import { Injectable } from "@nestjs/common";
import { Result } from "src/common/errors/result-error.factory";
import { computeHours } from "src/common/utils/date-utils";
import { PrismaService } from "src/prisma/prisma.service";

@Injectable()
export class ShiftsDeleteService {
    constructor(private readonly prisma: PrismaService) { }
    //_________________________________________________________________
    //                              DELETE
    //_________________________________________________________________
    //finds shifts using shit_ids
    //ajust paid-time-off banks
    //blocs deletion if approved
    async deleteShift(shift_id: number): Promise<Result<number, string>> {
        try {
            return await this.prisma.$transaction(async (tx) => {
                const paid_time_off_types: string[] = ['SICK', 'VACATION', 'BANKING', 'WITHDRAW_BANKED'];
                const shift = await tx.shifts.findUnique({
                    where: { id: shift_id },
                    select: {
                        id: true,
                        date: true,
                        start_time: true,
                        end_time: true,
                        timesheet: true,
                        bank_code: { select: { type: true } }
                    },
                });
                if (!shift) return { success: false, error: `SHIFT_NOT_FOUND` };
                const ajusted_hours = computeHours(shift.start_time, shift.end_time);

                //manage banked types, ensures update of amount of hours in bank is ajusted when a paid_time_off shift is deleted
                if (paid_time_off_types.includes(shift.bank_code.type)) {
                    switch (shift.bank_code.type) {
                        case 'SICK':
                            await this.prisma.paidTimeOff.update({
                                where: { employee_id: shift.timesheet.employee_id },
                                data: {
                                    sick_hours: { increment: ajusted_hours },
                                },
                            });
                            break;
                        case 'VACATION':
                            await this.prisma.paidTimeOff.update({
                                where: { employee_id: shift.timesheet.employee_id },
                                data: {
                                    vacation_hours: { increment: ajusted_hours },
                                },
                            });
                            break;
                        case 'WITHDRAW_BANKED':
                            await this.prisma.paidTimeOff.update({
                                where: { employee_id: shift.timesheet.employee_id },
                                data: {
                                    banked_hours: { decrement: ajusted_hours },
                                },
                            });
                        case 'BANKING':
                            await this.prisma.paidTimeOff.update({
                                where: { employee_id: shift.timesheet.employee_id },
                                data: {
                                    banked_hours: { increment: ajusted_hours },
                                },
                            });
                            break;
                        default:
                            break;
                    }
                }

                await tx.shifts.delete({ where: { id: shift_id } });
                return { success: true, data: shift.id };
            });
        } catch (error) {
            return { success: false, error: `SHIFT_NOT_FOUND` }
        }
    }
}