import copy
import json
from json.decoder import JSONDecodeError

from boltons.urlutils import URL
from flask import g, request
from flask_wtf import FlaskForm
from sqlalchemy import or_
from sqlalchemy.util import OrderedSet
from wtforms import (
    BooleanField,
    DateField,
    FileField,
    FloatField,
    Form,
    HiddenField,
    IntegerField,
    MultipleFileField,
    SelectField,
    StringField,
    TextAreaField,
    URLField,
    validators,
)
from wtforms.fields import FormField

from ereuse_devicehub.db import db
from ereuse_devicehub.resources.action.models import RateComputer, Snapshot, Trade
from ereuse_devicehub.resources.action.rate.v1_0 import CannotRate
from ereuse_devicehub.resources.action.schemas import Snapshot as SnapshotSchema
from ereuse_devicehub.resources.action.views.snapshot import move_json, save_json
from ereuse_devicehub.resources.device.models import (
    SAI,
    Cellphone,
    Computer,
    Device,
    Keyboard,
    MemoryCardReader,
    Monitor,
    Mouse,
    Smartphone,
    Tablet,
)
from ereuse_devicehub.resources.device.sync import Sync
from ereuse_devicehub.resources.documents.models import DataWipeDocument
from ereuse_devicehub.resources.enums import Severity, SnapshotSoftware
from ereuse_devicehub.resources.hash_reports import insert_hash
from ereuse_devicehub.resources.lot.models import Lot
from ereuse_devicehub.resources.tag.model import Tag
from ereuse_devicehub.resources.tradedocument.models import TradeDocument
from ereuse_devicehub.resources.user.exceptions import InsufficientPermission
from ereuse_devicehub.resources.user.models import User

DEVICES = {
    "All": ["All"],
    "Computer": [
        "Desktop",
        "Laptop",
        "Server",
    ],
    "Monitor": ["ComputerMonitor", "Monitor", "TelevisionSet", "Projector"],
    "Mobile, tablet & smartphone": ["Mobile", "Tablet", "Smartphone", "Cellphone"],
    "DataStorage": ["HardDrive", "SolidStateDrive"],
    "Accessories & Peripherals": [
        "GraphicCard",
        "Motherboard",
        "NetworkAdapter",
        "Processor",
        "RamModule",
        "SoundCard",
        "Battery",
        "Keyboard",
        "Mouse",
        "MemoryCardReader",
    ],
}


class FilterForm(FlaskForm):
    filter = SelectField(
        '', choices=DEVICES, default="Computer", render_kw={'class': "form-select"}
    )

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        types_of_devices = [item for sublist in DEVICES.values() for item in sublist]
        dev = request.args.get('filter')
        self.device = dev if dev in types_of_devices else None
        if self.device:
            self.filter.data = self.device

    def search(self):

        if self.device:
            return [self.device]

        return ['Desktop', 'Laptop', 'Server']


class LotDeviceForm(FlaskForm):
    lot = StringField('Lot', [validators.UUID()])
    devices = StringField('Devices', [validators.length(min=1)])

    def validate(self, extra_validators=None):
        is_valid = super().validate(extra_validators)

        if not is_valid:
            return False

        self._lot = (
            Lot.query.outerjoin(Trade)
            .filter(Lot.id == self.lot.data)
            .filter(
                or_(
                    Trade.user_from == g.user,
                    Trade.user_to == g.user,
                    Lot.owner_id == g.user.id,
                )
            )
            .one()
        )

        devices = set(self.devices.data.split(","))
        self._devices = (
            Device.query.filter(Device.id.in_(devices))
            .filter(Device.owner_id == g.user.id)
            .distinct()
            .all()
        )

        return bool(self._devices)

    def save(self, commit=True):
        trade = self._lot.trade
        if trade:
            for dev in self._devices:
                if trade not in dev.actions:
                    trade.devices.add(dev)

        if self._devices:
            self._lot.devices.update(self._devices)
            db.session.add(self._lot)

        if commit:
            db.session.commit()

    def remove(self, commit=True):
        if self._devices:
            self._lot.devices.difference_update(self._devices)
            db.session.add(self._lot)

        if commit:
            db.session.commit()


class LotForm(FlaskForm):
    name = StringField('Name', [validators.length(min=1)])

