import { BadRequestException, Injectable, Logger, NotFoundException } from "@nestjs/common";
import { DayShiftResponse } from "../types-and-interfaces/shifts-upsert.types";
import { EmailToIdResolver } from "src/modules/shared/utils/resolve-email-id.utils";
import { Prisma, Shifts } from "@prisma/client";
import { UpsertShiftDto } from "../dtos/upsert-shift.dto";
import { BaseApprovalService } from "src/common/shared/base-approval.service";
import { PrismaService } from "src/prisma/prisma.service";
import { toDateOnly } from "../helpers/shifts-date-time-helpers";
import { UpsertAction } from "src/modules/shared/types/upsert-actions.types";
import { ShiftsHelpersService } from "../helpers/shifts.helpers";
import { BankCodesResolver } from "src/modules/shared/utils/resolve-bank-type-id.utils";

@Injectable()
export class ShiftsCommandService extends BaseApprovalService<Shifts> {
	private readonly logger = new Logger(ShiftsCommandService.name);

	constructor(
		prisma: PrismaService,
		private readonly emailResolver: EmailToIdResolver,
		private readonly typeResolver: BankCodesResolver,
		private readonly helpersService: ShiftsHelpersService,
	) { super(prisma); }

	//_____________________________________________________________________________________________
	//                            APPROVAL AND DELEGATE METHODS
	//_____________________________________________________________________________________________
	protected get delegate() {
		return this.prisma.shifts;
	}

	protected delegateFor(transaction: Prisma.TransactionClient) {
		return transaction.shifts;
	}

	async updateApproval(id: number, is_approved: boolean): Promise<Shifts> {
		return this.prisma.$transaction((transaction) =>
			this.updateApprovalWithTransaction(transaction, id, is_approved),
		);
	}

	//_____________________________________________________________________________________________
	//                                  MASTER CRUD METHOD
	//_____________________________________________________________________________________________
	async upsertShifts(
		email: string,
		action: UpsertAction,
		dto: UpsertShiftDto,
	): Promise<{
		action: UpsertAction;
		day: DayShiftResponse[];
	}> {
		if (!dto.old_shift && !dto.new_shift) throw new BadRequestException('At least one of old or new shift must be provided');

		const date = dto.new_shift?.date ?? dto.old_shift?.date;
		if (!date) throw new BadRequestException("A date (YYYY-MM-DD) must be provided in old_shift or new_shift");
		if (dto.old_shift?.date && dto.new_shift?.date && dto.old_shift.date !== dto.new_shift.date) {
			throw new BadRequestException('old_shift.date and new_shift.date must be identical');
		}

		const employee_id = await this.emailResolver.findIdByEmail(email);//resolve employee id using email

		if(action === 'create') {
			if(!dto.new_shift || dto.old_shift) {
				throw new BadRequestException(`Only new_shift must be provided for create`);
			}
			return this.createShift(employee_id, date, dto);
		}
		if(action === 'update'){
			if(!dto.old_shift || !dto.new_shift) {
				throw new BadRequestException(`Both new_shift and old_shift must be provided for update`);
			}
			return this.updateShift(employee_id, date, dto);
		}
		throw new BadRequestException(`Unknown action: ${action}`);
	}

    //_________________________________________________________________
    //                              CREATE
    //_________________________________________________________________
	private async createShift(
		employee_id: number, 
		date_iso: string,
		dto: UpsertShiftDto, 
	): Promise<{action: UpsertAction; day: DayShiftResponse[]}> {
		return this.prisma.$transaction(async (tx) => {
			const date_only = toDateOnly(date_iso);
			const { id: timesheet_id } = await this.helpersService.ensureTimesheet(tx, employee_id, date_only);

			const new_norm_shift = await this.helpersService.normalizeRequired(dto.new_shift);
			const new_bank_code_id = await this.helpersService.resolveBankIdRequired(tx, new_norm_shift.type, 'new_shift');

			const day_shifts = await this.helpersService.getDayShifts(tx, timesheet_id, date_only);

			await this.helpersService.assertNoOverlap(day_shifts, new_norm_shift);

