import { Validator } from './Validator';
import { ValidationError } from './ValidationError';
import { ValidationMetadata } from '../metadata/ValidationMetadata';
import { ValidatorOptions } from './ValidatorOptions';
import { ValidationTypes } from './ValidationTypes';
import { ConstraintMetadata } from '../metadata/ConstraintMetadata';
import { ValidationArguments } from './ValidationArguments';
import { ValidationUtils } from './ValidationUtils';
import { isPromise, convertToArray } from '../utils';
import { getMetadataStorage } from '../metadata/MetadataStorage';

/**
 * Executes validation over given object.
 */
export class ValidationExecutor {
  // -------------------------------------------------------------------------
  // Properties
  // -------------------------------------------------------------------------

  awaitingPromises: Promise<any>[] = [];
  ignoreAsyncValidations: boolean = false;

  // -------------------------------------------------------------------------
  // Private Properties
  // -------------------------------------------------------------------------

  private metadataStorage = getMetadataStorage();

  // -------------------------------------------------------------------------
  // Constructor
  // -------------------------------------------------------------------------

  constructor(private validator: Validator, private validatorOptions?: ValidatorOptions) {}

  // -------------------------------------------------------------------------
  // Public Methods
  // -------------------------------------------------------------------------

  execute(object: object, targetSchema: string, validationErrors: ValidationError[]): void {
    /**
     * If there is no metadata registered it means possibly the dependencies are not flatterned and
     * more than one instance is used.
     *
     * TODO: This needs proper handling, forcing to use the same container or some other proper solution.
     */
    if (!this.metadataStorage.hasValidationMetaData && this.validatorOptions?.enableDebugMessages === true) {
      console.warn(
        `No validation metadata found. No validation will be  performed. There are multiple possible reasons:\n` +
          `  - There may be multiple class-validator versions installed. You will need to flatten your dependencies to fix the issue.\n` +
          `  - This validation runs before any file with validation decorator was parsed by NodeJS.`
      );
    }

    const groups = this.validatorOptions ? this.validatorOptions.groups : undefined;
    const strictGroups = (this.validatorOptions && this.validatorOptions.strictGroups) || false;
    const always = (this.validatorOptions && this.validatorOptions.always) || false;
    /** Forbid unknown values are turned on by default and any other value than false will enable it. */
    const forbidUnknownValues =
      this.validatorOptions?.forbidUnknownValues === undefined || this.validatorOptions.forbidUnknownValues !== false;

    const targetMetadatas = this.metadataStorage.getTargetValidationMetadatas(
      object.constructor,
      targetSchema,
      always,
      strictGroups,
      groups
    );
    const groupedMetadatas = this.metadataStorage.groupByPropertyName(targetMetadatas);

    if (this.validatorOptions && forbidUnknownValues && !targetMetadatas.length) {
      const validationError = new ValidationError();

      if (
        !this.validatorOptions ||
        !this.validatorOptions.validationError ||
        this.validatorOptions.validationError.target === undefined ||
        this.validatorOptions.validationError.target === true
      )
        validationError.target = object;

      validationError.value = undefined;
      validationError.property = undefined;
      validationError.children = [];
      validationError.constraints = { unknownValue: 'an unknown value was passed to the validate function' };

      validationErrors.push(validationError);

      return;
    }

    if (this.validatorOptions && this.validatorOptions.whitelist)
      this.whitelist(object, groupedMetadatas, validationErrors);

    // General validation
    Object.keys(groupedMetadatas).forEach(propertyName => {
      const value = (object as any)[propertyName];
      const definedMetadatas = groupedMetadatas[propertyName].filter(
        metadata => metadata.type === ValidationTypes.IS_DEFINED
      );
      const metadatas = groupedMetadatas[propertyName].filter(
        metadata => metadata.type !== ValidationTypes.IS_DEFINED && metadata.type !== ValidationTypes.WHITELIST
      );

      if (
        value instanceof Promise &&
        metadatas.find(metadata => metadata.type === ValidationTypes.PROMISE_VALIDATION)
      ) {
        this.awaitingPromises.push(
          value.then(resolvedValue => {
            this.performValidations(object, resolvedValue, propertyName, definedMetadatas, metadatas, validationErrors);
          })
        );
      } else {
        this.performValidations(object, value, propertyName, definedMetadatas, metadatas, validationErrors);
      }
    });
  }

  whitelist(
    object: any,
    groupedMetadatas: { [propertyName: string]: ValidationMetadata[] },
    validationErrors: ValidationError[]
  ): void {
    const notAllowedProperties: string[] = [];

