from __future__ import annotations

import xml.etree.ElementTree as ET
from dataclasses import dataclass, field
from pathlib import Path
from typing import Iterable

from .config import validate_file_name as validate_pipeline_file_name


@dataclass
class ParticipantRow:
    file_name: str
    operation_index: int
    record_id: str
    operation_fields: dict[str, str]
    participant_fields: dict[str, str]


@dataclass
class OperationParseError:
    operation_index: int
    record_id: str
    reason: str


@dataclass
class FileParseResult:
    file_name: str
    rows: list[ParticipantRow] = field(default_factory=list)
    total_operations: int = 0
    operation_errors: list[OperationParseError] = field(default_factory=list)
    fatal_error: str | None = None

    @property
    def is_fatal(self) -> bool:
        return self.fatal_error is not None


def validate_file_name(file_name: str) -> bool:
    return validate_pipeline_file_name(file_name)


def parse_xml_file(file_path: Path) -> FileParseResult:
    try:
        content = file_path.read_bytes()
    except OSError as exc:
        result = FileParseResult(file_name=file_path.name)
        result.fatal_error = f"Ошибка чтения файла: {exc}"
        return result
    return parse_xml_content(file_name=file_path.name, xml_content=content)


def parse_xml_content(file_name: str, xml_content: bytes | str) -> FileParseResult:
    result = FileParseResult(file_name=file_name)

    if not validate_file_name(file_name):
        result.fatal_error = "Некорректное имя файла"
        return result

    try:
        root = ET.fromstring(xml_content)
    except ET.ParseError as exc:
        result.fatal_error = f"Ошибка XML: {exc}"
        return result

    try:
        operations = _get_operations(root)
        common_fields = _extract_common_fields(root)
    except ValueError as exc:
        result.fatal_error = str(exc)
        return result

    for index, operation in enumerate(operations, start=1):
        result.total_operations += 1
        record_id = f"ОПЕРАЦИЯ_{index}"
        try:
            operation_fields = _extract_direct_fields(
                operation, excluded_tags={"УчастникОп"}
            )
            operation_fields = {**common_fields, **operation_fields}
            record_id = _extract_record_id(operation_fields, index)
            participants = _find_children_by_name(operation, "УчастникОп")

            if participants:
                for participant in participants:
                    participant_fields = _extract_direct_fields(participant)
                    result.rows.append(
                        ParticipantRow(
                            file_name=file_name,
                            operation_index=index,
                            record_id=record_id,
                            operation_fields=operation_fields,
                            participant_fields=participant_fields,
                        )
                    )
            else:
                result.rows.append(
                    ParticipantRow(
                        file_name=file_name,
                        operation_index=index,
                        record_id=record_id,
                        operation_fields=operation_fields,
                        participant_fields={},
                    )
                )
        except Exception as exc:  # noqa: BLE001
            result.operation_errors.append(
                OperationParseError(
                    operation_index=index,
                    record_id=record_id,
                    reason=f"Ошибка обработки операции: {exc}",
                )
            )

    return result


def _get_operations(root: ET.Element) -> list[ET.Element]:
    if _normalize_tag(root.tag) != "СообщОперКО":
        raise ValueError("Некорректный корневой элемент XML (ожидался СообщОперКО)")

    inform_part = _find_child_by_name(root, "ИнформЧасть")
    if inform_part is None:
        raise ValueError("В XML отсутствует элемент ИнформЧасть")

    details = _find_child_by_name(inform_part, "СведКО")
    if details is None:
        raise ValueError("В XML отсутствует элемент СведКО")

    return _find_children_by_name(details, "Операция")


def _extract_direct_fields(
    element: ET.Element,
    excluded_tags: Iterable[str] | None = None,
) -> dict[str, str]:
    excluded = set(excluded_tags or ())
    fields: dict[str, str] = {}

    for child in element:
        tag = _normalize_tag(child.tag)
        if tag in excluded:
            continue
        _collect_leaf_fields(child, tag, fields)

    return fields


def _extract_record_id(operation_fields: dict[str, str], operation_index: int) -> str:
    possible_keys = (
        "ИдентификаторЗаписи",
        "НомерЗаписи",
        "ИдЗаписи",
        "ИдЗап",
        "ИдОпер",
        "ID",
    )
    for key in possible_keys:
        if operation_fields.get(key):
            return operation_fields[key]
    return f"ОПЕРАЦИЯ_{operation_index}"


def _normalize_tag(tag: str) -> str:
    if "}" in tag:
        return tag.split("}", maxsplit=1)[1]
    return tag


def _find_child_by_name(parent: ET.Element, child_name: str) -> ET.Element | None:
    for child in parent:
        if _normalize_tag(child.tag) == child_name:
            return child
    return None


def _find_children_by_name(parent: ET.Element, child_name: str) -> list[ET.Element]:
    return [child for child in parent if _normalize_tag(child.tag) == child_name]


def _extract_common_fields(root: ET.Element) -> dict[str, str]:
    common: dict[str, str] = {}

    service_part = _find_child_by_name(root, "СлужЧасть")
    if service_part is not None:
        common.update(_extract_direct_fields(service_part))

    inform_part = _find_child_by_name(root, "ИнформЧасть")
    if inform_part is None:
        return common

    info_bank = _find_child_by_name(inform_part, "ИнфБанк")
    if info_bank is not None:
        common.update(_extract_direct_fields(info_bank))

    details = _find_child_by_name(inform_part, "СведКО")
    if details is None:
        return common

    common.update(
        _extract_direct_fields(details, excluded_tags={"Операция", "ИнфФилиал"})
    )
    branch_info = _find_child_by_name(details, "ИнфФилиал")
    if branch_info is not None:
        common.update(_extract_direct_fields(branch_info))

    return common


def _collect_leaf_fields(
    element: ET.Element, current_path: str, fields: dict[str, str]
) -> None:
    children = list(element)
    if not children:
        _append_value(fields, current_path, (element.text or "").strip())
        return

    for child in children:
        child_name = _normalize_tag(child.tag)
        _collect_leaf_fields(child, f"{current_path}.{child_name}", fields)


def _append_value(fields: dict[str, str], key: str, value: str) -> None:
    if key not in fields:
        fields[key] = value
        return

    existing = fields[key]
    if not value:
        return
    if not existing:
        fields[key] = value
        return
    if value in existing.split("; "):
        return

    fields[key] = f"{existing}; {value}"