import { AWSError, S3 } from "aws-sdk";
import { getJsonConfig, DatalakeConfig } from "./config";

export class S3Client {
    private config: DatalakeConfig;
    private innerClient: S3;

    public constructor(config: string | DatalakeConfig) {
        if (typeof config === "string") {
            this.config = getJsonConfig("datalake.reader");
        } else {
            this.config = config;
        }
        this.innerClient = new S3({
            accessKeyId: this.config.accessKeyId,
            secretAccessKey: this.config.secretAccessKey
        });
    }

    private withPrefix(path: string): string {
        let result = this.config.bucketPath;
        if (!result.endsWith('/')) {
            result += "/";
        }
        if (path.includes(result)) {
            return path;
        }
        return result + path;
    }

    public async keyExists(key: string): Promise<boolean> {
        const params = {
            Bucket: this.config.bucketName,
            Key: this.withPrefix(key)
        };
        return new Promise<boolean>( (resolve, reject) => {
            this.innerClient.headObject(params, (err: AWSError) => {
                if (err) {
                    if (err.code === "NotFound") {
                        resolve(false);
                    } else {
                        reject(err);
                    }
                } else {
                    resolve(true);
                }
            });
        });
    }
}

if (!exists) {
    reject(Error(`Key not found in the datalake:
    Bucket:     ${this.datalakeConfig.bucketName}
    BucketPath: ${this.datalakeConfig.bucketPath}
    Key:        ${key}`));
}