_node"]

    def set_target(self, target):
        """Set translation unit target."""
        self._invalidate_target()
        # Delete the empty target element
        if not target:
            xmlnode = self.get_xliff_node()
            if xmlnode is not None:
                xmlnode.getparent().remove(xmlnode)
            return
        try:
            converted = xliff_string_to_rich(target)
        except (XMLSyntaxError, TypeError, KeyError):
            # KeyError happens on missing attribute
            converted = [target]
        if self.template is not None:
            if self.parent.is_template:
                # Use source for monolingual files if editing template
                self.unit.rich_source = converted
            elif self.unit.source:
                # Update source to match current source
                self.unit.rich_source = self.template.rich_source
        # Always set target, even in monolingual template
        self.unit.rich_target = converted

    def get_xliff_node(self):
        try:
            return self.unit.getlanguageNode(lang=None, index=1)
        except AttributeError:
            return None

    @cached_property
    def xliff_node(self):
        return self.get_xliff_node()

    @property
    def xliff_state(self):
        node = self.xliff_node
        if node is None:
            return None
        return node.get("state", None)

    @cached_property
    def context(self):
        """Return context of message.

        Use resname if available as it usually is more interesting for the translator
        than ID.
        """
        resname = self.mainunit.xmlelement.get("resname")
        if resname:
            return resname
        return self.mainunit.getid().replace(ID_SEPARATOR, "///")

    @cached_property
    def locations(self):
        """Return comma separated list of locations."""
        return ""

    def is_translated(self):
        """Check whether unit is translated.

        We replace Translate Toolkit logic here as the isfuzzy is pretty much wrong
        there, see is_fuzzy docs.
        """
        return bool(self.target)

    def is_fuzzy(self, fallback=False):
        """Check whether unit needs edit.

        The isfuzzy on XLIFF is really messing up the "approved" flag with "fuzzy"
        flag, leading to various problems.

        That's why we handle it on our own.
        """
        return self.target and self.xliff_state in XLIFF_FUZZY_STATES

    def set_state(self, state):
        """Set fuzzy /approved flag on translated unit."""
        self.unit.markapproved(state == STATE_APPROVED)
        if state == STATE_FUZZY:
            # Always set state for fuzzy
            self.xliff_node.set("state", "needs-translation")
        elif self.xliff_state:
            # Only update state if it exists
            if state == STATE_APPROVED:
                self.xliff_node.set("state", "final")
            elif state == STATE_TRANSLATED:
                self.xliff_node.set("state", "translated")
            else:
                self.xliff_node.set("state", "new")

    def is_approved(self, fallback=False):
        """Check whether unit is appoved."""
        if self.unit is None:
            return fallback
        if hasattr(self.unit, "isapproved"):
            return self.unit.isapproved()
        return fallback

    def has_content(self):
        """Check whether unit has content.

        For some reason, blank string does not mean non-translatable unit in XLIFF, so
        lets skip those as well.
        """
        return (
            not self.mainunit.isheader()
            and bool(rich_to_xliff_string(self.mainunit.rich_source))
            and not self.mainunit.isobsolete()
        )


class FlatXMLUnit(TTKitUnit):
    @cached_property
    def context(self):
        if self.template is not None:
            return self.template.source
        return self.mainunit.source

    @cached_property
    def source(self):
        return get_string(self.mainunit.target)

    def has_content(self):
        """Check whether unit has content.

        The attribute-less units will have context None.
        """
        if self.context is None:
            return False
        return super().has_content()


class MonolingualIDUnit(TTKitUnit):
    @cached_property
    def context(self):
        if self.template is not None:
            return self.template.getid()
        return self.mainunit.getcontext()


class TSUnit(MonolingualIDUnit):
    @cached_property
    def source(self):
        if self.template is None and self.mainunit.hasplural():
            # Need to apply special magic for plurals here
            # as there is no singlular/plural in the source string
            source = self.unit.source
            return get_string([source.replace("(s)", ""), source.replace("(s)", "s")])
        return super().source

    @cached_property
    def locations(self):
        """Return a comma-separated list of locations."""
        result = super().locations
        # Do not try to handle relative locations in Qt TS, see
        # http://doc.qt.io/qt-5/linguist-ts-file-format.html
        if LOCATIONS_RE.match(result):
            return ""
        return result

