<script>
  const courseRelationships = {
    'ENGL 101': {
      prereqs: [],
      unlocks: ['ENGL 102']
    },
    'ENGL 102': {
      prereqs: ['ENGL 101'],
      unlocks: []
    },
    'MATH 111': {
      prereqs: [],
      unlocks: ['MATH 112', 'PHYS 121']
    },
    'MATH 112': {
      prereqs: ['MATH 111'],
      unlocks: ['MATH 243', 'PHYS 122', 'MATH 232', 'MATH 211', 'MATH 234']
    },
    'CHEM 115': {
      prereqs: [],
      unlocks: []
    },
    'GENS 101': {
      prereqs: [],
      unlocks: []
    },
    'GENS 100': {
      prereqs: [],
      unlocks: ['GENS 300']
    },
    'PHYS 121': {
      prereqs: ['MATH 111'],
      unlocks: ['PHYS 122']
    },
    'COSC 114': {
      prereqs: [],
      unlocks: ['COSC 202', 'CCEN 210', 'COSC 230', 'CCEN 350']
    },
    'HUMA/BUSS XXX': {
      prereqs: [],
      unlocks: []
    },
    'CCEN 210': {
      prereqs: ['COSC 114'],
      unlocks: ['CCEN 350', 'CCEN 316', 'CCEN 356']
    },
    'MATH 211': {
      prereqs: ['MATH 112'],
      unlocks: []
    },
    'PHYS 122': {
      prereqs: ['PHYS 121', 'MATH 112'],
      unlocks: ['ELEN 221']
    },
    'COSC 202': {
      prereqs: ['COSC 114'],
      unlocks: []
    },
    'HUMA 107/108': {
      prereqs: [],
      unlocks: []
    },
    'MATH 232': {
      prereqs: ['COSC 114'],
      unlocks: ['CCEN 302', 'ELEN 221']
    },
    'COSC 230': {
      prereqs: ['COSC 114'],
      unlocks: ['COSC 336', 'COSC 310']
    },
    'MATH 243': {
      prereqs: ['MATH 112'],
      unlocks: []
    },
    'ELEN 221': {
      prereqs: ['MATH 232', 'PHYS 122'],
      unlocks: ['CCEN 302']
    },
    'COSC 336': {
      prereqs: ['COSC 230'],
      unlocks: []
    },
    'CCEN 302': {
      prereqs: ['ELEN 221', 'MATH 232'],
      unlocks: []
    },
    'CCEN 350': {
      prereqs: ['CCEN 210', 'COSC 114'],
      unlocks: ['COSC 354']
    },
    'ELEN 312': {
      prereqs: ['ELEN 221'],
      unlocks: ['ECCE 497']
    },
    'MATH 234': {
      prereqs: ['MATH 112'],
      unlocks: []
    },
    'COSC 310': {
      prereqs: ['COSC 230'],
      unlocks: []
    },
    'CCEN 316': {
      prereqs: ['CCEN 210'],
      unlocks: ['CCEN 450', 'ECCE 497']
    },
    'BUSS XXX': {
      prereqs: [],
      unlocks: []
    },
    'GENS 300': {
      prereqs: ['GENS 100'],
      unlocks: ['GENS 400', 'CCEN 399']
    },
    'COSC 354': {
      prereqs: ['COSC 230'],
      unlocks: []
    },
    'COSC 340': {
      prereqs: ['COSC 354'],
      unlocks: []
    },
    'CCEN 356': {
      prereqs: ['CCEN 210'],
      unlocks: []
    },
    'CCEN 399': {
      prereqs: ['GENS 300'],
      unlocks: []
    },
    'CCEN 450': {
      prereqs: ['CCEN 316'],
      unlocks: []
    },
    'HUMA 105/106': {
      prereqs: [],
      unlocks: []
    },
    'Technical Elective': {
      prereqs: [],
      unlocks: []
    },
    'GENS 400': {
      prereqs: ['GENS 300'],
      unlocks: []
    },
    'BUSS 322': {
      prereqs: ['BUSS XXX'],
      unlocks: ['ECCE 497']
    },
    'ECCE 497': {
      prereqs: ['CCEN 316', 'ELEN 312'],
      unlocks: ['CCEN 498']
    },
    'CCEN 498': {
      prereqs: ['ECCE 497'],
      unlocks: []
    }
  };
  
