### Initial UI Setup for Hex Picker (JavaScript)

Source: https://github.com/alti3/hexpicker/blob/master/index.html

This section contains the initial setup calls for the hex picker's user interface. It ensures that copy buttons are updated and the list of zones is rendered when the application loads.

```javascript
// Initial UI setup
updateCopyButtons();
renderZonesList();
```

--------------------------------

### Toggle Zone Editing Function

Source: https://github.com/alti3/hexpicker/blob/master/index.html

Enables or disables the editing mode for a specific zone. When editing starts, it disables certain UI controls (like creating new zones) and shows a 'Finish Editing' button. When editing finishes, it restores the UI controls.

```javascript
function toggleEditZone(zoneId) {
  if (editingZoneId === zoneId) {
    finishEditing();
    return;
  }
  if (editingZoneId !== null) return;
  editingZoneId = zoneId;
  drawButton.disabled = true;
  resolutionSelect.disabled = true;
  createZoneButton.disabled = true;
  importGeoButton.disabled = true;
  finishEditButton.style.display = "block";
  renderZonesList();
}

finishEditButton.addEventListener("click", finishEditing);

function finishEditing() {
  editingZoneId = null;
  drawButton.disabled = false;
  resolutionSelect.disabled = false;
  createZoneButton.disabled = selectedCells.size === 0;
  importGeoButton.disabled = false;
  finishEditButton.style.display = "none";
  renderZonesList();
}
```

--------------------------------

### Importing Libraries and Initializing Map in HexPicker

Source: https://github.com/alti3/hexpicker/blob/master/index.html

This snippet demonstrates how to import necessary libraries (Leaflet, Leaflet-Draw, h3-js) using ESM CDN links and initializes the Leaflet map with specified center and tile layer. It also sets up global constants and initial layer groups.

```javascript
// Use ESM versions from a CDN. We pin Leaflet for the Draw plugin with ?deps=. 
import * as L from "https://esm.sh/leaflet@1.9.4";
import "https://esm.sh/leaflet-draw@1.0.4?deps=leaflet@1.9.4";
import * as h3 from "https://esm.sh/h3-js@4.1.0";

const DEFAULT_RESOLUTION = 8;
const MAP_CENTER = [32.85, 13.1913];
const HEX_COLOR_REGEX = /^#(?:[0-9a-fA-F]{3}|[0-9a-fA-F]{6}|[0-9a-fA-F]{8})$/;

let h3Resolution = DEFAULT_RESOLUTION;

const map = L.map("map").setView(MAP_CENTER, 13);
L.tileLayer("https://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png", {
    attribution: "© OpenStreetMap contributors",
}).addTo(map);

// Layers
const cellsLayer = L.layerGroup().addTo(map);
const zoneOutlinesLayer = L.layerGroup().addTo(map);

// Data stores
let drawnCells = new Set();
let cellPolygons = {};
let selectedCells = new Set();
let zones = [];
let hexToZone = {};
let editingZoneId = null;
let zoneCounter = 0;
```