    @cached_property
    def target(self):
        """Return target string from a Translate Toolkit unit."""
        if self.unit is None:
            return ""
        if not self.unit.isreview() and not self.unit.istranslated():
            # For Qt ts, empty translated string means source should be used
            return self.source
        return super().target

    def is_translated(self):
        """Check whether unit is translated."""
        if self.unit is None:
            return False
        # For Qt ts, empty translated string means source should be used
        return not self.unit.isreview() or self.unit.istranslated()


class MonolingualSimpleUnit(MonolingualIDUnit):
    @cached_property
    def locations(self):
        return ""

    @cached_property
    def source(self):
        if self.template is None:
            return self.mainunit.getid().lstrip(".")
        return get_string(self.template.target)

    def has_content(self):
        return not self.mainunit.isheader()

    def is_readonly(self):
        return False


class JSONUnit(MonolingualSimpleUnit):
    @cached_property
    def context(self):
        context = super().context
        if context.startswith("."):
            return context[1:]
        return context


class WebExtensionJSONUnit(JSONUnit):
    @cached_property
    def flags(self):
        placeholders = self.mainunit.placeholders
        if not placeholders:
            return ""
        return "placeholders:{}".format(
            ":".join(
                Flags.format_value(f"${key.upper()}$") for key in placeholders.keys()
            )
        )


class ARBJSONUnit(JSONUnit):
    @cached_property
    def flags(self):
        placeholders = self.mainunit.placeholders
        if not placeholders:
            return ""
        return "placeholders:{}".format(
            ":".join(
                Flags.format_value(f"{{{key.upper()}}}") for key in placeholders.keys()
            )
        )


class CSVUnit(MonolingualSimpleUnit):
    @staticmethod
    def unescape_csv(string):
        r"""
        Removes Excel-specific escaping from CSV.

        See weblate.formats.exporters.CSVExporter.string_filter

        Note: | is replaced by \ in the condition as it is escaped
        """
        if (
            len(string) > 2
            and string[0] == "'"
            and string[-1] == "'"
            and string[1] in ("=", "+", "-", "@", "\\", "%")
        ):
            return get_string(string[1:-1].replace("\\|", "|"))
        return get_string(string)

    @cached_property
    def context(self):
        # Needed to avoid Translate Toolkit construct ID
        # as context\04source
        if self.template is not None:
            if self.template.id:
                return self.template.id
            if self.template.context:
                return self.template.context
            return self.template.getid()
        return self.unescape_csv(self.mainunit.getcontext())

    @cached_property
    def locations(self):
        return self.mainunit.location

    @cached_property
    def source(self):
        # Needed to avoid Translate Toolkit construct ID
        # as context\04source
        if self.template is None:
            return self.unescape_csv(get_string(self.mainunit.source))
        return self.unescape_csv(super().source)

    @cached_property
    def target(self):
        return self.unescape_csv(super().target)


class RESXUnit(TTKitUnit):
    @cached_property
    def locations(self):
        return ""

    @cached_property
    def context(self):
        if self.template is not None:
            return self.template.getid()
        return self.unit.getid()

    @cached_property
    def source(self):
        if self.template is None:
            return self.mainunit.getid()
        return get_string(self.template.target)


class PHPUnit(KeyValueUnit):
    @cached_property
    def locations(self):
        return ""

    @cached_property
    def source(self):
        if self.template is not None:
            return get_string(self.template.source)
        return get_string(self.unit.getid())

    @cached_property
    def target(self):
        if self.unit is None:
            return ""
        return get_string(self.unit.source)


class INIUnit(TTKitUnit):
    @cached_property
    def locations(self):
        return ""

    @cached_property
    def context(self):
        if self.template is not None:
            return self.template.location
        return self.unit.location

    def has_content(self):
        return True

    def is_readonly(self):
        return False


class BasePoFormat(TTKitFormat, BilingualUpdateMixin):
    loader = pofile

    @classmethod
    def get_plural(cls, language, store=None):
        """Return matching plural object."""
        from weblate.lang.models import Plural

        if store:
            header = store.store.parseheader()
        else:
            # This will trigger KeyError later
            header = {}
        try:
            number, formula = Plural.parse_plural_forms(header["Plural-Forms"])
        except (ValueError, KeyError):
            return super().get_plural(language, store)

        # Find matching one
        for plural in language.plural_set.iterator():
            if plural.same_plural(number, formula):
                return plural

