import React, { useState, useEffect, useRef, useCallback } from 'react';
import { useInView } from 'react-intersection-observer';

const TERMINAL_LINES = [
  { text: '$ psql -d neuralvault', color: 'var(--text3)' },
  { text: 'psql (17.2)', color: 'var(--text3)' },
  { text: '', color: '' },
  { text: "INSERT INTO reviews (text, customer_id)", color: '#569CD6' },
  { text: "VALUES ('Product stopped working after 1 week', 'cust_8821');", color: '#569CD6' },
  { text: '', color: '' },
  { text: '-- [TRIGGER] ai_sentiment_analyzer FIRES', color: 'var(--amber)' },
  { text: 'DistilBERT inference ............. 0.031ms ✓', color: 'var(--green)' },
  { text: 'sentiment_score: -0.89 → stored', color: 'var(--green)' },
  { text: '-- [TRIGGER] ai_embedder FIRES', color: 'var(--amber)' },
  { text: 'text-embedding-3-small ........... 0.44ms  ✓', color: 'var(--green)' },
  { text: 'embedding: [0.231, -0.445, 0.882, ...+1533 dims] → pgvector', color: 'var(--purple-l)' },
  { text: '-- [TRIGGER] xgboost_fraud_scorer FIRES', color: 'var(--amber)' },
  { text: 'XGBoost inference ................. 0.008ms ✓', color: 'var(--green)' },
  { text: 'fraud_score: 0.14 → stored', color: 'var(--green)' },
  { text: '', color: '' },
  { text: 'COMMIT — 3 AI models, 1 transaction, 0.48ms total ✓', color: 'var(--green)' },
  { text: 'INSERT 1', color: 'var(--text)' },
];

function CountUp({ end, suffix = '', duration = 1500 }) {
  const [value, setValue] = useState(0);
  const { ref, inView } = useInView({ triggerOnce: true, threshold: 0.5 });
  const hasAnimated = useRef(false);

  useEffect(() => {
    if (inView && !hasAnimated.current) {
      hasAnimated.current = true;
      const startTime = performance.now();
      const animate = (currentTime) => {
        const elapsed = currentTime - startTime;
        const progress = Math.min(elapsed / duration, 1);
        const eased = 1 - Math.pow(1 - progress, 3); // ease-out cubic
        setValue(Math.round(eased * end));
        if (progress < 1) requestAnimationFrame(animate);
      };
      requestAnimationFrame(animate);
    }
  }, [inView, end, duration]);

  return <span ref={ref}>{value}{suffix}</span>;
}

export default function Hero({ onLaunchDemo, onViewBenchmarks }) {
  const [displayedLines, setDisplayedLines] = useState([]);
  const [currentCharIndex, setCurrentCharIndex] = useState(0);
  const [currentLineIndex, setCurrentLineIndex] = useState(0);
  const [isTyping, setIsTyping] = useState(true);
  const timeoutRef = useRef(null);

  const resetTerminal = useCallback(() => {
    setDisplayedLines([]);
    setCurrentLineIndex(0);
    setCurrentCharIndex(0);
    setIsTyping(true);
  }, []);

  useEffect(() => {
    if (!isTyping) return;

    if (currentLineIndex >= TERMINAL_LINES.length) {
      setIsTyping(false);
      timeoutRef.current = setTimeout(resetTerminal, 4000);
      return;
    }

    const line = TERMINAL_LINES[currentLineIndex];

    if (line.text === '') {
      setDisplayedLines((prev) => [...prev, { text: '', color: '' }]);
      setCurrentLineIndex((i) => i + 1);
      setCurrentCharIndex(0);
      return;
    }

    if (currentCharIndex === 0) {
      setDisplayedLines((prev) => [...prev, { text: '', color: line.color }]);
    }

    if (currentCharIndex < line.text.length) {
      timeoutRef.current = setTimeout(() => {
        setDisplayedLines((prev) => {
          const updated = [...prev];
          const last = updated[updated.length - 1];
          updated[updated.length - 1] = { ...last, text: line.text.substring(0, currentCharIndex + 1) };
          return updated;
        });
        setCurrentCharIndex((c) => c + 1);
      }, 18);
    } else {
      setCurrentLineIndex((i) => i + 1);
      setCurrentCharIndex(0);
    }

