import uuid

from datetime import datetime
from decimal import Decimal
from typing import List

import brewman.schemas.input as schema_in
import brewman.schemas.voucher as output

from fastapi import APIRouter, Depends, File, HTTPException, Request, Security, status
from sqlalchemy.exc import SQLAlchemyError
from sqlalchemy.orm import Session

from ..core.security import get_current_active_user as get_user
from ..core.session import get_date, set_date
from ..db.session import SessionLocal
from ..models import AccountBase
from ..models.voucher import Batch, Inventory, Journal, Voucher, VoucherType
from ..schemas.auth import UserToken
from .db_image import save_files, update_files
from .voucher import (
    blank_voucher,
    check_voucher_edit_allowed,
    check_voucher_lock_info,
    voucher_info,
)


router = APIRouter()


# Dependency
def get_db() -> Session:
    try:
        db = SessionLocal()
        yield db
    finally:
        db.close()


@router.post("", response_model=output.Voucher)
def save_route(
    request: Request,
    data: schema_in.PurchaseIn = Depends(schema_in.PurchaseIn.load_form),
    db: Session = Depends(get_db),
    i: List[bytes] = File(None),
    t: List[bytes] = File(None),
    user: UserToken = Security(get_user, scopes=["purchase-return"]),
):
    try:
        item: Voucher = save(data, user, db)
        save_inventories(item, data.inventories, db)
        save_journals(item, data.vendor, db)
        save_files(item.id, i, t, db)
        db.commit()
        set_date(data.date_.strftime("%d-%b-%Y"), request.session)
        info = voucher_info(item, db)
        return info
    except SQLAlchemyError as e:
        db.rollback()
        raise HTTPException(
            status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,
            detail=str(e),
        )
    except Exception:
        db.rollback()
        raise


def save(data: schema_in.PurchaseIn, user: UserToken, db: Session) -> Voucher:
    check_voucher_lock_info(None, data.date_, db)
    voucher = Voucher(
        date=data.date_,
        narration=data.narration,
        is_starred=data.is_starred,
        user_id=user.id_,
        type_=VoucherType.by_name(data.type_),
    )
    db.add(voucher)
    return voucher


def save_inventories(
    voucher: Voucher, inventories: List[schema_in.Inventory], db: Session
):
    for item in inventories:
        batch = db.query(Batch).filter(Batch.id == item.batch.id_).first()

        if item.quantity > batch.quantity_remaining:
            raise HTTPException(
                status_code=status.HTTP_422_UNPROCESSABLE_ENTITY,
                detail=f"Maximum quantity is {batch.quantity_remaining}.",
            )
        if batch.name > voucher.date:
            raise HTTPException(
                status_code=status.HTTP_422_UNPROCESSABLE_ENTITY,
                detail=f"Return date cannot be before {batch.product.name.strftime('%d-%b-%Y')}",
            )

        batch.quantity_remaining -= item.quantity

        item = Inventory(
            product=batch.product,
            quantity=item.quantity,
            rate=batch.rate,
            tax=batch.tax,
            discount=batch.discount,
            batch=batch,
        )
        voucher.inventories.append(item)
        db.add(item)


def save_journals(voucher: Voucher, ven: schema_in.AccountLink, db: Session):
    vendor = db.query(AccountBase).filter(AccountBase.id == ven.id_).first()
    journals = {}
    amount = 0
    for item in voucher.inventories:
        account = item.product.account
        amount += round(item.amount, 2)
        if account.id in journals:
            journals[account.id].amount += round(item.amount, 2)
        else:
            journals[account.id] = Journal(
                debit=-1,
                cost_centre_id=account.cost_centre_id,
                account_id=account.id,
                amount=round(item.amount, 2),
            )
    journals[vendor.id] = Journal(
        debit=1,
        cost_centre_id=vendor.cost_centre_id,
        account_id=vendor.id,
        amount=amount,
    )
    for item in journals.values():
        voucher.journals.append(item)
        db.add(item)


