chart/static/chart.js

class ConfluenceChart {
  constructor() {
    this.chart = null;
    this.candles = null;
    this.resizeObserver = null;
    this.levelSeries = new Map();
    this.priceLines = new Map();
    this.previewLine = null;
    this.bars = [];
    this.levels = [];
    this.onChartClick = null;
    this.onChartMove = null;
    this.tooltip = null;
    this.chartEl = null;
    this.clickListener = null;
    this.selectedLineId = null;
    this.anchorHandles = [];
    this.draggingAnchor = null;
    this.onLineChange = null;
    this.anchorMoveListener = null;
    this.anchorUpListener = null;
    this.contextMenu = null;
    this.contextCutoff = null;
    this.contextListener = null;
    this.onLineEnd = null;
  }

  create(el) {
    this.chartEl = el;
    this.chart = LightweightCharts.createChart(el, {
      autoSize: true,
      layout: {
        background: { color: getComputedStyle(document.documentElement).getPropertyValue('--chart-bg').trim() },
        textColor: getComputedStyle(document.documentElement).getPropertyValue('--muted').trim(),
      },
      grid: {
        vertLines: { color: 'rgba(128,128,128,.10)' },
        horzLines: { color: 'rgba(128,128,128,.10)' },
      },
      timeScale: { timeVisible: true, secondsVisible: false },
      rightPriceScale: { borderVisible: false },
    });
    this.candles = this.chart.addSeries(LightweightCharts.CandlestickSeries, {
      upColor: '#27825c', downColor: '#bd4545', borderVisible: true,
      borderUpColor: '#1d6849', borderDownColor: '#963737',
      wickUpColor: '#1d6849', wickDownColor: '#963737',
    });
    this.resizeObserver = new ResizeObserver(() => {
      this.chart.applyOptions({ width: el.clientWidth, height: el.clientHeight });
      requestAnimationFrame(() => this.renderAnchorHandles());
    });
    this.resizeObserver.observe(el);
    this.tooltip = document.createElement('div');
    this.tooltip.className = 'chart-tooltip';
    el.appendChild(this.tooltip);
    const preview = document.createElementNS('http://www.w3.org/2000/svg', 'svg');
    preview.classList.add('chart-preview');
    preview.setAttribute('aria-hidden', 'true');
    this.previewLine = document.createElementNS('http://www.w3.org/2000/svg', 'line');
    this.previewLine.setAttribute('hidden', '');
    preview.appendChild(this.previewLine);
    el.appendChild(preview);
    const handles = document.createElementNS('http://www.w3.org/2000/svg', 'svg');
    handles.classList.add('chart-handles');
    handles.setAttribute('aria-hidden', 'true');
    for (const anchor of ['start', 'end']) {
      const handle = document.createElementNS('http://www.w3.org/2000/svg', 'circle');
      handle.classList.add('chart-anchor');
      handle.dataset.anchor = anchor;
      handle.setAttribute('r', '6');
      handle.setAttribute('hidden', '');
      handle.addEventListener('pointerdown', event => this.startAnchorDrag(event, anchor));
      handle.addEventListener('click', event => event.stopPropagation());
      handles.appendChild(handle);
      this.anchorHandles.push(handle);
    }
    el.appendChild(handles);
    this.contextMenu = document.createElement('div');
    this.contextMenu.className = 'chart-context-menu';
    this.contextMenu.hidden = true;
    const endHere = document.createElement('button');
    endHere.type = 'button';
    endHere.textContent = 'End trendline here';
    endHere.addEventListener('click', event => {
      event.stopPropagation();
      this.endSelectedLineHere();
    });
    this.contextMenu.addEventListener('click', event => event.stopPropagation());
    this.contextMenu.appendChild(endHere);
    el.appendChild(this.contextMenu);
    this.anchorMoveListener = event => this.moveAnchor(event);
    this.anchorUpListener = event => this.finishAnchorDrag(event);
    window.addEventListener('pointermove', this.anchorMoveListener);
    window.addEventListener('pointerup', this.anchorUpListener);
    this.contextListener = event => this.showContextMenu(event);
    el.addEventListener('contextmenu', this.contextListener);
    this.clickListener = event => {
      this.hideContextMenu();
      if (!this.onChartClick) return;
      const bounds = el.getBoundingClientRect();
      const point = { x: event.clientX - bounds.left, y: event.clientY - bounds.top };
      const time = this.chart.timeScale().coordinateToTime(point.x);
      if (time != null) this.onChartClick({ point, time });
    };
    el.addEventListener('click', this.clickListener);
    this.chart.subscribeCrosshairMove(param => {
      if (!param.point || !param.time) {
        this.tooltip.hidden = true;
        return;
      }
      this.updateLineTooltip(param);
      if (this.onChartMove) this.onChartMove(param);
    });
    this.chart.timeScale().subscribeVisibleLogicalRangeChange(() => this.renderAnchorHandles());
  }

