import re
from datetime import date, datetime, timedelta
from decimal import Decimal
from enum import Enum
from functools import reduce
from http import HTTPStatus
from typing import Any, Literal, NotRequired, TypedDict, cast
from uuid import uuid4

from aws_lambda_powertools import Logger
from aws_lambda_powertools.event_handler.api_gateway import Router
from aws_lambda_powertools.event_handler.exceptions import (
    NotFoundError,
)
from layercake.dateutils import now, ttl
from layercake.dynamodb import DynamoDBPersistenceLayer, KeyPair, SortKey, TransactKey
from layercake.extra_types import CnpjStr, CpfStr, CreditCard, NameStr
from pydantic import (
    UUID4,
    BaseModel,
    ConfigDict,
    EmailStr,
    Field,
    field_validator,
    model_validator,
)

from api_gateway import JSONResponse
from boto3clients import dynamodb_client
from config import DUE_DAYS, ORDER_TABLE, USER_TABLE
from routes.enrollments.enroll import Enrollment

router = Router()
logger = Logger(__name__)
dyn = DynamoDBPersistenceLayer(ORDER_TABLE, dynamodb_client)


class CouponNotFoundError(NotFoundError): ...


class PaymentMethod(str, Enum):
    PIX = 'PIX'
    CREDIT_CARD = 'CREDIT_CARD'
    BANK_SLIP = 'BANK_SLIP'
    # MANUAL = 'MANUAL'


class User(BaseModel):
    id: UUID4 | str
    name: NameStr


class Address(BaseModel):
    model_config = ConfigDict(str_strip_whitespace=True)

    postcode: str
    address1: str
    address2: str | None = None
    neighborhood: str
    city: str
    state: str

    @field_validator('postcode')
    @classmethod
    def ensure_numbers(cls, v: str) -> str:
        return re.sub(r'\D', '', v)


class Item(BaseModel):
    id: UUID4
    name: str
    unit_price: Decimal = Field(..., ge=1)
    quantity: int = Field(1, ge=1)


class Coupon(BaseModel):
    code: str
    type: Literal['PERCENT', 'FIXED']
    amount: Decimal = Field(..., ge=1)


class Checkout(BaseModel):
    model_config = ConfigDict(
        str_strip_whitespace=True,
        use_enum_values=True,
    )

    id: UUID4 = Field(default_factory=uuid4)
    name: str
    email: EmailStr
    address: Address
    payment_method: PaymentMethod
    items: tuple[Item, ...]
    enrollments: tuple[Enrollment, ...] = tuple()
    coupon: Coupon | None = None
    org_id: UUID4 | str | None = None
    user_id: UUID4 | str | None = None
    cnpj: CnpjStr | None = None
    cpf: CpfStr | None = None
    created_by: User | None = None
    credit_card: CreditCard | None = None
    installments: int | None = Field(None, ge=1, le=12)

    @model_validator(mode='after')
    def verify_fields(self):
        if not any([self.cnpj, self.cpf]):
            raise ValueError('cnpj or cpf is required')

        if self.cnpj is not None:
            if self.org_id is None:
                raise ValueError('org_id is missing')

            if self.created_by is None:
                raise ValueError('created_by is missing')

        if self.cpf is not None and self.user_id is None:
            raise ValueError('user_id is missing')

        return self

    def model_dump(self, **kwargs) -> dict[str, Any]:
        return super().model_dump(
            exclude_none=True,
            exclude={
                'items',
                'address',
                'created_by',
                'coupon',
                'credit_card',
                'enrollments',
            },
            **kwargs,
        )


@router.post('/')
def checkout(payload: Checkout):
    now_ = now()
    settings = _get_settings(str(payload.org_id or payload.user_id))
    order_id = payload.id
    address = payload.address
    credit_card = payload.credit_card
    created_by = payload.created_by
    items = payload.items
    enrollments = payload.enrollments
    coupon = payload.coupon
    payment_method = payload.payment_method
    installments = payload.installments
    subtotal = _sum_items(items)
    due_date = (
        _calc_due_date(now_, settings['due_days'])
        if payment_method == 'BANK_SLIP'
        else now_ + timedelta(hours=1)
    )
    discount = (
        _apply_discount(subtotal, coupon.amount, coupon.type) * -1 if coupon else 0
    )
    total = subtotal + discount if subtotal > 0 else 0
    interest_amount = (
        _calc_interest(total, installments) - total
        if payment_method == 'CREDIT_CARD' and installments
        else 0
    )