@router.put("/{id_}", response_model=output.Voucher)
def update_route(
    id_: uuid.UUID,
    request: Request,
    data: schema_in.PurchaseIn = Depends(schema_in.PurchaseIn.load_form),
    db: Session = Depends(get_db),
    i: List[bytes] = File(None),
    t: List[bytes] = File(None),
    user: UserToken = Security(get_user, scopes=["purchase-return"]),
):
    try:
        item: Voucher = update(id_, data, user, db)
        update_inventory(item, data.inventories, db)
        update_journals(item, data.vendor, db)
        # journals_valid(voucher)
        update_files(item.id, data.files, i, t, db)
        db.commit()
        set_date(data.date_.strftime("%d-%b-%Y"), request.session)
        return voucher_info(item, db)
    except SQLAlchemyError as e:
        db.rollback()
        raise HTTPException(
            status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,
            detail=str(e),
        )
    except Exception:
        db.rollback()
        raise


def update(
    id_: uuid.UUID, data: schema_in.PurchaseIn, user: UserToken, db: Session
) -> Voucher:
    voucher: Voucher = db.query(Voucher).filter(Voucher.id == id_).first()
    check_voucher_lock_info(voucher.date, data.date_, db)
    check_voucher_edit_allowed(voucher, user)
    voucher.date = data.date_
    voucher.is_starred = data.is_starred
    voucher.narration = data.narration
    voucher.user_id = user.id_
    voucher.posted = False
    voucher.last_edit_date = datetime.utcnow()
    return voucher


def update_inventory(
    voucher: Voucher, new_inventories: List[schema_in.Inventory], db: Session
):
    for it in range(len(voucher.inventories), 0, -1):
        item = voucher.inventories[it - 1]
        found = False
        for j in range(len(new_inventories), 0, -1):
            new_inventory = new_inventories[j - 1]
            if new_inventory.id_ == item.id:
                found = True
                if item.product_id != new_inventory.product.id_:
                    raise HTTPException(
                        status_code=status.HTTP_422_UNPROCESSABLE_ENTITY,
                        detail="Product cannot be changed",
                    )
                old_quantity = round(Decimal(item.quantity), 2)
                quantity_remaining = round(Decimal(item.batch.quantity_remaining), 2)
                if new_inventory.quantity - old_quantity > quantity_remaining:
                    raise HTTPException(
                        status_code=status.HTTP_422_UNPROCESSABLE_ENTITY,
                        detail=f"{old_quantity + quantity_remaining} is the maximum for {item.product.full_name}.",
                    )
                if item.batch.name > voucher.date:
                    raise HTTPException(
                        status_code=status.HTTP_422_UNPROCESSABLE_ENTITY,
                        detail=f"Voucher cannot be before {item.product.name.strftime('%d-%b-%Y')}",
                    )
                item.batch.quantity_remaining -= new_inventory.quantity - old_quantity
                item.quantity = new_inventory.quantity
                new_inventories.remove(new_inventory)
                break
        if not found:
            item.batch.quantity_remaining += item.quantity
            voucher.inventories.remove(item)
            db.delete(item)
    save_inventories(voucher, new_inventories, db)


def update_journals(voucher: Voucher, ven: schema_in.AccountLink, db):
    vendor = db.query(AccountBase).filter(AccountBase.id == ven.id_).first()
    journals = {}
    amount = 0
    for item in voucher.inventories:
        account = item.product.account
        amount += item.amount
        if account.id in journals:
            journals[account.id].amount += item.amount
        else:
            journals[account.id] = Journal(
                debit=-1,
                cost_centre_id=account.cost_centre_id,
                account_id=account.id,
                amount=item.amount,
            )
    journals[vendor.id] = Journal(
        debit=1,
        cost_centre_id=vendor.cost_centre_id,
        account_id=vendor.id,
        amount=amount,
    )
    for i in range(len(voucher.journals), 0, -1):
        item = voucher.journals[i - 1]
        if item.account_id in journals:
            item.debit = journals[item.account_id].debit
            item.amount = round(journals[item.account_id].amount, 2)
            item.cost_centre_id = journals[item.account_id].cost_centre_id
            del journals[item.account_id]
        else:
            db.delete(item)
            voucher.journals.remove(item)
    for item in journals.values():
        item.amount = round(item.amount, 2)
        voucher.journals.append(item)
        db.add(item)


@router.get("/{id_}", response_model=output.Voucher)
def get_id(
    id_: uuid.UUID,
    db: Session = Depends(get_db),
    user: UserToken = Security(get_user, scopes=["purchase-return"]),
):
    try:
        item: Voucher = db.query(Voucher).filter(Voucher.id == id_).first()
        return voucher_info(item, db)
    except SQLAlchemyError as e:
        db.rollback()
        raise HTTPException(
            status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,
            detail=str(e),
        )
    except Exception:
        db.rollback()
        raise


@router.get("", response_model=output.Voucher)
def show_blank(
    request: Request,
    db: Session = Depends(get_db),
    user: UserToken = Security(get_user, scopes=["purchase-return"]),
):
    additional_info = {"date": get_date(request.session), "type": "Purchase Return"}
    return blank_voucher(additional_info, db)