'use strict';

const AWS = require('aws-sdk');
const BbPromise = require('bluebird');
const crypto = require('crypto');
const fs = require('fs');
const _ = require('lodash');
const path = require('path');
const ServerlessError = require('../../../../serverless-error');
const deepSortObjectByKey = require('../../../../utils/deepSortObjectByKey');
const getHashForFilePath = require('../lib/getHashForFilePath');
const parseS3URI = require('../../utils/parse-s3-uri');

class AwsCompileFunctions {
  constructor(serverless, options) {
    this.serverless = serverless;
    this.options = options;
    const serviceDir = this.serverless.serviceDir || '';
    this.packagePath =
      this.serverless.service.package.path || path.join(serviceDir || '.', '.serverless');

    this.provider = this.serverless.getProvider('aws');

    this.ensureTargetExecutionPermission = _.memoize(this.ensureTargetExecutionPermission);
    if (
      this.serverless.service.provider.name === 'aws' &&
      this.serverless.service.provider.versionFunctions == null
    ) {
      this.serverless.service.provider.versionFunctions = true;
    }

    this.hooks = {
      'initialize': () => {
        if (_.get(this.serverless.service.serviceObject, 'awsKmsKeyArn')) {
          this.serverless._logDeprecation(
            'AWS_KMS_KEY_ARN',
            'Starting with next major version, ' +
              '"awsKmsKeyArn" service property will be replaced by "provider.kmsKeyArn"'
          );
        }
        if (
          Object.values(this.serverless.service.functions).some(({ awsKmsKeyArn }) => awsKmsKeyArn)
        ) {
          this.serverless._logDeprecation(
            'AWS_KMS_KEY_ARN',
            'Starting with next major version, ' +
              '"awsKmsKeyArn" function property will be replaced by "kmsKeyArn"'
          );
        }
        if (
          !this.serverless.service.provider.lambdaHashingVersion &&
          Object.keys(this.serverless.service.functions).length &&
          Object.values(this.serverless.service.functions).some(({ handler }) => handler) &&
          (this.serverless.service.provider.versionFunctions ||
            Object.values(this.serverless.service.functions).some(
              ({ versionFunction }) => versionFunction
            ))
        ) {
          this.serverless._logDeprecation(
            'LAMBDA_HASHING_VERSION_V2',
            'Resolution of lambda version hashes was improved with better algorithm, ' +
              'which will be used in next major release.\n' +
              'Switch to it now by setting "provider.lambdaHashingVersion" to "20201221"'
          );
        }
        if (
          !this.serverless.service.provider.runtime &&
          Object.keys(this.serverless.service.functions).length &&
          Object.values(this.serverless.service.functions).some(
            ({ handler, runtime }) => handler && !runtime
          )
        ) {
          this.serverless._logDeprecation(
            'CHANGE_OF_DEFAULT_RUNTIME_TO_NODEJS14X',
            'Starting with `v3.0.0`, the default runtime will change from `nodejs12.x` to `nodejs14.x`. In order to hide the deprecation message and ensure seamless upgrade, please set the runtime explicitly.'
          );
        }
      },
      'package:compileFunctions': async () =>
        BbPromise.bind(this).then(this.downloadPackageArtifacts).then(this.compileFunctions),
    };
  }

  compileRole(newFunction, role) {
    const compiledFunction = newFunction;
    if (typeof role === 'string') {
      if (role.startsWith('arn:')) {
        // role is a statically defined iam arn
        compiledFunction.Properties.Role = role;
      } else if (role === 'IamRoleLambdaExecution') {
        // role is the default role generated by the framework
        compiledFunction.Properties.Role = { 'Fn::GetAtt': [role, 'Arn'] };
      } else {
        // role is a Logical Role Name
        compiledFunction.Properties.Role = { 'Fn::GetAtt': [role, 'Arn'] };
        compiledFunction.DependsOn = (compiledFunction.DependsOn || []).concat(role);
      }
    } else if ('Fn::GetAtt' in role) {
      // role is an "Fn::GetAtt" object
      compiledFunction.Properties.Role = role;
      compiledFunction.DependsOn = (compiledFunction.DependsOn || []).concat(role['Fn::GetAtt'][0]);
    } else {
      // role is an "Fn::ImportValue" or "Fn::Sub" object
      compiledFunction.Properties.Role = role;
    }
  }

