import { Injectable, NotFoundException } from "@nestjs/common";
import { PrismaService } from "src/prisma/prisma.service";
import { DayExpensesDto as ExpenseListResponseDto, ExpenseDto } from "src/modules/timesheets/dtos/timesheet-period.dto";
import { round2, toUTCDateOnly } from "src/modules/timesheets/utils-helpers-others/timesheet.helpers";
import { EXPENSE_TYPES } from "src/modules/timesheets/utils-helpers-others/timesheet.types";
import { EmailToIdResolver } from "src/modules/shared/utils/resolve-email-id.utils";

@Injectable()
export class ExpensesQueryService {
    constructor(
        private readonly prisma: PrismaService,
        private readonly employeeRepo: EmailToIdResolver,
    ) {}


    //fetchs all expenses for a selected employee using email, pay-period-year and number
    async findExpenseListByPayPeriodAndEmail(
        email: string, 
        year: number, 
        period_no: number
    ): Promise<ExpenseListResponseDto> {
        //fetch employe_id using email
        const employee_id = await this.employeeRepo.findIdByEmail(email);
        if(!employee_id) throw new NotFoundException(`Employee with email: ${email} not found`);

        //fetch pay-period using year and period_no
        const pay_period = await this.prisma.payPeriods.findFirst({
            where: { 
                pay_year: year, 
                pay_period_no: period_no 
            },
            select: { period_start: true, period_end: true },
        });
        if(!pay_period) throw new NotFoundException(`Pay period ${year}- ${period_no} not found`);

        const start = toUTCDateOnly(pay_period.period_start);
        const end   = toUTCDateOnly(pay_period.period_end);

        //sets rows data
        const rows  = await this.prisma.expenses.findMany({
            where: { 
                date: { gte: start, lte: end },
                timesheet: { is: { employee_id } },
            },
            orderBy: { date: 'asc'},
            select: {
                amount:  true,
                mileage: true,
                comment: true,
                is_approved: true,
                supervisor_comment: true,
                bank_code: {select: { type: true } },
            },
        });
        
        //declare return values
        const expenses: ExpenseDto[] = [];
        let total_amount = 0;
        let total_mileage = 0;

        //set rows
        for(const row of rows) {
            const type    = (row.bank_code?.type ?? '').toUpperCase();
            const amount  = round2(Number(row.amount ?? 0));
            const mileage = round2(Number(row.mileage ?? 0));

            if(type === EXPENSE_TYPES.MILEAGE) {
                total_mileage += mileage;
            } else {
                total_amount  += amount;
            }

            //fills rows array
            expenses.push({
                type,
                amount,
                mileage,
                comment: row.comment ?? '',
                is_approved: row.is_approved ?? false,
                supervisor_comment: row.supervisor_comment ?? '',
            });
        }

        return {
            expenses,
            total_expense: round2(total_amount),
            total_mileage: round2(total_mileage),
        };
}

    //_____________________________________________________________________________________________
    //                                  Deprecated or unused methods
    //_____________________________________________________________________________________________
    
    // async create(dto: CreateExpenseDto): Promise<Expenses> {
    //     const { timesheet_id, bank_code_id, date, amount:rawAmount,
    //         comment, is_approved,supervisor_comment} = dto;
    //     //fetches type and modifier
    //     const bank_code = await this.prisma.bankCodes.findUnique({
    //         where: { id: bank_code_id },
    //         select: { type: true, modifier: true },
    //     });
    //     if(!bank_code) throw new NotFoundException(`bank_code #${bank_code_id} not found`);

    //     //if mileage -> service, otherwise the ratio is amount:1
    //     let final_amount: number;
    //     if(bank_code.type === 'mileage') {
    //         final_amount = await this.mileageService.calculateReimbursement(rawAmount, bank_code_id);
    //     }else {
    //         final_amount = parseFloat( (rawAmount * bank_code.modifier).toFixed(2));
    //     }

    //     return this.prisma.expenses.create({
    //         data: { 
    //             timesheet_id, 
    //             bank_code_id, 
    //             date, 
    //             amount: final_amount, 
    //             comment, 
    //             is_approved, 
    //             supervisor_comment
    //         },
    //         include: { timesheet: { include: { employee: { include: { user: true }}}},
    //         bank_code: true,
    //         },
    //     })
    // }

    // async findAll(filters: SearchExpensesDto): Promise<Expenses[]> {
    //     const where = buildPrismaWhere(filters);
    //     const expenses = await this.prisma.expenses.findMany({ where })
    //     return expenses;
    // }

    // async findOne(id: number): Promise<Expenses> {
    //     const expense = await this.prisma.expenses.findUnique({
    //         where: { id },
    //         include: { timesheet: { include: { employee: { include: { user:true } } } },
    //         bank_code: true,
    //         },
    //     });
    //     if (!expense) {
    //         throw new NotFoundException(`Expense #${id} not found`);
    //     }
    //     return expense;
    // }

    // async update(id: number, dto: UpdateExpenseDto): Promise<Expenses> {
    //     await this.findOne(id);
    //     const { timesheet_id, bank_code_id, date, amount,
    //          comment, is_approved, supervisor_comment} = dto;
    //     return this.prisma.expenses.update({
    //         where: { id },
    //         data: {
    //             ...(timesheet_id !== undefined && { timesheet_id}),
    //             ...(bank_code_id !== undefined && { bank_code_id }),
    //             ...(date !== undefined && { date }),
    //             ...(amount !== undefined && { amount }),
    //             ...(comment !== undefined && { comment }),
    //             ...(is_approved !== undefined && { is_approved }),
    //             ...(supervisor_comment !== undefined && { supervisor_comment }),
    //         },
    //         include: { timesheet: { include: { employee: { include: { user: true } } } },
    //         bank_code: true,
    //         },
    //     });
    // }

    // async remove(id: number): Promise<Expenses> {
    //     await this.findOne(id);
    //     return this.prisma.expenses.delete({ where: { id } });
    // }

}