    def __init__(self, *args, **kwargs):
        self.id = kwargs.pop('id', None)
        self.instance = None
        if self.id:
            self.instance = (
                Lot.query.filter(Lot.id == self.id)
                .filter(Lot.owner_id == g.user.id)
                .one()
            )
        super().__init__(*args, **kwargs)
        if self.instance and not self.name.data:
            self.name.data = self.instance.name

    def save(self):
        if not self.id:
            self.instance = Lot(name=self.name.data)

        self.populate_obj(self.instance)

        if not self.id:
            self.id = self.instance.id
            db.session.add(self.instance)
            db.session.commit()
            return self.id

        db.session.commit()
        return self.id

    def remove(self):
        if self.instance and not self.instance.trade:
            self.instance.delete()
            db.session.commit()
        return self.instance


class UploadSnapshotForm(FlaskForm):
    snapshot = MultipleFileField('Select a Snapshot File', [validators.DataRequired()])

    def validate(self, extra_validators=None):
        is_valid = super().validate(extra_validators)

        if not is_valid:
            return False

        data = request.files.getlist(self.snapshot.name)
        if not data:
            return False
        self.snapshots = []
        self.result = {}
        for d in data:
            filename = d.filename
            self.result[filename] = 'Not processed'
            d = d.stream.read()
            if not d:
                self.result[filename] = 'Error this snapshot is empty'
                continue

            try:
                d_json = json.loads(d)
            except JSONDecodeError:
                self.result[filename] = 'Error this snapshot is not a json'
                continue

            uuid_snapshot = d_json.get('uuid')
            if Snapshot.query.filter(Snapshot.uuid == uuid_snapshot).all():
                self.result[filename] = 'Error this snapshot exist'
                continue

            self.snapshots.append((filename, d_json))

        if not self.snapshots:
            return False

        return True

    def save(self, commit=True):
        if any([x == 'Error' for x in self.result.values()]):
            return
        # result = []
        self.sync = Sync()
        schema = SnapshotSchema()
        # self.tmp_snapshots = app.config['TMP_SNAPSHOTS']
        # TODO @cayop get correct var config
        self.tmp_snapshots = '/tmp/'
        for filename, snapshot_json in self.snapshots:
            path_snapshot = save_json(snapshot_json, self.tmp_snapshots, g.user.email)
            snapshot_json.pop('debug', None)
            snapshot_json = schema.load(snapshot_json)
            response = self.build(snapshot_json)

            if hasattr(response, 'type'):
                self.result[filename] = 'Ok'
            else:
                self.result[filename] = 'Error'

            move_json(self.tmp_snapshots, path_snapshot, g.user.email)

        if commit:
            db.session.commit()
        return response

    def build(self, snapshot_json):  # noqa: C901
        # this is a copy adaptated from ereuse_devicehub.resources.action.views.snapshot
        device = snapshot_json.pop('device')  # type: Computer
        components = None
        if snapshot_json['software'] == (
            SnapshotSoftware.Workbench or SnapshotSoftware.WorkbenchAndroid
        ):
            components = snapshot_json.pop('components', None)
            if isinstance(device, Computer) and device.hid:
                device.add_mac_to_hid(components_snap=components)
        snapshot = Snapshot(**snapshot_json)

        # Remove new actions from devices so they don't interfere with sync
        actions_device = set(e for e in device.actions_one)
        device.actions_one.clear()
        if components:
            actions_components = tuple(
                set(e for e in c.actions_one) for c in components
            )
            for component in components:
                component.actions_one.clear()

        assert not device.actions_one
        assert all(not c.actions_one for c in components) if components else True
        db_device, remove_actions = self.sync.run(device, components)

        del device  # Do not use device anymore
        snapshot.device = db_device
        snapshot.actions |= remove_actions | actions_device  # Set actions to snapshot
        # commit will change the order of the components by what
        # the DB wants. Let's get a copy of the list so we preserve order
        ordered_components = OrderedSet(x for x in snapshot.components)

        # Add the new actions to the db-existing devices and components
        db_device.actions_one |= actions_device
        if components:
            for component, actions in zip(ordered_components, actions_components):
                component.actions_one |= actions
                snapshot.actions |= actions

        if snapshot.software == SnapshotSoftware.Workbench:
            # Check ownership of (non-component) device to from current.user
            if db_device.owner_id != g.user.id:
                raise InsufficientPermission()
            # Compute ratings
            try:
                rate_computer, price = RateComputer.compute(db_device)
            except CannotRate:
                pass
            else:
                snapshot.actions.add(rate_computer)
                if price:
                    snapshot.actions.add(price)
        elif snapshot.software == SnapshotSoftware.WorkbenchAndroid:
            pass  # TODO try except to compute RateMobile
        # Check if HID is null and add Severity:Warning to Snapshot
        if snapshot.device.hid is None:
            snapshot.severity = Severity.Warning

