import { Injectable, Logger, OnModuleInit } from '@nestjs/common';
import { ConfigService } from '@nestjs/config';
import { PlatformGraphqlService } from '../platform/platform-graphql.service';
import { SessionService } from '../auth/session.service';

// Master data: cached lookups for departments, doctors, clinics.
// Fetched from the platform on first request, cached in Redis with TTL.
// Frontend dropdowns use these instead of direct GraphQL queries.

const CACHE_TTL = 300; // 5 minutes
const KEY_DEPARTMENTS = 'masterdata:departments';
const KEY_DOCTORS = 'masterdata:doctors';
const KEY_CLINICS = 'masterdata:clinics';

@Injectable()
export class MasterdataService implements OnModuleInit {
    private readonly logger = new Logger(MasterdataService.name);
    private readonly apiKey: string;

    constructor(
        private config: ConfigService,
        private platform: PlatformGraphqlService,
        private cache: SessionService,
    ) {
        this.apiKey = this.config.get<string>('platform.apiKey') ?? process.env.PLATFORM_API_KEY ?? '';
    }

    async onModuleInit() {
        // Warm cache on startup
        try {
            await this.getDepartments();
            await this.getDoctors();
            await this.getClinics();
            this.logger.log('Master data cache warmed');
        } catch (err: any) {
            this.logger.warn(`Cache warm failed: ${err.message}`);
        }
    }

    async getDepartments(): Promise<string[]> {
        const cached = await this.cache.getCache(KEY_DEPARTMENTS);
        if (cached) return JSON.parse(cached);

        const auth = `Bearer ${this.apiKey}`;
        const data = await this.platform.queryWithAuth<any>(
            `{ doctors(first: 500) { edges { node { department } } } }`,
            undefined, auth,
        );

        const departments = Array.from(new Set(
            data.doctors.edges
                .map((e: any) => e.node.department)
                .filter((d: string) => d && d.trim()),
        )).sort() as string[];

        await this.cache.setCache(KEY_DEPARTMENTS, JSON.stringify(departments), CACHE_TTL);
        this.logger.log(`Cached ${departments.length} departments`);
        return departments;
    }

    async getDoctors(): Promise<Array<{ id: string; name: string; department: string; qualifications: string }>> {
        const cached = await this.cache.getCache(KEY_DOCTORS);
        if (cached) return JSON.parse(cached);

        const auth = `Bearer ${this.apiKey}`;
        const data = await this.platform.queryWithAuth<any>(
            `{ doctors(first: 500) { edges { node {
                id name department qualifications specialty active
                fullName { firstName lastName }
            } } } }`,
            undefined, auth,
        );

        const doctors = data.doctors.edges
            .map((e: any) => ({
                id: e.node.id,
                name: e.node.name ?? `${e.node.fullName?.firstName ?? ''} ${e.node.fullName?.lastName ?? ''}`.trim(),
                department: e.node.department ?? '',
                qualifications: e.node.qualifications ?? '',
                specialty: e.node.specialty ?? '',
                active: e.node.active ?? true,
            }))
            .filter((d: any) => d.active !== false);

        await this.cache.setCache(KEY_DOCTORS, JSON.stringify(doctors), CACHE_TTL);
        this.logger.log(`Cached ${doctors.length} doctors`);
        return doctors;
    }

    async getClinics(): Promise<Array<{ id: string; name: string; phone: string; address: string; opensAt: string; closesAt: string }>> {
        const cached = await this.cache.getCache(KEY_CLINICS);
        if (cached) return JSON.parse(cached);

        const auth = `Bearer ${this.apiKey}`;
        const data = await this.platform.queryWithAuth<any>(
            `{ clinics(first: 50) { edges { node {
                id clinicName status opensAt closesAt
                phone { primaryPhoneNumber }
                addressCustom { addressCity addressState }
            } } } }`,
            undefined, auth,
        );

        const clinics = data.clinics.edges
            .filter((e: any) => e.node.status !== 'INACTIVE')
            .map((e: any) => ({
                id: e.node.id,
                name: e.node.clinicName ?? '',
                phone: e.node.phone?.primaryPhoneNumber ?? '',
                opensAt: e.node.opensAt ?? '08:00',
                closesAt: e.node.closesAt ?? '20:00',
                address: [e.node.addressCustom?.addressCity, e.node.addressCustom?.addressState].filter(Boolean).join(', '),
            }));

        await this.cache.setCache(KEY_CLINICS, JSON.stringify(clinics), CACHE_TTL);
        this.logger.log(`Cached ${clinics.length} clinics`);
        return clinics;
    }