        # Create new one
        return Plural.objects.create(
            language=language,
            source=Plural.SOURCE_GETTEXT,
            number=number,
            formula=formula,
        )

    def untranslate_store(self, language, fuzzy=False):
        """Remove translations from Translate Toolkit store."""
        super().untranslate_store(language, fuzzy)
        plural = language.plural

        self.store.updateheader(
            last_translator="Automatically generated",
            plural_forms=plural.plural_form,
            language_team="none",
        )

    def update_header(self, **kwargs):
        """Update store header if available."""
        kwargs["x_generator"] = f"Weblate {weblate.utils.version.VERSION}"

        # Adjust Content-Type header if needed
        header = self.store.parseheader()
        if (
            "Content-Type" not in header
            or "charset=CHARSET" in header["Content-Type"]
            or "charset=ASCII" in header["Content-Type"]
        ):
            kwargs["Content_Type"] = "text/plain; charset=UTF-8"

        self.store.updateheader(**kwargs)

    @classmethod
    def do_bilingual_update(cls, in_file: str, out_file: str, template: str, **kwargs):
        """Wrapper around msgmerge."""
        args = [
            "--output-file",
            out_file,
            in_file,
            template,
        ]
        if "args" in kwargs:
            args = kwargs["args"] + args
        else:
            args = ["--previous"] + args

        cmd = ["msgmerge"] + args
        try:
            result = subprocess.run(
                cmd,
                env=get_clean_env(),
                cwd=os.path.dirname(out_file),
                capture_output=True,
                check=True,
                text=True,
            )
            # The warnings can cause corruption (for example in case
            # PO file header is missing ASCII encoding is assumed)
            errors = []
            for line in result.stderr.splitlines():
                if (
                    "warning: internationalized messages should not contain the" in line
                    or ". done." in line
                ):
                    continue
                errors.append(line)
            if errors:
                raise UpdateError(" ".join(cmd), "\n".join(errors))
        except OSError as error:
            report_error(cause="Failed msgmerge")
            raise UpdateError(" ".join(cmd), error)
        except subprocess.CalledProcessError as error:
            report_error(cause="Failed msgmerge")
            raise UpdateError(" ".join(cmd), error.output + error.stderr)

    def add_unit(self, ttkit_unit):
        self.store.require_index()
        # Check if there is matching obsolete unit
        old_unit = self.store.id_index.get(ttkit_unit.getid())
        if old_unit and old_unit.isobsolete():
            self.store.removeunit(old_unit)
        super().add_unit(ttkit_unit)


class PoFormat(BasePoFormat):
    name = _("gettext PO file")
    format_id = "po"
    monolingual = False
    autoload = ("*.po", "*.pot")
    unit_class = PoUnit

    @classmethod
    def get_new_file_content(cls):
        """Empty PO file content."""
        return b""


class PoMonoFormat(BasePoFormat):
    name = _("gettext PO file (monolingual)")
    format_id = "po-mono"
    monolingual = True
    autoload = ()
    new_translation = (
        'msgid ""\n'
        'msgstr "X-Generator: Weblate\\n'
        "MIME-Version: 1.0\\n"
        "Content-Type: text/plain; charset=UTF-8\\n"
        'Content-Transfer-Encoding: 8bit"'
    )
    unit_class = PoMonoUnit
    bilingual_class = PoFormat
    set_context_bilingual = False

    def create_unit_key(
        self, key: str, source: Union[str, List[str], multistring]
    ) -> Union[str, multistring]:
        if isinstance(source, (list, multistring)):
            return multistring([key, f"{key}_plural"])
        return key


class TSFormat(TTKitFormat):
    name = _("Qt Linguist translation file")
    format_id = "ts"
    loader = tsfile
    autoload = ("*.ts",)
    unit_class = TSUnit
    set_context_bilingual = False

    def untranslate_store(self, language, fuzzy: bool = False):
        """Remove translations from Translate Toolkit store."""
        # We need to mark all units as fuzzy to get
        # type="unfinished" on empty strings, which are otherwise
        # treated as translated same as source
        super().untranslate_store(language, True)


class XliffFormat(TTKitFormat):
    name = _("XLIFF translation file")
    format_id = "xliff"
    loader = xlifffile
    autoload: Tuple[str, ...] = ("*.xlf", "*.xliff", "*.sdlxliff", "*.mxliff")
    unit_class = XliffUnit
    language_format = "bcp"
    use_settarget = True

