from django.contrib.contenttypes.models import ContentType
from django.core.exceptions import ValidationError
from django.db import IntegrityError, transaction

from mes.models import (
    CapacityUnitEnum,
    Device,
    DeviceCategory,
    ProductionAssignment,
    ProductionAssignmentStatusEnum,
)


UNSET = object()

ALLOWED_PRODUCTION_ASSIGNMENT_STATUS_TRANSITIONS = {
    ProductionAssignmentStatusEnum.DRAFT: {
        ProductionAssignmentStatusEnum.DRAFT,
        ProductionAssignmentStatusEnum.PUBLISHED,
        ProductionAssignmentStatusEnum.CANCELLED,
    },
    ProductionAssignmentStatusEnum.PUBLISHED: {
        ProductionAssignmentStatusEnum.PUBLISHED,
        ProductionAssignmentStatusEnum.ACCEPTED,
        ProductionAssignmentStatusEnum.CANCELLED,
    },
    ProductionAssignmentStatusEnum.ACCEPTED: {
        ProductionAssignmentStatusEnum.ACCEPTED,
        ProductionAssignmentStatusEnum.COMPLETED,
    },
    ProductionAssignmentStatusEnum.CANCELLED: {
        ProductionAssignmentStatusEnum.CANCELLED,
    },
    ProductionAssignmentStatusEnum.COMPLETED: {
        ProductionAssignmentStatusEnum.COMPLETED,
    },
}


def _normalize_name(name: str, field_name: str = 'name') -> str:
    normalized = (name or '').strip()
    if not normalized:
        raise ValueError(f'{field_name}不能为空')
    return normalized


def _assert_operator_belongs_to_merchant(*, operator, merchant) -> None:
    if operator is None:
        raise ValueError('操作人不能为空')
    if operator.merchant_id != merchant.id:
        raise ValueError('操作人不属于当前商户')


def _assert_category_belongs_to_merchant(*, category: DeviceCategory, merchant) -> None:
    if category.merchant_id != merchant.id:
        raise ValueError('设备分类不属于当前商户')


def _assert_employee_belongs_to_merchant(*, employee, merchant, role: str) -> None:
    if employee is None:
        raise ValueError(f'{role}不能为空')
    if employee.merchant_id != merchant.id:
        raise ValueError(f'{role}不属于当前商户')


def _validate_peak_capacity(peak_capacity: int) -> int:
    if peak_capacity is None:
        raise ValueError('峰值产能不能为空')
    if int(peak_capacity) <= 0:
        raise ValueError('峰值产能必须大于0')
    return int(peak_capacity)


def _validate_capacity_unit(capacity_unit: int) -> int:
    valid_values = {choice[0] for choice in CapacityUnitEnum.choices}
    if capacity_unit not in valid_values:
        raise ValueError('产能单位不合法')
    return capacity_unit


def _validate_production_quantity(production_quantity: int) -> int:
    if production_quantity is None:
        raise ValueError('生产数量不能为空')
    if int(production_quantity) <= 0:
        raise ValueError('生产数量必须大于0')
    return int(production_quantity)


def _validate_production_assignment_status(status: int) -> int:
    valid_values = {choice[0] for choice in ProductionAssignmentStatusEnum.choices}
    if status not in valid_values:
        raise ValueError('生产指派状态不合法')
    return status


def _validate_production_assignment_status_transition(*, current_status: int, next_status: int) -> int:
    next_status = _validate_production_assignment_status(next_status)
    allowed_statuses = ALLOWED_PRODUCTION_ASSIGNMENT_STATUS_TRANSITIONS.get(current_status, {current_status})
    if next_status not in allowed_statuses:
        raise ValueError('当前状态不允许变更为目标状态')
    return next_status


def _validate_content_object_merchant(*, content_type, object_id: int, merchant) -> None:
    try:
        content_object = content_type.get_object_for_this_type(pk=object_id)
    except Exception as exc:
        raise ValueError('关联对象不存在') from exc
    content_object_merchant_id = getattr(content_object, 'merchant_id', None)
    if content_object_merchant_id is not None and content_object_merchant_id != merchant.id:
        raise ValueError('关联对象不属于当前商户')


