'use strict';

const _ = require('lodash');
const BbPromise = require('bluebird');
const { addCustomResourceToService } = require('../../../../custom-resources');
const ServerlessError = require('../../../../../../serverless-error');

class AwsCompileS3Events {
  constructor(serverless, options) {
    this.serverless = serverless;
    this.options = options;
    this.provider = this.serverless.getProvider('aws');

    this.serverless.configSchemaHandler.defineFunctionEvent('aws', 's3', {
      anyOf: [
        { type: 'string' },
        {
          type: 'object',
          properties: {
            bucket: {
              anyOf: [
                { type: 'string' },
                { $ref: '#/definitions/awsCfFunction' },
                { $ref: '#/definitions/awsCfIf' },
              ],
            },
            event: { type: 'string', pattern: '^s3:.+$' },
            existing: { type: 'boolean' },
            rules: {
              type: 'array',
              items: {
                type: 'object',
                properties: {
                  prefix: {
                    anyOf: [{ type: 'string' }, { $ref: '#/definitions/awsCfFunction' }],
                  },
                  suffix: {
                    anyOf: [{ type: 'string' }, { $ref: '#/definitions/awsCfFunction' }],
                  },
                },
                maxProperties: 1,
                additionalProperties: false,
              },
            },
          },
          required: ['bucket'],
          additionalProperties: false,
        },
      ],
    });

    this.hooks = {
      'package:compileEvents': async () => {
        return BbPromise.bind(this).then(this.newS3Buckets).then(this.existingS3Buckets);
      },
    };
  }

  newS3Buckets() {
    const bucketsLambdaConfigurations = {};
    const bucketsMeta = {};
    const s3EnabledFunctions = [];
    const providerS3 = this.serverless.service.provider.s3 || {};

    this.serverless.service.getAllFunctions().forEach((functionName) => {
      const functionObj = this.serverless.service.getFunction(functionName);

      if (functionObj.events) {
        functionObj.events.forEach((event) => {
          if (event.s3) {
            // return immediately if it's an existing S3 event since we treat them differently
            if (event.s3.existing) return null;

            let bucketRef;
            let notificationEvent = 's3:ObjectCreated:*';
            let filter = {};

            if (typeof event.s3 === 'object') {
              if (_.isObject(event.s3.bucket)) {
                throw new ServerlessError(
                  'When specifying "s3.bucket" with CloudFormation intrinsic function, you need to specify that the bucket is existing via "existing: true" property.',
                  'S3_INVALID_NEW_BUCKET_FORMAT'
                );
              }
              bucketRef = event.s3.bucket;
              if (event.s3.event) {
                notificationEvent = event.s3.event;
              }
              if (event.s3.rules) {
                const rules = [];
                event.s3.rules.forEach((rule) => {
                  const name = Object.keys(rule)[0];
                  const value = rule[name];
                  rules.push({ Name: name, Value: value });
                });
                filter = { Filter: { S3Key: { Rules: rules } } };
              }
            } else {
              bucketRef = event.s3;
            }

            const lambdaLogicalId = this.provider.naming.getLambdaLogicalId(functionName);
            let bucketName;
            if (providerS3[bucketRef]) {
              bucketName = providerS3[bucketRef].name || bucketRef;
              const logicalId = this.provider.naming.getBucketLogicalId(bucketRef);
              bucketsMeta[bucketName] = { logicalId, bucketRef };
            } else {
              bucketName = bucketRef;
            }

            if (
              !new RegExp(
                this.serverless.configSchemaHandler.schema.definitions.awsS3BucketName.pattern
              ).test(bucketName)
            ) {
              const errorMessage = [
                `${bucketName} - Bucket name must conform to pattern ${this.serverless.configSchemaHandler.schema.definitions.awsS3BucketName.pattern}.`,
                `Please check provider.s3.${bucketRef} and/or s3 events of function "${functionName}".`,
              ].join(' ');
              throw new ServerlessError(errorMessage, 'S3_INVALID_BUCKET_PATTERN');
            }

            if (bucketsLambdaConfigurations[bucketName]) {
              // check if the bucket already defined
              // in another S3 event in the service
              let newLambdaConfiguration = {
                Event: notificationEvent,
                Function: {
                  'Fn::GetAtt': [lambdaLogicalId, 'Arn'],
                },
              };