    with dyn.transact_writer() as transact:
        transact.put(
            item={
                'id': order_id,
                'sk': '0',
                'status': 'PENDING',
                'subtotal': subtotal,
                'total': total + interest_amount,
                'discount': discount,
                'due_date': due_date,
                # Post-migration (orders): rename `create_date` to `created_at`
                'create_date': now_,
            }
            | ({'coupon': coupon.code} if coupon else {})
            | (
                {
                    'installments': payload.installments,
                    'interest_amount': interest_amount,
                }
                if payload.installments
                else {}
            )
            | ({'is_test': True} if 'iugu_api_token' in settings else {})
            | payload.model_dump()
        )

        transact.put(
            item={
                'id': order_id,
                'sk': 'ITEMS',
                'items': [item.model_dump() for item in items],
                'created_at': now_,
            }
        )
        transact.put(
            item={
                'id': order_id,
                'sk': 'ADDRESS',
                'created_at': now_,
            }
            | address.model_dump()
        )

        if created_by:
            transact.put(
                item={
                    'id': order_id,
                    'sk': 'CREATED_BY',
                    'user_id': created_by.id,
                    'name': created_by.name,
                    'created_at': now_,
                }
            )

        if credit_card:
            transact.put(
                item={
                    'id': order_id,
                    'sk': 'CREDIT_CARD',
                    'brand': credit_card.brand,
                    'last4': credit_card.last4,
                    'created_at': now_,
                }
            )
            transact.put(
                item={
                    'id': order_id,
                    'sk': 'CREDIT_CARD#PAYMENT_INTENT',
                    'ttl': ttl(start_dt=now_, minutes=5),
                    'created_at': now_,
                }
                | credit_card.model_dump(),
            )

        if coupon:
            transact.put(
                item={
                    'id': order_id,
                    'sk': 'METADATA#COUPON',
                    'created_at': now_,
                }
                | coupon.model_dump()
            )
            transact.condition(
                key=KeyPair('COUPON', coupon.code),
                cond_expr='attribute_exists(sk) \
                           AND discount_type = :type \
                           AND discount_amount = :amount',
                expr_attr_values={
                    ':type': coupon.type,
                    ':amount': coupon.amount,
                },
                exc_cls=CouponNotFoundError,
            )

        for enrollment in enrollments:
            transact.put(
                item={
                    'id': order_id,
                    'sk': f'ENROLLMENT#{enrollment.id}',
                    'status': 'PENDING',
                    'created_at': now_,
                }
                | enrollment.model_dump(exclude={'id'})
            )

        if 'iugu_api_token' in settings:
            transact.put(
                item={
                    'id': order_id,
                    'sk': 'METADATA#TEST_MODE',
                    'iugu_api_token': settings['iugu_api_token'],
                    'created_at': now_,
                }
            )
            transact.put(
                item={
                    'id': order_id,
                    'sk': 'SCHEDULED#AUTO_CLEANUP',
                    'ttl': ttl(start_dt=now_, days=7),
                    'created_at': now_,
                }
            )

    return JSONResponse(
        body={'id': order_id},
        status_code=HTTPStatus.CREATED,
    )


def _sum_items(items: tuple[Item, ...]):
    def sum(total: Decimal, item: Item) -> Decimal:
        return total + item.unit_price * item.quantity

    return reduce(sum, items, Decimal(0))


def _calc_interest(total, installments: int) -> Decimal:
    rate2to6 = 0.055
    rate7to12 = 0.0608
    rate = rate7to12 if installments >= 7 else rate2to6
    return total * Decimal((1 - 0.0382) / (1 - rate))


def _apply_discount(
    subtotal: Decimal,
    discount_amount: Decimal,
    discount_type: Literal['FIXED', 'PERCENT'],
) -> Decimal:
    if subtotal <= Decimal('0'):
        return Decimal('0')

    amount = (
        (subtotal * discount_amount) / Decimal('100')
        if discount_type == 'PERCENT'
        else discount_amount
    )

    return min(amount, subtotal)


def _calc_due_date(
    start_date: datetime,
    business_days: int,
    holidays: set[date] | None = None,
) -> datetime:
    holidays = holidays or set()

    due_date = start_date + timedelta(days=business_days)

    while due_date.weekday() >= 5 or due_date.date() in holidays:
        due_date += timedelta(days=1)

    return due_date


Settings = TypedDict(
    'Settings',
    {
        'due_days': int,
        'iugu_api_token': NotRequired[str],
    },
)


def _get_settings(id: str) -> Settings:
    r = dyn.collection.get_items(
        TransactKey(id, table_name=USER_TABLE)
        + SortKey(
            sk='METADATA#BILLING',
            path_spec='due_days',
            rename_key='due_days',
        )
        + SortKey(
            'METADATA#TEST_MODE',
            path_spec='iugu_api_token',
            rename_key='iugu_api_token',
        ),
        flatten_top=False,
    )

    if 'due_days' not in r:
        r['due_days'] = DUE_DAYS
    else:
        r['due_days'] = int(r['due_days'])

    return cast(Settings, r)