// Copyright: © 2026 TWWIM UG. All rights reserved. (www.twwim.com)
/**
 * Plugin-settings form validation.
 *
 * Produces machine-readable codes; UI maps them to i18n keys (+ optional
 * variables) so messages stay in sync between EN and DE.
 *
 * @layer Presentation
 */

import { PHRASE_LIST_CONSTRAINTS } from '../components/PhraseListEditor';
import { DOCK_OPTIONS, type FormState, type TFunction } from './constants';

export type ValidationError =
  | { code: 'errWelcomeDelay' }
  | { code: 'errWelcomeHold' }
  | { code: 'errIdleMin' }
  | { code: 'errIdleMax' }
  | { code: 'errIdleMinGtMax' }
  | { code: 'errIdleDisplay' }
  | { code: 'errPhraseEmpty' }
  | { code: 'errPhraseTooLong'; max: number }
  | { code: 'errTheme' }
  | { code: 'errDock' }
  | { code: 'errUiCacheTtl' }
  | { code: 'errScenario' }
  | { code: 'errDeploymentTarget' };

export interface ValidationResult {
  errors: ValidationError[];
  isValid: boolean;
}

const THEME_REGEX = /^[a-z0-9-]+$/i;
const DEPLOYMENT_TARGET_OPTIONS = ['shopify'] as const;

function isIntInRange(n: number, min: number, max: number): boolean {
  return Number.isInteger(n) && n >= min && n <= max;
}

function validateTimings(form: FormState): ValidationError[] {
  const errors: ValidationError[] = [];
  const { welcome, idle } = form.attention;
  if (!isIntInRange(welcome.delaySeconds, 0, 60))
    errors.push({ code: 'errWelcomeDelay' });
  if (!isIntInRange(welcome.holdSeconds, 1, 60))
    errors.push({ code: 'errWelcomeHold' });
  if (!isIntInRange(idle.minIntervalSeconds, 5, 3600))
    errors.push({ code: 'errIdleMin' });
  if (!isIntInRange(idle.maxIntervalSeconds, 5, 3600))
    errors.push({ code: 'errIdleMax' });
  if (idle.minIntervalSeconds > idle.maxIntervalSeconds)
    errors.push({ code: 'errIdleMinGtMax' });
  if (!isIntInRange(idle.displaySeconds, 1, 60))
    errors.push({ code: 'errIdleDisplay' });
  return errors;
}

function validatePhrases(form: FormState): ValidationError[] {
  const errors: ValidationError[] = [];
  const allPhrases = [
    ...Object.values(form.attention.welcome.messages).flat(),
    ...Object.values(form.attention.idle.messages).flat(),
  ];
  if (allPhrases.some((p) => p.trim().length === 0))
    errors.push({ code: 'errPhraseEmpty' });
  if (allPhrases.some((p) => p.length > PHRASE_LIST_CONSTRAINTS.MAX_CHARS))
    errors.push({
      code: 'errPhraseTooLong',
      max: PHRASE_LIST_CONSTRAINTS.MAX_CHARS,
    });
  return errors;
}

export function validateSnippet(form: FormState): ValidationError[] {
  const errors: ValidationError[] = [];
  const { snippet } = form;

  const theme = snippet.theme;
  if (
    typeof theme !== 'string' ||
    theme.length < 1 ||
    theme.length > 50 ||
    !THEME_REGEX.test(theme)
  ) {
    errors.push({ code: 'errTheme' });
  }

  if (!DOCK_OPTIONS.includes(snippet.dock)) {
    errors.push({ code: 'errDock' });
  }

  if (!isIntInRange(snippet.uiCacheTTL, 0, 86400)) {
    errors.push({ code: 'errUiCacheTtl' });
  }

  if (snippet.scenario !== null) {
    if (
      typeof snippet.scenario !== 'string' ||
      snippet.scenario.length < 1 ||
      snippet.scenario.length > 50
    ) {
      errors.push({ code: 'errScenario' });
    }
  }

  if (
    snippet.deploymentTarget !== null &&
    !DEPLOYMENT_TARGET_OPTIONS.includes(
      snippet.deploymentTarget as (typeof DEPLOYMENT_TARGET_OPTIONS)[number],
    )
  ) {
    errors.push({ code: 'errDeploymentTarget' });
  }

  return errors;
}

export function validate(form: FormState): ValidationResult {
  const errors = [
    ...validateTimings(form),
    ...validatePhrases(form),
    ...validateSnippet(form),
  ];
  return { errors, isValid: errors.length === 0 };
}

export function renderError(t: TFunction, err: ValidationError): string {
  if (err.code === 'errPhraseTooLong') {
    return t('tenants.pluginSettings.errPhraseTooLong', { max: err.max });
  }
  return t(`tenants.pluginSettings.${err.code}`);
}