import React, { useEffect, useMemo, useState } from 'react';

import { ipcChannels } from '../../shared/ipc/contracts';
import {
  DEFAULT_SESSION_TIMER_DURATION_MS,
  formatSessionTimerMs,
  getSessionTimerRemainingMs,
  parseSessionTimerDurationInput,
} from '../../shared/types/sessionTimer';
import { useEditorI18n } from '../editor/i18n/EditorI18nContext';
import { getDndApi } from '../shared/dndApi';
import { useSessionTimerState } from '../shared/sessionTimer/useSessionTimerState';
import { Button, Input } from '../shared/ui/controls';

import styles from './TimerApp.module.css';

const PRESETS_MS = [60_000, 5 * 60_000, 10 * 60_000] as const;

function durationInputFromMs(ms: number): string {
  return formatSessionTimerMs(ms);
}

export function TimerApp() {
  const { t } = useEditorI18n();
  const api = getDndApi();
  const [state, timerApi] = useSessionTimerState();
  const [now, setNow] = useState(() => Date.now());
  const [durationDraft, setDurationDraft] = useState(durationInputFromMs(DEFAULT_SESSION_TIMER_DURATION_MS));

  useEffect(() => {
    if (!state || state.running) return;
    setDurationDraft(durationInputFromMs(state.durationMs));
  }, [state]);

  useEffect(() => {
    if (!state?.running) return;
    const id = window.setInterval(() => setNow(Date.now()), 200);
    return () => window.clearInterval(id);
  }, [state?.running]);

  useEffect(() => {
    const onKey = (e: KeyboardEvent) => {
      if (e.key === 'Escape') {
        void api.invoke(ipcChannels.windows.closeTimer, {});
      }
    };
    window.addEventListener('keydown', onKey);
    return () => window.removeEventListener('keydown', onKey);
  }, [api]);

  const remainingMs = useMemo(() => {
    if (!state) return DEFAULT_SESSION_TIMER_DURATION_MS;
    return getSessionTimerRemainingMs(state, now);
  }, [now, state]);

  useEffect(() => {
    if (!state?.running) return;
    if (remainingMs > 0) return;
    void timerApi.dispatch({ kind: 'pause' });
  }, [remainingMs, state?.running, timerApi]);

  if (!state) {
    return <div className={styles.page} data-testid="timer-app" />;
  }

  const applyDurationDraft = async () => {
    const parsed = parseSessionTimerDurationInput(durationDraft);
    if (parsed == null) {
      setDurationDraft(durationInputFromMs(state.durationMs));
      return;
    }
    await timerApi.dispatch({ kind: 'setDuration', durationMs: parsed });
  };

  return (
    <div className={styles.page} data-testid="timer-app">
      <div className={styles.clock} data-expired={remainingMs <= 0 ? '1' : '0'}>
        {formatSessionTimerMs(remainingMs)}
      </div>

      <div className={styles.presets}>
        {PRESETS_MS.map((ms) => (
          <Button
            key={ms}
            variant="ghost"
            disabled={state.running}
            onClick={() => {
              setDurationDraft(durationInputFromMs(ms));
              void timerApi.dispatch({ kind: 'setDuration', durationMs: ms });
            }}
          >
            {formatSessionTimerMs(ms)}
          </Button>
        ))}
      </div>

      <label className={styles.field}>
        <span className={styles.fieldLabel}>{t('sessionTimer.duration')}</span>
        <Input
          value={durationDraft}
          onChange={setDurationDraft}
          onBlur={() => void applyDurationDraft()}
          onKeyDown={(e) => {
            if (e.key === 'Enter') {
              e.preventDefault();
              void applyDurationDraft();
            }
          }}
        />
      </label>

      <div className={styles.actions}>
        {state.running ? (
          <Button variant="primary" onClick={() => void timerApi.dispatch({ kind: 'pause' })}>
            {t('sessionTimer.pause')}
          </Button>
        ) : (
          <Button variant="primary" onClick={() => void timerApi.dispatch({ kind: 'start' })}>
            {t('sessionTimer.start')}
          </Button>
        )}
        <Button variant="ghost" onClick={() => void timerApi.dispatch({ kind: 'reset' })}>
          {t('sessionTimer.reset')}
        </Button>
      </div>

      <label className={styles.checkRow}>
        <input
          type="checkbox"
          checked={state.visibleToPlayers}
          onChange={(e) =>
            void timerApi.dispatch({ kind: 'setVisibleToPlayers', visible: e.target.checked })
          }
        />
        <span>{t('sessionTimer.showToPlayers')}</span>
      </label>

      <div className={styles.hint}>{t('sessionTimer.positionHint')}</div>
    </div>
  );
}