        db.session.add(snapshot)
        return snapshot


class NewDeviceForm(FlaskForm):
    type = StringField('Type', [validators.DataRequired()])
    label = StringField('Label')
    serial_number = StringField('Seria Number', [validators.DataRequired()])
    model = StringField('Model', [validators.DataRequired()])
    manufacturer = StringField('Manufacturer', [validators.DataRequired()])
    appearance = StringField('Appearance', [validators.Optional()])
    functionality = StringField('Functionality', [validators.Optional()])
    brand = StringField('Brand')
    generation = IntegerField('Generation')
    version = StringField('Version')
    weight = FloatField('Weight', [validators.DataRequired()])
    width = FloatField('Width', [validators.DataRequired()])
    height = FloatField('Height', [validators.DataRequired()])
    depth = FloatField('Depth', [validators.DataRequired()])
    variant = StringField('Variant', [validators.Optional()])
    sku = StringField('SKU', [validators.Optional()])
    image = StringField('Image', [validators.Optional(), validators.URL()])
    imei = IntegerField('IMEI', [validators.Optional()])
    meid = StringField('MEID', [validators.Optional()])
    resolution = IntegerField('Resolution width', [validators.Optional()])
    screen = FloatField('Screen size', [validators.Optional()])

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self.devices = {
            "Smartphone": Smartphone,
            "Tablet": Tablet,
            "Cellphone": Cellphone,
            "Monitor": Monitor,
            "Mouse": Mouse,
            "Keyboard": Keyboard,
            "SAI": SAI,
            "MemoryCardReader": MemoryCardReader,
        }

        if not self.generation.data:
            self.generation.data = 1

        if not self.weight.data:
            self.weight.data = 0.1

        if not self.height.data:
            self.height.data = 0.1

        if not self.width.data:
            self.width.data = 0.1

        if not self.depth.data:
            self.depth.data = 0.1

    def validate(self, extra_validators=None):  # noqa: C901
        error = ["Not a correct value"]
        is_valid = super().validate(extra_validators)

        if self.generation.data < 1:
            self.generation.errors = error
            is_valid = False

        if self.weight.data < 0.1:
            self.weight.errors = error
            is_valid = False

        if self.height.data < 0.1:
            self.height.errors = error
            is_valid = False

        if self.width.data < 0.1:
            self.width.errors = error
            is_valid = False

        if self.depth.data < 0.1:
            self.depth.errors = error
            is_valid = False

        if self.imei.data:
            if not 13 < len(str(self.imei.data)) < 17:
                self.imei.errors = error
                is_valid = False

        if self.meid.data:
            meid = self.meid.data
            if not 13 < len(meid) < 17:
                is_valid = False
            try:
                int(meid, 16)
            except ValueError:
                self.meid.errors = error
                is_valid = False

        if not is_valid:
            return False

        if self.image.data == '':
            self.image.data = None
        if self.manufacturer.data:
            self.manufacturer.data = self.manufacturer.data.lower()
        if self.model.data:
            self.model.data = self.model.data.lower()
        if self.serial_number.data:
            self.serial_number.data = self.serial_number.data.lower()

        return True

    def save(self, commit=True):

        json_snapshot = {
            'type': 'Snapshot',
            'software': 'Web',
            'version': '11.0',
            'device': {
                'type': self.type.data,
                'model': self.model.data,
                'manufacturer': self.manufacturer.data,
                'serialNumber': self.serial_number.data,
                'brand': self.brand.data,
                'version': self.version.data,
                'generation': self.generation.data,
                'sku': self.sku.data,
                'weight': self.weight.data,
                'width': self.width.data,
                'height': self.height.data,
                'depth': self.depth.data,
                'variant': self.variant.data,
                'image': self.image.data,
            },
        }

        if self.appearance.data or self.functionality.data:
            json_snapshot['device']['actions'] = [
                {
                    'type': 'VisualTest',
                    'appearanceRange': self.appearance.data,
                    'functionalityRange': self.functionality.data,
                }
            ]

        upload_form = UploadSnapshotForm()
        upload_form.sync = Sync()

        schema = SnapshotSchema()
        self.tmp_snapshots = '/tmp/'
        path_snapshot = save_json(json_snapshot, self.tmp_snapshots, g.user.email)
        snapshot_json = schema.load(json_snapshot)

