# Copyright Mozilla Foundation
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

from __future__ import annotations

from collections import defaultdict
from collections.abc import Iterator

from lxml import etree

from ...model import (
    Entry,
    Expression,
    Markup,
    Message,
    Metadata,
    PatternMessage,
    VariableRef,
)
from .common import attrib_as_metadata, element_as_metadata, pretty_name, xliff_ns
from .parse_xcode import parse_xcode_pattern


def parse_trans_unit(unit: etree._Element, is_xcode: bool) -> Entry[Message]:
    id = unit.attrib.get("id", None)
    if id is None:
        raise ValueError(f'Missing "id" attribute for <trans-unit>: {unit}')
    meta = attrib_as_metadata(unit, None, ("id",))
    if unit.text and not unit.text.isspace():
        raise ValueError(f"Unexpected text in <trans-unit>: {unit.text}")

    target = None
    note = None
    seen: dict[str, int] = defaultdict(int)
    for el in unit:
        if isinstance(el, etree._Comment):
            meta.append(Metadata("comment()", el.text))
        else:
            name = pretty_name(el, el.tag)
            if name == "target":
                if target:
                    raise ValueError(f"Duplicate <target> in <trans-unit> {id}: {unit}")
                target = el
                meta += attrib_as_metadata(el, "target")
            elif name == "note" and note is None and el.text:
                note = el
                note_attrib = attrib_as_metadata(el, "note")
                if note_attrib:
                    meta += note_attrib
                elif el != unit[-1]:
                    # If there are elements after this <note>,
                    # add a marker for its relative position.
                    meta.append(Metadata("note", ""))
                seen[name] += 1
            else:
                idx = seen[name] + 1
                base = f"{name}[{idx}]" if idx > 1 else name
                meta += element_as_metadata(el, base, True)
                seen[name] = idx
        if el.tail and not el.tail.isspace():
            raise ValueError(f"Unexpected text in <trans-unit>: {el.tail}")

    comment = "" if note is None else note.text or ""
    msg = PatternMessage(
        [] if target is None else list(parse_pattern(target, is_xcode))
    )
    return Entry((id,), msg, comment, meta)


def parse_pattern(
    el: etree._Element, is_xcode: bool
) -> Iterator[str | Expression | Markup]:
    if el.text:
        if is_xcode:
            yield from parse_xcode_pattern(el.text)
        else:
            yield el.text
    for child in el:
        q = etree.QName(child.tag)
        ns = q.namespace
        name = q.localname if not ns or ns in xliff_ns else q.text
        options: dict[str, str | VariableRef] = dict(child.attrib)
        if name in ("x", "bx", "ex"):
            yield Markup("standalone", name, options)
        elif isinstance(child.tag, str):
            yield Markup("open", name, options)
            yield from parse_pattern(child, is_xcode)
            yield Markup("close", name)
        if child.tail:
            yield child.tail