(function() {
  var C = window.ExplorerCommon;

  /* ── State ──────────────────────────────────────────────────────────────── */
  var state = {
    txSeries:       [],   // tx counts per recent block (oldest → newest)
    intervalSeries: [],   // block intervals in seconds
    supplyHistory:  [],   // cumulative tx count (proxy sparkline for supply)
    tpsSeries:      [],   // same as txSeries, used for strip micro-bar
  };

  /* ── Address / Block links ──────────────────────────────────────────────── */
  function linkAddress(value, label) {
    return '<a href="/address?address=' + encodeURIComponent(value) + '">' +
           C.esc(label || value) + '</a>';
  }

  function linkBlock(index) {
    return '<a href="#" class="block-link" data-index="' + C.esc(index) + '">#' +
           C.esc(index) + '</a>';
  }

  /* ── Micro chart helpers (strip sparklines) ─────────────────────────────── */

  function resizeMicro(canvas) {
    var dpr = window.devicePixelRatio || 1;
    var w = canvas.offsetWidth || 80;
    var h = canvas.offsetHeight || 36;
    canvas.width  = Math.max(1, Math.floor(w * dpr));
    canvas.height = Math.max(1, Math.floor(h * dpr));
    var ctx = canvas.getContext('2d');
    ctx.setTransform(dpr, 0, 0, dpr, 0, 0);
    return { ctx: ctx, w: w, h: h };
  }

  /** Tiny bar chart for the TPS strip cell */
  function drawMicroBars(canvas, values, color) {
    if (!canvas) return;
    var r = resizeMicro(canvas);
    var ctx = r.ctx; var w = r.w; var h = r.h;
    ctx.clearRect(0, 0, w, h);
    if (!values || !values.length) return;
    var n   = Math.min(values.length, 24);
    var vs  = values.slice(-n);
    var max = Math.max.apply(null, vs.concat([1]));
    var gap = 2;
    var bw  = Math.max(2, (w - gap * (n + 1)) / n);
    ctx.fillStyle = color;
    for (var i = 0; i < vs.length; i++) {
      var bh = Math.max(2, (vs[i] / max) * (h - 4));
      var x  = gap + i * (bw + gap);
      var y  = h - bh;
      ctx.fillRect(x, y, bw, bh);
    }
  }

  /** Tiny sparkline with gradient fill for the Supply strip cell */
  function drawSparkline(canvas, values, color) {
    if (!canvas) return;
    var r = resizeMicro(canvas);
    var ctx = r.ctx; var w = r.w; var h = r.h;
    ctx.clearRect(0, 0, w, h);
    if (!values || values.length < 2) {
      // draw a flat line when no data
      ctx.strokeStyle = color + '55';
      ctx.lineWidth = 1.5;
      ctx.beginPath();
      ctx.moveTo(2, h / 2);
      ctx.lineTo(w - 2, h / 2);
      ctx.stroke();
      return;
    }
    var n  = Math.min(values.length, 24);
    var vs = values.slice(-n);
    var mn = Math.min.apply(null, vs);
    var mx = Math.max.apply(null, vs);
    if (mn === mx) { mn = mn - 1; mx = mx + 1; }
    var span = mx - mn;
    var pad = 3;

    var pts = [];
    for (var i = 0; i < vs.length; i++) {
      var x = pad + (i / (vs.length - 1)) * (w - pad * 2);
      var y = (h - pad) - ((vs[i] - mn) / span) * (h - pad * 2);
      pts.push([x, y]);
    }

    // gradient fill
    var grad = ctx.createLinearGradient(0, 0, 0, h);
    grad.addColorStop(0, color + '40');
    grad.addColorStop(1, color + '05');
    ctx.beginPath();
    ctx.moveTo(pts[0][0], pts[0][1]);
    for (var j = 1; j < pts.length; j++) ctx.lineTo(pts[j][0], pts[j][1]);
    ctx.lineTo(pts[pts.length - 1][0], h);
    ctx.lineTo(pts[0][0], h);
    ctx.closePath();
    ctx.fillStyle = grad;
    ctx.fill();

    // line
    ctx.beginPath();
    ctx.moveTo(pts[0][0], pts[0][1]);
    for (var k = 1; k < pts.length; k++) ctx.lineTo(pts[k][0], pts[k][1]);
    ctx.strokeStyle = color;
    ctx.lineWidth = 1.5;
    ctx.stroke();
  }