        if self.type.data == 'Monitor':
            snapshot_json['device'].resolution_width = self.resolution.data
            snapshot_json['device'].size = self.screen.data

        if self.type.data in ['Smartphone', 'Tablet', 'Cellphone']:
            snapshot_json['device'].imei = self.imei.data
            snapshot_json['device'].meid = self.meid.data

        snapshot = upload_form.build(snapshot_json)

        move_json(self.tmp_snapshots, path_snapshot, g.user.email)
        if self.type.data == 'Monitor':
            snapshot.device.resolution = self.resolution.data
            snapshot.device.screen = self.screen.data

        if commit:
            db.session.commit()
        return snapshot


class TagDeviceForm(FlaskForm):
    tag = SelectField('Tag', choices=[])
    device = StringField('Device', [validators.Optional()])

    def __init__(self, *args, **kwargs):
        self.delete = kwargs.pop('delete', None)
        self.device_id = kwargs.pop('device', None)

        super().__init__(*args, **kwargs)

        if self.delete:
            tags = (
                Tag.query.filter(Tag.owner_id == g.user.id)
                .filter_by(device_id=self.device_id)
                .order_by(Tag.id)
            )
        else:
            tags = (
                Tag.query.filter(Tag.owner_id == g.user.id)
                .filter_by(device_id=None)
                .order_by(Tag.id)
            )

        self.tag.choices = [(tag.id, tag.id) for tag in tags]

    def validate(self, extra_validators=None):
        is_valid = super().validate(extra_validators)

        if not is_valid:
            return False

        self._tag = (
            Tag.query.filter(Tag.id == self.tag.data)
            .filter(Tag.owner_id == g.user.id)
            .one()
        )

        if not self.delete and self._tag.device_id:
            self.tag.errors = [("This tag is actualy in use.")]
            return False

        if self.device.data:
            try:
                self.device.data = int(self.device.data.split(',')[-1])
            except:  # noqa: E722
                self.device.data = None

        if self.device_id or self.device.data:
            self.device_id = self.device_id or self.device.data
            self._device = (
                Device.query.filter(Device.id == self.device_id)
                .filter(Device.owner_id == g.user.id)
                .one()
            )

        return True

    def save(self):
        self._tag.device_id = self._device.id
        db.session.add(self._tag)
        db.session.commit()

    def remove(self):
        self._tag.device = None
        db.session.add(self._tag)
        db.session.commit()


class NewActionForm(FlaskForm):
    name = StringField(
        'Name',
        [validators.length(max=50)],
        description="A name or title of the event. Something to look for.",
    )
    devices = HiddenField()
    date = DateField(
        'Date',
        [validators.Optional()],
        description="""When the action ends. For some actions like booking
                                    the time when it expires, for others like renting the
                                    time that the end rents. For specific actions, it is the
                                    time in which they are carried out; differs from created
                                    in that created is where the system receives the action.""",
    )
    severity = SelectField(
        'Severity',
        choices=[(v.name, v.name) for v in Severity],
        description="""An indicator that evaluates the execution of the event.
                                          For example, failed events are set to Error""",
    )
    description = TextAreaField('Description')
    lot = HiddenField()
    type = HiddenField()

    def validate(self, extra_validators=None):
        is_valid = self.generic_validation(extra_validators=extra_validators)

        if not is_valid:
            return False

        self._devices = OrderedSet()
        if self.devices.data:
            devices = set(self.devices.data.split(","))
            self._devices = OrderedSet(
                Device.query.filter(Device.id.in_(devices))
                .filter(Device.owner_id == g.user.id)
                .all()
            )

            if not self._devices:
                return False

        return True

    def generic_validation(self, extra_validators=None):
        # Some times we want check validations without devices list
        return super().validate(extra_validators)

    def save(self):
        Model = db.Model._decl_class_registry.data[self.type.data]()
        self.instance = Model()
        devices = self.devices.data
        severity = self.severity.data
        self.devices.data = self._devices
        self.severity.data = Severity[self.severity.data]

        self.populate_obj(self.instance)
        db.session.add(self.instance)
        db.session.commit()

        self.devices.data = devices
        self.severity.data = severity

        return self.instance

    def check_valid(self):
        if self.type.data in ['', None]:
            return