  async downloadPackageArtifact(functionName) {
    const { region } = this.options;
    const S3 = new AWS.S3({ region });

    const functionObject = this.serverless.service.getFunction(functionName);
    if (functionObject.image) return;

    const artifactFilePath =
      _.get(functionObject, 'package.artifact') ||
      _.get(this, 'serverless.service.package.artifact');

    const s3Object = parseS3URI(artifactFilePath);
    if (!s3Object) return;
    if (process.env.SLS_DEBUG) {
      this.serverless.cli.log(`Downloading ${s3Object.Key} from bucket ${s3Object.Bucket}`);
    }
    await new Promise((resolve, reject) => {
      const tmpDir = this.serverless.utils.getTmpDirPath();
      const filePath = path.join(tmpDir, path.basename(s3Object.Key));

      const readStream = S3.getObject(s3Object).createReadStream();

      const writeStream = fs.createWriteStream(filePath);
      readStream
        .pipe(writeStream)
        .on('error', reject)
        .on('close', () => {
          if (functionObject.package.artifact) {
            functionObject.package.artifact = filePath;
          } else {
            this.serverless.service.package.artifact = filePath;
          }
          return resolve(filePath);
        });
    });
  }

  async addFileToHash(filePath, hash) {
    const lambdaHashingVersion = this.serverless.service.provider.lambdaHashingVersion;
    if (lambdaHashingVersion) {
      const filePathHash = await getHashForFilePath(filePath);
      hash.write(filePathHash);
    } else {
      await addFileContentsToHashes(filePath, [hash]);
    }
  }

  async compileFunction(functionName) {
    const cfTemplate = this.serverless.service.provider.compiledCloudFormationTemplate;
    const functionResource = this.cfLambdaFunctionTemplate();
    const functionObject = this.serverless.service.getFunction(functionName);
    functionObject.package = functionObject.package || {};

    if (!functionObject.handler && !functionObject.image) {
      throw new ServerlessError(
        `Either "handler" or "image" property needs to be set on function "${functionName}"`,
        'FUNCTION_NEITHER_HANDLER_NOR_IMAGE_DEFINED_ERROR'
      );
    }
    if (functionObject.handler && functionObject.image) {
      throw new ServerlessError(
        `Either "handler" or "image" property (not both) needs to be set on function "${functionName}".`,
        'FUNCTION_BOTH_HANDLER_AND_IMAGE_DEFINED_ERROR'
      );
    }

    let functionImageUri;
    let functionImageSha;

    if (functionObject.image) {
      ({ functionImageUri, functionImageSha } = await this.provider.resolveImageUriAndSha(
        functionName
      ));
      if (_.isObject(functionObject.image)) {
        const imageConfig = {};
        if (functionObject.image.command) {
          imageConfig.Command = functionObject.image.command;
        }

        if (functionObject.image.entryPoint) {
          imageConfig.EntryPoint = functionObject.image.entryPoint;
        }

        if (functionObject.image.workingDirectory) {
          imageConfig.WorkingDirectory = functionObject.image.workingDirectory;
        }

        if (Object.keys(imageConfig).length) {
          functionResource.Properties.ImageConfig = imageConfig;
        }
      }
    }

