(function(){
  // Safari-safe: no ?? and no mixed ?? with ||/&&
  var DATA = (window.PHI_DATA && typeof window.PHI_DATA === 'object')
    ? window.PHI_DATA
    : { nodes: [], links: [] };

  var svg = d3.select('#graph');
  var tooltip = d3.select('#tooltip');
  var sidebar = document.getElementById('sidebar-content');
  var searchInput = document.getElementById('search');

  var width  = svg.node().clientWidth  || 1200;
  var height = svg.node().clientHeight || 800;

  var minR = 6, maxR = 24, ellipseAspect = 1.6;
  var satDot = 4.6, spiralStepR = 8, spiralStepTheta = 0.48*Math.PI, spiralStartR = 52;

  function esc(s){return String(s||'').replace(/[&<>"']/g,function(c){return ({'&':'&amp;','<':'&lt;','>':'&gt;','"':'&quot;',"'":'&#039;'}[c]);});}
  function safeArray(x){return Array.isArray(x)?x:[];}
  function ageClass(d){
    var a = d && d.ageDays;
    if (a == null) return 'age-old';
    if (a <= 14)  return 'age-very-new';
    if (a <= 45)  return 'age-new';
    if (a <= 120) return 'age-mid';
    if (a <= 270) return 'age-old';
    return 'age-very-old';
  }

  svg.attr('viewBox', '0 0 ' + width + ' ' + height);
  var root = svg.append('g');
  var linkLayer = root.append('g').attr('class','links');
  var nodeLayer = root.append('g').attr('class','nodes');
  var satLayer  = root.append('g').attr('class','satellites');

  var zoom = d3.zoom().scaleExtent([0.35, 4]).on('zoom', function(ev){ root.attr('transform', ev.transform); });
  svg.call(zoom);

  // clear selection when clicking background
  svg.on('click', function(ev){
    if (ev.target === svg.node()){
      clearSatellites(); clearFocus(); sidebar.innerHTML = '';
    }
  });

  // Build graph
  var idToNode = new Map(DATA.nodes.map(function(n){ return [n.id, n]; }));
  var links = DATA.links.map(function(l){
    var s = idToNode.get(l.source) || l.source;
    var t = idToNode.get(l.target) || l.target;
    return { source:s, target:t };
  }).filter(function(l){ return l.source && l.target; });

  // degree as fallback for sizing
  var degree = new Map();
  links.forEach(function(l){
    degree.set(l.source.id, (degree.get(l.source.id)||0)+1);
    degree.set(l.target.id, (degree.get(l.target.id)||0)+1);
  });

  var centralities = DATA.nodes.map(function(n){
    return (typeof n.centrality === 'number') ? n.centrality : (degree.get(n.id)||0);
  });
  var cMin = d3.min(centralities); if (cMin == null) cMin = 0;
  var cMax = d3.max(centralities); if (cMax == null) cMax = 1;
  var rScale = d3.scaleSqrt().domain([ (cMin||0.0001), (cMax||1) ]).range([minR, maxR]);

  var sim = d3.forceSimulation(DATA.nodes)
    .force('link', d3.forceLink(links).id(function(d){return d.id;}).distance(75).strength(0.7))
    .force('charge', d3.forceManyBody().strength(-180))
    .force('center', d3.forceCenter(width/2, height/2))
    .force('collision', d3.forceCollide().radius(function(d){
      var c = (typeof d.centrality === 'number') ? d.centrality : (degree.get(d.id)||1);
      return rScale(c) * 1.2;
    }));

  var linkSel = linkLayer.selectAll('line')
    .data(links)
    .join('line')
    .attr('class','link')
    .attr('stroke','#b9c7dd')
    .attr('stroke-opacity', .28);

  var nodeSel = nodeLayer.selectAll('g.node')
    .data(DATA.nodes, function(d){ return d.id; })
    .join(function(enter){
      var g = enter.append('g').attr('class','node');

      g.append('ellipse')
        .attr('rx', function(d){ var c=(typeof d.centrality==='number')?d.centrality:(degree.get(d.id)||1); return rScale(c)*ellipseAspect; })
        .attr('ry', function(d){ var c=(typeof d.centrality==='number')?d.centrality:(degree.get(d.id)||1); return rScale(c); });

      g.append('text')
        .attr('x', function(d){ var c=(typeof d.centrality==='number')?d.centrality:(degree.get(d.id)||1); return rScale(c)*ellipseAspect + 4; })
        .attr('y', 4)
        .text(function(d){ return d.id; });

      g.on('mouseover', function(ev,d){ showTagTooltip(ev, d.id); })
       .on('mousemove', moveTooltip)
       .on('mouseout', hideTooltip)
       .on('click', function(ev,d){ ev.stopPropagation(); onTagClick(d.id); });

      return g;
    });

  sim.on('tick', function(){
    linkSel
      .attr('x1', function(d){return d.source.x;})
      .attr('y1', function(d){return d.source.y;})
      .attr('x2', function(d){return d.target.x;})
      .attr('y2', function(d){return d.target.y;});

    nodeSel.attr('transform', function(d){ return 'translate('+d.x+','+d.y+')'; });

    // keep satellites stuck to hosts
    satLayer.selectAll('g.satellite')
      .attr('transform', function(d){ return 'translate('+(d.host.x + d._xoff)+','+(d.host.y + d._yoff)+')'; });
  });