        if not self.validate():
            return self.type.data


class AllocateForm(NewActionForm):
    start_time = DateField('Start time')
    end_time = DateField('End time')
    final_user_code = StringField('Final user code', [validators.length(max=50)])
    transaction = StringField('Transaction', [validators.length(max=50)])
    end_users = IntegerField('End users')

    def validate(self, extra_validators=None):
        is_valid = super().validate(extra_validators)

        start_time = self.start_time.data
        end_time = self.end_time.data
        if start_time and end_time and end_time < start_time:
            error = ['The action cannot finish before it starts.']
            self.start_time.errors = error
            self.end_time.errors = error
            is_valid = False

        if not self.end_users.data:
            self.end_users.errors = ["You need to specify a number of users"]
            is_valid = False

        return is_valid


class DataWipeDocumentForm(Form):
    date = DateField(
        'Date', [validators.Optional()], description="Date when was data wipe"
    )
    url = URLField(
        'Url', [validators.Optional()], description="Url where the document resides"
    )
    success = BooleanField(
        'Success', [validators.Optional()], description="The erase was success or not?"
    )
    software = StringField(
        'Software',
        [validators.Optional()],
        description="Which software has you use for erase the disks",
    )
    id_document = StringField(
        'Document Id',
        [validators.Optional()],
        description="Identification number of document",
    )
    file_name = FileField(
        'File',
        [validators.DataRequired()],
        description="""This file is not stored on our servers, it is only used to
                                  generate a digital signature and obtain the name of the file.""",
    )

    def validate(self, extra_validators=None):
        is_valid = super().validate(extra_validators)

        return is_valid

    def save(self, commit=True):
        file_name = ''
        file_hash = ''
        if self.file_name.data:
            file_name = self.file_name.data.filename
            file_hash = insert_hash(self.file_name.data.read(), commit=False)

        self.url.data = URL(self.url.data)
        self._obj = DataWipeDocument(
            document_type='DataWipeDocument',
        )
        self.populate_obj(self._obj)
        self._obj.file_name = file_name
        self._obj.file_hash = file_hash
        db.session.add(self._obj)
        if commit:
            db.session.commit()

        return self._obj


class DataWipeForm(NewActionForm):
    document = FormField(DataWipeDocumentForm)

    def save(self):
        self.document.form.save(commit=False)

        Model = db.Model._decl_class_registry.data[self.type.data]()
        self.instance = Model()
        devices = self.devices.data
        severity = self.severity.data
        self.devices.data = self._devices
        self.severity.data = Severity[self.severity.data]

        document = copy.copy(self.document)
        del self.document
        self.populate_obj(self.instance)
        self.instance.document = document.form._obj
        db.session.add(self.instance)
        db.session.commit()

        self.devices.data = devices
        self.severity.data = severity
        self.document = document

        return self.instance


class TradeForm(NewActionForm):
    user_from = StringField(
        'Supplier',
        [validators.Optional()],
        description="Please enter the supplier's email address",
        render_kw={'data-email': ""},
    )
    user_to = StringField(
        'Receiver',
        [validators.Optional()],
        description="Please enter the receiver's email address",
        render_kw={'data-email': ""},
    )
    confirm = BooleanField(
        'Confirm',
        [validators.Optional()],
        default=True,
        description="I need confirmation from the other user for every device and document.",
    )
    code = StringField(
        'Code',
        [validators.Optional()],
        description="If you don't need confirm, you need put a code for trace the user in the statistics.",
    )

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self.user_from.render_kw['data-email'] = g.user.email
        self.user_to.render_kw['data-email'] = g.user.email
        self._lot = (
            Lot.query.outerjoin(Trade)
            .filter(Lot.id == self.lot.data)
            .filter(
                or_(
                    Trade.user_from == g.user,
                    Trade.user_to == g.user,
                    Lot.owner_id == g.user.id,
                )
            )
            .one()
        )

    def validate(self, extra_validators=None):
        is_valid = self.generic_validation(extra_validators=extra_validators)
        email_from = self.user_from.data
        email_to = self.user_to.data

        if not self.confirm.data and not self.code.data:
            self.code.errors = ["If you don't want to confirm, you need a code"]
            is_valid = False

        if (
            self.confirm.data
            and not (email_from and email_to)
            or email_to == email_from
            or g.user.email not in [email_from, email_to]
        ):

            errors = ["If you want confirm, you need a correct email"]
            self.user_to.errors = errors
            self.user_from.errors = errors