    // Available time slots for a doctor on a given date.
    // Reads DoctorVisitSlot entities for the matching dayOfWeek,
    // then generates 30-min slots within each visiting window.
    async getAvailableSlots(doctorId: string, date: string): Promise<Array<{ time: string; label: string; clinicId: string; clinicName: string }>> {
        const dayOfWeek = new Date(date).toLocaleDateString('en-US', { weekday: 'long' }).toUpperCase();
        const cacheKey = `masterdata:slots:${doctorId}:${dayOfWeek}`;

        // Cache stores the UNFILTERED full-day slot list (keyed by dayOfWeek,
        // so it's reusable across dates that fall on the same weekday). The
        // "hide past slots on today" filter is applied AFTER cache read so it
        // stays correct as real-time advances without cache churn.
        const cached = await this.cache.getCache(cacheKey);
        if (cached) return this.filterPastSlotsForToday(JSON.parse(cached), date);

        const auth = `Bearer ${this.apiKey}`;
        const data = await this.platform.queryWithAuth<any>(
            `{ doctorVisitSlots(first: 100, filter: { doctorId: { eq: "${doctorId}" }, dayOfWeek: { eq: ${dayOfWeek} } }) {
                edges { node { id startTime endTime clinic { id clinicName } } }
            } }`,
            undefined, auth,
        );

        const slots: Array<{ time: string; label: string; clinicId: string; clinicName: string }> = [];

        for (const edge of data.doctorVisitSlots?.edges ?? []) {
            const node = edge.node;
            const clinicId = node.clinic?.id ?? '';
            const clinicName = node.clinic?.clinicName ?? '';
            const startTime = node.startTime ?? '09:00';
            const endTime = node.endTime ?? '17:00';

            // Generate 30-min slots within visiting window
            const [startH, startM] = startTime.split(':').map(Number);
            const [endH, endM] = endTime.split(':').map(Number);
            let h = startH, m = startM ?? 0;
            const endMin = endH * 60 + (endM ?? 0);

            while (h * 60 + m < endMin) {
                const hh = h.toString().padStart(2, '0');
                const mm = m.toString().padStart(2, '0');
                const ampm = h < 12 ? 'AM' : 'PM';
                const displayH = h === 0 ? 12 : h > 12 ? h - 12 : h;
                slots.push({
                    time: `${hh}:${mm}`,
                    label: `${displayH}:${mm.toString().padStart(2, '0')} ${ampm} — ${clinicName}`,
                    clinicId,
                    clinicName,
                });
                m += 30;
                if (m >= 60) { h++; m = 0; }
            }
        }

        // Sort by time
        slots.sort((a, b) => a.time.localeCompare(b.time));

        // Cache the full UNFILTERED list so reuse across dates (same dayOfWeek)
        // doesn't mis-serve filtered data from an earlier date.
        await this.cache.setCache(cacheKey, JSON.stringify(slots), CACHE_TTL);
        this.logger.log(`Generated ${slots.length} slots for doctor ${doctorId} on ${dayOfWeek}`);

        return this.filterPastSlotsForToday(slots, date);
    }

    // When the requested date is today (IST), hide slots whose time has
    // already passed (30-min buffer so we don't offer the impossible-to-keep
    // "in 5 minutes" slot). Applies to both cache-hit and fresh fetch paths.
    private filterPastSlotsForToday(
        slots: Array<{ time: string; label: string; clinicId: string; clinicName: string }>,
        date: string,
    ): Array<{ time: string; label: string; clinicId: string; clinicName: string }> {
        const todayIst = new Date().toLocaleDateString('en-CA', { timeZone: 'Asia/Kolkata' });
        if (date !== todayIst) return slots;

        const nowHHMM = new Date().toLocaleTimeString('en-GB', {
            timeZone: 'Asia/Kolkata', hour: '2-digit', minute: '2-digit',
        });
        const [nowH, nowM] = nowHHMM.split(':').map(Number);
        const cutoff = nowH * 60 + nowM + 30; // 30-min buffer
        const filtered = slots.filter((s) => {
            const [h, m] = s.time.split(':').map(Number);
            return h * 60 + m >= cutoff;
        });
        this.logger.log(`[SLOTS] Today filter: ${slots.length} → ${filtered.length} (now=${nowHHMM} IST, cutoff=${Math.floor(cutoff / 60)}:${String(cutoff % 60).padStart(2, '0')})`);
        return filtered;
    }

    async invalidateAll(): Promise<void> {
        await this.cache.setCache(KEY_DEPARTMENTS, '', 1);
        await this.cache.setCache(KEY_DOCTORS, '', 1);
        await this.cache.setCache(KEY_CLINICS, '', 1);
        this.logger.log('Master data cache invalidated');
    }
}