const admin = require("firebase-admin");
const { PrismaClient: CMSClient } = require("../../prisma/clients/cms");
const logger = require("./logger.services");
const { localTime } = require("./time.services.js");

const prisma = new CMSClient();

async function sendNotification(token, title, body, data = {}, imageUrl = null) {
    if (!token) throw new Error("Missing FCM token");

    const stringData = {};
    for (const [key, value] of Object.entries(data)) {
        stringData[key] = typeof value === 'string' ? value : JSON.stringify(value);
    }

    if (imageUrl) {
        stringData.image = imageUrl;
    }

    const message = {
        notification: { title, body },
        data: stringData,
        token,
    };

    if (imageUrl) {
        message.android = {
            notification: {
                imageUrl: imageUrl
            }
        };
    }

    return await admin.messaging().send(message);
}

async function sendToTopic(title, body, data = {}, imageUrl = null) {
    if (!title || !body) throw new Error("Missing notification title or body");

    const tokens = await prisma.usersToken.findMany({
        select: {
            UserID_UT: true,
            Token_UT: true
        }
    });

    const tokenList = tokens.filter(t => t.Token_UT);

    if (tokenList.length === 0) {
        return {
            successCount: 0,
            failureCount: 0,
            targetUsers: 0,
            deliveryDetails: [],
            message: "No tokens registered"
        };
    }

    const stringData = {};
    for (const [key, value] of Object.entries(data)) {
        stringData[key] = typeof value === 'string' ? value : JSON.stringify(value);
    }

    if (imageUrl) {
        stringData.image = imageUrl;
    }

    const chunkSize = 500;
    let successTotal = 0;
    let failureTotal = 0;
    const deliveryDetails = [];

    for (let i = 0; i < tokenList.length; i += chunkSize) {
        const tokensChunk = tokenList.slice(i, i + chunkSize);
        const tokensOnly = tokensChunk.map(t => t.Token_UT);

        const message = {
            notification: { title, body },
            data: stringData,
            tokens: tokensOnly,
        };

        if (imageUrl) {
            message.android = {
                notification: {
                    imageUrl: imageUrl
                }
            };
        }

        const response = await admin.messaging().sendEachForMulticast(message);
        successTotal += response.successCount;
        failureTotal += response.failureCount;

        response.responses.forEach((resp, index) => {
            const userToken = tokensChunk[index];
            deliveryDetails.push({
                userID: userToken.UserID_UT,
                token: userToken.Token_UT,
                success: resp.success,
                messageId: resp.messageId || null,
                error: resp.error ? {
                    code: resp.error.code,
                    message: resp.error.message
                } : null
            });
        });
    }

    logger.info(`Sent ${successTotal} notifications successfully and ${failureTotal} notifications failed`);

    return {
        successCount: successTotal,
        failureCount: failureTotal,
        targetUsers: tokenList.length,
        deliveryRate: tokenList.length > 0 ? ((successTotal / tokenList.length) * 100).toFixed(2) : 0,
        deliveryDetails: deliveryDetails
    };
}

async function sendCampaignWithTracking(campaignID, title, body, data = {}, imageUrl = null) {
    try {
        const sentAt = new Date();

        const users = await prisma.usersToken.findMany({
            select: {
                UserID_UT: true,
                Token_UT: true
            }
        });

        const validUsers = users.filter(u => u.Token_UT);

        if (validUsers.length === 0) {
            return {
                success: false,
                message: "No valid tokens found",
                targetUsers: 0,
                successCount: 0,
                failureCount: 0
            };
        }

        await prisma.campaignDelivery.createMany({
            data: validUsers.map(user => ({
                Campaign_CD: campaignID,
                UserID_CD: user.UserID_UT,
                Token_CD: user.Token_UT,
                Status_CD: 'pending',
                CreatedAt_CD: sentAt
            }))
        });

        const result = await sendToTopic(title, body, { ...data, campaignID }, imageUrl);

        for (const delivery of result.deliveryDetails) {
            const updateData = {
                SentAt_CD: sentAt,
                UpdatedAt_CD: localTime(new Date())
            };

            if (delivery.success) {
                updateData.Status_CD = 'delivered';
                updateData.DeliveredAt_CD = localTime(new Date());
                updateData.ResponseData_CD = JSON.stringify({ messageId: delivery.messageId });
            } else {
                updateData.Status_CD = 'failed';
                updateData.FailedAt_CD = localTime(new Date());
                updateData.ErrorMessage_CD = delivery.error ? delivery.error.message : 'Unknown error';
                updateData.ResponseData_CD = JSON.stringify(delivery.error);
            }

            await prisma.campaignDelivery.updateMany({
                where: {
                    Campaign_CD: campaignID,
                    UserID_CD: delivery.userID
                },
                data: updateData
            });
        }

        return {
            success: true,
            targetUsers: validUsers.length,
            successCount: result.successCount,
            failureCount: result.failureCount,
            deliveryRate: result.deliveryRate,
            sentAt: sentAt
        };

    } catch (error) {
        logger.error(`Error in sendCampaignWithTracking: ${error}`);
        throw error;
    }
}

module.exports = {
    sendNotification,
    sendToTopic,
    sendCampaignWithTracking,
};