def _save_with_validation(instance):
    try:
        instance.full_clean()
        instance.save()
    except ValidationError as exc:
        if hasattr(exc, 'message_dict'):
            first_error = next(iter(exc.message_dict.values()))
            if isinstance(first_error, list) and first_error:
                raise ValueError(first_error[0]) from exc
        raise ValueError(str(exc)) from exc
    except IntegrityError as exc:
        raise ValueError('名称已存在') from exc
    return instance


def list_device_categories_for_merchant(*, merchant):
    return DeviceCategory.objects.filter(merchant=merchant).select_related('merchant', 'created_by', 'operator')


def get_device_category_for_merchant(*, merchant, category_id: int) -> DeviceCategory:
    return list_device_categories_for_merchant(merchant=merchant).get(id=category_id)


@transaction.atomic
def create_device_category(*, merchant, name: str, created_by, operator) -> DeviceCategory:
    _assert_operator_belongs_to_merchant(operator=operator, merchant=merchant)
    category = DeviceCategory(
        merchant=merchant,
        name=_normalize_name(name, '设备分类名称'),
        created_by=created_by,
        operator=operator,
    )
    return _save_with_validation(category)


@transaction.atomic
def update_device_category(*, category: DeviceCategory, operator, name=UNSET) -> DeviceCategory:
    _assert_operator_belongs_to_merchant(operator=operator, merchant=category.merchant)
    category = DeviceCategory.objects.select_for_update().get(pk=category.pk)
    category.operator = operator
    if name is not UNSET:
        category.name = _normalize_name(name, '设备分类名称')
    return _save_with_validation(category)


@transaction.atomic
def delete_device_category(*, category: DeviceCategory, operator) -> None:
    _assert_operator_belongs_to_merchant(operator=operator, merchant=category.merchant)
    category = DeviceCategory.objects.select_for_update().get(pk=category.pk)
    category.delete()


def list_devices_for_merchant(*, merchant, category_id: int | None = None, extra_json_path: list[str] | None = None,
                              extra_json_value=UNSET):
    queryset = Device.objects.filter(merchant=merchant).select_related('merchant', 'category', 'created_by', 'operator')
    if category_id is not None:
        queryset = queryset.filter(category_id=category_id)
    if extra_json_path:
        lookup = '__'.join(['extra', *extra_json_path])
        queryset = queryset.filter(**{lookup: extra_json_value})
    return queryset


def get_device_for_merchant(*, merchant, device_id: int) -> Device:
    return list_devices_for_merchant(merchant=merchant).get(id=device_id)


@transaction.atomic
def create_device(*, merchant, category: DeviceCategory, name: str, created_by, operator, peak_capacity: int,
                  capacity_unit: int = CapacityUnitEnum.METER, extra=None) -> Device:
    _assert_operator_belongs_to_merchant(operator=operator, merchant=merchant)
    _assert_category_belongs_to_merchant(category=category, merchant=merchant)
    device = Device(
        merchant=merchant,
        category=category,
        name=_normalize_name(name, '设备名称'),
        peak_capacity=_validate_peak_capacity(peak_capacity),
        capacity_unit=_validate_capacity_unit(capacity_unit),
        extra=extra,
        created_by=created_by,
        operator=operator,
    )
    return _save_with_validation(device)


@transaction.atomic
def update_device(*, device: Device, operator, name=UNSET, category=UNSET, peak_capacity=UNSET,
                  capacity_unit=UNSET, extra=UNSET):
    device = Device.objects.select_for_update().get(pk=device.pk)
    _assert_operator_belongs_to_merchant(operator=operator, merchant=device.merchant)
    device.operator = operator
    if name is not UNSET:
        device.name = _normalize_name(name, '设备名称')
    if category is not UNSET:
        _assert_category_belongs_to_merchant(category=category, merchant=device.merchant)
        device.category = category
    if peak_capacity is not UNSET:
        device.peak_capacity = _validate_peak_capacity(peak_capacity)
    if capacity_unit is not UNSET:
        device.capacity_unit = _validate_capacity_unit(capacity_unit)
    if extra is not UNSET:
        device.extra = extra
    return _save_with_validation(device)