            is_valid = False

        if self.confirm.data and is_valid:
            user_to = User.query.filter_by(email=email_to).first() or g.user
            user_from = User.query.filter_by(email=email_from).first() or g.user
            if user_to == user_from:
                is_valid = False
            else:
                self.db_user_to = user_to
                self.db_user_from = user_from

        self.has_errors = not is_valid
        return is_valid

    def save(self, commit=True):
        if self.has_errors:
            raise ValueError(
                "The %s could not be saved because the data didn't validate."
                % (self.instance._meta.object_name)
            )
        if not self.confirm.data:
            self.create_phantom_account()
        self.prepare_instance()
        self.create_automatic_trade()

        if commit:
            db.session.commit()

        return self.instance

    def prepare_instance(self):
        Model = db.Model._decl_class_registry.data['Trade']()
        self.instance = Model()
        self.instance.user_from = self.db_user_from
        self.instance.user_to = self.db_user_to
        self.instance.lot_id = self._lot.id
        self.instance.devices = self._lot.devices
        self.instance.code = self.code.data
        self.instance.confirm = self.confirm.data
        self.instance.date = self.date.data
        self.instance.name = self.name.data
        self.instance.description = self.description.data
        db.session.add(self.instance)

    def create_phantom_account(self):
        """
        If exist both users not to do nothing
        If exist from but not to:
            search if exist in the DB
                if exist use it
                else create new one
        The same if exist to but not from

        """
        user_from = self.user_from.data
        user_to = self.user_to.data
        code = self.code.data

        if user_from and user_to:
            #  both users exist, no further action is necessary
            return

        # Create receiver (to) phantom account
        if user_from and not user_to:
            assert g.user.email == user_from

            self.user_from = g.user
            self.user_to = self.get_or_create_user(code)

        # Create supplier (from) phantom account
        if not user_from and user_to:
            assert g.user.email == user_to

            self.user_from = self.get_or_create_user(code)
            self.user_to = g.user

        self.db_user_to = self.user_to
        self.db_user_from = self.user_from

    def get_or_create_user(self, code):
        email = "{}_{}@dhub.com".format(str(g.user.id), code)
        user = User.query.filter_by(email=email).first()
        if not user:
            user = User(email=email, password='', active=False, phantom=True)
            db.session.add(user)
        return user

    def create_automatic_trade(self):
        # This method change the ownership of devices
        # do nothing if an explicit confirmation is required
        if self.confirm.data:
            return

        # Change the owner for every devices
        for dev in self._lot.devices:
            dev.change_owner(self.db_user_to)

    def check_valid(self):
        if self.user_from.data == self.user_to.data:
            return

        if self.user_from.data == g.user.email:
            return 'user_to'

        if self.user_to.data == g.user.email:
            return 'user_from'


class TradeDocumentForm(FlaskForm):
    url = URLField(
        'Url',
        [validators.Optional()],
        render_kw={'class': "form-control"},
        description="Url where the document resides",
    )
    description = StringField(
        'Description',
        [validators.Optional()],
        render_kw={'class': "form-control"},
        description="",
    )
    id_document = StringField(
        'Document Id',
        [validators.Optional()],
        render_kw={'class': "form-control"},
        description="Identification number of document",
    )
    date = DateField(
        'Date',
        [validators.Optional()],
        render_kw={'class': "form-control"},
        description="",
    )
    file_name = FileField(
        'File',
        [validators.DataRequired()],
        render_kw={'class': "form-control"},
        description="""This file is not stored on our servers, it is only used to
                                  generate a digital signature and obtain the name of the file.""",
    )

    def __init__(self, *args, **kwargs):
        lot_id = kwargs.pop('lot')
        super().__init__(*args, **kwargs)
        self._lot = Lot.query.filter(Lot.id == lot_id).one()

    def validate(self, extra_validators=None):
        is_valid = super().validate(extra_validators)

        if g.user not in [self._lot.trade.user_from, self._lot.trade.user_to]:
            is_valid = False

        return is_valid

    def save(self, commit=True):
        file_name = ''
        file_hash = ''
        if self.file_name.data:
            file_name = self.file_name.data.filename
            file_hash = insert_hash(self.file_name.data.read(), commit=False)

        self.url.data = URL(self.url.data)
        self._obj = TradeDocument(lot_id=self._lot.id)
        self.populate_obj(self._obj)
        self._obj.file_name = file_name
        self._obj.file_hash = file_hash
        db.session.add(self._obj)
        self._lot.trade.documents.add(self._obj)
        if commit:
            db.session.commit()

        return self._obj