somod-chat-service/build/lib/message.js

Serverless Chat Service from SOMOD

import { marshall } from "@aws-sdk/util-dynamodb";
import { DynamoDBClient, PutItemCommand } from "@aws-sdk/client-dynamodb";
import { threadCache } from "./threadCache";
const dynamodb = new DynamoDBClient();
const msgTTL = parseInt(process.env.CHAT_MESSAGE_TTL ?? "7776000", 10); // 3 months in seconds
export const getMessageTTL = (now) => {
    const _now = now ?? Date.now();
    const __now = Math.floor(_now / 1000);
    return __now + msgTTL;
};
export const putMessage = async (tableName, userId, message) => {
    const msg = {
        ...message,
        seqNo: Date.now()
    };
    const messageWithKeys = {
        ...msg,
        userId,
        expiresAt: getMessageTTL()
    };
    const putItemCommand = new PutItemCommand({
        TableName: tableName,
        Item: marshall(messageWithKeys),
        ConditionExpression: "attribute_not_exists(#userId) AND attribute_not_exists(#seqNo)",
        ExpressionAttributeNames: {
            "#userId": "userId",
            "#seqNo": "seqNo"
        }
    });
    await dynamodb.send(putItemCommand);
    return msg;
};
export const validateIncomingMessage = async (message, userId, typeToAllowedActionsMap) => {
    let errorMessage = undefined;
    const thread = await threadCache.get(message.threadId);
    if (thread === undefined) {
        errorMessage = "Invalid threadId : does not exist";
    }
    else if (!thread.participants.includes(userId)) {
        errorMessage = `Invalid threadId : from '${userId}' is not a participant in thread '${thread.id}'`;
    }
    else if (!typeToAllowedActionsMap[message.type]) {
        errorMessage = `Invalid type : type must be one of (${typeToAllowedActionsMap[message.type].join(", ")})`;
    }
    else if (!typeToAllowedActionsMap[message.type].includes(message.action)) {
        errorMessage = `Invalid action : action must be '${typeToAllowedActionsMap[message.type].join(",")}' for '${message.type}' type`;
    }
    if (errorMessage) {
        return {
            statusCode: 400,
            headers: { "Content-Type": "application/json; charset=utf-8" },
            body: JSON.stringify({
                message: errorMessage,
                threadId: message.threadId
            })
        };
    }
};