@transaction.atomic
def delete_device(*, device: Device, operator) -> None:
    _assert_operator_belongs_to_merchant(operator=operator, merchant=device.merchant)
    device = Device.objects.select_for_update().get(pk=device.pk)
    device.delete()


def list_production_assignments_for_merchant(*, merchant, device_id: int | None = None, content_type_id: int | None = None,
                                             object_id: int | None = None, status: int | None = None):
    queryset = ProductionAssignment.objects.filter(merchant=merchant).select_related(
        'merchant', 'device', 'content_type', 'assigner', 'assignee', 'created_by', 'operator'
    )
    if device_id is not None:
        queryset = queryset.filter(device_id=device_id)
    if content_type_id is not None:
        queryset = queryset.filter(content_type_id=content_type_id)
    if object_id is not None:
        queryset = queryset.filter(object_id=object_id)
    if status is not None:
        queryset = queryset.filter(status=status)
    return queryset


def get_production_assignment_for_merchant(*, merchant, assignment_id: int) -> ProductionAssignment:
    return list_production_assignments_for_merchant(merchant=merchant).get(id=assignment_id)


@transaction.atomic
def create_production_assignment(*, merchant, device: Device, content_type: ContentType, object_id: int,
                                 assigner, production_quantity: int, assignee=None, created_by=None, operator=None,
                                 status: int = ProductionAssignmentStatusEnum.DRAFT, extra=None) -> ProductionAssignment:
    _assert_employee_belongs_to_merchant(employee=assigner, merchant=merchant, role='指派者')
    if assignee is not None:
        _assert_employee_belongs_to_merchant(employee=assignee, merchant=merchant, role='被指派人')
    _assert_employee_belongs_to_merchant(employee=operator, merchant=merchant, role='操作人')
    if device.merchant_id != merchant.id:
        raise ValueError('设备不属于当前商户')
    _validate_content_object_merchant(content_type=content_type, object_id=object_id, merchant=merchant)
    assignment = ProductionAssignment(
        merchant=merchant,
        device=device,
        content_type=content_type,
        object_id=object_id,
        assigner=assigner,
        assignee=assignee,
        production_quantity=_validate_production_quantity(production_quantity),
        status=_validate_production_assignment_status(status),
        created_by=created_by,
        operator=operator,
        extra=extra,
    )
    return _save_with_validation(assignment)


@transaction.atomic
def update_production_assignment(*, assignment: ProductionAssignment, operator, device=UNSET, assignee=UNSET,
                                 production_quantity=UNSET, status=UNSET, extra=UNSET):
    assignment = ProductionAssignment.objects.select_for_update().get(pk=assignment.pk)
    _assert_employee_belongs_to_merchant(employee=operator, merchant=assignment.merchant, role='操作人')
    assignment.operator = operator
    if device is not UNSET:
        if device.merchant_id != assignment.merchant_id:
            raise ValueError('设备不属于当前商户')
        assignment.device = device
    if assignee is not UNSET:
        if assignee is not None:
            _assert_employee_belongs_to_merchant(employee=assignee, merchant=assignment.merchant, role='被指派人')
        assignment.assignee = assignee
    if production_quantity is not UNSET:
        assignment.production_quantity = _validate_production_quantity(production_quantity)
    if status is not UNSET:
        assignment.status = _validate_production_assignment_status_transition(
            current_status=assignment.status,
            next_status=status,
        )
    if extra is not UNSET:
        assignment.extra = extra
    return _save_with_validation(assignment)


@transaction.atomic
def delete_production_assignment(*, assignment: ProductionAssignment, operator) -> None:
    _assert_employee_belongs_to_merchant(employee=operator, merchant=assignment.merchant, role='操作人')
    assignment = ProductionAssignment.objects.select_for_update().get(pk=assignment.pk)
    assignment.delete()