import { Db, ObjectId } from 'mongodb';
import { BillingLocation, BillsNotificationStatus, EmailStatus, RentNotificationStatus, UserSettings, generateShareId } from '@evidencija-rezija/shared-code';
import { sendEmail } from './mailgunService';
import { createLogger } from './logger';
import { loadAndRender } from './emailTemplates';

const log = createLogger("email:senders");

/**
 * Send email verification requests
 * @param db Database instance
 * @param budget Remaining email budget
 * @returns Number of emails sent
 */
export async function sendVerificationRequests(db: Db, budget: number): Promise<number> {
    if (budget <= 0) {
        log('Budget exhausted, skipping verification requests');
        return 0;
    }

    const now = new Date();
    const currentYear = now.getFullYear();
    const currentMonth = now.getMonth() + 1; // JavaScript months are 0-indexed

    log(`Fetching locations for verification: year=${currentYear}, month=${currentMonth}`);

    const locations = await db.collection<BillingLocation>('lokacije')
        .find({
            'yearMonth.year': currentYear,
            'yearMonth.month': currentMonth,
            'tenantEmailStatus': EmailStatus.Unverified
        })
        .toArray();

    log(`Found ${locations.length} locations needing verification`);

    let sentCount = 0;

    for (const location of locations) {
        if (budget <= 0) {
            log('Budget exhausted during verification sending');
            break;
        }

        if (!location.tenantEmail) {
            log(`Skipping location ${location._id}: no tenant email`);
            continue;
        }

        // Fetch user settings
        const userSettings = await db.collection<UserSettings>('userSettings')
            .findOne({ userId: location.userId });

        const ownerName = userSettings?.ownerName || '';
        const shareId = generateShareId(location._id.toString());

        const html = loadAndRender('email-validation', {
            'location.tenantName': location.tenantName || 'there',
            'ownerName': ownerName,
            'location.name': location.name,
            'shareId': shareId
        }, location.tenantEmailLanguage || 'hr');

        const success = await sendEmail({
            to: location.tenantEmail,
            subject: `${ownerName} has invited you to rezije.app`,
            html
        });

        // Update location status
        const newStatus = success ? EmailStatus.VerificationPending : EmailStatus.VerificationFailed;
        await db.collection<BillingLocation>('lokacije').updateOne(
            { _id: location._id },
            { $set: { tenantEmailStatus: newStatus } }
        );

        if (success) {
            sentCount++;
            log(`Verification email sent to ${location.tenantEmail}`);
        } else {
            log(`Failed to send verification email to ${location.tenantEmail}`);
        }

        budget--;
    }

    log(`Sent ${sentCount} verification emails`);
    return sentCount;
}

/**
 * Send rent due notifications
 * @param db Database instance
 * @param budget Remaining email budget
 * @returns Number of emails sent
 */
export async function sendRentDueNotifications(db: Db, budget: number): Promise<number> {
    if (budget <= 0) {
        log('Budget exhausted, skipping rent due notifications');
        return 0;
    }

    const now = new Date();

    // Use CET timezone
    const cetDate = new Date(now.toLocaleString('en-US', { timeZone: 'Europe/Belgrade' }));
    const currentYear = cetDate.getFullYear();
    const currentMonth = cetDate.getMonth() + 1;
    const currentDay = cetDate.getDate();

    log(`Fetching locations for rent due: year=${currentYear}, month=${currentMonth}, day=${currentDay}`);

    const locations = await db.collection<BillingLocation>('lokacije')
        .find({
            'yearMonth.year': currentYear,
            'yearMonth.month': currentMonth,
            'tenantEmailStatus': EmailStatus.Verified,
            'rentNotificationEnabled': true,
            'rentDueDay': currentDay,
            $or: [
                { 'rentNotificationStatus': { $exists: false } },
                { 'rentNotificationStatus': null }
            ]
        })
        .toArray();

    log(`Found ${locations.length} locations needing rent due notifications`);

    let sentCount = 0;

    for (const location of locations) {
        if (budget <= 0) {
            log('Budget exhausted during rent due sending');
            break;
        }

        if (!location.tenantEmail) {
            log(`Skipping location ${location._id}: no tenant email`);
            continue;
        }

        // Fetch user settings
        const userSettings = await db.collection<UserSettings>('userSettings')
            .findOne({ userId: location.userId });

        const ownerName = userSettings?.ownerName || '';
        const shareId = generateShareId(location._id.toString());