    def untranslate_unit(self, unit, plural, fuzzy: bool):
        super().untranslate_unit(unit, plural, fuzzy)
        # Delete empty <target/> tag
        try:
            xmlnode = self.unit.getlanguageNode(lang=None, index=1)
            if xmlnode is not None:
                xmlnode.getparent().remove(xmlnode)
        except AttributeError:
            pass

    def construct_unit(self, source: str):
        unit = super().construct_unit(source)
        # Make sure new unit is using same namespace as the original
        # file (xliff 1.1/1.2)
        unit.namespace = self.store.namespace
        unit.xmlelement = etree.Element(unit.namespaced(unit.rootNode))
        setXMLspace(unit.xmlelement, "preserve")
        return unit

    def create_unit(
        self,
        key: str,
        source: Union[str, List[str]],
        target: Optional[Union[str, List[str]]] = None,
    ):
        unit = super().create_unit(key, source, target)
        unit.marktranslated()
        unit.markapproved(False)
        return unit


class PoXliffFormat(XliffFormat):
    name = _("XLIFF with gettext extensions")
    format_id = "poxliff"
    autoload = ("*.poxliff",)
    loader = PoXliffFile


class PropertiesBaseFormat(TTKitFormat):
    unit_class = PropertiesUnit

    def is_valid(self):
        result = super().is_valid()
        if not result:
            return False

        # Accept emty file, but reject file without a delimiter.
        # Translate Toolkit happily parses anything into a property
        # even if there is no delimiter used in the line.
        return not self.store.units or self.store.units[0].delimiter

    @staticmethod
    def mimetype():
        """Return most common media type for format."""
        # Properties files do not expose mimetype
        return "text/plain"

    def construct_unit(self, source: str):
        return self.store.UnitClass(source, personality=self.store.personality.name)


class StringsFormat(PropertiesBaseFormat):
    name = _("iOS strings (UTF-16)")
    format_id = "strings"
    loader = ("properties", "stringsfile")
    new_translation: Optional[Union[str, bytes]] = "\n".encode("utf-16")
    autoload = ("*.strings",)
    language_format = "bcp"


class StringsUtf8Format(StringsFormat):
    name = _("iOS strings (UTF-8)")
    format_id = "strings-utf8"
    loader = ("properties", "stringsutf8file")
    new_translation = "\n"


class PropertiesUtf8Format(PropertiesBaseFormat):
    name = _("Java Properties (UTF-8)")
    format_id = "properties-utf8"
    loader = ("properties", "javautf8file")
    new_translation = "\n"
    language_format = "java"
    check_flags = ("auto-java-messageformat",)


class PropertiesUtf16Format(PropertiesBaseFormat):
    name = _("Java Properties (UTF-16)")
    format_id = "properties-utf16"
    loader = ("properties", "javafile")
    language_format = "java"
    new_translation = "\n"

    def fixup(self, store):
        """Force encoding.

        Translate Toolkit autodetection might fail in some cases.
        """
        store.encoding = "utf-16"


class PropertiesFormat(PropertiesBaseFormat):
    name = _("Java Properties (ISO 8859-1)")
    format_id = "properties"
    loader = ("properties", "javafile")
    language_format = "java"
    new_translation = "\n"
    autoload = ("*.properties",)

    def fixup(self, store):
        """Force encoding.

        Java properties need to be ISO 8859-1, but Translate Toolkit converts them to
        UTF-8.
        """
        store.encoding = "iso-8859-1"


class JoomlaFormat(PropertiesBaseFormat):
    name = _("Joomla language file")
    format_id = "joomla"
    loader = ("properties", "joomlafile")
    monolingual = True
    new_translation = "\n"
    autoload = ("*.ini",)


class GWTFormat(StringsFormat):
    name = _("GWT properties")
    format_id = "gwt"
    loader = ("properties", "gwtfile")
    new_translation = "\n"
    check_flags = ("auto-java-messageformat",)


class PhpFormat(TTKitFormat):
    name = _("PHP strings")
    format_id = "php"
    loader = ("php", "phpfile")
    new_translation = "<?php\n"
    autoload = ("*.php",)
    unit_class = PHPUnit

    @staticmethod
    def mimetype():
        """Return most common media type for format."""
        return "text/x-php"