    // publish these properties to the platform
    functionObject.memory =
      functionObject.memorySize || this.serverless.service.provider.memorySize || 1024;
    if (!functionObject.timeout) {
      functionObject.timeout = this.serverless.service.provider.timeout || 6;
    }

    let artifactFilePath;

    if (functionObject.handler) {
      const serviceArtifactFileName = this.provider.naming.getServiceArtifactName();
      const functionArtifactFileName = this.provider.naming.getFunctionArtifactName(functionName);

      artifactFilePath =
        functionObject.package.artifact || this.serverless.service.package.artifact;

      if (
        !artifactFilePath ||
        (this.serverless.service.artifact && !functionObject.package.artifact)
      ) {
        let artifactFileName = serviceArtifactFileName;
        if (this.serverless.service.package.individually || functionObject.package.individually) {
          artifactFileName = functionArtifactFileName;
        }

        artifactFilePath = path.join(this.serverless.serviceDir, '.serverless', artifactFileName);
      }

      functionObject.runtime = this.provider.getRuntime(functionObject.runtime);
      functionResource.Properties.Handler = functionObject.handler;
      functionResource.Properties.Code.S3Bucket = this.serverless.service.package.deploymentBucket
        ? this.serverless.service.package.deploymentBucket
        : { Ref: 'ServerlessDeploymentBucket' };

      functionResource.Properties.Code.S3Key = `${
        this.serverless.service.package.artifactDirectoryName
      }/${artifactFilePath.split(path.sep).pop()}`;
      functionResource.Properties.Runtime = functionObject.runtime;
    } else {
      functionResource.Properties.Code.ImageUri = functionImageUri;
      functionResource.Properties.PackageType = 'Image';
    }
    functionResource.Properties.FunctionName = functionObject.name;
    functionResource.Properties.MemorySize = functionObject.memory;
    functionResource.Properties.Timeout = functionObject.timeout;

    if (functionObject.description) {
      functionResource.Properties.Description = functionObject.description;
    }

    if (functionObject.condition) {
      functionResource.Condition = functionObject.condition;
    }

    if (functionObject.dependsOn) {
      functionResource.DependsOn = (functionResource.DependsOn || []).concat(
        functionObject.dependsOn
      );
    }

    if (functionObject.tags || this.serverless.service.provider.tags) {
      const tags = Object.assign({}, this.serverless.service.provider.tags, functionObject.tags);
      functionResource.Properties.Tags = [];
      Object.entries(tags).forEach(([Key, Value]) => {
        functionResource.Properties.Tags.push({ Key, Value });
      });
    }

    if (functionObject.onError) {
      const arn = functionObject.onError;

      if (typeof arn === 'string') {
        const iamRoleLambdaExecution = cfTemplate.Resources.IamRoleLambdaExecution;
        functionResource.Properties.DeadLetterConfig = {
          TargetArn: arn,
        };

        // update the PolicyDocument statements (if default policy is used)
        if (iamRoleLambdaExecution) {
          iamRoleLambdaExecution.Properties.Policies[0].PolicyDocument.Statement.push({
            Effect: 'Allow',
            Action: ['sns:Publish'],
            Resource: [arn],
          });
        }
      } else {
        functionResource.Properties.DeadLetterConfig = {
          TargetArn: arn,
        };
      }
    }

    let kmsKeyArn;
    const serviceObj = this.serverless.service.serviceObject;
    if (serviceObj && serviceObj.awsKmsKeyArn) kmsKeyArn = serviceObj.awsKmsKeyArn;
    if (this.serverless.service.provider.kmsKeyArn) {
      kmsKeyArn = this.serverless.service.provider.kmsKeyArn;
    }
    if (functionObject.awsKmsKeyArn) kmsKeyArn = functionObject.awsKmsKeyArn;
    if (functionObject.kmsKeyArn) kmsKeyArn = functionObject.kmsKeyArn;

    if (kmsKeyArn) {
      if (typeof kmsKeyArn === 'string') {
        functionResource.Properties.KmsKeyArn = kmsKeyArn;

