import { create } from 'zustand';
import type { SessionRow, QueueItem } from '@flashcard/shared';
import { sessionsApi } from '../api/sessions.js';

interface SessionState {
  session: SessionRow | null;
  current: QueueItem | null;
  done: boolean;
  showAnswer: boolean;
  shownAt: number | null;
  start: (input: { lessonId: number; maxCards: number | null; shuffle: boolean; direction: 'forward' | 'backward' | 'both' }) => Promise<void>;
  reveal: () => void;
  answer: (result: 'correct' | 'incorrect') => Promise<void>;
  end: () => Promise<void>;
  abandon: () => Promise<void>;
  reset: () => void;
}

export const useSession = create<SessionState>((set, get) => ({
  session: null, current: null, done: false, showAnswer: false, shownAt: null,

  start: async (input) => {
    const { session } = await sessionsApi.start(input);
    const nx = await sessionsApi.next(session.id);
    set({
      session,
      done: nx.done,
      current: nx.done ? null : nx.item,
      showAnswer: false,
      shownAt: Date.now(),
    });
  },

  reveal: () => set({ showAnswer: true }),

  answer: async (result) => {
    const s = get();
    if (!s.session || !s.current) return;
    const ttm = s.shownAt ? Date.now() - s.shownAt : null;
    await sessionsApi.attempt(s.session.id, {
      cardId: s.current.cardId, direction: s.current.direction, result, timeToAnswerMs: ttm,
    });
    const nx = await sessionsApi.next(s.session.id);
    if (nx.done) {
      set({ done: true, current: null, showAnswer: false });
    } else {
      set({ current: nx.item, showAnswer: false, shownAt: Date.now() });
    }
  },

  end: async () => {
    const s = get();
    if (!s.session) return;
    const finished = await sessionsApi.end(s.session.id);
    set({ session: finished });
  },

  abandon: async () => {
    const s = get();
    if (!s.session) return;
    await sessionsApi.abandon(s.session.id);
    set({ session: null, current: null, done: false, showAnswer: false });
  },

  reset: () => set({ session: null, current: null, done: false, showAnswer: false, shownAt: null }),
}));