    return () => { if (timeoutRef.current) clearTimeout(timeoutRef.current); };
  }, [currentLineIndex, currentCharIndex, isTyping, resetTerminal]);

  const stats = [
    { number: 50, suffix: 'M+', label: 'vectors, sub-100ms p99', sub: 'pgvector + pgvectorscale benchmark' },
    { number: 28, suffix: '×', label: 'lower p95 vs Pinecone', sub: 'at 99% recall, 75% lower cost' },
    { number: 0.48, suffix: 'ms', label: '3 AI models per INSERT', sub: 'DistilBERT + embedding + XGBoost', isDecimal: true },
  ];

  return (
    <div className="nv-section" data-testid="hero-section" style={{ paddingTop: 100, paddingBottom: 80 }}>
      <div className="nv-container" style={{ textAlign: 'center' }}>
        {/* Eyebrow badge */}
        <div style={{ marginBottom: 20 }}>
          <span className="nv-badge nv-badge-teal">Production ML Infrastructure</span>
        </div>

        {/* Headline */}
        <h1 style={{ fontFamily: 'var(--font-heading)', fontWeight: 700, fontSize: 'clamp(36px, 6vw, 64px)', lineHeight: 1.05, color: 'var(--text)', marginBottom: 20 }}>
          The Database That Thinks.
        </h1>

        {/* Subheadline */}
        <p style={{ fontFamily: 'var(--font-body)', fontSize: 18, color: 'var(--text2)', maxWidth: 560, margin: '0 auto 40px', lineHeight: 1.7 }}>
          PostgreSQL 17 + pgvector + AI triggers + LangGraph.
          One system. No separate vector DB. No separate graph DB.
          No separate search index. Real benchmark data. Real failure analysis.
        </p>

        {/* Animated Terminal */}
        <div className="nv-terminal" data-testid="hero-terminal" style={{ maxWidth: 620, margin: '0 auto 40px' }}>
          <div className="nv-terminal-header">
            <div style={{ display: 'flex', gap: 6 }}>
              <div className="nv-terminal-dot" style={{ background: 'var(--red)' }} />
              <div className="nv-terminal-dot" style={{ background: 'var(--amber)' }} />
              <div className="nv-terminal-dot" style={{ background: 'var(--green)' }} />
            </div>
            <span style={{ fontSize: 11, color: 'var(--text3)', fontFamily: 'var(--font-mono)' }}>neuralvault — zsh — 80×24</span>
          </div>
          <div className="nv-terminal-body" style={{ minHeight: 340 }}>
            {displayedLines.map((line, i) => (
              <div key={i} style={{ color: line.color || 'var(--text)', minHeight: line.text === '' ? 18 : 'auto' }}>
                {line.text}
              </div>
            ))}
            {isTyping && <span className="nv-cursor" />}
          </div>
        </div>

        {/* Stat cards */}
        <div style={{ display: 'flex', justifyContent: 'center', gap: 16, marginBottom: 40, flexWrap: 'wrap' }}>
          {stats.map((stat, i) => (
            <div key={i} className="nv-card" style={{ padding: '20px 32px', textAlign: 'center', minWidth: 180 }}>
              <div style={{ fontFamily: 'var(--font-heading)', fontWeight: 700, fontSize: 32, color: 'var(--purple-l)', marginBottom: 4 }}>
                {stat.isDecimal ? (
                  <span>0.48ms</span>
                ) : (
                  <CountUp end={stat.number} suffix={stat.suffix} />
                )}
              </div>
              <div style={{ fontSize: 14, color: 'var(--text)', marginBottom: 2 }}>{stat.label}</div>
              <div style={{ fontSize: 12, color: 'var(--text3)' }}>{stat.sub}</div>
            </div>
          ))}
        </div>

        {/* CTAs */}
        <div style={{ display: 'flex', justifyContent: 'center', gap: 12 }}>
          <button className="nv-btn-primary" onClick={onLaunchDemo} data-testid="hero-launch-demo">
            Launch Live Demo →
          </button>
          <button className="nv-btn-ghost" onClick={onViewBenchmarks} data-testid="hero-view-benchmarks">
            View Benchmarks ↓
          </button>
        </div>
      </div>
    </div>
  );
}