        // update the PolicyDocument statements (if default policy is used)
        const iamRoleLambdaExecution = cfTemplate.Resources.IamRoleLambdaExecution;
        if (iamRoleLambdaExecution) {
          iamRoleLambdaExecution.Properties.Policies[0].PolicyDocument.Statement = _.unionWith(
            iamRoleLambdaExecution.Properties.Policies[0].PolicyDocument.Statement,
            [
              {
                Effect: 'Allow',
                Action: ['kms:Decrypt'],
                Resource: [kmsKeyArn],
              },
            ],
            _.isEqual
          );
        }
      } else {
        functionResource.Properties.KmsKeyArn = kmsKeyArn;
      }
    }

    const tracing =
      functionObject.tracing ||
      (this.serverless.service.provider.tracing && this.serverless.service.provider.tracing.lambda);

    if (tracing) {
      let mode = tracing;

      if (typeof tracing === 'boolean') {
        mode = 'Active';
      }

      const iamRoleLambdaExecution = cfTemplate.Resources.IamRoleLambdaExecution;

      functionResource.Properties.TracingConfig = {
        Mode: mode,
      };

      const stmt = {
        Effect: 'Allow',
        Action: ['xray:PutTraceSegments', 'xray:PutTelemetryRecords'],
        Resource: ['*'],
      };

      // update the PolicyDocument statements (if default policy is used)
      if (iamRoleLambdaExecution) {
        iamRoleLambdaExecution.Properties.Policies[0].PolicyDocument.Statement = _.unionWith(
          iamRoleLambdaExecution.Properties.Policies[0].PolicyDocument.Statement,
          [stmt],
          _.isEqual
        );
      }
    }

    if (functionObject.environment || this.serverless.service.provider.environment) {
      functionResource.Properties.Environment = {};
      functionResource.Properties.Environment.Variables = Object.assign(
        {},
        this.serverless.service.provider.environment,
        functionObject.environment
      );
    }

    const role = this.provider.getCustomExecutionRole(functionObject);
    this.compileRole(functionResource, role || 'IamRoleLambdaExecution');

    if (!functionObject.vpc) functionObject.vpc = {};
    if (!this.serverless.service.provider.vpc) this.serverless.service.provider.vpc = {};

    functionResource.Properties.VpcConfig = {
      SecurityGroupIds:
        functionObject.vpc.securityGroupIds ||
        this.serverless.service.provider.vpc.securityGroupIds,
      SubnetIds: functionObject.vpc.subnetIds || this.serverless.service.provider.vpc.subnetIds,
    };

    if (
      !functionResource.Properties.VpcConfig.SecurityGroupIds ||
      !functionResource.Properties.VpcConfig.SubnetIds
    ) {
      delete functionResource.Properties.VpcConfig;
    }

    const fileSystemConfig = functionObject.fileSystemConfig;

    if (fileSystemConfig) {
      if (!functionResource.Properties.VpcConfig) {
        const errorMessage = [
          `Function "${functionName}": when using fileSystemConfig, `,
          'ensure that function has vpc configured ',
          'on function or provider level',
        ].join('');
        throw new ServerlessError(errorMessage, 'LAMBDA_FILE_SYSTEM_CONFIG_MISSING_VPC');
      }

      const iamRoleLambdaExecution = cfTemplate.Resources.IamRoleLambdaExecution;

      const stmt = {
        Effect: 'Allow',
        Action: ['elasticfilesystem:ClientMount', 'elasticfilesystem:ClientWrite'],
        Resource: [fileSystemConfig.arn],
      };

      // update the PolicyDocument statements (if default policy is used)
      if (iamRoleLambdaExecution) {
        iamRoleLambdaExecution.Properties.Policies[0].PolicyDocument.Statement.push(stmt);
      }

      const cfFileSystemConfig = {
        Arn: fileSystemConfig.arn,
        LocalMountPath: fileSystemConfig.localMountPath,
      };

      functionResource.Properties.FileSystemConfigs = [cfFileSystemConfig];
    }

    if (functionObject.reservedConcurrency || functionObject.reservedConcurrency === 0) {
      functionResource.Properties.ReservedConcurrentExecutions = functionObject.reservedConcurrency;
    }