    @staticmethod
    def extension():
        """Return most common file extension for format."""
        return "php"


class LaravelPhpFormat(PhpFormat):
    name = _("Laravel PHP strings")
    format_id = "laravel"
    loader = ("php", "LaravelPHPFile")


class RESXFormat(TTKitFormat):
    name = _(".NET resource file")
    format_id = "resx"
    loader = RESXFile
    monolingual = True
    unit_class = RESXUnit
    new_translation = RESXFile.XMLskeleton
    autoload = ("*.resx",)
    language_format = "bcp"


class AndroidFormat(TTKitFormat):
    name = _("Android String Resource")
    format_id = "aresource"
    loader = ("aresource", "AndroidResourceFile")
    monolingual = True
    unit_class = MonolingualIDUnit
    new_translation = '<?xml version="1.0" encoding="utf-8"?>\n<resources></resources>'
    autoload = ("strings*.xml", "values*.xml")
    language_format = "android"
    check_flags = ("java-format",)


class DictStoreMixin:
    @classmethod
    def validate_context(cls, context: str):
        id_class = cls.get_class().UnitClass.IdClass

        try:
            id_class.from_string(context)
        except Exception as error:
            raise ValidationError(gettext("Failed to parse the key: %s") % error)


class JSONFormat(DictStoreMixin, TTKitFormat):
    name = _("JSON file")
    format_id = "json"
    loader = JsonFile
    unit_class = JSONUnit
    autoload: Tuple[str, ...] = ("*.json",)
    new_translation = "{}\n"
    set_context_bilingual = False

    @staticmethod
    def mimetype():
        """Return most common media type for format."""
        return "application/json"

    @staticmethod
    def extension():
        """Return most common file extension for format."""
        return "json"


class JSONNestedFormat(JSONFormat):
    name = _("JSON nested structure file")
    format_id = "json-nested"
    loader = ("jsonl10n", "JsonNestedFile")
    autoload = ()


class WebExtensionJSONFormat(JSONFormat):
    name = _("WebExtension JSON file")
    format_id = "webextension"
    loader = ("jsonl10n", "WebExtensionJsonFile")
    monolingual = True
    autoload = ("messages*.json",)
    unit_class = WebExtensionJSONUnit


class I18NextFormat(JSONFormat):
    name = _("i18next JSON file v3")
    format_id = "i18next"
    loader = ("jsonl10n", "I18NextFile")
    autoload = ()
    check_flags = ("i18next-interpolation",)


class GoI18JSONFormat(JSONFormat):
    name = _("go-i18n JSON file")
    format_id = "go-i18n-json"
    loader = ("jsonl10n", "GoI18NJsonFile")
    autoload = ()


class ARBFormat(JSONFormat):
    name = _("ARB file")
    format_id = "arb"
    loader = ("jsonl10n", "ARBJsonFile")
    autoload = ("*.arb",)
    unit_class = ARBJSONUnit
    check_flags = ("icu-message-format",)


class CSVFormat(TTKitFormat):
    name = _("CSV file")
    format_id = "csv"
    loader = ("csvl10n", "csvfile")
    unit_class = CSVUnit
    autoload: Tuple[str, ...] = ("*.csv",)
    encoding = "auto"

    def __init__(
        self,
        storefile,
        template_store=None,
        language_code: Optional[str] = None,
        source_language: Optional[str] = None,
        is_template: bool = False,
    ):
        super().__init__(
            storefile,
            template_store=template_store,
            language_code=language_code,
            source_language=source_language,
            is_template=is_template,
        )
        # Remove template if the file contains source, this is needed
        # for import, but probably usable elsewhere as well
        if "source" in self.store.fieldnames and not isinstance(
            template_store, CSVFormat
        ):
            self.template_store = None

    @staticmethod
    def mimetype():
        """Return most common media type for format."""
        return "text/csv"

    @staticmethod
    def extension():
        """Return most common file extension for format."""
        return "csv"

    @staticmethod
    def get_content_and_filename(storefile):
        # Did we get file or filename or file object?
        if hasattr(storefile, "read"):
            filename = getattr(storefile, "name", getattr(storefile, "filename", None))
            content = storefile.read()
            storefile.close()
        else:
            filename = storefile
            with open(filename, "rb") as handle:
                content = handle.read()
        return content, filename

    def parse_store(self, storefile):
        """Parse the store."""
        storeclass = self.get_class()

        content, filename = self.get_content_and_filename(storefile)