--------------------------------

### Create Zone Button Event Listener

Source: https://github.com/alti3/hexpicker/blob/master/index.html

Handles the click event for creating a new zone. It prompts the user for a unique zone name and color, validates the inputs, assigns selected hexagons to the new zone, applies styling, and updates the UI. It prevents overlapping zones and ensures unique names and colors.

```javascript
createZoneButton.addEventListener("click", () => {
  if (selectedCells.size === 0) return;
  let name;
  while (true) {
    name = prompt("Zone name:");
    if (name === null) return;
    name = name.trim();
    if (name === "") {
      alert("Zone name cannot be empty. Please enter a name.");
      continue;
    }
    if (zones.some((z) => z.name.toLowerCase() === name.toLowerCase())) {
      alert("Zone name must be unique. Please try a different name.");
      continue;
    }
    break;
  }
  let color;
  while (true) {
    color = prompt("Zone color (#RRGGBB or #RGB):", "#ff0000");
    if (color === null) return;
    if (!isValidHexColor(color)) {
      alert("Color must be a valid hex code starting with # (e.g., #ff0000 or #f00).");
      continue;
    }
    if (zones.some((z) => z.color.toLowerCase() === color.toLowerCase())) {
      alert("Zone color must be unique. Please choose a different color.");
      continue;
    }
    break;
  }
  const overlap = Array.from(selectedCells).filter((h) => hexToZone[h] !== undefined);
  if (overlap.length) {
    alert("Some selected hexagons are already assigned to zones.");
    return;
  }
  const area = computeArea(selectedCells);
  const zone = {
    id: zoneCounter++,
    name,
    color,
    hexagons: new Set(selectedCells),
    area,
    outlinePolys: []
  };
  zones.push(zone);
  zone.hexagons.forEach((hex) => {
    hexToZone[hex] = zone.id;
    const poly = cellPolygons[hex];
    if (poly) {
      applyZoneStyle(poly, zone);
      poly.inZone = true;
    }
  });
  drawZoneOutline(zone);
  selectedCells.clear();
  updateHexagonCounter();
  renderZonesList();
});
```

--------------------------------

### Create Zone from Selection (JavaScript)

Source: https://context7.com/alti3/hexpicker/llms.txt

Converts a set of selected hexagons into a named, color-coded zone. It calculates the total area, prompts the user for a unique name and color, checks for overlaps with existing zones, updates hexagon styles, and draws an outline for the new zone. Dependencies include the H3 library for geospatial indexing and Leaflet for map rendering.

```javascript
let zones = [];
let hexToZone = {};
let zoneCounter = 0;

// Compute total area from hexagon set
const computeArea = (hexSet) => {
  let total = 0;
  hexSet.forEach((h) => (total += h3.cellArea(h, "m2")));
  return total;
};

// Create zone button handler
document.getElementById("createZoneButton").addEventListener("click", () => {
  if (selectedCells.size === 0) {
    alert("No hexagons selected");
    return;
  }

  // Prompt for unique zone name
  let name;
  while (true) {
    name = prompt("Zone name:");
    if (name === null) return;
    name = name.trim();
    if (name === "") {
      alert("Zone name cannot be empty");
      continue;
    }
    if (zones.some((z) => z.name.toLowerCase() === name.toLowerCase())) {
      alert("Zone name must be unique");
      continue;
    }
    break;
  }

  // Prompt for unique color
  let color;
  while (true) {
    color = prompt("Zone color (#RRGGBB or #RGB):", "#ff0000");
    if (color === null) return;
    const HEX_COLOR_REGEX = /^#(?:[0-9a-fA-F]{3}|[0-9a-fA-F]{6}|[0-9a-fA-F]{8})$/;
    if (!HEX_COLOR_REGEX.test(color)) {
      alert("Invalid hex color format");
      continue;
    }
    if (zones.some((z) => z.color.toLowerCase() === color.toLowerCase())) {
      alert("Zone color must be unique");
      continue;
    }
    break;
  }

  // Check for overlaps
  const overlap = Array.from(selectedCells).filter(
    (h) => hexToZone[h] !== undefined
  );
  if (overlap.length) {
    alert("Some hexagons are already assigned to zones");
    return;
  }

  // Create zone
  const area = computeArea(selectedCells);
  const zone = {
    id: zoneCounter++,
    name,
    color,
    hexagons: new Set(selectedCells),
    area,
    outlinePolys: []
  };

  zones.push(zone);

  // Update mappings and styles
  zone.hexagons.forEach((hex) => {
    hexToZone[hex] = zone.id;
    const poly = cellPolygons[hex];
    if (poly) {
      poly.setStyle({
        fillOpacity: 0.5,
        fillColor: zone.color,
        weight: 0
      });
      poly.inZone = true;
    }
  });

  // Draw zone outline
  const multiLngLat = h3.cellsToMultiPolygon(Array.from(zone.hexagons), true);
  multiLngLat.forEach((polyLngLat) => {
    const latlngs = polyLngLat.map((ringLngLat) =>
      ringLngLat.map(([lng, lat]) => [lat, lng])
    );
    const outline = L.polygon(latlngs, {
      color: zone.color,
      weight: 3,
      fillOpacity: 0,
      interactive: false
    });
    zoneOutlinesLayer.addLayer(outline);
    zone.outlinePolys.push(outline);
  });

  selectedCells.clear();
  console.log(`Zone "${name}" created with ${zone.hexagons.size} hexagons`);
});