        // Format rent due date
        const rentDueDate = `${location.yearMonth.month}/${location.rentDueDay}/${location.yearMonth.year}`;

        // Format rent amount (convert from cents to display format)
        const rentAmount = location.rentAmount ? (location.rentAmount).toFixed(2) : '0.00';
        const currency = userSettings?.currency || 'EUR';

        const html = loadAndRender('rent-due', {
            'location.tenantName': location.tenantName || 'there',
            'location.name': location.name,
            'rentDueDate': rentDueDate,
            'rentAmount': rentAmount,
            'currency': currency,
            'ownerName': ownerName,
            'shareId': shareId
        }, location.tenantEmailLanguage || 'hr');

        const success = await sendEmail({
            to: location.tenantEmail,
            subject: `Rent due for ${location.tenantName || 'your apartment'}`,
            html
        });

        // Update location status
        const newStatus = success ? RentNotificationStatus.Sent : RentNotificationStatus.Failed;
        await db.collection<BillingLocation>('lokacije').updateOne(
            { _id: location._id },
            { $set: { rentNotificationStatus: newStatus } }
        );

        if (success) {
            sentCount++;
            log(`Rent due notification sent to ${location.tenantEmail}`);
        } else {
            log(`Failed to send rent due notification to ${location.tenantEmail}`);
        }

        budget--;
    }

    log(`Sent ${sentCount} rent due notifications`);
    return sentCount;
}

/**
 * Send utility bills due notifications
 * @param db Database instance
 * @param budget Remaining email budget
 * @returns Number of emails sent
 */
export async function sendUtilityBillsNotifications(db: Db, budget: number): Promise<number> {
    if (budget <= 0) {
        log('Budget exhausted, skipping utility bills notifications');
        return 0;
    }

    const now = new Date();
    const currentYear = now.getFullYear();
    const currentMonth = now.getMonth() + 1;

    log(`Fetching locations for utility bills: year=${currentYear}, month=${currentMonth}`);

    const locations = await db.collection<BillingLocation>('lokacije')
        .find({
            'yearMonth.year': currentYear,
            'yearMonth.month': currentMonth,
            'tenantEmailStatus': EmailStatus.Verified,
            'billsNotificationEnabled': true,
            'billsNotificationStatus': BillsNotificationStatus.Scheduled
        })
        .toArray();

    log(`Found ${locations.length} locations needing utility bills notifications`);

    let sentCount = 0;

    for (const location of locations) {
        if (budget <= 0) {
            log('Budget exhausted during utility bills sending');
            break;
        }

        if (!location.tenantEmail) {
            log(`Skipping location ${location._id}: no tenant email`);
            continue;
        }

        // Fetch user settings
        const userSettings = await db.collection<UserSettings>('userSettings')
            .findOne({ userId: location.userId });

        const ownerName = userSettings?.ownerName || '';
        const shareId = generateShareId(location._id.toString());

        // Calculate total amount from all bills
        const totalAmountCents = (location.bills || []).reduce((sum, bill) => {
            return sum + (bill.payedAmount || 0);
        }, 0);
        const totalAmount = (totalAmountCents / 100).toFixed(2);
        const currency = userSettings?.currency || 'EUR';

        const html = loadAndRender('util-bills-due', {
            'location.tenantName': location.tenantName || 'there',
            'location.name': location.name,
            'totalAmount': totalAmount,
            'currency': currency,
            'ownerName': ownerName,
            'shareId': shareId
        }, location.tenantEmailLanguage || 'hr');

        const success = await sendEmail({
            to: location.tenantEmail,
            subject: `Utility bills due for ${location.tenantName || 'your apartment'}`,
            html
        });

        // Update location status
        const newStatus = success ? BillsNotificationStatus.Sent : BillsNotificationStatus.Failed;
        await db.collection<BillingLocation>('lokacije').updateOne(
            { _id: location._id },
            { $set: { billsNotificationStatus: newStatus } }
        );

        if (success) {
            sentCount++;
            log(`Utility bills notification sent to ${location.tenantEmail}`);
        } else {
            log(`Failed to send utility bills notification to ${location.tenantEmail}`);
        }

        budget--;
    }

    log(`Sent ${sentCount} utility bills notifications`);
    return sentCount;
}