    if (!functionObject.disableLogs) {
      functionResource.DependsOn = [this.provider.naming.getLogGroupLogicalId(functionName)].concat(
        functionResource.DependsOn || []
      );
    }

    if (functionObject.layers) {
      functionResource.Properties.Layers = functionObject.layers;
    } else if (this.serverless.service.provider.layers) {
      functionResource.Properties.Layers = this.serverless.service.provider.layers;
    }

    const functionLogicalId = this.provider.naming.getLambdaLogicalId(functionName);
    const newFunctionObject = {
      [functionLogicalId]: functionResource,
    };

    Object.assign(cfTemplate.Resources, newFunctionObject);

    const shouldVersionFunction =
      functionObject.versionFunction != null
        ? functionObject.versionFunction
        : this.serverless.service.provider.versionFunctions;

    if (shouldVersionFunction || functionObject.provisionedConcurrency) {
      // Create hashes for the artifact and the logical id of the version resource
      // The one for the version resource must include the function configuration
      // to make sure that a new version is created on configuration changes and
      // not only on source changes.

      const versionHash = crypto.createHash('sha256');
      versionHash.setEncoding('base64');
      const layerConfigurations = _.cloneDeep(
        extractLayerConfigurationsFromFunction(functionResource.Properties, cfTemplate)
      );

      const versionResource = this.cfLambdaVersionTemplate();

      if (functionImageSha) {
        versionResource.Properties.CodeSha256 = functionImageSha;
      } else {
        const fileHash = await getHashForFilePath(artifactFilePath);
        versionResource.Properties.CodeSha256 = fileHash;

        await this.addFileToHash(artifactFilePath, versionHash);
      }
      // Include all referenced layer code in the version id hash
      const layerArtifactPaths = [];
      layerConfigurations.forEach((layer) => {
        const layerArtifactPath = this.provider.resolveLayerArtifactName(layer.name);
        layerArtifactPaths.push(layerArtifactPath);
      });

      for (const layerArtifactPath of layerArtifactPaths.sort()) {
        await this.addFileToHash(layerArtifactPath, versionHash);
      }

      // Include function and layer configuration details in the version id hash
      for (const layerConfig of layerConfigurations) {
        delete layerConfig.properties.Content.S3Key;
      }

      const functionProperties = _.cloneDeep(functionResource.Properties);
      // In `image` case, we assume it's path to ECR image digest
      if (!functionObject.image) delete functionProperties.Code;
      // Properties applied to function globally (not specific to version or alias)
      delete functionProperties.ReservedConcurrentExecutions;
      delete functionProperties.Tags;

      const lambdaHashingVersion = this.serverless.service.provider.lambdaHashingVersion;
      if (lambdaHashingVersion) {
        functionProperties.layerConfigurations = layerConfigurations;
        versionHash.write(JSON.stringify(deepSortObjectByKey(functionProperties)));
      } else {
        // sort the layer configurations for hash consistency
        const sortedLayerConfigurations = {};
        const byKey = ([key1], [key2]) => key1.localeCompare(key2);
        for (const { name, properties: layerProperties } of layerConfigurations) {
          sortedLayerConfigurations[name] = _.fromPairs(
            Object.entries(layerProperties).sort(byKey)
          );
        }
        functionProperties.layerConfigurations = sortedLayerConfigurations;
        const sortedFunctionProperties = _.fromPairs(
          Object.entries(functionProperties).sort(byKey)
        );

        versionHash.write(JSON.stringify(sortedFunctionProperties));
      }

      versionHash.end();
      const versionDigest = versionHash.read();

      versionResource.Properties.FunctionName = { Ref: functionLogicalId };
      if (functionObject.description) {
        versionResource.Properties.Description = functionObject.description;
      }

      // use the version SHA in the logical resource ID of the version because
      // AWS::Lambda::Version resource will not support updates
      const versionLogicalId = this.provider.naming.getLambdaVersionLogicalId(
        functionName,
        versionDigest
      );
      functionObject.versionLogicalId = versionLogicalId;
      const newVersionObject = {
        [versionLogicalId]: versionResource,
      };

