import React, { useState } from 'react';
import { Sparkles, Clock, Terminal, ChevronDown, ChevronUp, AlertCircle, Brain, Cpu } from 'lucide-react';

// Render LaTeX and text mixed together
function RenderLatex({ text }) {
  if (!text) return null;

  // Split text by $$ (block math) first, then by $ (inline math)
  const blockParts = text.split(/(\$\$.*?\$\$)/g);
  
  return (
    <>
      {blockParts.map((bp, bpIdx) => {
        if (bp.startsWith('$$') && bp.endsWith('$$')) {
          const formula = bp.slice(2, -2);
          try {
            if (window.katex) {
              const html = window.katex.renderToString(formula, { displayMode: true, throwOnError: false });
              return <div key={bpIdx} dangerouslySetInnerHTML={{ __html: html }} style={{ margin: '0.8rem 0' }} />;
            }
          } catch (e) {
            console.error(e);
          }
          return <div key={bpIdx} style={{ margin: '0.8rem 0', fontFamily: 'monospace' }}>{bp}</div>;
        }

        // Inline math split
        const inlineParts = bp.split(/(\$.*?\$)/g);
        return (
          <React.Fragment key={bpIdx}>
            {inlineParts.map((ip, ipIdx) => {
              if (ip.startsWith('$') && ip.endsWith('$')) {
                const formula = ip.slice(1, -1);
                if (formula.trim()) {
                  try {
                    if (window.katex) {
                      const html = window.katex.renderToString(formula, { displayMode: false, throwOnError: false });
                      return <span key={ipIdx} dangerouslySetInnerHTML={{ __html: html }} />;
                    }
                  } catch (e) {
                    console.error(e);
                  }
                }
                return <span key={ipIdx}>{ip}</span>;
              }
              
              return <span key={ipIdx} dangerouslySetInnerHTML={{ __html: formatInline(ip) }} />;
            })}
          </React.Fragment>
        );
      })}
    </>
  );
}

// A simple local Markdown parser that converts basic markdown elements to safe HTML
function SafeMarkdown({ content }) {
  if (!content) return null;

  const parts = content.split(/(```[\s\S]*?```)/g);

  return (
    <div className="chat-response-content">
      {parts.map((part, index) => {
        if (part.startsWith('```') && part.endsWith('```')) {
          const code = part.slice(3, -3).replace(/^\w+\n/, ''); 
          return (
            <pre key={index}>
              <code>{code}</code>
            </pre>
          );
        }

        const formatted = part
          .split('\n\n')
          .map((para, paraIdx) => {
            if (!para.trim()) return null;

            // Handle bullet points
            if (para.trim().startsWith('- ') || para.trim().startsWith('* ')) {
              const items = para.split(/\n\s*[-*]\s+/);
              return (
                <ul key={paraIdx} style={{ marginBottom: '1rem', paddingLeft: '1.5rem' }}>
                  {items.map((item, itemIdx) => {
                    let cleanItem = item;
                    if (itemIdx === 0) {
                      cleanItem = item.replace(/^\s*[-*]\s+/, '');
                    }
                    if (!cleanItem.trim()) return null;
                    return (
                      <li key={itemIdx}>
                        <RenderLatex text={cleanItem} />
                      </li>
                    );
                  })}
                </ul>
              );
            }

            return (
              <p key={paraIdx}>
                <RenderLatex text={para} />
              </p>
            );
          });

        return <React.Fragment key={index}>{formatted}</React.Fragment>;
      })}
    </div>
  );
}

// Format bold (**), italics (*), and inline code (`)
function formatInline(text) {
  return text
    .replace(/\*\*([^*]+)\*\*/g, '<strong>$1</strong>')
    .replace(/\*([^*]+)\*/g, '<em>$1</em>')
    .replace(/`([^`]+)`/g, '<code>$1</code>')
    .replace(/\n/g, '<br />');
}

export default function ChatWindow({ 
  history = [], 
  loading, 
  error,
  onSubmitFollowUp
}) {
  const [openInspectors, setOpenInspectors] = useState({});

  const toggleInspector = (idx) => {
    setOpenInspectors(prev => ({
      ...prev,
      [idx]: !prev[idx]
    }));
  };

  // Render loading skeleton
  if (loading && history.length === 0) {
    return (
      <div className="single-column-chat">
        <div className="column-card">
          <div className="column-header">
            <div className="column-title-wrapper">
              <h2><Cpu size={18} color="var(--primary)" /> Socratic Tutor</h2>
              <p>Analyzing Sentiment...</p>
            </div>
            <div className="latency-badge">--s</div>
          </div>
          <div className="column-body">
            <div className="skeleton-box" />
            <div className="skeleton-wrapper">
              <div className="skeleton-line long" />
              <div className="skeleton-line medium" />
              <div className="skeleton-line long" />
              <div className="skeleton-line short" />
            </div>
          </div>
        </div>
      </div>
    );
  }