```

--------------------------------

### Import GeoJSON and Process Zones (JavaScript)

Source: https://context7.com/alti3/hexpicker/llms.txt

Handles the import of GeoJSON files, converts polygons to H3 hexagonal cells, organizes cells into zones, and updates the global state. It includes error handling for file reading and processing, and provides user feedback via alerts.

```javascript
const reader = new FileReader();

reader.onload = (event) => {
  try {
    const geojsonData = JSON.parse(event.target.result);
    const features = geojsonData.features;
    let importedCellCount = 0;
    const importedZonesBatch = [];
    let zoneCounter = zones.length;

    features.forEach(feature => {
      const { properties, geometry } = feature;
      const zoneName = properties.name || `Zone ${zoneCounter}`;
      const zoneColor = properties.color || '#ffffff';
      const zoneH3Cells = new Set();
      const hexToZone = {}; // Assumed to be defined globally or passed in
      const zones = []; // Assumed to be defined globally or passed in
      const redrawGrid = () => {}; // Placeholder for function
      const computeArea = (cells) => 0; // Placeholder for function
      const h3 = { cellToBoundary: (cell) => [[0,0]] }; // Mock H3 object

      // Simplified processing for demonstration
      // In a real scenario, this would involve H3 conversion from geometry
      if (geometry.type === 'Polygon' || geometry.type === 'MultiPolygon') {
        // Assume cells are derived from geometry here
        const cell = 'some_h3_cell'; // Placeholder
        if (hexToZone[cell] === undefined) {
          let cellInBatch = false;
          for (const bz of importedZonesBatch) {
            if (bz.hexagons.has(cell)) {
              cellInBatch = true;
              break;
            }
          }
          if (!cellInBatch) {
            zoneH3Cells.add(cell);
          }
        }
      }
    });

    if (zoneH3Cells.size > 0) {
      importedZonesBatch.push({
        id: -1,
        name: zoneName,
        color: zoneColor,
        hexagons: zoneH3Cells,
        area: computeArea(zoneH3Cells),
        outlinePolys: []
      });
      importedCellCount += zoneH3Cells.size;
    }
  } catch (h3Error) {
    console.error("Error converting polygon to H3 cells:", h3Error);
  }
});


if (zoneH3Cells.size > 0) {
  importedZonesBatch.push({
    id: -1,
    name: zoneName,
    color: zoneColor,
    hexagons: zoneH3Cells,
    area: computeArea(zoneH3Cells),
    outlinePolys: []
  });
  importedCellCount += zoneH3Cells.size;
}

// Add imported zones to global state
importedZonesBatch.forEach(newZoneData => {
  newZoneData.id = zoneCounter++;
  zones.push(newZoneData);
  newZoneData.hexagons.forEach(hex => {
    hexToZone[hex] = newZoneData.id;
  });
});

if (importedZonesBatch.length > 0) {
  redrawGrid();
  alert(
    `Imported ${importedZonesBatch.length} zones with ${importedCellCount} cells`
  );
} else {
  alert("No zones imported. Check console for details.");
}

} catch (error) {
  console.error("Error importing GeoJSON:", error);
  alert(`Error importing GeoJSON: ${error.message}`);
} finally {
  event.target.value = null;
}
};

reader.onerror = () => {
  alert("Error reading file");
  event.target.value = null;
};

reader.readAsText(file);
};
```

