feat(bokeh): implement waterfall-basic (#5742)

## Implementation: `waterfall-basic` - python/bokeh

Implements the **python/bokeh** version of `waterfall-basic`.

**File:** `plots/waterfall-basic/implementations/python/bokeh.py`

**Parent Issue:** #777

---
:robot: *[impl-generate
workflow](https://github.com/MarkusNeusinger/anyplot/actions/runs/25410718422)*

---------

Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>
Co-authored-by: Markus Neusinger <2921697+MarkusNeusinger@users.noreply.github.com>

Author: github-actions[bot]

plots/waterfall-basic/implementations/python/bokeh.py

@@ -1,63 +1,86 @@
-""" pyplots.ai
+""" anyplot.ai
 waterfall-basic: Basic Waterfall Chart
-Library: bokeh 3.8.1 | Python 3.13.11
-Quality: 91/100 | Created: 2025-12-24
+Library: bokeh 3.9.0 | Python 3.13.13
+Quality: 86/100 | Updated: 2026-05-06
 """
 
-from bokeh.io import export_png
-from bokeh.models import ColumnDataSource, FactorRange, Label
-from bokeh.plotting import figure, save
+import os
+import time
+from pathlib import Path
 
+from bokeh.io import output_file, save
+from bokeh.models import ColumnDataSource, FactorRange, HoverTool, Label
+from bokeh.plotting import figure
+from selenium import webdriver
+from selenium.webdriver.chrome.options import Options
 
-# Data - quarterly financial breakdown from revenue to net income
+
+THEME = os.getenv("ANYPLOT_THEME", "light")
+PAGE_BG = "#FAF8F1" if THEME == "light" else "#1A1A17"
+ELEVATED_BG = "#FFFDF6" if THEME == "light" else "#242420"
+INK = "#1A1A17" if THEME == "light" else "#F0EFE8"
+INK_SOFT = "#4A4A44" if THEME == "light" else "#B8B7B0"
+
+# Okabe-Ito palette
+POSITIVE = "#009E73"  # brand green for positive changes
+NEGATIVE = "#D55E00"  # vermillion for negative changes
+TOTAL = "#0072B2"  # blue for totals
+
+# Data - quarterly financial breakdown
 categories = ["Starting Revenue", "Product Sales", "Services", "Refunds", "Operating Costs", "Marketing", "Net Income"]
-# First value is the starting total, last value will be calculated as final total
-# Middle values are changes (positive = increase, negative = decrease)
-changes = [150000, 50000, 35000, -8000, -75000, -22000, 0]  # Last is placeholder for total
+changes = [150000, 50000, 35000, -8000, -75000, -22000, 0]
 
 # Calculate waterfall positions
 running_total = 0
 bar_bottoms = []
 bar_tops = []
 bar_colors = []
-display_values = []  # For labels
+display_values = []
 
 for i, (_cat, change) in enumerate(zip(categories, changes, strict=True)):
     if i == 0:
         # Starting total - full bar from 0
         running_total = change
         bar_bottoms.append(0)
         bar_tops.append(running_total)
-        bar_colors.append("#306998")  # Python Blue for totals
+        bar_colors.append(TOTAL)
         display_values.append(running_total)
     elif i == len(categories) - 1:
         # Final total - full bar from 0 to current running total
         bar_bottoms.append(0)
         bar_tops.append(running_total)
-        bar_colors.append("#306998")  # Python Blue for totals
+        bar_colors.append(TOTAL)
         display_values.append(running_total)
     else:
         # Intermediate changes
         if change >= 0:
             bar_bottoms.append(running_total)
             bar_tops.append(running_total + change)
-            bar_colors.append("#2ECC71")  # Green for positive
+            bar_colors.append(POSITIVE)
         else:
             bar_bottoms.append(running_total + change)
             bar_tops.append(running_total)
-            bar_colors.append("#E74C3C")  # Red for negative
+            bar_colors.append(NEGATIVE)
         running_total += change
         display_values.append(change)
 
 # Create data source
-source = ColumnDataSource(data={"categories": categories, "bottom": bar_bottoms, "top": bar_tops, "color": bar_colors})
+source = ColumnDataSource(
+    data={
+        "categories": categories,
+        "bottom": bar_bottoms,
+        "top": bar_tops,
+        "color": bar_colors,
+        "display": [f"${v:,.0f}" for v in display_values],
+    }
+)
 
-# Create figure (4800 x 2700 px)
+# Create figure
 p = figure(
     x_range=FactorRange(*categories, range_padding=0.1),
     width=4800,
     height=2700,
-    title="waterfall-basic · bokeh · pyplots.ai",
+    title="waterfall-basic · bokeh · anyplot.ai",
     x_axis_label="Financial Category",
     y_axis_label="Amount ($)",
     toolbar_location=None,
@@ -71,11 +94,15 @@
     width=0.6,
     source=source,
     color="color",
-    line_color="white",
+    line_color=INK_SOFT,
     line_width=2,
     alpha=0.9,
 )
 