  // Render error message
  if (error) {
    return (
      <div style={{
        background: 'rgba(244, 63, 94, 0.1)',
        border: '1px solid var(--color-frustrated)',
        borderRadius: '12px',
        padding: '1.5rem',
        display: 'flex',
        alignItems: 'flex-start',
        gap: '1rem',
        color: 'var(--color-frustrated)',
        marginBottom: '1rem'
      }}>
        <AlertCircle size={24} style={{ flexShrink: 0 }} />
        <div>
          <h3 style={{ fontWeight: 700, marginBottom: '0.3rem' }}>Analysis Failed</h3>
          <p style={{ color: 'var(--text-primary)', fontSize: '0.95rem' }}>{error}</p>
        </div>
      </div>
    );
  }

  // Render empty state
  if (history.length === 0) {
    return (
      <div className="empty-state">
        <Brain size={48} className="empty-state-icon" style={{ color: 'var(--primary)' }} />
        <h3>Welcome to Socratic Sentiment Tutor</h3>
        <p>Ask any question about math, science, or programming. The Socratic tutor will detect your mood and guide you towards the answers without giving them away directly.</p>
      </div>
    );
  }

  return (
    <div className="single-column-chat" style={{ display: 'flex', flexDirection: 'column', gap: '1rem', width: '100%' }}>
      
      {/* Scrollable Conversation Thread */}
      <div style={{ display: 'flex', flexDirection: 'column', gap: '1.2rem', width: '100%' }}>
        {history.map((msg, idx) => {
          const isUser = msg.role === 'user';
          
          if (isUser) {
            return (
              <div
                key={idx}
                style={{
                  alignSelf: 'flex-end',
                  background: 'linear-gradient(135deg, var(--primary-dark), var(--primary))',
                  border: '1px solid rgba(255, 255, 255, 0.1)',
                  borderRadius: '16px 16px 4px 16px',
                  padding: '0.9rem 1.25rem',
                  maxWidth: '85%',
                  boxShadow: '0 4px 12px rgba(99, 102, 241, 0.15)',
                }}
              >
                <span style={{
                  fontSize: '0.65rem',
                  fontWeight: 800,
                  textTransform: 'uppercase',
                  color: 'rgba(255, 255, 255, 0.7)',
                  display: 'block',
                  marginBottom: '0.25rem',
                  letterSpacing: '0.5px'
                }}>
                  You
                </span>
                <p style={{ margin: 0, fontSize: '0.975rem', lineHeight: 1.5, color: '#fff' }}>
                  {msg.content}
                </p>
              </div>
            );
          }

          // Assistant / Tutor Bubble
          return (
            <div
              key={idx}
              className="column-card"
              style={{
                alignSelf: 'flex-start',
                width: '100%',
                maxWidth: '90%',
                margin: 0,
                boxShadow: '0 8px 24px rgba(0, 0, 0, 0.12)',
              }}
            >
              {/* Card Header with sentiment state & metrics */}
              <div className="column-header" style={{ padding: '0.8rem 1.25rem', borderBottom: '1px solid var(--border-color)' }}>
                <div className="column-title-wrapper">
                  <h3 style={{ display: 'flex', alignItems: 'center', gap: '0.4rem', fontSize: '0.95rem', fontWeight: 700, margin: 0 }}>
                    <Sparkles size={15} color="var(--secondary)" /> 
                    Socratic Tutor
                  </h3>
                </div>
                
                {msg.sentiment && (
                  <div className="column-meta" style={{ gap: '0.6rem' }}>
                    <div className="latency-badge" title="Response Latency & Tokens">
                      <Clock size={12} style={{ display: 'inline', marginRight: '4px', verticalAlign: 'middle' }} />
                      {msg.latency}s
                      {msg.tokens !== undefined && (
                        <>
                          <span style={{ margin: '0 4px', opacity: 0.3 }}>|</span>
                          <span>{msg.tokens}t</span>
                        </>
                      )}
                      {msg.cost !== undefined && (
                        <>
                          <span style={{ margin: '0 4px', opacity: 0.3 }}>|</span>
                          <span>${msg.cost.toFixed(5)}</span>
                        </>
                      )}
                    </div>
                  </div>
                )}
              </div>