      Object.assign(cfTemplate.Resources, newVersionObject);

      // Add function versions to Outputs section
      const functionVersionOutputLogicalId =
        this.provider.naming.getLambdaVersionOutputLogicalId(functionName);
      const newVersionOutput = this.cfOutputLatestVersionTemplate();

      newVersionOutput.Value = { Ref: versionLogicalId };

      Object.assign(cfTemplate.Outputs, {
        [functionVersionOutputLogicalId]: newVersionOutput,
      });

      if (functionObject.provisionedConcurrency) {
        if (!shouldVersionFunction) delete versionResource.DeletionPolicy;

        const provisionedConcurrency = Number(functionObject.provisionedConcurrency);
        const aliasLogicalId =
          this.provider.naming.getLambdaProvisionedConcurrencyAliasLogicalId(functionName);
        const aliasName = this.provider.naming.getLambdaProvisionedConcurrencyAliasName();

        functionObject.targetAlias = { name: aliasName, logicalId: aliasLogicalId };

        const aliasResource = {
          Type: 'AWS::Lambda::Alias',
          Properties: {
            FunctionName: { Ref: functionLogicalId },
            FunctionVersion: { 'Fn::GetAtt': [versionLogicalId, 'Version'] },
            Name: aliasName,
            ProvisionedConcurrencyConfig: {
              ProvisionedConcurrentExecutions: provisionedConcurrency,
            },
          },
          DependsOn: functionLogicalId,
        };

        cfTemplate.Resources[aliasLogicalId] = aliasResource;
      }
    }

    this.compileFunctionEventInvokeConfig(functionName);
  }

  compileFunctionEventInvokeConfig(functionName) {
    const functionObject = this.serverless.service.getFunction(functionName);
    const { destinations, maximumEventAge, maximumRetryAttempts } = functionObject;

    if (!destinations && !maximumEventAge && maximumRetryAttempts == null) {
      return;
    }

    const destinationConfig = {};

    if (destinations) {
      const executionRole = this.provider.getCustomExecutionRole(functionObject);
      const hasAccessPoliciesHandledExternally = Boolean(executionRole);

      if (destinations.onSuccess) {
        if (!hasAccessPoliciesHandledExternally) {
          this.ensureTargetExecutionPermission(destinations.onSuccess);
        }
        destinationConfig.OnSuccess = {
          Destination: destinations.onSuccess.startsWith('arn:')
            ? destinations.onSuccess
            : this.provider.resolveFunctionArn(destinations.onSuccess),
        };
      }

      if (destinations.onFailure) {
        if (!hasAccessPoliciesHandledExternally) {
          this.ensureTargetExecutionPermission(destinations.onFailure);
        }
        destinationConfig.OnFailure = {
          Destination: destinations.onFailure.startsWith('arn:')
            ? destinations.onFailure
            : this.provider.resolveFunctionArn(destinations.onFailure),
        };
      }
    }

    const cfResources = this.serverless.service.provider.compiledCloudFormationTemplate.Resources;
    const functionLogicalId = this.provider.naming.getLambdaLogicalId(functionName);

    const resource = {
      Type: 'AWS::Lambda::EventInvokeConfig',
      Properties: {
        FunctionName: { Ref: functionLogicalId },
        DestinationConfig: destinationConfig,
        Qualifier: functionObject.targetAlias ? functionObject.targetAlias.name : '$LATEST',
      },
    };

    if (maximumEventAge) {
      resource.Properties.MaximumEventAgeInSeconds = maximumEventAge;
    }

    if (maximumRetryAttempts != null) {
      resource.Properties.MaximumRetryAttempts = maximumRetryAttempts;
    }

    cfResources[this.provider.naming.getLambdaEventConfigLogicalId(functionName)] = resource;
  }

