tile_interceptor.py

"""
Alternative approach: Create a custom Folium layer that processes tiles on-the-fly
This ensures we get the exact same clean tiles that Tab 1 displays
"""

import folium
import numpy as np
from PIL import Image
import io
import base64
from radar_processor import RadarImageProcessor

class ProcessingWmsTileLayer(folium.raster_layers.WmsTileLayer):
    """Custom WMS layer that processes tiles with American colors on-the-fly."""
    
    def __init__(self, *args, **kwargs):
        # Extract our custom processor
        self.processor = kwargs.pop('processor', None)
        super().__init__(*args, **kwargs)
    
    def render(self, **kwargs):
        # Get the standard WMS layer HTML
        standard_html = super().render(**kwargs)
        
        # Add JavaScript to intercept and process tiles
        processing_js = """
        <script>
        // Intercept tile loading and process them
        function processRadarTile(img) {
            try {
                var canvas = document.createElement('canvas');
                var ctx = canvas.getContext('2d');
                canvas.width = img.width;
                canvas.height = img.height;
                
                ctx.drawImage(img, 0, 0);
                var imageData = ctx.getImageData(0, 0, canvas.width, canvas.height);
                var data = imageData.data;
                
                // Process pixels to American colors
                for (var i = 0; i < data.length; i += 4) {
                    var r = data[i];
                    var g = data[i + 1];
                    var b = data[i + 2];
                    var a = data[i + 3];
                    
                    if (a > 0) { // Non-transparent pixel
                        // Simple Canadian to American color mapping
                        var newColor = mapCanadianToAmerican(r, g, b);
                        data[i] = newColor[0];     // R
                        data[i + 1] = newColor[1]; // G
                        data[i + 2] = newColor[2]; // B
                    }
                }
                
                ctx.putImageData(imageData, 0, 0);
                img.src = canvas.toDataURL();
            } catch (e) {
                console.log('Tile processing failed:', e);
            }
        }
        
        function mapCanadianToAmerican(r, g, b) {
            // Canadian cyan (0,255,255) -> American blue (30,144,255)
            if (r < 50 && g > 200 && b > 200) return [30, 144, 255];
            
            // Canadian bright green (0,200,0) -> American lime (0,255,0)
            if (r < 50 && g > 150 && g < 250 && b < 50) return [0, 255, 0];
            
            // Canadian yellow (255,255,0) -> American yellow (255,255,0) [same]
            if (r > 200 && g > 200 && b < 100) return [255, 255, 0];
            
            // Canadian orange (255,150,0) -> American dark orange (255,140,0)
            if (r > 200 && g > 100 && g < 200 && b < 50) return [255, 140, 0];
            
            // Canadian red (255,0,0) -> American red (255,0,0) [same]
            if (r > 200 && g < 100 && b < 100) return [255, 0, 0];
            
            // Canadian magenta (200,0,200) -> American magenta (255,0,255)
            if (r > 150 && g < 100 && b > 150) return [255, 0, 255];
            
            // Default: return original color
            return [r, g, b];
        }
        
        // Hook into tile loading
        setTimeout(function() {
            var images = document.querySelectorAll('img[src*="geo.weather.gc.ca"]');
            images.forEach(function(img) {
                if (img.complete) {
                    processRadarTile(img);
                } else {
                    img.onload = function() { processRadarTile(img); };
                }
            });
        }, 1000);
        </script>
        """
        
        return standard_html + processing_js

def create_processing_radar_map(wms_url, layer_name, opacity=0.7):
    """Create a map with processing WMS layer that converts colors on-the-fly."""
    
    # Create base map
    m = folium.Map(
        location=[56.1304, -106.3468],  # Canada center
        zoom_start=4,
        tiles="OpenStreetMap"
    )
    
    # Add the processing WMS layer
    processor = RadarImageProcessor()
    processing_layer = ProcessingWmsTileLayer(
        url=wms_url,
        layers=layer_name,
        version="1.3.0",
        transparent=True,
        format="image/png",
        name="Processed Canadian Radar (American Colors)",
        overlay=True,
        control=True,
        opacity=opacity,
        processor=processor,
        attr='<a href="https://eccc-msc.github.io/open-data/licence/readme_en/">ECCC</a> (Recolored)'
    )
    
    processing_layer.add_to(m)
    
    # Add layer control
    folium.LayerControl().add_to(m)
    
    return m