  // courses
  const curriculum = {
    Freshman: {
      Fall: [
        { code: 'ENGL 101', name: 'Academic English I', credits: 3 },
        { code: 'MATH 111', name: 'Calculus I', credits: 4 },
        { code: 'CHEM 115', name: 'General Chemistry I', credits: 4 },
        { code: 'GENS 101', name: 'Grand Challenges', credits: 4 },
        { code: 'GENS 100', name: 'Academic Development & Success', credits: 1 }
      ],
      Spring: [
        { code: 'ENGL 102', name: 'Academic English II', credits: 3 },
        { code: 'MATH 112', name: 'Calculus II', credits: 4 },
        { code: 'PHYS 121', name: 'University Physics I', credits: 4 },
        { code: 'COSC 114', name: 'Introduction to Computing using Python', credits: 4 }
      ],
      Summer: [
      ]
    },
  
    Sophomore: {
      Fall: [
        { code: 'CCEN 210', name: 'Digital Logic Design', credits: 4 },
        { code: 'MATH 232', name: 'Engineering Mathematics', credits: 3 },
        { code: 'PHYS 122', name: 'University Physics II', credits: 4 },
        { code: 'COSC 202', name: 'Data Science and Artificial Intelligence', credits: 3 },
        { code: 'HUMA 107/108', name: 'Introduction to Arabic and Islamic Heritage / Arabic and Islamic Heritage', credits: 3 }
        
      ],
      Spring: [
        { code: 'MATH 211', name: 'Differential Equations and Linear Algebra', credits: 4 },
        { code: 'COSC 230', name: 'Object-Oriented Programming', credits: 4 },
        { code: 'MATH 243', name: 'Probability & Statistical Inference', credits: 3 },
        { code: 'ELEN 221', name: 'Electric Circuits I', credits: 4 }
      ],
      Summer: []
    },
  
    Junior: {
      Fall: [
        { code: 'COSC 336', name: 'Introduction to Software Engineering', credits: 3 },
        { code: 'CCEN 302', name: 'Signals and Communication Systems', credits: 3 },
        { code: 'CCEN 350', name: 'Computer Architecture and Organization', credits: 3 },
        { code: 'MATH 234', name: 'Discrete Mathematics', credits: 3 },
        { code: 'CCEN 316', name: 'Microprocessor Systems', credits: 4 },
        { code: 'GENS 300', name: 'Career Preparation', credits: 1 }
      ],
      Spring: [
        { code: 'COSC 354', name: 'Operating Systems', credits: 3 },
        { code: 'CCEN 356', name: 'Computer Networks', credits: 4 },
        { code: 'ELEN 312', name: 'Electronic Circuits & Devices', credits: 4 },
        { code: 'COSC 310', name: 'Data Structures', credits: 3 },
        { code: 'BUSS XXX', name: 'Business Elective', credits: 3 }
      ],
      Summer: [
        { code: 'CCEN 399', name: 'Computer Engineering Internship', credits: 1 }
      ]
    },
  
    Senior: {
      Fall: [
        { code: 'CCEN 450', name: 'Embedded Systems', credits: 3 },
        { code: 'Technical Elective', name: 'Technical Elective', credits: 3 },
        { code: 'Technical Elective', name: 'Technical Elective', credits: 3 },
        { code: 'BUSS 322', name: 'Fundamentals of Innovation and Entrepreneurship', credits: 3 },
        { code: 'GENS 400', name: 'Enhancing Employability and Job Readiness', credits: 1 },
        { code: 'ECCE 497', name: 'Senior Design Project I', credits: 3 }
      ],
      Spring: [
        { code: 'HUMA 105/106', name: 'UAE Studies', credits: 3 },
        { code: 'Technical Elective', name: 'Technical Elective', credits: 3 },
        { code: 'Technical Elective', name: 'Technical Elective', credits: 3 },
        { code: 'Technical Elective', name: 'Technical Elective', credits: 3 },
        { code: 'CCEN 498', name: 'Senior Design Project II', credits: 3 }
        
      ],
      Summer: [
        { code: 'CCEN 399', name: 'Computer Engineering Internship', credits: 1 }
      ]
    }
  };
  
  
  let hoveredCode = null;
  let clickedCode = null;
  
  function renderApp() {
    const app = document.getElementById('app');
    // Clear
    while (app.firstChild) {
      app.removeChild(app.firstChild);
    }
  
    const yearGrid = document.createElement('div');
    yearGrid.className = "year-grid";
    app.appendChild(yearGrid);
  
