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

function PredefinedPuzzlePage() {
  // For puzzle index and puzzle data
  const [puzzleIndex, setPuzzleIndex] = useState(0);
  const [puzzleText, setPuzzleText] = useState("");
  const [expectedSolution, setExpectedSolution] = useState(null);

  // sysContent can be editted, default using Example.txt
  const [sysContent, setSysContent] = useState("");

  // Interaction results
  const [generatedCode, setGeneratedCode] = useState("");
  const [executionSuccess, setExecutionSuccess] = useState(null);
  const [attempts, setAttempts] = useState(0);
  const [isSolving, setIsSolving] = useState(false);
  const [problematicConstraints, setProblematicConstraints] = useState("");

  // UI state
  const [currentStep, setCurrentStep] = useState(1);
  const [expandedSections, setExpandedSections] = useState({
    puzzle: true,
    sysContent: false,
    result: false
  });

  // Frontend fetch sysContent in default
  useEffect(() => {
    fetch(`/default_sys_content`)
      .then(res => res.json())
      .then(data => {
        if(data.success) {
          setSysContent(data.sysContent);
        }
      })
      .catch(e => console.error(e));
  }, []);

  // When puzzleIndex changing，auto get puzzle
  useEffect(() => {
    fetch(`/get_puzzle?index=${puzzleIndex}`)
      .then(res => res.json())
      .then(data => {
        if(data.success) {
          setPuzzleText(data.puzzle);
          setExpectedSolution(data.expected_solution);
        } else {
          console.error("Failed to fetch puzzle", data.error);
          setPuzzleText("");
          setExpectedSolution(null);
        }
      })
      .catch(e => console.error(e));
  }, [puzzleIndex]);

  const handleSolve = () => {
    if(!puzzleText || !expectedSolution) {
      alert("puzzle or expectedSolution incomplete");
      return;
    }
    const payload = {
      index: puzzleIndex,
      puzzle: puzzleText,
      expected_solution: expectedSolution,
      sys_content: sysContent,
      problematic_constraints: problematicConstraints
    };

    setIsSolving(true);
    setCurrentStep(3);
    setExpandedSections({...expandedSections, result: true});

    fetch(`/solve`, {
      method: "POST",
      headers: { "Content-Type": "application/json" },
      body: JSON.stringify(payload)
    })
    .then(res => res.json())
    .then(data => {
      if(!data.success) {
        alert("Backend error: " + data.error);
        return;
      }
      const result = data.result;
      setGeneratedCode(result.generatedCode || "");
      setExecutionSuccess(result.success);
      setAttempts(result.attempts || 0);
      setProblematicConstraints(result.problematicConstraints || "");
    })
    .catch(e => console.error(e))
    .finally(() => {
      setIsSolving(false);
    });
  };

  const toggleSection = (section) => {
    setExpandedSections({
      ...expandedSections,
      [section]: !expandedSections[section]
    });
  };

  const nextStep = () => {
    if (currentStep < 3) {
      setCurrentStep(currentStep + 1);
      if (currentStep === 1) {
        setExpandedSections({puzzle: false, sysContent: true, result: false});
      } else if (currentStep === 2) {
        setExpandedSections({puzzle: false, sysContent: false, result: true});
      }
    }
  };

  const prevStep = () => {
    if (currentStep > 1) {
      setCurrentStep(currentStep - 1);
      if (currentStep === 2) {
        setExpandedSections({puzzle: true, sysContent: false, result: false});
      } else if (currentStep === 3) {
        setExpandedSections({puzzle: false, sysContent: true, result: false});
      }
    }
  };

  return (
    <>
      {/* Progress Steps */}
      <div className="progress-container">
        <div className="progress-steps">
          <div className={`step ${currentStep >= 1 ? 'active' : ''}`}>
            <div className="step-number">1</div>
            <div className="step-label">Select Puzzle</div>
          </div>
          <div className={`step ${currentStep >= 2 ? 'active' : ''}`}>
            <div className="step-number">2</div>
            <div className="step-label">Configure System</div>
          </div>
          <div className={`step ${currentStep >= 3 ? 'active' : ''}`}>
            <div className="step-number">3</div>
            <div className="step-label">Solve & Results</div>
          </div>
        </div>
      </div>

      <main className="main-content">
        {/* Step 1: Puzzle Selection */}
        <section className={`content-section ${expandedSections.puzzle ? 'expanded' : 'collapsed'}`}>
          <div className="section-header" onClick={() => toggleSection('puzzle')}>
            <h2>📋 Puzzle Selection</h2>
            <span className="toggle-icon">{expandedSections.puzzle ? '▼' : '▶'}</span>
          </div>
          