  /* ── Full-size chart helpers (main chart panels) ────────────────────────── */

  function resizeCanvas(canvas) {
    var dpr = window.devicePixelRatio || 1;
    var w   = canvas.clientWidth;
    var h   = canvas.clientHeight;
    canvas.width  = Math.max(1, Math.floor(w * dpr));
    canvas.height = Math.max(1, Math.floor(h * dpr));
    var ctx = canvas.getContext('2d');
    ctx.setTransform(dpr, 0, 0, dpr, 0, 0);
    return ctx;
  }

  function chartLayout(width, height) {
    return {
      left:  44,
      right: 10,
      top:   10,
      bottom: 26,
      plotW: Math.max(10, width - 54),
      plotH: Math.max(10, height - 36)
    };
  }

  function fmtTick(v) {
    if (Math.abs(v) >= 1000) return String(Math.round(v));
    if (Math.abs(v) >= 10)   return (Math.round(v * 10) / 10).toFixed(1);
    return (Math.round(v * 100) / 100).toFixed(2);
  }

  function drawAxes(ctx, w, h, b, minY, maxY) {
    ctx.strokeStyle = '#334155';
    ctx.lineWidth = 1;
    ctx.beginPath(); ctx.moveTo(b.left, b.top);          ctx.lineTo(b.left, h - b.bottom); ctx.stroke();
    ctx.beginPath(); ctx.moveTo(b.left, h - b.bottom);   ctx.lineTo(w - b.right, h - b.bottom); ctx.stroke();
    ctx.fillStyle = '#94a3b8';
    ctx.font = '11px "Inter", sans-serif';
    for (var i = 0; i <= 4; i++) {
      var ratio = i / 4;
      var y     = b.top + b.plotH * ratio;
      var val   = maxY - (maxY - minY) * ratio;
      ctx.beginPath(); ctx.moveTo(b.left - 4, y); ctx.lineTo(b.left, y); ctx.stroke();
      ctx.fillText(fmtTick(val), 4, y + 3);
    }
    ctx.fillText('oldest', b.left,                     h - 8);
    ctx.fillText('newest', w - b.right - 36,            h - 8);
  }

  function drawBars(canvas, values, color) {
    if (!canvas) return;
    var ctx = resizeCanvas(canvas);
    var w = canvas.clientWidth; var h = canvas.clientHeight;
    ctx.clearRect(0, 0, w, h);
    var b = chartLayout(w, h);
    var max = Math.max.apply(null, (values || []).concat([1]));
    drawAxes(ctx, w, h, b, 0, max);
    if (!values || !values.length) return;
    var gap = 5;
    var bw  = Math.max(2, (b.plotW - gap * (values.length + 1)) / values.length);
    ctx.fillStyle = color;
    for (var i = 0; i < values.length; i++) {
      var bh = max > 0 ? (values[i] / max) * b.plotH : 2;
      var x  = b.left + gap + i * (bw + gap);
      var y  = b.top + b.plotH - bh;
      ctx.fillRect(x, y, bw, bh);
    }
  }

  function drawLine(canvas, values, color) {
    if (!canvas) return;
    var ctx = resizeCanvas(canvas);
    var w = canvas.clientWidth; var h = canvas.clientHeight;
    ctx.clearRect(0, 0, w, h);
    var b = chartLayout(w, h);
    if (!values || !values.length) { drawAxes(ctx, w, h, b, 0, 1); return; }
    var mn   = Math.min.apply(null, values);
    var mx   = Math.max.apply(null, values);
    if (mn === mx) { mn = mn - 1; mx = mx + 1; }
    drawAxes(ctx, w, h, b, mn, mx);
    var span = mx - mn;
    ctx.beginPath();
    for (var i = 0; i < values.length; i++) {
      var x = values.length === 1 ? b.left + b.plotW / 2
                                   : b.left + (i * b.plotW) / (values.length - 1);
      var ratio = span === 0 ? 0.5 : (values[i] - mn) / span;
      var y = b.top + b.plotH - ratio * b.plotH;
      if (i === 0) ctx.moveTo(x, y); else ctx.lineTo(x, y);
    }
    ctx.strokeStyle = color;
    ctx.lineWidth = 2;
    ctx.stroke();
  }

  function renderCharts() {
    drawBars(document.getElementById('txChart'),       state.txSeries,       '#2563eb');
    drawLine(document.getElementById('intervalChart'), state.intervalSeries,  '#0f766e');
  }

  function renderStripCharts() {
    drawSparkline(document.getElementById('supplyChart'), state.supplyHistory, '#7db5ff');
    drawMicroBars(document.getElementById('tpsChart'),    state.tpsSeries,     '#41c98a');
  }

  /* ── renderStats ────────────────────────────────────────────────────────── */

  function renderStats(net, blocks) {
    // Supply strip
    document.getElementById('sSupply').textContent = C.toTokenShort(net.total_supply);

