import { Injectable } from '@nestjs/common';
import { PrismaClient } from '@prisma/client';
import { ACTIVITY_INTERNAL_STATUS, SCHEDULING_TYPE } from '../../../common/utils/constants/host.constant';
import ApiError from '../../../common/utils/helper/ApiError';
import { ScheduleActivityDTO } from '../../../common/utils/validation/host/createSchedulingOfAct.validation';

@Injectable()
export class SchedulingService {
    constructor(private prisma: PrismaClient) { }

    async addSchedulingForActivity(data: ScheduleActivityDTO) {
        const {
            activityXid,
            scheduleType,
            dateRange,
            rules,
            venues,
            earlyCheckInMins,
            bookingCutOffMins,
        } = data;

        return this.prisma.$transaction(async (tx) => {
            const createdHeaders: number[] = [];

            for (const venue of venues) {

                const header = await tx.scheduleHeader.create({
                    data: {
                        activityXid,
                        activityVenueXid: venue.venueXid,
                        scheduleType,
                        startDate: new Date(dateRange.startDate),
                        endDate: dateRange.endDate ? new Date(dateRange.endDate) : null,
                        earlyCheckInMins,
                        bookingCutOffMins,
                        isActive: true,
                    },
                });

                createdHeaders.push(header.id);

                // WEEKLY
                if (scheduleType === SCHEDULING_TYPE.WEEKLY) {
                    await tx.scheduleRecurrence.createMany({
                        data: rules.weekdays!.map(day => ({
                            scheduleHeaderXid: header.id,
                            weekDay: day,
                            isActive: true,
                        })),
                    });
                }

                // MONTHLY
                if (scheduleType === SCHEDULING_TYPE.MONTHLY) {
                    await tx.scheduleRecurrence.createMany({
                        data: rules.monthDates!.map(day => ({
                            scheduleHeaderXid: header.id,
                            dayOfMonth: day,
                            isActive: true,
                        })),
                    });
                }

                // CUSTOM / ONCE
                if (scheduleType === SCHEDULING_TYPE.CUSTOM || scheduleType === SCHEDULING_TYPE.ONCE) {
                    await tx.scheduleOccurences.createMany({
                        data: rules.customDates!.map(d => ({
                            scheduleHeaderXid: header.id,
                            occurenceDate: new Date(d),
                            isActive: true,
                        })),
                    });
                }

                // Slots
                for (const slot of venue.slots) {
                    await tx.scheduleDetails.create({
                        data: {
                            scheduleHeaderXid: header.id,
                            occurenceDate: slot.occurrenceDate ? new Date(slot.occurrenceDate) : null,
                            weekDay: slot.weekDay ?? null,
                            dayOfMonth: slot.dayOfMonth ?? null,
                            startTime: slot.startTime,
                            endTime: slot.endTime,
                            maxCapacity: slot.maxCapacity,
                            isActive: true,
                        },
                    });
                }
            }

            return { success: true, scheduleHeaderIds: createdHeaders };
        });
    }



    async getAvailableSlotsForDate(
        activityXid: number,
        selectedDate: string
    ) {
        const date = new Date(selectedDate);

        if (isNaN(date.getTime())) {
            throw new ApiError(400, 'Invalid date format');
        }

        const weekDay = date.toLocaleDateString('en-US', { weekday: 'long' }).toUpperCase();
        const dayOfMonth = date.getDate();

