# UGE / L2 / Intro to relational databases / Python project prototype
# Author: Pacien TRAN-GIRARD
# Licence: EUPL-1.2

from decimal import Decimal

from fastapi import APIRouter, Form, Depends, status
from fastapi.responses import RedirectResponse, HTMLResponse

from embrace.exceptions import IntegrityError
from psycopg2.errors import CheckViolation
from psycopg2.extensions import ISOLATION_LEVEL_SERIALIZABLE

from app_sessions import UserSession, FlashMessageQueue
from app_database import db_transaction
from app_templating import TemplateRenderer


to_wallet = RedirectResponse('/wallet', status_code=status.HTTP_303_SEE_OTHER)

router = APIRouter()


# TODO: add paging for the transaction history
@router.get('/wallet', response_class=HTMLResponse)
def wallet(
    session: UserSession=Depends(UserSession.authenticated),
    messages: FlashMessageQueue=Depends(FlashMessageQueue),
    render: TemplateRenderer=Depends(TemplateRenderer),
):
    with db_transaction() as tx:
        history = tx.fetch_transactions(user_id=session.get_user_id())
        # rendering done in the transaction to make use the iteration cursor
        return render('wallet.html.jinja', transactions=history)


@router.post('/wallet/transfer', response_class=HTMLResponse)
def wallet_transfer(
    session: UserSession=Depends(UserSession.authenticated),
    messages: FlashMessageQueue=Depends(FlashMessageQueue),
    recipient: str=Form(...),
    amount: Decimal=Form(...),
):
    if amount <= 0:
        messages.add('error', 'Invalid transaction amount.')
        return to_wallet

    try:
        with db_transaction(ISOLATION_LEVEL_SERIALIZABLE) as tx:
            recipient_user = tx.fetch_account_username(username=recipient)
            if recipient_user is None:
                raise LookupError('Could not find recipient')

            if recipient_user.id == session.get_user_id():
                raise LookupError('Cannot transfer money to oneself.')

            tx.transfer(
                from_user_id=session.get_user_id(),
                to_user_id=recipient_user.id,
                amount=amount,
                fee=amount * Decimal(0.10))

        messages.add('success', 'Your business is appreciated.')
        return to_wallet

    except LookupError as exception:
        messages.add('error', str(exception))
        return to_wallet

    except IntegrityError as exception:
        if isinstance(exception.__cause__, CheckViolation):
            messages.add('error', 'Insufficient funds.')
            return to_wallet
        else:
            raise exception


@router.post('/wallet/deposit')
def wallet_deposit(
    session: UserSession=Depends(UserSession.authenticated),
    messages: FlashMessageQueue=Depends(FlashMessageQueue),
    amount: Decimal=Form(...),
):
    if amount <= 0:
        messages.add('error', 'Invalid transaction amount.')
        return to_wallet

    with db_transaction(ISOLATION_LEVEL_SERIALIZABLE) as tx:
        tx.deposit(user_id=session.get_user_id(), amount=amount)

    messages.add('success', 'Your business is appreciated.')
    return to_wallet


@router.post('/wallet/withdraw')
def wallet_withdraw(
    session: UserSession=Depends(UserSession.authenticated),
    messages: FlashMessageQueue=Depends(FlashMessageQueue),
    render: TemplateRenderer=Depends(TemplateRenderer),
    amount: Decimal=Form(...),
):
    if amount <= 0:
        messages.add('error', 'Invalid transaction amount.')
        return to_wallet

    try:
        with db_transaction(ISOLATION_LEVEL_SERIALIZABLE) as tx:
            tx.withdraw(user_id=session.get_user_id(), amount=amount)

        messages.add('success', 'Annnnnd... It\'s gone.')
        return render('launder.html.jinja')

    except IntegrityError as exception:
        if isinstance(exception.__cause__, CheckViolation):
            messages.add('error', 'Insufficient funds.')
            return to_wallet
        else:
            raise exception