    // MOUSEMOVE => handle hover if not locked
    yearGrid.addEventListener('mousemove', e => {
      if (!clickedCode) {
        const card = e.target.closest('.course-card');
        if (card) {
          const code = card.getAttribute('data-code');
          if (code !== hoveredCode) {
            hoveredCode = code;
            renderApp();
          }
        } else if (hoveredCode) {
          hoveredCode = null;
          renderApp();
        }
      }
    });
  
    // CLICK to toggle highlight or clear if empty space
    yearGrid.addEventListener('click', e => {
      const card = e.target.closest('.course-card');
      if (card) {
        const code = card.getAttribute('data-code');
        if (clickedCode === code) {
          clickedCode = null;
          hoveredCode = null;
        } else {
          clickedCode = code;
        }
      } else {
        // empty space => clear
        clickedCode = null;
        hoveredCode = null;
      }
      renderApp();
    });
  
    // Build each year block
    Object.entries(curriculum).forEach(([yearName, terms]) => {
      const yearDiv = document.createElement('div');
      yearDiv.className = "year-block";
  
      const yearTitle = document.createElement('h2');
      yearTitle.className = "year-title";
      yearTitle.textContent = yearName;
      yearDiv.appendChild(yearTitle);
  
      // terms
      Object.entries(terms).forEach(([termName, courses]) => {
        const termDiv = document.createElement('div');
        termDiv.className = "term";
  
        const termTitle = document.createElement('h3');
        termTitle.className = "term-title";
        termTitle.textContent = termName;
        termDiv.appendChild(termTitle);
  
        const courseGrid = document.createElement('div');
        courseGrid.className = "course-grid";
  
        courses.forEach(course => {
          const cardDiv = document.createElement('div');
          cardDiv.className = "course-card";
          cardDiv.setAttribute('data-code', course.code);
  
          const isSelected = getSelectedCode() === course.code;
          const highlightClasses = buildHighlightClasses(course.code, isSelected);
          highlightClasses.forEach(c => cardDiv.classList.add(c));
  
          // content
          const codeDiv = document.createElement('div');
          codeDiv.className = "course-code";
          codeDiv.textContent = course.code;
  
          const nameDiv = document.createElement('div');
          nameDiv.className = "course-name";
          nameDiv.textContent = course.name;
  
          const creditsDiv = document.createElement('div');
          creditsDiv.className = "course-credits";
          creditsDiv.textContent = course.credits + "cr";
  
          cardDiv.appendChild(codeDiv);
          cardDiv.appendChild(nameDiv);
          cardDiv.appendChild(creditsDiv);
  
          courseGrid.appendChild(cardDiv);
        });
  
        termDiv.appendChild(courseGrid);
        yearDiv.appendChild(termDiv);
      });
  
      yearGrid.appendChild(yearDiv);
    });
  
    updateLegend();
  }
  
  function getSelectedCode() {
    return clickedCode || hoveredCode;
  }
  
  function buildHighlightClasses(courseCode, isSelected) {
    const classes = ["bg-white"];
    const sc = getSelectedCode();
    if (sc) {
      if (isSelected) {
        classes.push("bg-indigo-100", "ring-2-indigo");
      } else if (courseRelationships[sc]) {
        const { prereqs, unlocks } = courseRelationships[sc];
        if (prereqs.includes(courseCode)) {
          classes.push("bg-amber-50", "ring-2-amber");
        } else if (unlocks.includes(courseCode)) {
          classes.push("bg-emerald-50", "ring-2-emerald");
        }
      }
    }
    return classes;
  }
  
  function updateLegend() {
    const legend = document.getElementById('legend');
    const legendSelected = document.getElementById('legend-selected');
    const prereqCountSpan = document.getElementById('prereq-count');
    const unlockCountSpan = document.getElementById('unlock-count');
    const sc = getSelectedCode();
    
    if (sc && courseRelationships[sc]) { // Ensure the course exists in relationships
      const prereqCount = courseRelationships[sc].prereqs.length;
      const unlockCount = courseRelationships[sc].unlocks.length;
      
      legendSelected.textContent = `Selected: ${sc}`;
      prereqCountSpan.textContent = prereqCount;
      unlockCountSpan.textContent = unlockCount;
    } else {
      legendSelected.textContent = "Hover over any course";
      prereqCountSpan.textContent = '0';
      unlockCountSpan.textContent = '0';
    }
    
    // Show the legend
    legend.classList.remove('hidden');
  }
  
  // Initial
  renderApp();
</script>