        /* --------------------------------
           1️⃣ FETCH ACTIVE SCHEDULE HEADERS
        -------------------------------- */
        const scheduleHeaders = await this.prisma.scheduleHeader.findMany({
            where: {
                activityXid,
                isActive: true,
                startDate: { lte: date },
                OR: [
                    { endDate: null },
                    { endDate: { gte: date } },
                ],
            },
            include: {
                activityVenue: {
                    select: {
                        id: true,
                        venueName: true,
                        venueLabel: true,
                        venueCapacity: true,
                    },
                },
                scheduleRecurrences: {
                    where: { isActive: true },
                },
                ScheduleDetails: {
                    where: {
                        isActive: true,
                        OR: [
                            { occurenceDate: date },          // ONLY_ONCE / CUSTOM
                            { weekDay: weekDay },              // WEEKLY
                            { dayOfMonth: dayOfMonth },        // MONTHLY
                        ],
                    },
                },
                Cancellations: {
                    where: {
                        occurenceDate: date,
                        isActive: true,
                    },
                },
            },
        });

        if (!scheduleHeaders.length) {
            return [];
        }

        /* --------------------------------
           2️⃣ BUILD RESPONSE
        -------------------------------- */
        const response = [];

        for (const header of scheduleHeaders) {
            const cancelledSlotIds = new Set(
                header.Cancellations.map(c => c.slotXid)
            );

            const slots = header.ScheduleDetails
                .filter(slot => !cancelledSlotIds.has(slot.id))
                .map(slot => ({
                    slotId: slot.id,
                    startTime: slot.startTime,
                    endTime: slot.endTime,
                    maxCapacity: slot.maxCapacity,
                }));

            if (!slots.length) continue;

            response.push({
                venueXid: header.activityVenue.id,
                venueName: header.activityVenue.venueName,
                venueLabel: header.activityVenue.venueLabel,
                slots,
            });
        }

        return response;
    }

    async getVenueFromVenueXid(venueXid: number, activityXid: number) {
        return await this.prisma.activityVenues.findUnique({
            where: { id: venueXid, activityXid: activityXid, isActive: true },
            select: {
                id: true,
                venueName: true,
                venueLabel: true,
                venueCapacity: true,
            },
        });
    }

    async getActivityByXid(activityXid: number) {
        return await this.prisma.activities.findUnique({
            where: { id: activityXid, isActive: true },
            select: {
                id: true,
                activityTitle: true,
            }
        });
    }

    /**
     * Get activities by status and host ID
     * @param hostId - ID of the host
     * @param status - Filter by status (Listed, Unlisted, Not_Listed) - optional
     * @returns Array of activities matching the criteria
     */
    async getActivitiesByStatus(hostId: number, status?: string) {
        // Build where clause
        const whereClause: any = {
            hostXid: hostId,
            isActive: true,
            deletedAt: null,
            activityInternalStatus: {
                in: [ACTIVITY_INTERNAL_STATUS.ACTIVITY_APPROVED, ACTIVITY_INTERNAL_STATUS.ACTIVITY_UNLISTED, ACTIVITY_INTERNAL_STATUS.ACTIVITY_LISTED]
            }
        };

        // Add status filter if provided
        if (status) {
            whereClause.activityInternalStatus = status;
        }

        // Query activities
        const activities = await this.prisma.activities.findMany({
            where: whereClause,
            select: {
                id: true,
                activityRefNumber: true,
                activityTitle: true,
                activityDescription: true,
                activityDisplayStatus: true,
                activityInternalStatus: true,
                ActivitiesMedia: {
                    select: {
                        id: true,
                        mediaFileName: true,
                        mediaType: true,
                    },
                },
            },
            orderBy: {
                createdAt: 'desc',
            },
        });

        // Transform response
        return activities.map((activity) => ({
            activityId: activity.id,
            activityRefNumber: activity.activityRefNumber,
            activityName: activity.activityTitle,
            activityDescription: activity.activityDescription,
            activityInternalStatus: activity.activityInternalStatus,
            activityDisplayStatus: activity.activityDisplayStatus,
            media: activity.ActivitiesMedia,
        }));
    }

    async getVenueDurationByAct(activityXid: number, hostId: number) {
        const result = await this.prisma.activities.findUnique({
            where: { id: activityXid, hostXid: hostId, isActive: true },
            select: {
                id: true,
                activityDurationMins: true,
                ActivityVenues: {
                    select: {
                        id: true,
                        venueName: true,
                        venueLabel: true,
                    }
                }
            }
        })
        return result;
    }
}