        # Parse file
        store = storeclass()
        store.parse(content, sample_length=None)
        # Did detection of headers work?
        if store.fieldnames != ["location", "source", "target"]:
            return store

        fileobj = csv.StringIO(
            store.detect_encoding(content, default_encodings=["utf-8", "utf-16"])[0]
        )

        # Try reading header
        reader = csv.reader(fileobj, store.dialect)
        header = next(reader)
        fileobj.close()

        # Check if the file is not two column only
        if len(header) != 2:
            return store

        return self.parse_simple_csv(content, filename)

    def parse_simple_csv(self, content, filename):
        storeclass = self.get_class()
        result = storeclass(fieldnames=["source", "target"], encoding=self.encoding)
        result.parse(content, sample_length=None)
        result.filename = filename
        return result


class CSVSimpleFormat(CSVFormat):
    name = _("Simple CSV file")
    format_id = "csv-simple"
    autoload: Tuple[str, ...] = ("*.txt",)
    encoding = "auto"

    @staticmethod
    def extension():
        """Return most common file extension for format."""
        return "csv"

    def parse_store(self, storefile):
        """Parse the store."""
        content, filename = self.get_content_and_filename(storefile)

        return self.parse_simple_csv(content, filename)


class CSVSimpleFormatISO(CSVSimpleFormat):
    name = _("Simple CSV file (ISO-8859-1)")
    format_id = "csv-simple-iso"
    encoding = "iso-8859-1"
    autoload = ()


class YAMLFormat(DictStoreMixin, TTKitFormat):
    name = _("YAML file")
    format_id = "yaml"
    loader = ("yaml", "YAMLFile")
    unit_class = MonolingualSimpleUnit
    autoload: Tuple[str, ...] = ("*.pyml",)
    new_translation = "{}\n"

    @staticmethod
    def mimetype():
        """Return most common media type for format."""
        return "text/yaml"

    @staticmethod
    def extension():
        """Return most common file extension for format."""
        return "yml"


class RubyYAMLFormat(YAMLFormat):
    name = _("Ruby YAML file")
    format_id = "ruby-yaml"
    loader = ("yaml", "RubyYAMLFile")
    autoload = ("*.ryml", "*.yml", "*.yaml")


class DTDFormat(TTKitFormat):
    name = _("DTD file")
    format_id = "dtd"
    loader = ("dtd", "dtdfile")
    autoload = ("*.dtd",)
    unit_class = MonolingualSimpleUnit
    new_translation = "\n"

    @staticmethod
    def mimetype():
        """Return most common media type for format."""
        return "application/xml-dtd"

    @staticmethod
    def extension():
        """Return most common file extension for format."""
        return "dtd"

    @property
    def all_store_units(self):
        """Wrapper for all store unit filtering out null."""
        return (unit for unit in self.store.units if not unit.isblank())


class SubtitleUnit(MonolingualIDUnit):
    @cached_property
    def source(self):
        return self.template.source

    @cached_property
    def target(self):
        """Return target string from a Translate Toolkit unit."""
        if self.unit is None:
            return ""
        return get_string(self.unit.source)

    def is_translated(self):
        """Check whether unit is translated."""
        return bool(self.target)


class SubRipFormat(TTKitFormat):
    name = _("SubRip subtitle file")
    format_id = "srt"
    loader = ("subtitles", "SubRipFile")
    unit_class = SubtitleUnit
    autoload = ("*.srt",)
    monolingual = True

    @staticmethod
    def mimetype():
        """Return most common media type for format."""
        return "text/plain"


class MicroDVDFormat(SubRipFormat):
    name = _("MicroDVD subtitle file")
    format_id = "sub"
    loader = ("subtitles", "MicroDVDFile")
    autoload = ("*.sub",)


class AdvSubStationAlphaFormat(SubRipFormat):
    name = _("Advanced SubStation Alpha subtitle file")
    format_id = "ass"
    loader = ("subtitles", "AdvSubStationAlphaFile")
    autoload = ("*.ass",)


class SubStationAlphaFormat(SubRipFormat):
    name = _("SubStation Alpha subtitle file")
    format_id = "ssa"
    loader = ("subtitles", "SubStationAlphaFile")
    autoload = ("*.ssa",)


class FlatXMLFormat(TTKitFormat):
    name = _("Flat XML file")
    format_id = "flatxml"
    loader = ("flatxml", "FlatXMLFile")
    monolingual = True
    unit_class = FlatXMLUnit
    new_translation = '<?xml version="1.0" encoding="utf-8"?>\n<root></root>'


class INIFormat(TTKitFormat):
    name = _("INI file")
    format_id = "ini"
    loader = ("ini", "inifile")
    monolingual = True
    unit_class = INIUnit
    new_translation = "\n"

