import { onDocumentCreated } from "firebase-functions/v2/firestore";
import { getLogger } from "../shared/config";
import { getAdmin } from "../shared/config";
import * as admin from 'firebase-admin';

const app = getAdmin();
const logger = getLogger();

interface NotificationData {
    notificationSent?: boolean;
    userId?: string;
    clientId?: string;
    invitorId?: string;
    phoneNumber?: string;
    message?: string;
    type?: string;
    status?: string;
    gymName?: string;
    trainerName?: string;
    membershipId?: string;
    subscriptionName?: string;
    name?: string;
    clientEmail?: string;
    invitationId?: string;
    [key: string]: any;
}

export const processNotificationOnCreate = onDocumentCreated({
    region: '#{SERVICES_RGN}#',
    document: 'notifications/{notificationId}'
}, async (event) => {
    try {
        const notificationSnapshot = event.data;
        const notificationId = event.params.notificationId;

        if (!notificationSnapshot) {
            logger.error(`No data found for notification ${notificationId}`);
            return;
        }

        const notification = notificationSnapshot.data() as NotificationData;
        if (notification.notificationSent === true) {
            logger.info(`Notification ${notificationId} already sent, skipping.`);
            return;
        }

        const { fcmToken } = await getUserAndFCMToken(notification);
        if (!fcmToken) {
            logger.error(`FCM token not found for notification ${notificationId}`);
            await updateNotificationWithError(notificationId, 'FCM token not found for user');
            return;
        }

        const message = prepareNotificationMessage(notification, fcmToken);
        try {
            const fcmResponse = await app.messaging().send({
                ...message,
                token: fcmToken
            });

            logger.info(`FCM notification sent successfully: ${fcmResponse}`);
            await markNotificationAsSent(notificationId);

        } catch (error) {
            logger.error(`Error sending notification ${notificationId}:`, error);
            await updateNotificationWithError(notificationId, error instanceof Error ? error.message : String(error));
        }
    } catch (error) {
        logger.error('Error processing notification:', error);
    }
});

async function getUserAndFCMToken(notification: NotificationData): Promise<{ userId: string | null; fcmToken: string | null }> {
    let userId: string | null = null;
    let fcmToken: string | null = null;

    if (notification.userId) {
        userId = notification.userId;
        fcmToken = await getFCMTokenFromUserDoc(userId);
    } else if (notification.clientId) {
        userId = notification.clientId;
        fcmToken = await getFCMTokenFromUserDoc(userId);
    } else if (notification.invitorId) {
        userId = notification.invitorId;
        fcmToken = await getFCMTokenFromUserDoc(userId);
    } else if (notification.phoneNumber) {
        const userQuery = await app
            .firestore()
            .collection('users')
            .where('phoneNumber', '==', notification.phoneNumber)
            .limit(1)
            .get();

        if (!userQuery.empty) {
            const userDoc = userQuery.docs[0];
            userId = userDoc.id;
            fcmToken = userDoc.data()?.fcmToken;
        }
    }

    return { userId, fcmToken };
}

async function getFCMTokenFromUserDoc(userId: string): Promise<string | null> {
    const userDoc = await app.firestore().collection('users').doc(userId).get();
    return userDoc.exists ? userDoc.data()?.fcmToken : null;
}

function prepareNotificationMessage(notification: NotificationData, fcmToken: string): admin.messaging.Message {
    let title = 'New Notification';
    let body = notification.message || 'You have a new notification';
    let data: Record<string, string> = {
        type: notification.type || 'general',
    };

    switch (notification.type) {
        case 'day_pass_entry':
            const isAccepted = notification.status === 'ACCEPTED';
            title = isAccepted ? 'Day Pass Approved' : 'Day Pass Denied';
            body = notification.message || (isAccepted ?
                'Your day pass has been approved' :
                'Your day pass has been denied');
            data.gymName = notification.gymName || '';
            break;

        case 'trainer_assigned_to_client':
            title = 'Trainer Assigned';
            body = notification.message || `${notification.trainerName} has been assigned as your trainer`;
            data.trainerName = notification.trainerName || '';
            data.membershipId = notification.membershipId || '';
            break;

        case 'client_invitations':
            if (notification.userId || notification.invitorId) {
                const isAccept = notification.status === 'ACCEPTED';
                title = isAccept ? 'Invitation Accepted' : 'Invitation Rejected';
                body = notification.message || (isAccept ?
                    `The invitation for ${notification.subscriptionName} you shared with ${notification.name} has been accepted` :
                    `The invitation for ${notification.subscriptionName} you shared with ${notification.name} has been rejected`);
            } else if (notification.phoneNumber) {
                const invitationStatus = getInvitationStatus(notification.status);
                title = getInvitationTitle(invitationStatus);
                body = notification.message || getInvitationBody(invitationStatus, notification.name);
                data.status = invitationStatus;
            }
            data.gymName = notification.gymName || '';
            data.clientEmail = notification.clientEmail || '';
            data.clientName = notification.name || '';
            data.invitationId = notification.invitationId || '';
            data.subscriptionName = notification.subscriptionName || '';
            break;

        default:
            logger.info(`Using default handling for notification type: ${notification.type}`);
            break;
    }

    const notificationMessage: admin.messaging.Message = {
        notification: { title, body },
        data,
        android: {
            priority: 'high',
            notification: {
                channelId: 'notifications_channel',
                priority: 'high',
                defaultSound: true,
                defaultVibrateTimings: true,
                icon: '@mipmap/ic_launcher',
                clickAction: 'FLUTTER_NOTIFICATION_CLICK',
            },
        },
        apns: {
            payload: {
                aps: {
                    sound: 'default',
                    badge: 1,
                },
            },
        },
        token: fcmToken,
    };
    return notificationMessage;
}

function getInvitationStatus(status?: string): string {
    if (status === 'ACCEPTED') return 'accepted';
    if (status === 'REJECTED') return 'rejected';
    if (status === 'PENDING') return 'pending';
    return 'unknown';
}

function getInvitationTitle(status: string): string {
    switch (status) {
        case 'accepted': return 'Invitation Accepted';
        case 'rejected': return 'Invitation Rejected';
        case 'pending': return 'New Invitation';
        default: return 'Invitation Update';
    }
}

function getInvitationBody(status: string, name?: string): string {
    switch (status) {
        case 'accepted': return `You have accepted the invitation from ${name}`;
        case 'rejected': return `You have rejected the invitation from ${name}`;
        case 'pending': return `You have a new invitation pending from ${name}`;
        default: return 'There is an update to your invitation';
    }
}

async function markNotificationAsSent(notificationId: string): Promise<void> {
    await app.firestore().collection('notifications').doc(notificationId).update({
        notificationSent: true,
        sentAt: app.firestore.FieldValue.serverTimestamp()
    });
}

async function updateNotificationWithError(notificationId: string, error: string): Promise<void> {
    await app.firestore().collection('notifications').doc(notificationId).update({
        notificationError: error,
        updatedAt: app.firestore.FieldValue.serverTimestamp()
    });
}