import { useCallback, useEffect, useState } from 'react';
import apiFetch from '@wordpress/api-fetch';

import type { AiAction } from '../lib/ai-runs';
import type { SeoEditorAi } from '../env';

/** What the AI buttons of the panel share: the right to press them, what ran, what is left. */
export interface AiGate {
  /** The user holds "AI with credits". */
  allowed: boolean;
  /** What the page is, as the questions name it: "post", "product". */
  kind: string;
  /** The actions that already spent credits on this page today. */
  ranToday: readonly string[];
  /** Credits left, once the site has asked Recomaze. */
  balance: number | null;
  /** An action went through: it counts as run today, and the balance is asked again. */
  onRan: (action: AiAction) => void;
}

/**
 * The AI gate of the page being edited. The balance is asked from the site
 * (the editors hold no Recomaze token) only when the user may spend it.
 *
 * @param ai      - What the server said at load.
 * @param kind    - What the page is: its type's label.
 * @param enabled - Whether the page offers any AI action at all.
 * @return The gate.
 */
export const useAiGate = (
  ai: SeoEditorAi | undefined,
  kind: string,
  enabled: boolean
): AiGate => {
  const allowed = ai?.allowed ?? false;
  const [ranToday, setRanToday] = useState<string[]>(ai?.ranToday ?? []);
  const [balance, setBalance] = useState<number | null>(null);
  const [asked, setAsked] = useState(0);

  useEffect(() => {
    if (!allowed || !enabled) return undefined;
    let current = true;
    apiFetch<{ balance: number | null }>({ path: '/recomaze/v1/seo/credits' })
      .then(answer => {
        if (current) setBalance(answer.balance ?? null);
      })
      .catch(() => {
        if (current) setBalance(null);
      });
    return () => {
      current = false;
    };
  }, [allowed, enabled, asked]);

  const onRan = useCallback((action: AiAction): void => {
    setRanToday(ran => (ran.includes(action) ? ran : [...ran, action]));
    setAsked(count => count + 1);
  }, []);

  return { allowed, kind: kind.toLowerCase(), ranToday, balance, onRan };
};