    // Height + last block time
    document.getElementById('sHeight').textContent = Number(net.total_blocks || 0);
    if (blocks.length) {
      document.getElementById('sLastTime').textContent = C.timeAgo(blocks[0].time);
    } else {
      document.getElementById('sLastTime').textContent = '—';
    }

    if (!blocks.length) {
      document.getElementById('sTps').textContent       = '—';
      document.getElementById('sBlockTime').textContent = '—';
      document.getElementById('sLastBlock').textContent = '—';
      document.getElementById('sLastHash').textContent  = '—';
      document.getElementById('sTxs').textContent       = net.total_txs || 0;
      document.getElementById('sTransfers').textContent = 'Transfers: ' + (net.total_transfers || 0);
      document.getElementById('sRelayProofs').textContent = net.total_relay_proofs || 0;
      document.getElementById('sRelayCount').textContent  = (net.relay_count || 0) + ' relay nodes';
      document.getElementById('sValidators').textContent  = net.validator_count || 0;
      document.getElementById('sTpsWindow').textContent   = 'no data yet';
      state.txSeries = []; state.intervalSeries = []; state.supplyHistory = []; state.tpsSeries = [];
      renderCharts();
      renderStripCharts();
      return;
    }

    // Newest block
    var newest = blocks[0];
    document.getElementById('sLastBlock').textContent = '#' + newest.index;
    document.getElementById('sLastHash').textContent  = C.short(newest.hash, 24);

    // TPS over window
    var totalTx = 0;
    for (var i = 0; i < blocks.length; i++) totalTx += Number(blocks[i].tx_count || 0);
    var t0    = new Date(blocks[blocks.length - 1].time).getTime();
    var t1    = new Date(blocks[0].time).getTime();
    var secs  = Math.max(1, (t1 - t0) / 1000);
    var tps   = (totalTx / secs).toFixed(2);
    document.getElementById('sTps').textContent       = tps;
    document.getElementById('sTpsWindow').textContent = 'window: ~' + Math.round(secs) + ' sec';

    // Avg block interval
    var asc       = blocks.slice().reverse();
    var intervals = [];
    for (var j = 1; j < asc.length; j++) {
      var prev = new Date(asc[j - 1].time).getTime();
      var cur  = new Date(asc[j].time).getTime();
      intervals.push(Math.max(0, (cur - prev) / 1000));
    }
    var avg = 0;
    if (intervals.length) {
      var sum = 0;
      for (var k = 0; k < intervals.length; k++) sum += intervals[k];
      avg = sum / intervals.length;
    }
    document.getElementById('sBlockTime').textContent = avg ? avg.toFixed(2) + 's' : '—';

    // Card stats
    document.getElementById('sTxs').textContent        = net.total_txs || 0;
    document.getElementById('sTransfers').textContent  = 'Transfers: ' + (net.total_transfers || 0);
    document.getElementById('sRelayProofs').textContent = net.total_relay_proofs || 0;
    document.getElementById('sRelayCount').textContent  = (net.relay_count || 0) + ' relay nodes';
    document.getElementById('sValidators').textContent  = net.validator_count || 0;

    // Series for charts
    state.txSeries       = asc.map(function(b) { return Number(b.tx_count || 0); });
    state.intervalSeries = intervals;

    // Cumulative tx sparkline (supply proxy — shows chain activity growth)
    var cum = 0;
    state.supplyHistory = asc.map(function(b) { cum += Number(b.tx_count || 0); return cum; });
    state.tpsSeries     = state.txSeries;

    renderCharts();
    renderStripCharts();
  }

  /* ── renderRecentBlocks ─────────────────────────────────────────────────── */

  function renderRecentBlocks(blocks) {
    var tbody = document.getElementById('blocksBody');
    if (!tbody) return;
    if (!blocks || !blocks.length) {
      tbody.innerHTML = '<tr><td colspan="6" class="tbl-empty">No blocks yet.</td></tr>';
      return;
    }

    var rows = '';
    var shown = blocks.slice(0, 20);
    for (var i = 0; i < shown.length; i++) {
      var b   = shown[i];
      var val = b.validator || b.proposer || '';
      var valShort = val ? C.shortAddress(val) : '—';
      var valCell  = val
        ? '<a href="/address?address=' + encodeURIComponent(val) + '" title="' + C.esc(val) + '">' + C.esc(valShort) + '</a>'
        : '—';
      var fees = b.total_fees_ut != null ? C.toToken(Number(b.total_fees_ut)) : '—';
      rows +=
        '<tr>' +
        '<td>' + linkBlock(b.index) + '</td>' +
        '<td class="mono">' + C.esc(C.short(b.hash, 20)) + '</td>' +
        '<td class="mono">' + valCell + '</td>' +
        '<td>' + C.esc(b.tx_count || 0) + '</td>' +
        '<td>' + C.esc(fees) + '</td>' +
        '<td title="' + C.esc(C.fmtTime(b.time)) + '">' + C.esc(C.timeAgo(b.time)) + '</td>' +
        '</tr>';
    }
    tbody.innerHTML = rows;
    C.refreshIcons();
  }

