// Copyright: © 2026 TWWIM UG. All rights reserved. (www.twwim.com)
/**
 * usePluginSettingsForm
 *
 * Owns the local form state for PluginSettingsPage: seeding from the server
 * response, exposing setter, validating, and computing the dirty flag against
 * a baseline snapshot of the last server-loaded (or saved) state.
 *
 * @layer Presentation
 */

import {
  useEffect,
  useMemo,
  useRef,
  useState,
  type Dispatch,
  type SetStateAction,
} from 'react';
import type { PluginSettingsResponse } from '@archer/api-interface';
import { DEFAULT_FORM, type FormState } from '../lib/constants';
import { normaliseForWire } from '../lib/wire';
import { validate, type ValidationResult } from '../lib/validate';

interface UsePluginSettingsFormApi {
  form: FormState;
  setForm: Dispatch<SetStateAction<FormState>>;
  isDirty: boolean;
  validation: ValidationResult;
  /** Update the dirty baseline (e.g. after a successful save). */
  resetBaseline: (next: FormState) => void;
}

function seedFromServer(data: PluginSettingsResponse): FormState {
  return {
    visibility: { ...data.visibility },
    snippet: { ...data.snippet },
    attention: {
      enabled: data.attention.enabled,
      welcome: {
        ...data.attention.welcome,
        messages: {
          en: data.attention.welcome.messages.en ?? [],
          de: data.attention.welcome.messages.de ?? [],
          ...data.attention.welcome.messages,
        },
      },
      idle: {
        ...data.attention.idle,
        messages: {
          en: data.attention.idle.messages.en ?? [],
          de: data.attention.idle.messages.de ?? [],
          ...data.attention.idle.messages,
        },
      },
    },
  };
}

export function usePluginSettingsForm(
  data: PluginSettingsResponse | undefined,
): UsePluginSettingsFormApi {
  const [form, setForm] = useState<FormState>(DEFAULT_FORM);
  const baselineRef = useRef<string>(JSON.stringify(DEFAULT_FORM));

  useEffect(() => {
    if (!data) return;
    const seeded = seedFromServer(data);
    setForm(seeded);
    baselineRef.current = JSON.stringify(normaliseForWire(seeded));
  }, [data]);

  const validation = useMemo(() => validate(form), [form]);
  const isDirty = useMemo(
    () => JSON.stringify(normaliseForWire(form)) !== baselineRef.current,
    [form],
  );

  const resetBaseline = (next: FormState) => {
    baselineRef.current = JSON.stringify(normaliseForWire(next));
  };

  return { form, setForm, isDirty, validation, resetBaseline };
}