--------------------------------

### Import GeoJSON Zones and Handle H3 Resolution

Source: https://github.com/alti3/hexpicker/blob/master/index.html

This JavaScript code handles the import of GeoJSON files, parses the data, validates its structure (must be a FeatureCollection with features), and checks for H3 resolution mismatches. It prompts the user to confirm resolution changes and existing zone overwrites. It then iterates through features, extracts zone names and colors, generates H3 cells using `h3.polygonToCells`, handles potential overlaps with existing or newly imported zones, and adds the new zones to the application's state. Includes error handling for file reading and GeoJSON parsing.

```javascript
const reader = new FileReader();
reader.onload = (e) => {
  try {
    const geojsonData = JSON.parse(e.target.result);
    if (geojsonData.type !== "FeatureCollection" || !Array.isArray(geojsonData.features)) throw new Error("Invalid GeoJSON: Must be a FeatureCollection with a 'features' array.");
    if (geojsonData.features.length === 0) {
      alert("No features found in the GeoJSON file.");
      event.target.value = null;
      return;
    }
    const importResolution = geojsonData.features[0]?.properties?.h3_resolution;
    if (importResolution !== undefined && importResolution !== h3Resolution) {
      if (!confirm(`The imported GeoJSON was created with H3 resolution ${importResolution}, but your current resolution is ${h3Resolution}. Cells will be generated using resolution ${h3Resolution}. This may lead to different results. Continue?`)) {
        event.target.value = null;
        return;
      }
    }
    if (zones.length > 0) {
      if (!confirm("Importing new GeoJSON will clear all existing zones. Continue?")) {
        event.target.value = null;
        return;
      }
      clearAllZones();
      if (selectedCells.size) clearButton.click();
    } else {
      genericZoneNameCounter = 1;
      defaultColorIndex = 0;
    }
    const importedZonesBatch = [];
    let importedCellCount = 0;
    for (const feature of geojsonData.features) {
      if (feature.type !== "Feature" || !feature.geometry || feature.geometry.type !== "MultiPolygon") {
        console.warn("Skipping invalid feature:", feature);
        continue;
      }
      let zoneName = feature.properties?.zone_name;
      let zoneColor = feature.properties?.zone_color;
      if (!zoneName || String(zoneName).trim() === "") {
        zoneName = generateUniqueZoneName(zones, importedZonesBatch);
      } else {
        zoneName = String(zoneName).trim();
        if (zones.some(z => z.name.toLowerCase() === zoneName.toLowerCase()) || importedZonesBatch.some(nz => nz.name.toLowerCase() === zoneName.toLowerCase())) {
          console.warn(`Zone name "${zoneName}" from file already exists or is duplicated. Assigning a generic name.`);
          zoneName = generateUniqueZoneName(zones, importedZonesBatch);
        }
      }
      if (!zoneColor || !isValidHexColor(zoneColor)) {
        if (zoneColor) console.warn(`Invalid color "${zoneColor}" for zone "${zoneName}". Assigning default.`);
        zoneColor = generateUniqueZoneColor(zones, importedZonesBatch);
      } else {
        if (zones.some(z => z.color.toLowerCase() === zoneColor.toLowerCase()) || importedZonesBatch.some(nz => nz.color.toLowerCase() === zoneColor.toLowerCase())) {
          console.warn(`Zone color "${zoneColor}" for zone "${zoneName}" already exists or is duplicated. Assigning new default.`);
          zoneColor = generateUniqueZoneColor(zones, importedZonesBatch);
        }
      }
      const zoneH3Cells = new Set();
      for (const polygonGeoJsonCoords of feature.geometry.coordinates) {
        if (polygonGeoJsonCoords && polygonGeoJsonCoords.length > 0 && polygonGeoJsonCoords[0].length >= 3) {
          try {
            const cellsFromPolygon = h3.polygonToCells(polygonGeoJsonCoords, h3Resolution, true);
            cellsFromPolygon.forEach(cell => {
              if (hexToZone[cell] !== undefined) {
                const existingGlobalZone = zones.find(z => z.id === hexToZone[cell]);
                console.warn(`Hex ${cell} for "${zoneName}" already in existing zone "${existingGlobalZone?.name}". Skipping cell.`);
              } else {
                let cellInBatch = false;
                for (const bz of importedZonesBatch) {
                  if (bz.hexagons.has(cell)) {
                    console.warn(`Hex ${cell} for "${zoneName}" already in another new zone "${bz.name}" from this import. Skipping cell.`);
                    cellInBatch = true;
                    break;
                  }
                }
                if (!cellInBatch) zoneH3Cells.add(cell);
              }
            });
          } catch (h3Error) {
            console.error(`Error converting polygon to H3 cells for zone "${zoneName}":`, h3Error, "Polygon data:", polygonGeoJsonCoords);
          }
        } else {
          console.warn(`Skipping malformed polygon within MultiPolygon for zone "${zoneName}".`);
        }
      }
      if (zoneH3Cells.size > 0) {
        importedZonesBatch.push({ id: -1, name: zoneName, color: zoneColor, hexagons: zoneH3Cells, area: computeArea(zoneH3Cells), outlinePolys: [] });
        importedCellCount += zoneH3Cells.size;
      } else {
        console.warn(`No valid, non-overlapping H3 cells generated for zone "${zoneName}". It might be too small, outside map, or entirely overlapping.`);
      }
    }
    importedZonesBatch.forEach(newZoneData => {
      newZoneData.id = zoneCounter++;
      zones.push(newZoneData);
      newZoneData.hexagons.forEach(hex => {
        hexToZone[hex] = newZoneData.id;
      });
    });
    if (importedZonesBatch.length > 0) {
      redrawGrid();
      renderZonesList();
      alert(`Successfully imported ${importedZonesBatch.length} zone(s) with a total of ${importedCellCount} unique cells.`);
    } else {
      alert("Import complete, but no new zones were added. Check console for details if features were expected.");
    }
  } catch (error) {
    console.error("Error importing GeoJSON:", error);
    alert(`Error importing GeoJSON: ${error.message}`);
  } finally {
    event.target.value = null;
  }
};
reader.onerror = () => {
  alert("Error reading file.");
  event.target.value = null;
};
reader.readAsText(file);
```