  /* ── Block detail panel ─────────────────────────────────────────────────── */

  function showBlockPanel(data) {
    var panel = document.getElementById('blockDetailPanel');
    var raw   = document.getElementById('blockRaw');
    if (!panel || !raw) return;
    raw.textContent = JSON.stringify(data, null, 2);
    panel.style.display = '';
    panel.scrollIntoView({ behavior: 'smooth', block: 'nearest' });
  }

  function hideBlockPanel() {
    var panel = document.getElementById('blockDetailPanel');
    if (panel) panel.style.display = 'none';
  }

  async function loadBlock(index) {
    C.setStatus('Loading block #' + index + '…', 'warn');
    try {
      var b = await C.fetchJSON('/api/block/' + encodeURIComponent(index));
      showBlockPanel(b);
      C.setStatus('Block #' + index + ' loaded.', 'ok');
    } catch (e) {
      C.setStatus('Block load failed: ' + e.message, 'err');
    }
  }

  /* ── Main refresh ───────────────────────────────────────────────────────── */

  async function refreshDashboard() {
    try {
      var data = await Promise.all([
        C.fetchJSON('/api/netstats'),
        C.fetchJSON('/api/blocks?limit=36'),
      ]);
      renderStats(data[0] || {}, data[1] || []);
      renderRecentBlocks(data[1] || []);
      C.setStatus('Updated at ' + new Date().toLocaleTimeString(), 'ok');
      C.refreshIcons();
    } catch (e) {
      C.setStatus('Refresh failed: ' + e.message, 'err');
    }
  }

  /* ── Search ─────────────────────────────────────────────────────────────── */

  function handleSearch() {
    var raw = (document.getElementById('searchInput').value || '').trim();
    if (!raw) return;

    // Pure integer → block lookup
    if (/^\d+$/.test(raw)) {
      loadBlock(raw);
      return;
    }

    // Hex tx id (32 bytes = 64 chars)  → tx page
    if (/^[0-9a-fA-F]{64}$/.test(raw)) {
      C.navAddress(raw);
      return;
    }

    // Short hex (16 chars) or partial → try as tx id
    if (/^[0-9a-fA-F]{16,63}$/.test(raw)) {
      C.navTx(raw);
      return;
    }

    // DC address or any remaining string → address page
    C.navAddress(raw);
  }

  /* ── Event wiring ───────────────────────────────────────────────────────── */

  var searchBtn = document.getElementById('searchBtn');
  if (searchBtn) searchBtn.addEventListener('click', handleSearch);

  var openNodeBtn = document.getElementById('openNodeBtn');
  if (openNodeBtn) {
    openNodeBtn.addEventListener('click', function() {
      var raw = (document.getElementById('searchInput').value || '').trim();
      if (raw && C.isPubKey(raw)) {
        window.location.href = '/node?node=' + encodeURIComponent(raw);
      } else {
        window.location.href = '/validators';
      }
    });
  }

  var searchInput = document.getElementById('searchInput');
  if (searchInput) {
    searchInput.addEventListener('keydown', function(e) {
      if (e.key === 'Enter') handleSearch();
    });
  }

  // Block link clicks inside the blocks table
  document.addEventListener('click', function(e) {
    var t = e.target;
    if (!t) return;
    var link = t.closest ? t.closest('a.block-link') : null;
    if (link) {
      e.preventDefault();
      loadBlock(link.dataset.index);
      return;
    }
  });

  // Redraw on resize (both full-size and strip charts)
  window.addEventListener('resize', function() {
    renderCharts();
    renderStripCharts();
  });

  /* ── Boot ───────────────────────────────────────────────────────────────── */

  // Polling fallback — active when SSE is unavailable or disconnected.
  var pollTimer = null;

  function startPolling() {
    if (pollTimer) return;
    pollTimer = setInterval(refreshDashboard, 10000);
  }

  function stopPolling() {
    if (pollTimer) { clearInterval(pollTimer); pollTimer = null; }
  }

  var bootPromise = refreshDashboard();

  // SSE live feed — stop polling while connected; resume on disconnect.
  var sseConn = C.connectSSE({
    connected: function() {
      stopPolling();
      C.setStatus('● LIVE', 'ok');
    },
    block: function(/*ev*/) {
      // A new block was committed — refresh everything immediately.
      refreshDashboard();
    },
    error: function() {
      startPolling();
      C.setStatus('Offline — polling every 10s', 'warn');
    }
  });

  // If SSE is not supported by the browser, fall back to polling immediately.
  if (!sseConn) startPolling();

  // Handle /?block=N — navigated here from tx page block link
  var blockParam = C.q('block');
  if (blockParam) {
    bootPromise.then(function() { loadBlock(blockParam); });
  }

})();