              // Assign 'filter' if not empty
              newLambdaConfiguration = Object.assign(newLambdaConfiguration, filter);
              bucketsLambdaConfigurations[bucketName].push(newLambdaConfiguration);
            } else {
              bucketsLambdaConfigurations[bucketName] = [
                {
                  Event: notificationEvent,
                  Function: {
                    'Fn::GetAtt': [lambdaLogicalId, 'Arn'],
                  },
                },
              ];
              // Assign 'filter' if not empty
              bucketsLambdaConfigurations[bucketName][0] = Object.assign(
                bucketsLambdaConfigurations[bucketName][0],
                filter
              );
            }
            const s3EnabledFunction = { functionName, bucketName };
            s3EnabledFunctions.push(s3EnabledFunction);
          }

          return null;
        });
      }
    });

    // iterate over all buckets to be created
    // and compile them to CF resources
    Object.entries(bucketsLambdaConfigurations).forEach(
      ([bucketName, bucketLambdaConfiguration]) => {
        let bucketConf = null;
        if (bucketsMeta[bucketName]) {
          const providerBucket = providerS3[bucketsMeta[bucketName].bucketRef];
          bucketConf = {};
          for (const [key, value] of Object.entries(providerBucket)) {
            if (key !== 'name') {
              const property = _.upperFirst(key);
              bucketConf[property] = value;
            }
          }
        }
        let providedNotificationConfiguration = {};
        if (bucketConf && Object.keys(bucketConf).length > 0) {
          providedNotificationConfiguration = bucketConf.NotificationConfiguration;
          delete bucketConf.NotificationConfiguration;
        }

        const bucketTemplate = {
          Type: 'AWS::S3::Bucket',
          Properties: Object.assign(
            {
              BucketName: bucketName,
              NotificationConfiguration: Object.assign(
                {
                  LambdaConfigurations: bucketLambdaConfiguration,
                },
                providedNotificationConfiguration
              ),
            },
            bucketConf
          ),
          DependsOn: [],
        };

        // create the DependsOn properties for the buckets permissions (which are created later on)
        const dependsOnToCreate = s3EnabledFunctions.filter(
          (func) => func.bucketName === bucketName
        );

        dependsOnToCreate.forEach((item) => {
          const lambdaPermissionLogicalId = this.provider.naming.getLambdaS3PermissionLogicalId(
            item.functionName,
            (bucketsMeta[item.bucketName] && bucketsMeta[item.bucketName].bucketRef) ||
              item.bucketName
          );

          bucketTemplate.DependsOn.push(lambdaPermissionLogicalId);
        });

        const bucketLogicalId =
          (bucketsMeta[bucketName] && bucketsMeta[bucketName].logicalId) ||
          this.provider.naming.getBucketLogicalId(bucketName);
        const bucketCFResource = {
          [bucketLogicalId]: bucketTemplate,
        };
        _.merge(
          this.serverless.service.provider.compiledCloudFormationTemplate.Resources,
          bucketCFResource
        );
      }
    );

    // iterate over all functions with S3 events
    // and give S3 permission to invoke them all
    // by adding Lambda::Permission resource for each
    s3EnabledFunctions.forEach((s3EnabledFunction) => {
      const lambdaLogicalId = this.provider.naming.getLambdaLogicalId(
        s3EnabledFunction.functionName
      );
      const permissionTemplate = {
        Type: 'AWS::Lambda::Permission',
        Properties: {
          FunctionName: {
            'Fn::GetAtt': [lambdaLogicalId, 'Arn'],
          },
          Action: 'lambda:InvokeFunction',
          Principal: 's3.amazonaws.com',
          SourceArn: {
            'Fn::Join': [
              '',
              ['arn:', { Ref: 'AWS::Partition' }, `:s3:::${s3EnabledFunction.bucketName}`],
            ],
          },
          SourceAccount: { Ref: 'AWS::AccountId' },
        },
      };
      const lambdaPermissionLogicalId = this.provider.naming.getLambdaS3PermissionLogicalId(
        s3EnabledFunction.functionName,
        (bucketsMeta[s3EnabledFunction.bucketName] &&
          bucketsMeta[s3EnabledFunction.bucketName].bucketRef) ||
          s3EnabledFunction.bucketName
      );
      const permissionCFResource = {
        [lambdaPermissionLogicalId]: permissionTemplate,
      };
      _.merge(
        this.serverless.service.provider.compiledCloudFormationTemplate.Resources,
        permissionCFResource
      );
    });
  }

  existingS3Buckets() {
    const { service } = this.serverless;
    const { provider } = service;
    const { compiledCloudFormationTemplate } = provider;
    const { Resources } = compiledCloudFormationTemplate;
    const iamRoleStatements = [];
    let anyFuncUsesExistingS3Bucket = false;