  setBars(bars) {
    this.bars = bars;
    this.candles.setData(bars.map(this.toCandle));
    this.chart.timeScale().setVisibleLogicalRange({
      from: Math.max(0, bars.length - 160),
      to: bars.length + 5,
    });
    requestAnimationFrame(() => this.renderAnchorHandles());
  }

  updateBar(bar) {
    this.candles.update(this.toCandle(bar));
    if (this.bars.length && this.bars[this.bars.length - 1].t === bar.t) this.bars[this.bars.length - 1] = bar;
    else this.bars.push(bar);
    this.renderAnchorHandles();
  }

  // Flat levels are drawn as price lines rather than two-point series: they
  // span the whole chart regardless of scroll and get a price-axis label.
  syncPriceLines(levels) {
    const flat = levels.filter(level => level.kind === 'horizontal' && !level.hidden);
    const wanted = new Set(flat.map(level => level.id));
    for (const [id, line] of this.priceLines) {
      if (!wanted.has(id)) {
        this.candles.removePriceLine(line);
        this.priceLines.delete(id);
      }
    }
    for (const level of flat) {
      const options = {
        price: level.anchor_p,
        color: ConfluenceChart.levelColor(level),
        lineWidth: level.line_width || 1,
        lineStyle: LightweightCharts.LineStyle.Dashed,
        axisLabelVisible: true,
        title: level.label,
      };
      const existing = this.priceLines.get(level.id);
      if (existing) existing.applyOptions(options);
      else this.priceLines.set(level.id, this.candles.createPriceLine(options));
    }
  }

  syncLevels(levels) {
    this.levels = levels;
    this.syncPriceLines(levels);
    const drawn = levels.filter(level => level.kind !== 'horizontal');
    const wanted = new Set(drawn.filter(level => !level.hidden).map(level => level.id));
    for (const [id, entry] of this.levelSeries) {
      if (!wanted.has(id)) {
        this.chart.removeSeries(entry.series);
        this.levelSeries.delete(id);
      }
    }
    for (const level of drawn) {
      if (level.hidden) continue;
      let entry = this.levelSeries.get(level.id);
      // Both trace a series of points, but a higher-timeframe average holds its
      // value between closes while VWAP moves continuously.
      const hasPoints = level.kind === 'ma' || level.kind === 'vwap';
      const isMa = level.kind === 'ma';
      const options = {
        color: ConfluenceChart.levelColor(level),
        lineWidth: level.line_width || (level.tf === '1d' ? 2 : 1),
        lineType: isMa ? LightweightCharts.LineType.WithSteps : LightweightCharts.LineType.Simple,
        lineStyle: level.provisional ? LightweightCharts.LineStyle.Dashed : LightweightCharts.LineStyle.Solid,
        priceLineVisible: false,
        lastValueVisible: level.cutoff_t == null,
        title: level.label,
        // Overlays outside the visible price range must not flatten the candles.
        autoscaleInfoProvider: () => null,
      };
      if (!entry) {
        entry = { series: this.chart.addSeries(LightweightCharts.LineSeries, options) };
        this.levelSeries.set(level.id, entry);
      } else {
        entry.series.applyOptions(options);
      }
      let data;
      if (hasPoints) {
        data = (level.points || []).map(([time, value]) => ({ time, value }));
        const latestTime = this.bars[this.bars.length - 1]?.t;
        const latestValue = data[data.length - 1]?.value;
        if (latestTime != null && latestValue != null && latestTime > data[data.length - 1].time) {
          data.push({ time: latestTime, value: latestValue });
        }
      } else {
        data = this.lineData(level);
      }
      entry.series.setData(data);
    }
    this.renderAnchorHandles();
  }

  setClickHandler(handler) { this.onChartClick = handler; }

  setMoveHandler(handler) { this.onChartMove = handler; }

  setLineChangeHandler(handler) { this.onLineChange = handler; }

  setLineEndHandler(handler) { this.onLineEnd = handler; }

  setSelectedLine(id) {
    this.selectedLineId = id;
    this.hideContextMenu();
    this.renderAnchorHandles();
  }

  setLinePreview(start, end, color, lineWidth) {
    if (start.t === end.t) return;
    const x1 = this.chart.timeScale().timeToCoordinate(start.t);
    const x2 = this.chart.timeScale().timeToCoordinate(end.t);
    const y1 = this.candles.priceToCoordinate(start.p);
    const y2 = this.candles.priceToCoordinate(end.p);
    if ([x1, x2, y1, y2].some(value => value == null)) return;
    this.previewLine.removeAttribute('hidden');
    this.previewLine.setAttribute('x1', x1);
    this.previewLine.setAttribute('y1', y1);
    this.previewLine.setAttribute('x2', x2);
    this.previewLine.setAttribute('y2', y2);
    this.previewLine.setAttribute('stroke', color);
    this.previewLine.setAttribute('stroke-width', lineWidth);
    this.previewLine.setAttribute('stroke-dasharray', '6 4');
  }

