import { DynamoDB } from 'aws-sdk';

export type DynamoDbLockConfig = {
  dynamodb: DynamoDB.DocumentClient;
  lockTable: string;
};

export enum LockStatus {
  OK,
  EXISTED,
  ERROR,
}

export type LockResult = {
  status: LockStatus;
  id: string;
  key: string;
  message?: string;
  retriable?: boolean;
};

export class DynamoDbLockClient {
  config: DynamoDbLockConfig;
  constructor(config: DynamoDbLockConfig) {
    this.config = config;
  }

  acquireLock = async (id: string): Promise<LockResult> => {
    const { dynamodb, lockTable } = this.config;
    const key = `L#${id}`;
    return dynamodb
      .put({
        TableName: lockTable,
        Item: {
          PK: key,
          SK: key,
          EntityType: 'Lock',
        },
        ConditionExpression: 'attribute_not_exists(PK)',
      })
      .promise()
      .then(() => ({
        id: id,
        key: key,
        status: LockStatus.OK,
      }))
      .catch(e => {
        return e.code === 'ConditionalCheckFailedException'
          ? {
              id: id,
              key: key,
              status: LockStatus.EXISTED,
              message: 'lock existed',
            }
          : {
              id: id,
              key: key,
              status: LockStatus.ERROR,
              retryable: e.retryable,
              message: e.message,
            };
      });
  };

  acquireLocks = async (keys: string[]) => {
    const locks = await Promise.all(keys.map(key => this.acquireLock(key)));
    return locks.filter(key => !!key);
  };
}