    // used to keep track of the custom resources created for each bucket
    const bucketResources = {};

    service.getAllFunctions().forEach((functionName) => {
      let numEventsForFunc = 0;
      let currentBucketName = null;
      const functionObj = service.getFunction(functionName);
      const FunctionName = functionObj.name;

      if (functionObj.events) {
        functionObj.events.forEach((event) => {
          if (event.s3 && _.isObject(event.s3) && event.s3.existing) {
            numEventsForFunc++;
            let rules = null;
            const bucket = event.s3.bucket;
            // In order to property use it as key and during comparisons below,
            const stringifiedBucket = _.isObject(bucket) ? JSON.stringify(bucket) : bucket;
            const notificationEvent = event.s3.event || 's3:ObjectCreated:*';
            anyFuncUsesExistingS3Bucket = true;

            if (!currentBucketName) {
              currentBucketName = stringifiedBucket;
            }
            if (stringifiedBucket !== currentBucketName) {
              const errorMessage = [
                'Only one S3 Bucket can be configured per function.',
                ` In "${FunctionName}" you're attempting to configure "${currentBucketName}" and "${stringifiedBucket}" at the same time.`,
              ].join('');
              throw new ServerlessError(errorMessage, 'S3_MULTIPLE_BUCKETS_PER_FUNCTION');
            }

            rules = (event.s3.rules || []).map((rule) => {
              const key = Object.keys(rule)[0];
              const value = rule[key];
              return {
                [_.startCase(key)]: value,
              };
            });

            const eventFunctionLogicalId = this.provider.naming.getLambdaLogicalId(functionName);
            const customResourceFunctionLogicalId =
              this.provider.naming.getCustomResourceS3HandlerFunctionLogicalId();
            const customS3ResourceLogicalId =
              this.provider.naming.getCustomResourceS3ResourceLogicalId(functionName);

            // store how often the custom S3 resource is used
            if (bucketResources[stringifiedBucket]) {
              bucketResources[stringifiedBucket] = _.union(bucketResources[stringifiedBucket], [
                customS3ResourceLogicalId,
              ]);
            } else {
              Object.assign(bucketResources, {
                [stringifiedBucket]: [customS3ResourceLogicalId],
              });
            }

            let customS3Resource;
            if (numEventsForFunc === 1) {
              customS3Resource = {
                [customS3ResourceLogicalId]: {
                  Type: 'Custom::S3',
                  Version: 1.0,
                  DependsOn: [eventFunctionLogicalId, customResourceFunctionLogicalId],
                  Properties: {
                    ServiceToken: {
                      'Fn::GetAtt': [customResourceFunctionLogicalId, 'Arn'],
                    },
                    FunctionName,
                    BucketName: bucket,
                    BucketConfigs: [
                      {
                        Event: notificationEvent,
                        Rules: rules,
                      },
                    ],
                  },
                },
              };

              iamRoleStatements.push({
                Effect: 'Allow',
                Resource: {
                  'Fn::Join': [':', ['arn', { Ref: 'AWS::Partition' }, 's3', '', '', bucket]],
                },
                Action: ['s3:PutBucketNotification', 's3:GetBucketNotification'],
              });
            } else {
              Resources[customS3ResourceLogicalId].Properties.BucketConfigs.push({
                Event: notificationEvent,
                Rules: rules,
              });
            }

            _.merge(Resources, customS3Resource);
          }
        });
      }
    });

    if (anyFuncUsesExistingS3Bucket) {
      iamRoleStatements.push({
        Effect: 'Allow',
        Resource: {
          'Fn::Join': [
            ':',
            [
              'arn',
              { Ref: 'AWS::Partition' },
              'lambda',
              { Ref: 'AWS::Region' },
              { Ref: 'AWS::AccountId' },
              'function',
              '*',
            ],
          ],
        },
        Action: ['lambda:AddPermission', 'lambda:RemovePermission'],
      });
    }

    // check if we need to add DependsOn clauses in case more than 1
    // custom resources are created for one bucket (to avoid race conditions)
    if (Object.keys(bucketResources).length > 0) {
      Object.keys(bucketResources).forEach((bucket) => {
        const resources = bucketResources[bucket];
        if (resources.length > 1) {
          resources.forEach((currResourceLogicalId, idx) => {
            if (idx > 0) {
              const prevResourceLogicalId = resources[idx - 1];
              Resources[currResourceLogicalId].DependsOn.push(prevResourceLogicalId);
            }
          });
        }
      });
    }

    if (iamRoleStatements.length) {
      return addCustomResourceToService(this.provider, 's3', iamRoleStatements);
    }

    return null;
  }
}

module.exports = AwsCompileS3Events;