  clearLinePreview() {
    if (this.previewLine) this.previewLine.setAttribute('hidden', '');
  }

  updateLineTooltip(param) {
    const id = this.hitTest(param);
    const line = this.levels.find(level => level.id === id);
    this.tooltip.hidden = !line;
    if (!line) return;
    this.tooltip.textContent = `#${line.number} ${line.label}`;
    this.tooltip.style.left = `${param.point.x + 12}px`;
    this.tooltip.style.top = `${Math.max(8, param.point.y - 30)}px`;
  }

  pointFromClick(param, snap) {
    const rawPrice = this.candles.coordinateToPrice(param.point.y);
    let point = { t: Number(param.time), p: rawPrice, snappedSide: null };
    if (!snap || !this.bars.length) return point;
    const nearest = this.bars.reduce((best, bar) => Math.abs(bar.t - point.t) < Math.abs(best.t - point.t) ? bar : best);
    const candidates = [
      { p: nearest.h, side: 'resistance' },
      { p: nearest.l, side: 'support' },
    ];
    const snapped = candidates
      .map(value => ({ ...value, distance: Math.abs(this.candles.priceToCoordinate(value.p) - param.point.y) }))
      .sort((a, b) => a.distance - b.distance)[0];
    if (snapped.distance <= 8) point = { t: nearest.t, p: snapped.p, snappedSide: snapped.side };
    return point;
  }

  hitTest(param) {
    let best = null;
    for (const level of this.levels.filter(value => value.kind === 'manual')) {
      const points = this.lineData(level).map(point => ({
        x: this.chart.timeScale().timeToCoordinate(point.time),
        y: this.candles.priceToCoordinate(point.value),
      }));
      for (let index = 1; index < points.length; index += 1) {
        const [start, end] = [points[index - 1], points[index]];
        if ([start.x, start.y, end.x, end.y].some(value => value == null) || start.x === end.x) continue;
        if (param.point.x < Math.min(start.x, end.x) - 6 || param.point.x > Math.max(start.x, end.x) + 6) continue;
        const lineY = start.y + (end.y - start.y) * (param.point.x - start.x) / (end.x - start.x);
        const distance = Math.abs(lineY - param.point.y);
        if (distance <= 6 && (!best || distance < best.distance)) best = { id: level.id, distance };
      }
    }
    return best?.id || null;
  }

  lineData(level) {
    const secondPrice = level.anchor_p + level.slope * (level.last_t - level.anchor_t);
    const points = [
      { time: level.anchor_t, value: level.anchor_p },
      { time: level.last_t, value: secondPrice },
    ];
    const anchorIndex = this.bars.findIndex(bar => bar.t >= level.anchor_t);
    const secondIndex = this.bars.findIndex(bar => bar.t >= level.last_t);
    const cutoffIndex = level.cutoff_t == null
      ? -1
      : this.bars.findIndex(bar => bar.t >= level.cutoff_t);
    const targetIndex = cutoffIndex >= 0 ? cutoffIndex : this.bars.length - 1;
    if (anchorIndex >= 0 && secondIndex > anchorIndex && targetIndex > secondIndex) {
      const value = level.anchor_p
        + (secondPrice - level.anchor_p) * (targetIndex - anchorIndex) / (secondIndex - anchorIndex);
      points.push({ time: this.bars[targetIndex].t, value });
    }
    return points.filter((point, index) => index === 0 || point.time !== points[index - 1].time);
  }

  renderAnchorHandles() {
    const level = this.levels.find(value => value.id === this.selectedLineId && value.kind === 'manual');
    if (!level || !this.anchorHandles.length) {
      this.anchorHandles.forEach(handle => handle.setAttribute('hidden', ''));
      return;
    }
    const points = this.lineData(level).slice(0, 2);
    points.forEach((point, index) => {
      const x = this.chart.timeScale().timeToCoordinate(point.time);
      const y = this.candles.priceToCoordinate(point.value);
      const handle = this.anchorHandles[index];
      if (x == null || y == null) {
        handle.setAttribute('hidden', '');
        return;
      }
      handle.removeAttribute('hidden');
      handle.setAttribute('cx', x);
      handle.setAttribute('cy', y);
      handle.setAttribute('fill', ConfluenceChart.levelColor(level));
    });
  }

  startAnchorDrag(event, anchor) {
    event.preventDefault();
    event.stopPropagation();
    this.draggingAnchor = { id: this.selectedLineId, anchor };
  }

