import React, { useState, useEffect, useCallback, useRef } from 'react';
import './App.css';
import SimulationControls from './components/SimulationControls';
import InboxPanel from './components/InboxPanel';
import ActionPanel from './components/ActionPanel';
import TimelinePanel from './components/TimelinePanel';
import ScorePanel from './components/ScorePanel';
import { resetEnv, stepEnv, getGrade } from './api';

const STEP_DELAY = 1400; // ~0.5× — realistic LLM response cadence

/* Greedy agent: match pending goals first, then highest priority*urgency */
function pickBestAction(obs) {
  if (!obs) return null;
  const unhandled = (obs.inbox || []).filter(e => !e.handled);
  if (!unhandled.length) return null;

  const pendingGoals = [...(obs.pending_goals || [])].sort((a, b) => b.priority - a.priority);
  for (const goal of pendingGoals) {
    const email = unhandled.find(e => e.id === goal.target_email_id);
    if (email) return { type: goal.required_action, email_id: email.id };
  }

  const best = [...unhandled].sort(
    (a, b) => b.priority * b.urgency - a.priority * a.urgency
  )[0];
  return { type: best.priority <= 2 ? 'delegate' : 'reply', email_id: best.id };
}

const sleep = ms => new Promise(r => setTimeout(r, ms));

export default function App() {
  const [obs, setObs]               = useState(null);
  const [history, setHistory]       = useState([]);
  const [selectedEmail, setSelectedEmail] = useState(null);
  const [taskId, setTaskId]         = useState('easy');
  const [score, setScore]           = useState(0);
  const [loading, setLoading]       = useState(false);
  const [error, setError]           = useState(null);
  const [isAutoRunning, setIsAutoRunning] = useState(false);
  const [rewardPopups, setRewardPopups] = useState([]);
  const [firstLoad, setFirstLoad]   = useState(true); // eslint-disable-line no-unused-vars

  const obsRef        = useRef(obs);
  const autoRunRef    = useRef(false);
  const popupIdRef    = useRef(0);

  useEffect(() => { obsRef.current = obs; }, [obs]);

  /* ── helpers ─────────────────────────────────────── */
  const showRewardPopup = (reward, subject) => {
    const id = ++popupIdRef.current;
    setRewardPopups(prev => [...prev.slice(-4), { id, reward, label: subject?.slice(0, 32) }]);
    setTimeout(() => setRewardPopups(prev => prev.filter(p => p.id !== id)), 2200);
  };

  /* ── reset ───────────────────────────────────────── */
  const handleReset = useCallback(async (task = taskId) => {
    autoRunRef.current = false;
    setIsAutoRunning(false);
    setLoading(true);
    setError(null);
    try {
      const fresh = await resetEnv(task);
      setObs(fresh);
      setHistory([]);
      setSelectedEmail(null);
      setScore(0);
      setRewardPopups([]);
      setFirstLoad(false);
    } catch {
      setError('Cannot connect to server.');
    } finally {
      setLoading(false);
    }
  }, [taskId]);

  const handleTaskChange = useCallback((t) => {
    setTaskId(t);
    handleReset(t);
  }, [handleReset]);

  useEffect(() => { handleReset('easy'); }, []); // eslint-disable-line

  /* ── single step (returns new obs or null) ────────── */
  const executeStep = useCallback(async (action, currentObs) => {
    try {
      const result = await stepEnv(action);
      const newObs = result.observation || result;
      if (!('done' in newObs)) newObs.done = result.done ?? false;

      const entry = {
        step:           currentObs.step ?? 0,
        time:           currentObs.time,
        action:         action.type,
        email_id:       action.email_id,
        email_subject:  result.info?.email_subject ?? action.email_id,
        email_priority: (currentObs.inbox || []).find(e => e.id === action.email_id)?.priority,
        reward:         result.reward ?? 0,
      };

      setObs(newObs);
      setHistory(h => [...h, entry]);
      showRewardPopup(result.reward, entry.email_subject);

      if (newObs.done) {
        const g = await getGrade().catch(() => null);
        if (g) setScore(g.score);
      }

      return newObs;
    } catch (e) {
      setError(e?.detail || 'Step failed.');
      return null;
    }
  }, []);

  /* ── manual action ────────────────────────────────── */
  const handleAction = useCallback(async (action) => {
    if (!obs || obs.done || loading || isAutoRunning) return;
    setLoading(true);
    setError(null);
    await executeStep(action, obs);
    setSelectedEmail(null);
    setLoading(false);
  }, [obs, loading, isAutoRunning, executeStep]);