  // Memoized in a constructor
  ensureTargetExecutionPermission(functionAddress) {
    const iamPolicyStatements =
      this.serverless.service.provider.compiledCloudFormationTemplate.Resources
        .IamRoleLambdaExecution.Properties.Policies[0].PolicyDocument.Statement;

    const action = (() => {
      if (!functionAddress.startsWith('arn:') || functionAddress.includes(':function:')) {
        return 'lambda:InvokeFunction';
      }
      if (functionAddress.includes(':sqs:')) return 'sqs:SendMessage';
      if (functionAddress.includes(':sns:')) return 'sns:Publish';
      if (functionAddress.includes(':event-bus/')) return 'events:PutEvents';
      throw new ServerlessError(
        `Unsupported destination target ${functionAddress}`,
        'UNSUPPORTED_DESTINATION_TARGET'
      );
    })();
    iamPolicyStatements.push({
      Effect: 'Allow',
      Action: action,
      // Note: Cannot address function via { 'Fn::GetAtt': [targetLogicalId, 'Arn'] }
      // as same IAM settings are used for target function and that will introduce
      // circular dependency error. Relying on Fn::Sub as a workaround
      Resource: functionAddress.startsWith('arn:')
        ? functionAddress
        : {
            'Fn::Sub': `arn:\${AWS::Partition}:lambda:\${AWS::Region}:\${AWS::AccountId}:function:${
              this.serverless.service.getFunction(functionAddress).name
            }`,
          },
    });
  }

  async downloadPackageArtifacts() {
    const allFunctions = this.serverless.service.getAllFunctions();
    return BbPromise.each(allFunctions, (functionName) =>
      this.downloadPackageArtifact(functionName)
    );
  }

  async compileFunctions() {
    const allFunctions = this.serverless.service.getAllFunctions();
    return Promise.all(allFunctions.map((functionName) => this.compileFunction(functionName)));
  }

  cfLambdaFunctionTemplate() {
    return {
      Type: 'AWS::Lambda::Function',
      Properties: {
        Code: {},
      },
    };
  }

  cfLambdaVersionTemplate() {
    return {
      Type: 'AWS::Lambda::Version',
      // Retain old versions even though they will not be in future
      // CloudFormation stacks. On stack delete, these will be removed when
      // their associated function is removed.
      DeletionPolicy: 'Retain',
      Properties: {
        FunctionName: 'FunctionName',
        CodeSha256: 'CodeSha256',
      },
    };
  }

  cfOutputLatestVersionTemplate() {
    return {
      Description: 'Current Lambda function version',
      Value: 'Value',
    };
  }
}

async function addFileContentsToHashes(filePath, hashes) {
  return new Promise((resolve, reject) => {
    const readStream = fs.createReadStream(filePath);
    readStream
      .on('data', (chunk) => {
        hashes.forEach((hash) => {
          hash.write(chunk);
        });
      })
      .on('close', () => {
        resolve();
      })
      .on('error', (error) => {
        reject(new Error(`Could not add file content to hash: ${error}`));
      });
  });
}

function extractLayerConfigurationsFromFunction(functionProperties, cfTemplate) {
  const layerConfigurations = [];
  if (!functionProperties.Layers) return layerConfigurations;
  functionProperties.Layers.forEach((potentialLocalLayerObject) => {
    if (potentialLocalLayerObject.Ref) {
      const configuration = cfTemplate.Resources[potentialLocalLayerObject.Ref];
      if (!configuration) {
        throw new ServerlessError(
          `Could not find reference to layer: ${potentialLocalLayerObject.Ref}. Ensure that you are referencing layer defined in your service.`,
          'LAMBDA_LAYER_REFERENCE_NOT_FOUND'
        );
      }

      layerConfigurations.push({
        name: configuration._serverlessLayerName,
        ref: potentialLocalLayerObject.Ref,
        properties: configuration.Properties,
      });
    }
  });
  return layerConfigurations;
}

module.exports = AwsCompileFunctions;