    @staticmethod
    def mimetype():
        """Return most common media type for format."""
        # INI files do not expose mimetype
        return "text/plain"

    @classmethod
    def extension(cls):
        """Return most common file extension for format."""
        # INI files do not expose extension
        return "ini"

    def load(self, storefile, template_store):
        store = super().load(storefile, template_store)
        # Adjust store to have translations
        for unit in store.units:
            unit.target = unit.source
            unit.rich_target = unit.rich_source
        return store

    def create_unit(
        self,
        key: str,
        source: Union[str, List[str]],
        target: Optional[Union[str, List[str]]] = None,
    ):
        unit = super().create_unit(key, source, target)
        unit.location = key
        return unit


class InnoSetupINIFormat(INIFormat):
    name = _("Inno Setup INI file")
    format_id = "islu"
    loader = ("ini", "inifile")

    @classmethod
    def extension(cls):
        """Return most common file extension for format."""
        # INI files do not expose extension
        return "islu"

    @staticmethod
    def get_class_kwargs():
        return {"dialect": "inno"}


class XWikiUnit(PropertiesUnit):
    """Dedicated unit for XWiki.

    Inspired from PropertiesUnit, allow to override the methods to use the right
    XWikiDialect methods for decoding properties.
    """

    @cached_property
    def source(self):
        # Need to decode property encoded string
        return get_string(quote.xwiki_properties_decode(super().source))

    @cached_property
    def target(self):
        """Return target string from a Translate Toolkit unit."""
        if self.unit is None:
            return ""
        # Need to decode property encoded string
        # This is basically stolen from
        # translate.storage.properties.propunit.gettarget
        # which for some reason does not return translation
        value = quote.xwiki_properties_decode(self.unit.value)
        value = re.sub("\\\\ ", " ", value)
        return get_string(value)


class XWikiPropertiesFormat(PropertiesBaseFormat):
    """Represents an XWiki Java Properties translation file.

    This format specification is detailed in
    https://dev.xwiki.org/xwiki/bin/view/Community/XWiki%20Translations%20Formats/#HXWikiJavaProperties
    """

    unit_class = XWikiUnit
    name = "XWiki Java Properties"
    format_id = "xwiki-java-properties"
    loader = ("properties", "xwikifile")
    language_format = "java"
    autoload = ("*.properties",)
    new_translation = "\n"
    can_add_unit: bool = False
    set_context_bilingual: bool = True

    # Ensure that untranslated units are saved too as missing properties and
    # comments are preserved as in the original source file.
    def save_content(self, handle):
        current_units = self.all_units
        store_units = self.store.units

        # We empty the store units since we want to control what we'll serialize
        self.store.units = []

        for unit in current_units:
            # If the translation unit is missing and the current unit is not
            # only about comment.
            if unit.unit is None and unit.has_content():

                # We first check if the unit has not been translated as part of a
                # new language: in that case the unit is not linked yet.
                found_store_unit = None
                for store_unit in store_units:
                    if unit.context == store_unit.name:
                        found_store_unit = store_unit

                # If we found a unit for same context not linked, we just link it.
                if found_store_unit is not None:
                    unit.unit = found_store_unit
                # else it's a missing unit: we need to mark it as missing.
                else:
                    missingunit = self.unit_class(self, unit.mainunit, unit.template)
                    unit.unit = missingunit.unit
                    unit.unit.missing = True
            # if the unit was only a comment, we take back the original source file unit
            # to avoid any change.
            elif not unit.has_content():
                unit.unit = unit.mainunit
            self.add_unit(unit.unit)

        self.store.serialize(handle)


class XWikiPagePropertiesFormat(XWikiPropertiesFormat):
    """Represents an XWiki Page Properties translation file.