  /* ── auto-run ─────────────────────────────────────── */
  const handleAutoRun = useCallback(async () => {
    if (autoRunRef.current) {
      autoRunRef.current = false;
      setIsAutoRunning(false);
      return;
    }

    autoRunRef.current = true;
    setIsAutoRunning(true);
    setError(null);


    let current = obsRef.current;

    // Auto-reset if episode already finished
    if (current?.done) {
      setLoading(true);
      try {
        const fresh = await resetEnv(taskId);
        setObs(fresh);
        setHistory([]);
        setScore(0);
        setRewardPopups([]);
        setSelectedEmail(null);
        obsRef.current = fresh;
        current = fresh;
        await sleep(600);
      } finally {
        setLoading(false);
      }
    }

    while (autoRunRef.current && current && !current.done) {
      const action = pickBestAction(current);
      if (!action) break;

      // Highlight email briefly — looks like AI "thinking"
      const email = (current.inbox || []).find(e => e.id === action.email_id);
      if (email) {
        setSelectedEmail(email);
        await sleep(STEP_DELAY * 0.4);
      }
      if (!autoRunRef.current) break;

      current = await executeStep(action, current);
      if (!current) break;

      setSelectedEmail(null);
      await sleep(STEP_DELAY * 0.6);
    }

    autoRunRef.current = false;
    setIsAutoRunning(false);
    setSelectedEmail(null);
  }, [taskId, executeStep]);

  /* ── render ───────────────────────────────────────── */
  if (!obs && !error) {
    return (
      <div className="loading-screen">
        <div className="loading-spinner" />
        <div className="loading-text">Initializing NovaTech AI — CEO Simulation</div>
      </div>
    );
  }

  const inbox    = obs?.inbox    || [];
  const goals    = obs?.goals    || [];
  const calendar = obs?.calendar || [];

  return (
    <div className={`app ${isAutoRunning ? 'app--autorunning' : ''}`}>

      {/* Floating reward popups */}
      <div className="reward-popups">
        {rewardPopups.map(p => (
          <div key={p.id} className={`reward-popup ${p.reward >= 0 ? 'positive' : 'negative'}`}>
            <span className="popup-reward">{p.reward >= 0 ? '+' : ''}{p.reward.toFixed(3)}</span>
            <span className="popup-label">{p.label}</span>
          </div>
        ))}
      </div>

      {error && (
        <div className="error-banner">
          ⚠ {error}
          <button onClick={() => setError(null)}>✕</button>
        </div>
      )}

      <SimulationControls
        taskId={taskId}
        currentTime={obs?.time || '9:00 AM'}
        currentStep={obs?.step || 0}
        maxSteps={obs?.max_steps || 6}
        totalReward={obs?.total_reward || 0}
        done={obs?.done || false}
        taskName={obs?.task_name || ''}
        onReset={() => handleReset(taskId)}
        onTaskChange={handleTaskChange}
        loading={loading}
        isAutoRunning={isAutoRunning}
        onAutoRun={handleAutoRun}
      />

      <div className="main-grid">
        <div className="left-col">
          <InboxPanel
            emails={inbox}
            selectedEmailId={selectedEmail?.id}
            onSelect={setSelectedEmail}
            isAutoRunning={isAutoRunning}
          />
        </div>

        <div className="center-col">
          <ActionPanel
            selectedEmail={selectedEmail}
            onAction={handleAction}
            done={obs?.done || false}
            loading={loading || isAutoRunning}
          />

          {calendar.length > 0 && (
            <div className="panel calendar-panel">
              <div className="panel-header">
                <span className="panel-title">📅 Calendar</span>
              </div>
              <div className="calendar-list">
                {[...calendar]
                  .sort((a, b) => a.time_slot - b.time_slot)
                  .map((ev, i) => (
                    <div key={i} className={`calendar-event ${ev.locked ? 'locked' : 'scheduled'}`}>
                      <span className="cal-time">Slot {ev.time_slot + 1}</span>
                      <span className="cal-title">{ev.title}</span>
                      {ev.locked && <span className="cal-locked">🔒</span>}
                    </div>
                  ))}
              </div>
            </div>
          )}
        </div>

        <div className="right-col">
          <ScorePanel
            goals={goals}
            score={score}
            done={obs?.done || false}
            totalReward={obs?.total_reward || 0}
            currentStep={obs?.step || 0}
            maxSteps={obs?.max_steps || 6}
          />
        </div>
      </div>

      <div className="bottom-row">
        <TimelinePanel history={history} />
      </div>
    </div>
  );
}