  // Tooltip
  function showTagTooltip(evt, tag){
    var desc = (DATA.tagDescriptions && DATA.tagDescriptions[tag]) ? DATA.tagDescriptions[tag] : '—';
    var n = idToNode.get(tag);
    var deg = degree.get(tag) || 0;
    var cent = (n && typeof n.centrality==='number') ? n.centrality.toFixed(2) : String(deg||0);
    tooltip.html(
      '<div style="font-weight:700; margin-bottom:4px">'+esc(tag)+'</div>'+
      '<div style="color:#97a3b6; margin-bottom:6px">degree '+deg+' • centrality '+cent+'</div>'+
      '<div style="white-space:pre-wrap; opacity:.92">'+esc(desc)+'</div>'+
      '<div style="margin-top:6px; font-size:12px; color:#97a3b6">Click to reveal pulse satellites</div>'
    ).style('display','block');
    moveTooltip(evt);
  }
  function moveTooltip(evt){
    var pad=12;
    tooltip.style('left',(evt.clientX+pad)+'px').style('top',(evt.clientY+pad)+'px');
  }
  function hideTooltip(){ tooltip.style('display','none'); }

  // Focus / dim
  function setFocus(keepIds){
    var keep = new Set(keepIds);
    nodeSel.classed('dim', function(d){ return !keep.has(d.id); });
    linkSel.classed('dim', function(d){ return !(keep.has(d.source.id) && keep.has(d.target.id)); });
  }
  function clearFocus(){ nodeSel.classed('dim', false); linkSel.classed('dim', false); }

  // Satellites (spiral)
  function clearSatellites(){ satLayer.selectAll('*').remove(); }
  function spiralOffsets(n){
    var out=[], i;
    for(i=0;i<n;i++){
      var r = spiralStartR + i*spiralStepR;
      var t = i*spiralStepTheta;
      out.push({_xoff:r*Math.cos(t), _yoff:r*Math.sin(t)});
    }
    return out;
  }

  function onTagClick(tagId){
    // dim: tag + immediate neighbors
    var neighbors = new Set([tagId]);
    links.forEach(function(l){
      if (l.source.id===tagId) neighbors.add(l.target.id);
      if (l.target.id===tagId) neighbors.add(l.source.id);
    });
    setFocus(neighbors);

    clearSatellites();

    var host = idToNode.get(tagId);
    if (!host) return;

    var pulsesObj = DATA.pulsesByTag || {};
    var pulses = safeArray(pulsesObj[tagId]);
    if (!pulses.length) return;

    var offs = spiralOffsets(pulses.length);
    var g = satLayer.selectAll('g.satellite')
      .data(pulses.map(function(p,i){
        var o=offs[i], copy={};
        for (var k in p){ copy[k]=p[k]; }
        copy.host = host; copy._xoff=o._xoff; copy._yoff=o._yoff;
        return copy;
      }), function(d){ return d.id || d.title || d.date || Math.random(); });

    var enter = g.enter().append('g').attr('class','satellite');

    enter.append('circle').attr('r', satDot).attr('class', function(d){ return ageClass(d); });
    enter.append('text').attr('y', -9).attr('text-anchor','middle').attr('font-size', 9).attr('fill', '#a3b3c7')
      .text(function(d){ return d.date ? d.date.slice(2,10) : ''; });

    enter.on('click', function(ev,d){ ev.stopPropagation(); showPulseDetails(d); });

    sim.alpha(0.5).restart();
  }

  // Sidebar
  function renderLinks(label, items){
    if (!items || !items.length) return '';
    var norm = items.map(function(u){
      if (typeof u === 'string') return {title:u, url:u};
      if (u && u.url) return {title:(u.title||u.url), url:u.url};
      return {title:(u && u.title) ? u.title : '', url:(u && u.url) ? u.url : ''};
    });
    var html = '<div style="margin-top:12px"><strong>'+esc(label)+'</strong><ul style="padding-left:18px; margin:6px 0 0 0">';
    norm.forEach(function(it){
      var title = it.title || it.url || '';
      var href  = it.url   || it.title || '#';
      html += '<li><a class="ellipsis" href="'+esc(href)+'" target="_blank" rel="noopener">'+esc(title)+'</a></li>';
    });
    html += '</ul></div>';
    return html;
  }
  function showPulseDetails(p){
    var when = p.date ? ' <span class="muted">('+esc(p.date)+')</span>' : '';
    var html = '<h2 style="margin:.2rem 0 .6rem 0; font-size:20px">'+esc(p.title || p.id || 'Pulse')+when+'</h2>';
    if (p.summary) html += '<div style="white-space:pre-wrap; margin:.3rem 0 1rem 0">'+esc(p.summary)+'</div>';
    html += renderLinks('Papers', p.papers);
    html += renderLinks('Podcasts', p.podcasts);
    sidebar.innerHTML = html;
  }

  // Search
  function applyFilter(q){
    var s = (q||'').trim().toLowerCase();
    if (!s){ clearFocus(); return; }
    var keep = new Set(DATA.nodes.filter(function(n){ return n.id.toLowerCase().includes(s); }).map(function(n){ return n.id; }));
    setFocus(keep);
  }
  if (searchInput) searchInput.addEventListener('input', function(e){ applyFilter(e.target.value); });

  // Start empty (no redundant helper text)
  sidebar.innerHTML = '';
})();