    Object.keys(object).forEach(propertyName => {
      // does this property have no metadata?
      if (!groupedMetadatas[propertyName] || groupedMetadatas[propertyName].length === 0)
        notAllowedProperties.push(propertyName);
    });

    if (notAllowedProperties.length > 0) {
      if (this.validatorOptions && this.validatorOptions.forbidNonWhitelisted) {
        // throw errors
        notAllowedProperties.forEach(property => {
          const validationError: ValidationError = this.generateValidationError(object, object[property], property);
          validationError.constraints = { [ValidationTypes.WHITELIST]: `property ${property} should not exist` };
          validationError.children = undefined;
          validationErrors.push(validationError);
        });
      } else {
        // strip non allowed properties
        notAllowedProperties.forEach(property => delete object[property]);
      }
    }
  }

  stripEmptyErrors(errors: ValidationError[]): ValidationError[] {
    return errors.filter(error => {
      if (error.children) {
        error.children = this.stripEmptyErrors(error.children);
      }

      if (Object.keys(error.constraints).length === 0) {
        if (error.children.length === 0) {
          return false;
        } else {
          delete error.constraints;
        }
      }

      return true;
    });
  }

  // -------------------------------------------------------------------------
  // Private Methods
  // -------------------------------------------------------------------------

  private performValidations(
    object: any,
    value: any,
    propertyName: string,
    definedMetadatas: ValidationMetadata[],
    metadatas: ValidationMetadata[],
    validationErrors: ValidationError[]
  ): void {
    const customValidationMetadatas = metadatas.filter(metadata => metadata.type === ValidationTypes.CUSTOM_VALIDATION);
    const nestedValidationMetadatas = metadatas.filter(metadata => metadata.type === ValidationTypes.NESTED_VALIDATION);
    const conditionalValidationMetadatas = metadatas.filter(
      metadata => metadata.type === ValidationTypes.CONDITIONAL_VALIDATION
    );

    const validationError = this.generateValidationError(object, value, propertyName);
    validationErrors.push(validationError);

    const canValidate = this.conditionalValidations(object, value, conditionalValidationMetadatas);
    if (!canValidate) {
      return;
    }

    // handle IS_DEFINED validation type the special way - it should work no matter skipUndefinedProperties/skipMissingProperties is set or not
    this.customValidations(object, value, definedMetadatas, validationError);
    this.mapContexts(object, value, definedMetadatas, validationError);

    if (value === undefined && this.validatorOptions && this.validatorOptions.skipUndefinedProperties === true) {
      return;
    }

    if (value === null && this.validatorOptions && this.validatorOptions.skipNullProperties === true) {
      return;
    }

    if (
      (value === null || value === undefined) &&
      this.validatorOptions &&
      this.validatorOptions.skipMissingProperties === true
    ) {
      return;
    }

    this.customValidations(object, value, customValidationMetadatas, validationError);
    this.nestedValidations(value, nestedValidationMetadatas, validationError);

    this.mapContexts(object, value, metadatas, validationError);
    this.mapContexts(object, value, customValidationMetadatas, validationError);
  }

  private generateValidationError(object: object, value: any, propertyName: string): ValidationError {
    const validationError = new ValidationError();

    if (
      !this.validatorOptions ||
      !this.validatorOptions.validationError ||
      this.validatorOptions.validationError.target === undefined ||
      this.validatorOptions.validationError.target === true
    )
      validationError.target = object;

    if (
      !this.validatorOptions ||
      !this.validatorOptions.validationError ||
      this.validatorOptions.validationError.value === undefined ||
      this.validatorOptions.validationError.value === true
    )
      validationError.value = value;

    validationError.property = propertyName;
    validationError.children = [];
    validationError.constraints = {};

    return validationError;
  }

  private conditionalValidations(object: object, value: any, metadatas: ValidationMetadata[]): ValidationMetadata[] {
    return metadatas
      .map(metadata => metadata.constraints[0](object, value))
      .reduce((resultA, resultB) => resultA && resultB, true);
  }

  private customValidations(object: object, value: any, metadatas: ValidationMetadata[], error: ValidationError): void {
    metadatas.forEach(metadata => {
      this.metadataStorage.getTargetValidatorConstraints(metadata.constraintCls).forEach(customConstraintMetadata => {
        if (customConstraintMetadata.async && this.ignoreAsyncValidations) return;
        if (
          this.validatorOptions &&
          this.validatorOptions.stopAtFirstError &&
          Object.keys(error.constraints || {}).length > 0
        )
          return;

        const validationArguments: ValidationArguments = {
          targetName: object.constructor ? (object.constructor as any).name : undefined,
          property: metadata.propertyName,
          object: object,
          value: value,
          constraints: metadata.constraints,
        };

        if (!metadata.each || !(Array.isArray(value) || value instanceof Set || value instanceof Map)) {
          const validatedValue = customConstraintMetadata.instance.validate(value, validationArguments);
          if (isPromise(validatedValue)) {
            const promise = validatedValue.then(isValid => {
              if (!isValid) {
                const [type, message] = this.createValidationError(object, value, metadata, customConstraintMetadata);
                error.constraints[type] = message;
                if (metadata.context) {
                  if (!error.contexts) {
                    error.contexts = {};
                  }
                  error.contexts[type] = Object.assign(error.contexts[type] || {}, metadata.context);
                }
              }
            });
            this.awaitingPromises.push(promise);
          } else {
            if (!validatedValue) {
              const [type, message] = this.createValidationError(object, value, metadata, customConstraintMetadata);
              error.constraints[type] = message;
            }
          }

