const functions = require("firebase-functions");
const admin = require("firebase-admin");

admin.initializeApp();

// Helper function to send notifications
async function sendNotificationToTripParticipants(tripId, title, body, excludeUserId) {
    try {
        const tripDoc = await admin.firestore().collection("trips").doc(tripId).get();
        if (!tripDoc.exists) {
            console.log(`Trip ${tripId} not found`);
            return;
        }

        const trip = tripDoc.data();
        const participants = trip.participants || [];
        // Add creator if not in participants list (though usually they are)
        if (trip.createdBy && !participants.includes(trip.createdBy)) {
            participants.push(trip.createdBy);
        }

        const tokens = [];

        for (const userId of participants) {
            if (userId === excludeUserId) continue;

            const userDoc = await admin.firestore().collection("users").doc(userId).get();
            if (userDoc.exists) {
                const userData = userDoc.data();
                if (userData.fcmToken) {
                    tokens.push(userData.fcmToken);
                }
            }
        }

        if (tokens.length > 0) {
            const message = {
                notification: {
                    title: title,
                    body: body,
                },
                tokens: tokens,
                data: {
                    tripId: tripId,
                    click_action: "FLUTTER_NOTIFICATION_CLICK",
                },
            };

            const response = await admin.messaging().sendMulticast(message);
            console.log(`${response.successCount} messages were sent successfully`);
        }
    } catch (error) {
        console.error("Error sending notification:", error);
    }
}

exports.onActivityCreated = functions.firestore
    .document("trips/{tripId}/activities/{activityId}")
    .onCreate(async (snapshot, context) => {
        const activity = snapshot.data();
        const tripId = context.params.tripId;
        const createdBy = activity.createdBy || "Unknown"; // Assuming createdBy field exists

        // Fetch creator name if possible, otherwise use generic message
        let creatorName = "Quelqu'un";
        if (createdBy !== "Unknown") {
            const userDoc = await admin.firestore().collection("users").doc(createdBy).get();
            if (userDoc.exists) {
                creatorName = userDoc.data().prenom || "Quelqu'un";
            }
        }

        await sendNotificationToTripParticipants(
            tripId,
            "Nouvelle activité !",
            `${creatorName} a ajouté une nouvelle activité : ${activity.title}`,
            createdBy
        );
    });

exports.onMessageCreated = functions.firestore
    .document("trips/{tripId}/messages/{messageId}")
    .onCreate(async (snapshot, context) => {
        const message = snapshot.data();
        const tripId = context.params.tripId;
        const senderId = message.senderId;

        let senderName = "Quelqu'un";
        if (senderId) {
            const userDoc = await admin.firestore().collection("users").doc(senderId).get();
            if (userDoc.exists) {
                senderName = userDoc.data().prenom || "Quelqu'un";
            }
        }

        await sendNotificationToTripParticipants(
            tripId,
            "Nouveau message",
            `${senderName} : ${message.content}`,
            senderId
        );
    });

exports.onExpenseCreated = functions.firestore
    .document("trips/{tripId}/expenses/{expenseId}")
    .onCreate(async (snapshot, context) => {
        const expense = snapshot.data();
        const tripId = context.params.tripId;
        const paidBy = expense.paidBy;

        let payerName = "Quelqu'un";
        if (paidBy) {
            const userDoc = await admin.firestore().collection("users").doc(paidBy).get();
            if (userDoc.exists) {
                payerName = userDoc.data().prenom || "Quelqu'un";
            }
        }

        await sendNotificationToTripParticipants(
            tripId,
            "Nouvelle dépense",
            `${payerName} a ajouté une dépense : ${expense.amount} ${expense.currency || '€'}`,
            paidBy
        );
    });