import { AsyncValidatorFn, ValidatorFn } from '@angular/forms';
import { ValidationConfig, ValidationConfigItem, ValidationDefinitions } from './validation.model';
import { ValidationParam } from '../validation-config.model';

export type PluginValidatorType = `PLUGIN_${string}`;

interface BasePluginValidator {
  type: PluginValidatorType;
  defaultErrorMessage?: string;
}

export interface PluginValidator<VALIDATION_PARAM = ValidationParam> extends BasePluginValidator {
  validate: (validationParam?: VALIDATION_PARAM) => ValidatorFn;
}

export interface AsyncPluginValidator<VALIDATION_PARAM = ValidationParam>
  extends BasePluginValidator {
  validateAsync: (validationParam?: VALIDATION_PARAM) => AsyncValidatorFn;
}

export type PluginValidatorUnion = PluginValidator | AsyncPluginValidator;

let __pluginValidators: PluginValidatorUnion[];
export function __setPluginValidators(pluginValidators: PluginValidatorUnion[]) {
  if (__pluginValidators === undefined) {
    __pluginValidators = pluginValidators;
  }
}

function isAsyncValidator(validator: PluginValidatorUnion): validator is AsyncPluginValidator {
  return (validator as AsyncPluginValidator).validateAsync !== undefined;
}

function extractPluginValidationFactory(pv: PluginValidatorUnion) {
  return (item: ValidationConfigItem): ValidationConfig => ({
    validator: isAsyncValidator(pv)
      ? pv.validateAsync(item.validationParam)
      : pv.validate(item.validationParam),
    validatorName: pv.type,
    errorMessage: item.errorMessage || pv.defaultErrorMessage || '',
    async: isAsyncValidator(pv),
    validationParam: item.validationParam
  });
}

export function getPluginValidations(): ValidationDefinitions {
  return (__pluginValidators ?? []).reduce((acc, pv: PluginValidatorUnion) => {
    const pluginValidatorValidation = {
      // until TS supports regex in types, we cannot enforce that "type" field will be uppercase
      [pv.type.toUpperCase()]: extractPluginValidationFactory(pv)
    };

    return { ...acc, ...pluginValidatorValidation };
  }, {});
}