import type { FormulaRule, FormulaValidation } from '#/api/x/eln/formulas';

import { onBeforeUnmount, ref } from 'vue';

import { validateFormula } from '#/api/x/eln/formulas';

const VALIDATION_DEBOUNCE_MS = 400;

export function useFormulaValidation() {
  const error = ref('');
  const result = ref<FormulaValidation>();
  const loading = ref(false);
  let requestSequence = 0;
  let debounceTimer: ReturnType<typeof setTimeout> | undefined;
  let activeController: AbortController | undefined;
  let lastRule: FormulaRule | undefined;

  function clearScheduledValidation() {
    if (!debounceTimer) return;
    clearTimeout(debounceTimer);
    debounceTimer = undefined;
  }

  function schedule(rule: FormulaRule) {
    clearScheduledValidation();
    invalidateActiveValidation();
    debounceTimer = setTimeout(() => {
      debounceTimer = undefined;
      void validateNow(rule);
    }, VALIDATION_DEBOUNCE_MS);
  }

  function invalidateActiveValidation() {
    requestSequence++;
    activeController?.abort();
    activeController = undefined;
    error.value = '';
    loading.value = false;
    result.value = undefined;
  }

  async function validateNow(rule: FormulaRule): Promise<FormulaValidation | undefined> {
    clearScheduledValidation();
    lastRule = rule;
    activeController?.abort();
    const controller = new AbortController();
    activeController = controller;
    const sequence = ++requestSequence;
    loading.value = true;
    try {
      const response = await validateFormula(rule, controller.signal);
      if (sequence !== requestSequence) return undefined;
      result.value = response.data;
      error.value = '';
      return response.data;
    } catch (caughtError) {
      if (sequence !== requestSequence || controller.signal.aborted) return undefined;
      result.value = { diagnostics: [], latex: null };
      const message = caughtError instanceof Error ? caughtError.message : '公式校验请求失败';
      error.value = message || '公式校验请求失败';
      return undefined;
    } finally {
      if (sequence === requestSequence) loading.value = false;
    }
  }

  function cancel() {
    clearScheduledValidation();
    invalidateActiveValidation();
  }

  async function retry() {
    if (!lastRule) return undefined;
    return validateNow(lastRule);
  }

  onBeforeUnmount(cancel);

  return { cancel, error, loading, result, retry, schedule, validateNow };
}