+# Add HoverTool for interactivity
+hover = HoverTool(tooltips=[("Category", "@categories"), ("Amount", "@display")])
+p.add_tools(hover)
+
 # Calculate running totals for connector lines
 running_totals = []
 rt = 0
@@ -86,35 +113,30 @@
         rt += change
     running_totals.append(rt)
 
-# Draw connector lines between bars (showing running total flow)
-for i in range(len(categories) - 2):  # Don't draw connector to final total bar
-    # The connector should be at the running total level after bar i
+# Draw connector lines between bars
+for i in range(len(categories) - 2):
     connector_y = running_totals[i]
-
     p.line(
         x=[categories[i], categories[i + 1]],
         y=[connector_y, connector_y],
-        line_color="#7F8C8D",
+        line_color=INK_SOFT,
         line_width=2,
         line_dash="dashed",
-        alpha=0.7,
+        alpha=0.5,
     )
 
 # Add value labels on bars
 max_value = max(bar_tops)
-label_offset = max_value * 0.03  # 3% of max value for offset
+label_offset = max_value * 0.03
 
 for i, (_cat, _bottom, top, display_val) in enumerate(
     zip(categories, bar_bottoms, bar_tops, display_values, strict=True)
 ):
-    # Label position - above the bar
     label_y = top + label_offset
 
     if i == 0 or i == len(categories) - 1:
-        # Total bars - show absolute value
         label_text = f"${display_val:,.0f}"
     else:
-        # Change bars - show with sign
         if display_val >= 0:
             label_text = f"+${display_val:,.0f}"
         else:
@@ -127,33 +149,62 @@
         text_font_size="20pt",
         text_align="center",
         text_baseline="bottom",
-        text_color="#2C3E50",
+        text_color=INK,
     )
     p.add_layout(label)
 
 # Style
-p.title.text_font_size = "32pt"
-p.xaxis.axis_label_text_font_size = "24pt"
-p.yaxis.axis_label_text_font_size = "24pt"
+p.title.text_font_size = "28pt"
+p.title.text_color = INK
+
+p.xaxis.axis_label_text_font_size = "22pt"
+p.xaxis.axis_label_text_color = INK
+p.yaxis.axis_label_text_font_size = "22pt"
+p.yaxis.axis_label_text_color = INK
+
 p.xaxis.major_label_text_font_size = "18pt"
 p.yaxis.major_label_text_font_size = "18pt"
-p.xaxis.major_label_orientation = 0.5  # Slight rotation for readability
+p.xaxis.major_label_text_color = INK_SOFT
+p.yaxis.major_label_text_color = INK_SOFT
+p.xaxis.major_label_orientation = 0.3
+
+p.xaxis.axis_line_color = INK_SOFT
+p.yaxis.axis_line_color = INK_SOFT
+p.xaxis.major_tick_line_color = INK_SOFT
+p.yaxis.major_tick_line_color = INK_SOFT
 
-# Grid styling
 p.xgrid.grid_line_color = None
-p.ygrid.grid_line_alpha = 0.3
-p.ygrid.grid_line_dash = "dashed"
+p.ygrid.grid_line_color = INK
+p.ygrid.grid_line_alpha = 0.1
 
-# Background
-p.background_fill_color = "#FAFAFA"
-p.border_fill_color = "#FFFFFF"
+p.background_fill_color = PAGE_BG
+p.border_fill_color = PAGE_BG
+p.outline_line_color = INK_SOFT
 
-# Axis styling
-p.yaxis.formatter.use_scientific = False
 p.y_range.start = 0
-p.y_range.end = max_value * 1.15  # 15% padding above max
-p.min_border_left = 80  # Extra left margin for y-axis labels
-
-# Save as PNG and HTML
-export_png(p, filename="plot.png")
-save(p, filename="plot.html", title="waterfall-basic · bokeh · pyplots.ai")
+p.y_range.end = max_value * 1.15
+p.min_border_left = 80
+
+# Save HTML
+output_file(f"plot-{THEME}.html")
+save(p)
+
+# Screenshot with Selenium
+W, H = 4800, 2700
+opts = Options()
+for arg in (
+    "--headless=new",
+    "--no-sandbox",
+    "--disable-dev-shm-usage",
+    "--disable-gpu",
+    f"--window-size={W},{H}",
+    "--hide-scrollbars",
+):
+    opts.add_argument(arg)
+
+driver = webdriver.Chrome(options=opts)
+driver.set_window_size(W, H)
+driver.get(f"file://{Path(f'plot-{THEME}.html').resolve()}")
+time.sleep(3)
+driver.save_screenshot(f"plot-{THEME}.png")
+driver.quit()