          return;
        }

        // convert set and map into array
        const arrayValue = convertToArray(value);
        // Validation needs to be applied to each array item
        const validatedSubValues = arrayValue.map((subValue: any) =>
          customConstraintMetadata.instance.validate(subValue, validationArguments)
        );
        const validationIsAsync = validatedSubValues.some((validatedSubValue: boolean | Promise<boolean>) =>
          isPromise(validatedSubValue)
        );

        if (validationIsAsync) {
          // Wrap plain values (if any) in promises, so that all are async
          const asyncValidatedSubValues = validatedSubValues.map((validatedSubValue: boolean | Promise<boolean>) =>
            isPromise(validatedSubValue) ? validatedSubValue : Promise.resolve(validatedSubValue)
          );
          const asyncValidationIsFinishedPromise = Promise.all(asyncValidatedSubValues).then(
            (flatValidatedValues: boolean[]) => {
              const validationResult = flatValidatedValues.every((isValid: boolean) => isValid);
              if (!validationResult) {
                const [type, message] = this.createValidationError(object, value, metadata, customConstraintMetadata);
                error.constraints[type] = message;
                if (metadata.context) {
                  if (!error.contexts) {
                    error.contexts = {};
                  }
                  error.contexts[type] = Object.assign(error.contexts[type] || {}, metadata.context);
                }
              }
            }
          );

          this.awaitingPromises.push(asyncValidationIsFinishedPromise);

          return;
        }

        const validationResult = validatedSubValues.every((isValid: boolean) => isValid);
        if (!validationResult) {
          const [type, message] = this.createValidationError(object, value, metadata, customConstraintMetadata);
          error.constraints[type] = message;
        }
      });
    });
  }

  private nestedValidations(value: any, metadatas: ValidationMetadata[], error: ValidationError): void {
    if (value === void 0) {
      return;
    }

    metadatas.forEach(metadata => {
      if (metadata.type !== ValidationTypes.NESTED_VALIDATION && metadata.type !== ValidationTypes.PROMISE_VALIDATION) {
        return;
      } else if (
        this.validatorOptions &&
        this.validatorOptions.stopAtFirstError &&
        Object.keys(error.constraints || {}).length > 0
      ) {
        return;
      }

      if (Array.isArray(value) || value instanceof Set || value instanceof Map) {
        // Treats Set as an array - as index of Set value is value itself and it is common case to have Object as value
        const arrayLikeValue = value instanceof Set ? Array.from(value) : value;
        arrayLikeValue.forEach((subValue: any, index: any) => {
          this.performValidations(value, subValue, index.toString(), [], metadatas, error.children);
        });
      } else if (value instanceof Object) {
        const targetSchema = typeof metadata.target === 'string' ? metadata.target : metadata.target.name;
        this.execute(value, targetSchema, error.children);
      } else {
        const [type, message] = this.createValidationError(metadata.target as object, value, metadata);
        error.constraints[type] = message;
      }
    });
  }

  private mapContexts(object: object, value: any, metadatas: ValidationMetadata[], error: ValidationError): void {
    return metadatas.forEach(metadata => {
      if (metadata.context) {
        let customConstraint;
        if (metadata.type === ValidationTypes.CUSTOM_VALIDATION) {
          const customConstraints = this.metadataStorage.getTargetValidatorConstraints(metadata.constraintCls);
          customConstraint = customConstraints[0];
        }

        const type = this.getConstraintType(metadata, customConstraint);

        if (error.constraints[type]) {
          if (!error.contexts) {
            error.contexts = {};
          }

          error.contexts[type] = Object.assign(error.contexts[type] || {}, metadata.context);
        }
      }
    });
  }

  private createValidationError(
    object: object,
    value: any,
    metadata: ValidationMetadata,
    customValidatorMetadata?: ConstraintMetadata
  ): [string, string] {
    const targetName = object.constructor ? (object.constructor as any).name : undefined;
    const type = this.getConstraintType(metadata, customValidatorMetadata);
    const validationArguments: ValidationArguments = {
      targetName: targetName,
      property: metadata.propertyName,
      object: object,
      value: value,
      constraints: metadata.constraints,
    };

    let message = metadata.message || '';
    if (
      !metadata.message &&
      (!this.validatorOptions || (this.validatorOptions && !this.validatorOptions.dismissDefaultMessages))
    ) {
      if (customValidatorMetadata && customValidatorMetadata.instance.defaultMessage instanceof Function) {
        message = customValidatorMetadata.instance.defaultMessage(validationArguments);
      }
    }

    const messageString = ValidationUtils.replaceMessageSpecialTokens(message, validationArguments);
    return [type, messageString];
  }

  private getConstraintType(metadata: ValidationMetadata, customValidatorMetadata?: ConstraintMetadata): string {
    const type = customValidatorMetadata && customValidatorMetadata.name ? customValidatorMetadata.name : metadata.type;
    return type;
  }
}