          {expandedSections.puzzle && (
            <div className="section-content">
              <div className="puzzle-selector">
                <label htmlFor="puzzle-index">Choose puzzle index (0 - 999):</label>
                <div className="input-group">
                  <input
                    id="puzzle-index"
                    type="number"
                    value={puzzleIndex}
                    onChange={(e) => setPuzzleIndex(Number(e.target.value))}
                    min={0}
                    max={999}
                    className="number-input"
                  />
                  <button 
                    onClick={() => setPuzzleIndex(puzzleIndex)} 
                    className="btn btn-secondary"
                  >
                    Load Puzzle
                  </button>
                </div>
              </div>

              <div className="puzzle-display">
                <div className="puzzle-text">
                  <h3>📄 Puzzle Text</h3>
                  <div className="text-display">
                    {puzzleText || "Loading puzzle..."}
                  </div>
                </div>

                <div className="expected-solution">
                  <h3>🎯 Expected Solution</h3>
                  <div className="json-display">
                    {expectedSolution ? (
                      <pre>{JSON.stringify(expectedSolution, null, 2)}</pre>
                    ) : (
                      "Loading solution..."
                    )}
                  </div>
                </div>
              </div>
            </div>
          )}
        </section>

        {/* Step 2: System Configuration */}
        <section className={`content-section ${expandedSections.sysContent ? 'expanded' : 'collapsed'}`}>
          <div className="section-header" onClick={() => toggleSection('sysContent')}>
            <h2>⚙️ System Configuration</h2>
            <span className="toggle-icon">{expandedSections.sysContent ? '▼' : '▶'}</span>
          </div>
          
          {expandedSections.sysContent && (
            <div className="section-content">
              <div className="sys-content-editor">
                <h3>📝 System Content</h3>
                <p className="description">
                  Edit the system prompt that will guide the AI in solving the puzzle:
                </p>
                <textarea
                  value={sysContent}
                  onChange={(e) => setSysContent(e.target.value)}
                  className="sys-content-textarea"
                  placeholder="Enter system content..."
                />
              </div>
            </div>
          )}
        </section>

        {/* Step 3: Solve & Results */}
        <section className={`content-section ${expandedSections.result ? 'expanded' : 'collapsed'}`}>
          <div className="section-header" onClick={() => toggleSection('result')}>
            <h2>🚀 Solve & Results</h2>
            <span className="toggle-icon">{expandedSections.result ? '▼' : '▶'}</span>
          </div>
          
          {expandedSections.result && (
            <div className="section-content">
              <div className="solve-section">
                <button 
                  onClick={handleSolve} 
                  disabled={isSolving || !puzzleText || !expectedSolution}
                  className={`btn btn-primary solve-btn ${isSolving ? 'loading' : ''}`}
                >
                  {isSolving ? '🔄 Solving...' : '🧠 Solve Puzzle with AI'}
                </button>
              </div>

              <div className="results-section">
                <div className="result-summary">
                  <div className="result-item">
                    <span className="result-label">Status:</span>
                    <span className={`result-value ${executionSuccess === true ? 'success' : executionSuccess === false ? 'error' : 'pending'}`}>
                      {executionSuccess === null ? "⏳ Pending" : executionSuccess ? "✅ Success" : "❌ Failed"}
                    </span>
                  </div>
                  <div className="result-item">
                    <span className="result-label">Attempts:</span>
                    <span className="result-value">{attempts}</span>
                  </div>
                </div>

                {problematicConstraints && (
                  <div className="issues-section">
                    <h3>⚠️ Issues & Analysis</h3>
                    <div className="issues-display">
                      <pre>{problematicConstraints}</pre>
                    </div>
                  </div>
                )}

                {generatedCode && (
                  <div className="code-section">
                    <h3>💻 Generated Code</h3>
                    <div className="code-display">
                      <pre><code>{generatedCode}</code></pre>
                    </div>
                  </div>
                )}
              </div>
            </div>
          )}
        </section>
      </main>

      {/* Navigation */}
      <nav className="navigation">
        <button 
          onClick={prevStep} 
          disabled={currentStep <= 1}
          className="btn btn-outline"
        >
          ← Previous
        </button>
        <span className="step-indicator">
          Step {currentStep} of 3
        </span>
        <button 
          onClick={nextStep} 
          disabled={currentStep >= 3}
          className="btn btn-outline"
        >
          Next →
        </button>
      </nav>
    </>
  );
}

export default PredefinedPuzzlePage;