              {/* Chat Bubble Body */}
              <div className="column-body" style={{ padding: '1.25rem', gap: '1rem' }}>
                <SafeMarkdown content={msg.content} />
              </div>

              {/* Prompt Context Inspector Toggle */}
              {msg.prompt_context && (
                <div className="inspector-section" style={{ borderTop: '1px solid var(--border-color)', borderRadius: '0 0 12px 12px' }}>
                  <div 
                    className="inspector-header" 
                    onClick={() => toggleInspector(idx)}
                    style={{ padding: '0.6rem 1.25rem', fontSize: '0.8rem', background: 'rgba(255,255,255,0.01)' }}
                  >
                    <span style={{ display: 'flex', alignItems: 'center', gap: '0.4rem' }}>
                      <Terminal size={12} />
                      View Socratic Context Inspector
                    </span>
                    {openInspectors[idx] ? <ChevronUp size={14} /> : <ChevronDown size={14} />}
                  </div>
                  {openInspectors[idx] && (
                    <div className="inspector-body" style={{ fontSize: '0.8rem', whiteSpace: 'pre-wrap', borderTop: '1px solid var(--border-color)', display: 'flex', flexDirection: 'column', gap: '0.75rem' }}>
                      <div style={{ display: 'flex', alignItems: 'center', gap: '0.5rem' }}>
                        <strong>Detected Student Sentiment:</strong>
                        <span className={`sentiment-badge ${msg.sentiment}`} style={{ fontSize: '0.75rem', padding: '0.2rem 0.5rem', borderRadius: '4px' }}>
                          {msg.sentiment.replace(/_/g, ' ')}
                        </span>
                      </div>
                      <div>
                        <strong>Prompt Context:</strong>
                        <div style={{ marginTop: '0.25rem', opacity: 0.8 }}>
                          {msg.prompt_context}
                        </div>
                      </div>
                    </div>
                  )}
                </div>
              )}
            </div>
          );
        })}

        {/* Loading Bubble when generating */}
        {loading && (
          <div
            className="column-card"
            style={{
              alignSelf: 'flex-start',
              width: '100%',
              maxWidth: '90%',
              margin: 0,
              opacity: 0.7
            }}
          >
            <div className="column-header" style={{ padding: '0.8rem 1.25rem' }}>
              <div className="column-title-wrapper">
                <h3 style={{ display: 'flex', alignItems: 'center', gap: '0.4rem', fontSize: '0.95rem', fontWeight: 700, margin: 0 }}>
                  <Cpu size={15} color="var(--primary)" />
                  Socratic Tutor thinking...
                </h3>
              </div>
            </div>
            <div className="column-body" style={{ padding: '1.25rem' }}>
              <div className="skeleton-wrapper">
                <div className="skeleton-line long" />
                <div className="skeleton-line medium" />
                <div className="skeleton-line short" />
              </div>
            </div>
          </div>
        )}
      </div>

      {/* Follow-up / Reply Area */}
      {history.length > 0 && !loading && (
        <div 
          className="query-card" 
          style={{ 
            marginTop: '1.5rem', 
            background: 'rgba(99, 102, 241, 0.03)', 
            borderColor: 'var(--primary-glow)',
            boxShadow: 'none',
            padding: '1.25rem'
          }}
        >
          <div style={{ display: 'flex', flexDirection: 'column', gap: '0.3rem', marginBottom: '0.8rem' }}>
            <h3 style={{ fontSize: '0.95rem', fontWeight: 800, display: 'flex', alignItems: 'center', gap: '0.4rem', margin: 0 }}>
              <Brain size={16} color="var(--primary)" />
              Socratic Dialogue
            </h3>
            <p style={{ fontSize: '0.8rem', color: 'var(--text-secondary)', margin: 0 }}>
              Reply to the Socratic tutor's guide question to continue exploring the concept.
            </p>
          </div>
          <form 
            onSubmit={(e) => {
              e.preventDefault();
              const inputEl = e.target.elements.followUpText;
              const val = inputEl.value.trim();
              if (val) {
                onSubmitFollowUp(val);
                inputEl.value = '';
              }
            }}
            className="query-input-wrapper"
          >
            <textarea
              name="followUpText"
              placeholder="Provide your Socratic response..."
              className="query-textarea"
              style={{ minHeight: '60px' }}
              onKeyDown={(e) => {
                if (e.key === 'Enter' && !e.shiftKey) {
                  e.preventDefault();
                  e.target.form.requestSubmit();
                }
              }}
            />
            <button 
              type="submit" 
              className="send-button"
              style={{ padding: '0.6rem 1.25rem' }}
            >
              Reply
            </button>
          </form>
        </div>
      )}
    </div>
  );
}