// Create clients and set shared const values outside of the handler.

// Create a DocumentClient that represents the query to add an item
import { DynamoDBClient } from '@aws-sdk/client-dynamodb';
import { DynamoDBDocumentClient, ScanCommand } from '@aws-sdk/lib-dynamodb';

//DynamoDB Endpoint
const ENDPOINT_OVERRIDE = process.env.ENDPOINT_OVERRIDE;
let ddbClient = undefined;

if(ENDPOINT_OVERRIDE){
    ddbClient = new DynamoDBClient({ endpoint: ENDPOINT_OVERRIDE });    
}
else{
    
    ddbClient = new DynamoDBClient({});    // Use default values for DynamoDB endpoint
    console.warn("No value for ENDPOINT_OVERRIDE provided for DynamoDB, using default");
}

const ddbDocClient = DynamoDBDocumentClient.from(ddbClient);

// Get the DynamoDB table name from environment variables
const tableName = process.env.SAMPLE_TABLE;

/**
 * A simple example includes a HTTP get method to get all items from a DynamoDB table.
 */
export const getAllItemsHandler = async (event) => {
    if (event.httpMethod !== 'GET') {
        throw new Error(`getAllItems only accept GET method, you tried: ${event.httpMethod}`);
    }
    // All log statements are written to CloudWatch
    console.info('received:', event);

    // get all items from the table (only first 1MB data, you can use `LastEvaluatedKey` to get the rest of data)
    // https://docs.aws.amazon.com/AWSJavaScriptSDK/latest/AWS/DynamoDB/DocumentClient.html#scan-property
    // https://docs.aws.amazon.com/amazondynamodb/latest/APIReference/API_Scan.html
    var params = {
        TableName : tableName
    };

    try {
        const data = await ddbDocClient.send(new ScanCommand(params));
        var items = data.Items;
    } catch (err) {
        console.error("Error retrieving all items:", err.message);
        console.error("Error code:", err.code);
        console.error("Error name:", err.name);
        console.error("Error stack:", err.stack);
        
    throw err;
    }

    const response = {
        statusCode: 200,
        headers: {
            "Access-Control-Allow-Headers" : "Content-Type",
            "Access-Control-Allow-Origin": "*", //DO NOT USE THIS VALUE IN PRODUCTION - https://docs.aws.amazon.com/apigateway/latest/developerguide/http-api-cors.html
            "Access-Control-Allow-Methods": "OPTIONS,POST,GET"
        },
        body: JSON.stringify(items)
    };

    // All log statements are written to CloudWatch
    console.info(`response from: ${event.path} statusCode: ${response.statusCode} body: ${response.body}`);
    return response;
}