import express, { Router, Request, Response, NextFunction } from "express";
import Joi from "joi"
import dayjs from "dayjs"
import isoWeek from "dayjs/plugin/isoWeek"
import utc from "dayjs/plugin/utc"

import { client } from "../db";
import { DatabaseError } from "pg";
import Trainer from "../interfaces/trainer";
import { ReservedTimeslots, Timeslot, WeeklyTimeslot } from "../interfaces/timeslot";
import { idSchema, timeSchema } from "../schemas";

dayjs.extend(isoWeek);
dayjs.extend(utc);

const router: Router = express.Router();

const timeslotFiltersSchema = Joi.object({
    trainer: Joi.array().single().items(
        idSchema.required()
    ),
    center: idSchema,
    startDate: Joi.date().default(Date.now()),
    endDate: Joi.date().default(Date.now()),
    startTime: timeSchema,
    endTime: timeSchema
});

interface TimeslotFilters {
    trainer?: number[]
    center?: number
    startDate: string
    endDate: string
    startTime?: string
    endTime?: string
}

interface DatabaseResult {
    trainer: Trainer
    timeslots: WeeklyTimeslot[]
    reserved_timeslots: ReservedTimeslots[]
}

interface TrainerWithAvailableTimeslots extends Trainer {
    timeslots: Timeslot[]
}

router.get("/timeslot", async (req: Request, res: Response) => {
    try {

        const validation = timeslotFiltersSchema.validate(req.query, { abortEarly: false, stripUnknown: true });
        if (validation.error !== undefined) {
            return res.status(400).send(validation.error.details);
        }

        const timeslotFilters: TimeslotFilters = validation.value;
        
        let filterStartDate: dayjs.Dayjs = dayjs(timeslotFilters.startDate).utcOffset(0).startOf("date");
        const filterEndDate: dayjs.Dayjs = dayjs(timeslotFilters.endDate).utcOffset(0).startOf("date");

        const nowDate: dayjs.Dayjs = dayjs().utcOffset(0).startOf("date");
        
        if (filterStartDate.isBefore(nowDate)) {
            filterStartDate = nowDate;
        }

        let weekdays = [];
        for (let day: dayjs.Dayjs = filterStartDate; !day.isAfter(filterEndDate); day = day.add(1, "day")) {
            weekdays.push(day.isoWeekday());
        }

        const queryResult = await client.query(`
            SELECT
                weekly_timeslots.trainer_id,
                json_build_object(
                    'id',weekly_timeslots.trainer_id,
                    'first_name',users.first_name,
                    'last_name',users.last_name,
                    'center_id',trainers.center_id,
                    'center_name',centers.name
                ) as trainer,
                json_agg(json_build_object(
                    'day_of_week',day_of_week,
                    'start_time',start_time,
                    'end_time',end_time)
                ) as timeslots,
                (
                    SELECT json_agg(json_build_object(
                        'id', id,
                        'start_time', start_time,
                        'end_time', end_time
                    )) FROM public.reserved_timeslots
                    WHERE 
                        (start_time between $1 AND $2
                        OR end_time between $1 AND $2)
                        AND weekly_timeslots.trainer_id = reserved_timeslots.trainer_id
                ) as reserved_timeslots
            FROM
                weekly_timeslots
            JOIN trainers ON weekly_timeslots.trainer_id = trainers.id
            JOIN users ON trainers.user_id = users.id
            JOIN centers ON trainers.center_id = centers.id
            WHERE
                ((trainer_id = ANY($3)) OR $4)
                AND (day_of_week = ANY($5))
                AND (trainers.center_id = $6 OR $7)
            GROUP BY
                weekly_timeslots.trainer_id,
                users.first_name,
                users.last_name,
                trainers.center_id,
                centers.name,
                trainer_id;
        `, [
            new Date(timeslotFilters.startDate).toISOString(),
            new Date(timeslotFilters.endDate).toISOString(),
            timeslotFilters.trainer !== undefined ? timeslotFilters.trainer : [],
            timeslotFilters.trainer === undefined,
            weekdays,
            timeslotFilters.center,
            timeslotFilters.center === undefined
        ]);

        const databaseResult: DatabaseResult[] = queryResult.rows;

        const trainers: TrainerWithAvailableTimeslots[] = [];

        for (const trainer of databaseResult) {
            const trainerWithAvailableTimeslots: TrainerWithAvailableTimeslots = {
                ...trainer.trainer,
                timeslots: []
            }

            for (let day: dayjs.Dayjs = filterStartDate; !day.isAfter(filterEndDate); day = day.add(1, "day")) {
                const weekDay = day.isoWeekday();
                const reservedTimeslots = trainer.reserved_timeslots !== null ? trainer.reserved_timeslots : [];

                timeslots: for (const timeslot of trainer.timeslots) {
                    if (timeslot.day_of_week !== weekDay)
                        continue timeslots;
                    if (timeslotFilters.startTime) {
                        if (parseInt(timeslotFilters.startTime.split(":")[0]) > parseInt(timeslot.start_time.split(":")[0]))
                            continue timeslots;
                        if (timeslotFilters.startTime.split(":")[0] === timeslot.start_time.split(":")[0] &&
                            parseInt(timeslotFilters.startTime.split(":")[1]) > parseInt(timeslot.start_time.split(":")[1]))
                            continue timeslots;
                    }
                    if (timeslotFilters.endTime) {
                        if (parseInt(timeslotFilters.endTime.split(":")[0]) < parseInt(timeslot.end_time.split(":")[0]))
                            continue timeslots;
                        if (timeslotFilters.endTime.split(":")[0] === timeslot.end_time.split(":")[0] &&
                            parseInt(timeslotFilters.endTime.split(":")[1]) < parseInt(timeslot.end_time.split(":")[1]))
                            continue timeslots;
                    }
                    const startTime = day.clone()
                        .hour(parseInt(timeslot.start_time.split(":")[0]))
                        .minute(parseInt(timeslot.start_time.split(":")[1]))
                        .second(parseInt(timeslot.start_time.split(":")[2]));
                    const endTime = day.clone()
                        .hour(parseInt(timeslot.end_time.split(":")[0]))
                        .minute(parseInt(timeslot.end_time.split(":")[1]))
                        .second(parseInt(timeslot.end_time.split(":")[2]));
                    for (const reservedTimeslot of reservedTimeslots) {
                        const reservedTimeStart = dayjs(reservedTimeslot.start_time);
                        const reservedTimeEnd = dayjs(reservedTimeslot.end_time);
                        if ((!reservedTimeStart.isBefore(startTime) && !reservedTimeStart.isAfter(endTime)) ||
                            (!reservedTimeEnd.isBefore(startTime) && !reservedTimeStart.isAfter(endTime))) {
                            continue timeslots;
                        }
                    }
                    trainerWithAvailableTimeslots.timeslots.push({
                        startDate: startTime.toDate(),
                        endDate: endTime.toDate()
                    });
                }
            }

            trainers.push(trainerWithAvailableTimeslots);
        }

        return res.status(200).send(trainers);
    } catch (error: DatabaseError | Error | any) {
        console.error(error);
        return res.sendStatus(500);
    }
})

export default router;