    This format specification is detailed in
    https://dev.xwiki.org/xwiki/bin/view/Community/XWiki%20Translations%20Formats/#HXWikiPageProperties
    """

    name = "XWiki Page Properties"
    format_id = "xwiki-page-properties"
    loader = ("properties", "XWikiPageProperties")
    language_format = "java"

    def fixup(self, store):
        """Fix encoding.

        Force encoding to UTF-8 since we inherit from XWikiProperties which force
        for ISO-8859-1.
        """
        store.encoding = "utf-8"

    def save_content(self, handle):
        if self.store.root is None:
            self.store.root = self.template_store.store.root
        super().save_content(handle)


class XWikiFullPageFormat(XWikiPagePropertiesFormat):
    """Represents an XWiki Full Page translation file.

    This format specification is detailed in
    https://dev.xwiki.org/xwiki/bin/view/Community/XWiki%20Translations%20Formats/#HXWikiFullContentTranslation
    """

    name = "XWiki Full Page"
    format_id = "xwiki-fullpage"
    loader = ("properties", "XWikiFullPage")
    language_format = "java"


class TBXUnit(TTKitUnit):
    @cached_property
    def notes(self):
        """Return notes or notes from units."""
        notes = []
        for origin in ("pos", "definition", "developer"):
            note = self.unit.getnotes(origin)
            if note:
                notes.append(note)
        return "\n".join(notes)

    @cached_property
    def context(self):
        return self.unit.xmlelement.get("id") or ""


class TBXFormat(TTKitFormat):
    name = _("TermBase eXchange file")
    format_id = "tbx"
    loader = tbxfile
    autoload: Tuple[str, ...] = ("*.tbx",)
    new_translation = tbxfile.XMLskeleton
    unit_class = TBXUnit
    create_empty_bilingual: bool = True
    use_settarget = True
    monolingual = False

    def __init__(
        self,
        storefile,
        template_store=None,
        language_code: Optional[str] = None,
        source_language: Optional[str] = None,
        is_template: bool = False,
    ):
        super().__init__(
            storefile,
            template_store=template_store,
            language_code=language_code,
            is_template=is_template,
            source_language=source_language,
        )
        # Add language header if not present
        self.store.addheader()


class PropertiesMi18nFormat(PropertiesUtf8Format):
    name = _("mi18n lang file")
    format_id = "mi18n-lang"
    new_translation = "\n"
    language_format = "java"
    check_flags = ("es-format",)
    monolingual = True


class StringsdictFormat(DictStoreMixin, TTKitFormat):
    name = _("Stringsdict file")
    format_id = "stringsdict"
    loader = ("stringsdict", "StringsDictFile")
    unit_class = MonolingualSimpleUnit
    autoload: Tuple[str, ...] = ("*.stringsdict",)
    new_translation = """<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
    <dict>
    </dict>
</plist>
"""  # noqa: E501

    @staticmethod
    def mimetype():
        """Return most common media type for format."""
        return "application/xml"

    @staticmethod
    def extension():
        """Return most common file extension for format."""
        return "stringsdict"

    @classmethod
    def get_plural(cls, language, store=None):
        """Return matching plural object."""
        plural = super().get_plural(language, store)
        if plural.type in ZERO_PLURAL_TYPES:
            return plural

        from weblate.lang.models import Plural

        return language.plural_set.get_or_create(
            source=Plural.SOURCE_STRINGSDICT,
            defaults={
                "formula": FORMULA_WITH_ZERO[plural.formula],
                "number": plural.number + 1,
            },
        )[0]

    def fixup(self, store):
        if self.language_code:
            store.settargetlanguage(self.language_code)
        elif self.source_language:
            store.settargetlanguage(self.source_language)


class FluentUnit(MonolingualSimpleUnit):
    def set_target(self, target):
        super().set_target(target)
        self.unit.source = target


class FluentFormat(TTKitFormat):
    name = _("Fluent file")
    format_id = "fluent"
    loader = ("fluent", "FluentFile")
    unit_class = FluentUnit
    autoload: Tuple[str, ...] = ("*.ftl",)
    new_translation = ""

    @staticmethod
    def mimetype():
        """Return most common media type for format."""
        return "text/x-fluent"

    @staticmethod
    def extension():
        """Return most common file extension for format."""
        return "ftl"

    def create_unit(
        self,
        key: str,
        source: Union[str, List[str]],
        target: Optional[Union[str, List[str]]] = None,
    ):
        unit = super().create_unit(key, source, target)
        unit.source = unit.target
        return unit