  moveAnchor(event) {
    if (!this.draggingAnchor || !this.chartEl) return;
    const level = this.levels.find(value => value.id === this.draggingAnchor.id);
    if (!level || !this.bars.length) return;
    const bounds = this.chartEl.getBoundingClientRect();
    const x = Math.max(0, Math.min(bounds.width, event.clientX - bounds.left));
    const y = Math.max(0, Math.min(bounds.height, event.clientY - bounds.top));
    const rawTime = this.chart.timeScale().coordinateToTime(x);
    const price = this.candles.coordinateToPrice(y);
    if (rawTime == null || price == null) return;
    const time = this.bars.reduce((nearest, bar) =>
      Math.abs(bar.t - Number(rawTime)) < Math.abs(nearest.t - Number(rawTime)) ? bar : nearest
    ).t;
    const secondPrice = level.anchor_p + level.slope * (level.last_t - level.anchor_t);
    if (this.draggingAnchor.anchor === 'start') {
      if (time >= level.last_t) return;
      level.anchor_t = time;
      level.anchor_p = price;
      level.slope = (secondPrice - price) / (level.last_t - time);
    } else {
      if (time <= level.anchor_t) return;
      if (level.cutoff_t != null && time >= level.cutoff_t) return;
      level.last_t = time;
      level.slope = (price - level.anchor_p) / (time - level.anchor_t);
    }
    const entry = this.levelSeries.get(level.id);
    if (entry) entry.series.setData(this.lineData(level));
    this.renderAnchorHandles();
  }

  finishAnchorDrag(event) {
    if (!this.draggingAnchor) return;
    event.preventDefault();
    const level = this.levels.find(value => value.id === this.draggingAnchor.id);
    this.draggingAnchor = null;
    if (level && this.onLineChange) this.onLineChange({ ...level });
  }

  showContextMenu(event) {
    const level = this.levels.find(value => value.id === this.selectedLineId && value.kind === 'manual');
    if (!level || !this.bars.length) return;
    event.preventDefault();
    const bounds = this.chartEl.getBoundingClientRect();
    const x = event.clientX - bounds.left;
    const rawTime = this.chart.timeScale().coordinateToTime(x);
    if (rawTime == null) return;
    const cutoff = this.bars.reduce((nearest, bar) =>
      Math.abs(bar.t - Number(rawTime)) < Math.abs(nearest.t - Number(rawTime)) ? bar : nearest
    ).t;
    if (cutoff <= level.last_t) {
      this.hideContextMenu();
      return;
    }
    this.contextCutoff = cutoff;
    this.contextMenu.hidden = false;
    this.contextMenu.style.left = `${Math.min(x, bounds.width - 170)}px`;
    this.contextMenu.style.top = `${Math.min(event.clientY - bounds.top, bounds.height - 40)}px`;
  }

  hideContextMenu() {
    if (this.contextMenu) this.contextMenu.hidden = true;
    this.contextCutoff = null;
  }

  endSelectedLineHere() {
    const level = this.levels.find(value => value.id === this.selectedLineId);
    if (!level || this.contextCutoff == null) return;
    level.cutoff_t = this.contextCutoff;
    const entry = this.levelSeries.get(level.id);
    if (entry) entry.series.setData(this.lineData(level));
    this.hideContextMenu();
    if (this.onLineEnd) this.onLineEnd({ ...level });
  }

  toCandle(bar) {
    return { time: bar.t, open: bar.o, high: bar.h, low: bar.l, close: bar.c };
  }

  destroy() {
    if (this.resizeObserver) this.resizeObserver.disconnect();
    if (this.chartEl && this.clickListener) this.chartEl.removeEventListener('click', this.clickListener);
    if (this.chartEl && this.contextListener) this.chartEl.removeEventListener('contextmenu', this.contextListener);
    if (this.anchorMoveListener) window.removeEventListener('pointermove', this.anchorMoveListener);
    if (this.anchorUpListener) window.removeEventListener('pointerup', this.anchorUpListener);
    if (this.chart) this.chart.remove();
  }
}

ConfluenceChart.tfColors = {
  '1m':'#82909f', '2m':'#8a92df', '5m':'#65b7cf', '15m':'#45c39b',
  '30m':'#a8c85d', '1h':'#efb643', '4h':'#ec7b42', '1d':'#d96073',
};

// VWAP and the prior-day levels are both stamped 1d, so without their own
// colours they would be indistinguishable from the daily moving averages.
ConfluenceChart.kindColors = { vwap: '#b07ad6', horizontal: '#9fb0c4' };

ConfluenceChart.levelColor = level =>
  level.color || ConfluenceChart.kindColors[level.kind] || ConfluenceChart.tfColors[level.tf];

window.ConfluenceChart = ConfluenceChart;