			await tx.shifts.create({
				data: {
					timesheet_id,
					date: date_only,
					start_time: new_norm_shift.start_time,
					end_time: new_norm_shift.end_time,
					is_remote: new_norm_shift.is_remote,
					is_approved: new_norm_shift.is_approved,
					comment: new_norm_shift.comment ?? null,
					bank_code_id: new_bank_code_id,
				},
			});
			await this.helpersService.afterWriteOvertimeAndLog(tx, employee_id, date_only,'create');
			const fresh_shift = await this.helpersService.getDayShifts(tx, timesheet_id, date_only);
			return { action: 'create', day: await this.helpersService.mapDay(fresh_shift)};
		});
	}

	//_________________________________________________________________
    //                              UPDATE
    //_________________________________________________________________
	private async updateShift(
		employee_id: number, 
		date_iso: string,
		dto: UpsertShiftDto, 
	): Promise<{ action: UpsertAction; day: DayShiftResponse[];}>{
		return this.prisma.$transaction(async (tx) => {
			const date_only = toDateOnly(date_iso);
			const { id: timesheet_id } = await this.helpersService.ensureTimesheet(tx, employee_id, date_only);

			const old_norm_shift = await this.helpersService.normalizeRequired(dto.old_shift, 'old_shift');
			const new_norm_shift = await this.helpersService.normalizeRequired(dto.new_shift, 'new_shift');

			const old_bank_code_id = await this.helpersService.resolveBankIdRequired(tx, old_norm_shift.type, 'old_shift');
			const new_bank_code_id = await this.helpersService.resolveBankIdRequired(tx, new_norm_shift.type, 'new_shift');

			const day_shifts = await this.helpersService.getDayShifts(tx, timesheet_id, date_only);
			const existing = await this.helpersService.findExactOldShift(tx, { 
				timesheet_id, 
				date_only,
				norm: old_norm_shift,
				bank_code_id: old_bank_code_id,
			});
			if(!existing) throw new NotFoundException('[SHIFT_STALE]- The shift was modified or deleted by someone else');

			await this.helpersService.assertNoOverlap(day_shifts, new_norm_shift, existing.id);

			await tx.shifts.update({
				where: { id: existing.id },
				data: {
					start_time: new_norm_shift.start_time,
					end_time: new_norm_shift.end_time,
					is_remote: new_norm_shift.is_remote,
					comment: new_norm_shift.comment ?? null,
					bank_code_id: new_bank_code_id,
				},
			});
			await this.helpersService.afterWriteOvertimeAndLog(tx, employee_id, date_only, 'update');
			const fresh_shift = await this.helpersService.getDayShifts(tx, timesheet_id, date_only);
			return { action: 'update', day: await this.helpersService.mapDay(fresh_shift)};
		});

	}

	//_________________________________________________________________
    //                              DELETE
    //_________________________________________________________________
	async deleteShift(
		email: string, 
		date_iso: string, 
		dto: UpsertShiftDto,
	): Promise<{ day: DayShiftResponse[]; }>{
		return this.prisma.$transaction(async (tx) => {
			const date_only   = toDateOnly(date_iso);
			const employee_id = await this.emailResolver.findIdByEmail(email);
			
			const { id: timesheet_id } = await this.helpersService.ensureTimesheet(tx, employee_id, date_only);
			const norm_shift = await this.helpersService.normalizeRequired(dto.old_shift, 'old_shift');
			const bank_code_id = await this.typeResolver.findByType(norm_shift.type);

			const existing = await this.helpersService.findExactOldShift(tx, { 
				timesheet_id, 
				date_only,
				norm: norm_shift,
				bank_code_id: bank_code_id.id,
			});
			if(!existing) throw new NotFoundException('[SHIFT_STALE]- The shift was modified or deleted by someone else');

			await tx.shifts.delete({ where: { id: existing.id } });

			await this.helpersService.afterWriteOvertimeAndLog(tx, employee_id, date_only, 'delete');
			const fresh_shift = await this.helpersService.getDayShifts(tx, timesheet_id, date_only);
			return { day: await this.helpersService.mapDay(fresh_shift)};
		});
	}
}