import { PrismaClient as Prisma } from "@prisma/client";
import { PrismaClient as PrismaLegacy } from "@prisma/client-legacy"
import { toDateFromString, toHHmmFromDate, toStringFromDate } from "src/common/utils/date-utils";

const prisma_legacy = new PrismaLegacy({});
const prisma = new Prisma({});

type NewEmployee = {
    id: number;
    company_code: number;
    external_payroll_id: number;
}

type OldExpense = {
    time_sheet_id: string | null;
    date: string | null;
    code: string | null;
    description: string | null;
    value: number | null;
    status: boolean | null;
}

export const extractOldExpenses = async () => {
    for (let id = 1; id <= 61; id++) {

        console.log(`Start of Expense migration ***************************************************************`);

        const new_employee = await findOneNewEmployee(id);
        console.log(`Employee ${id} found in new DB`);

        const new_timesheets = await findManyNewTimesheets(new_employee.id);
        console.log(`New Timesheets found for employee ${id}`);

        const old_employee_id = await findOneOldEmployee(new_employee);
        console.log(`Employee ${new_employee.id} found in old DB`);
        
        const old_timesheets = await findManyOldTimesheets(old_employee_id);
        console.log(`Timesheets for employee ${old_employee_id}/${new_employee.id} found in old DB`);
        
        console.log('Start of Expense creation*****************************************************************');
        for (const old_timesheet of old_timesheets) {
            if (!old_timesheet.start_date) continue;
            const new_timesheet = new_timesheets.find((ts) => ts.start_date.getTime() === old_timesheet.start_date!.getTime());
            if (!new_timesheet) {
                console.warn(`No new timesheet matching legacy timesheet ${old_timesheet.id}`);
                continue;
            }
            const old_expenses = await prisma_legacy.expenses.findMany({
                where: { time_sheet_id: old_timesheet.id },
                select: {
                    time_sheet_id: true,
                    date: true,
                    code: true,
                    description: true,
                    value: true,
                    status: true,

                },
            });
            await createManyNewExpenses(new_timesheet.id, old_expenses);
        }

    }
    await prisma_legacy.$disconnect();
    await prisma.$disconnect();
}

const findOneNewEmployee = async (id: number): Promise<NewEmployee> => {
    const new_employee = await prisma.employees.findUnique({
        where: { id: id },
        select: {
            id: true,
            company_code: true,
            external_payroll_id: true,
        },
    });
    if (!new_employee) throw new Error(`New Employee with id ${id} not found`)
    return new_employee;
}

const findOneOldEmployee = async (new_employee: NewEmployee): Promise<string> => {
    const old_employee = await prisma_legacy.employees.findFirst({
        where: {
            company: new_employee.company_code,
            employee_number: new_employee.external_payroll_id.toString(),
        },
        select: {
            id: true,
        },
    });
    if (!old_employee) throw new Error(`Old Employee not found`);
    return old_employee.id;
}

const findManyOldTimesheets = async (old_employee_id: string) => {
    const old_timesheets = await prisma_legacy.time_sheets.findMany({
        where: { employee_id: old_employee_id },
        select: { id: true, start_date: true, status: true }
    });
    return old_timesheets;
}

const findManyNewTimesheets = async (employee_id: number) => {
    const timesheets = await prisma.timesheets.findMany({
        where: { employee_id: employee_id },
        select: { id: true, start_date: true }
    })
    return timesheets;
}

const createManyNewExpenses = async (timesheet_id: number, old_expenses: OldExpense[]) => {
    for (const old_expense of old_expenses) {
        let mileage: number = 0;
        let amount: number = old_expense.value ?? 0;
        if (old_expense.code === 'G503') {
            mileage = old_expense.value!;
            amount = mileage * 0.72;
        }
        if (mileage < 0 || amount < 0) {
            console.warn(`expense of value less than '0' found`)
            continue;
        }

        if (old_expense.date == null) {
            console.warn(`Expense date invalid ${old_expense.date}`);
            continue;
        }
        const date = toDateFromString(old_expense.date);

        if (old_expense.status == null) {
            console.warn(`status null for legacy expense ${old_expense}`);
            continue;
        }

        if (old_expense.code == null) {
            console.warn(`Code null for legacy expense ${old_expense.code}`);
            continue;
        }
        const bank_code_id = await findBankCodeIdUsingOldCode(old_expense.code);

        await prisma.expenses.create({
            // where: { unique_ts_id_date_amount_mileage: { timesheet_id: timesheet_id, date, amount, mileage } },
            // update: {
            //     is_approved: old_expense.status,
            // },
            data: {
                date: date,
                comment: old_expense.description ?? '',
                timesheet_id: timesheet_id,
                bank_code_id: bank_code_id,
                amount: amount,
                mileage: mileage,
            }
        });
    }
}

const findBankCodeIdUsingOldCode = async (code: string): Promise<number> => {
    const bank_code = await prisma.bankCodes.findFirst({
        where: { bank_code: code },
        select: { id: true },
    });
    if (!bank_code) throw new Error(`Bank_code_id not found for Code ${code}`)
    return bank_code.id;
}