--------------------------------

### Generate Unique Zone Names and Colors

Source: https://github.com/alti3/hexpicker/blob/master/index.html

Provides utility functions for creating unique zone names and colors when importing data. It checks against existing zones to avoid duplicates and cycles through a predefined list of default colors, falling back to random colors if necessary.

```javascript
let genericZoneNameCounter = 1;
const defaultColors = ["#E6194B", "#3CB44B", "#FFE119", "#4363D8", "#F58231", "#911EB4", "#46F0F0", "#F032E6", "#BCF60C", "#FABEBE", "#008080", "#E6BEFF", "#9A6324", "#FFFAC8", "#800000", "#AAFFC3", "#808000", "#FFD8B1", "#000075", "#808000", "#808080"]
let defaultColorIndex = 0;

function generateUniqueZoneName(currentGlobalZones, tempNewZonesList) {
  let name;
  do {
    name = `Zone ${genericZoneNameCounter++}`;
  } while (currentGlobalZones.some(z => z.name.toLowerCase() === name.toLowerCase()) || tempNewZonesList.some(nz => nz.name.toLowerCase() === name.toLowerCase()));
  return name;
}
```

```javascript
function generateUniqueZoneColor(currentGlobalZones, tempNewZonesList) {
  let color;
  let attempts = 0;
  const initialIndex = defaultColorIndex;
  do {
    color = defaultColors[defaultColorIndex % defaultColors.length];
    defaultColorIndex++;
    attempts++;
    if (attempts > defaultColors.length && defaultColorIndex % defaultColors.length === initialIndex % defaultColors.length) break;
  } while ((currentGlobalZones.some(z => z.color.toLowerCase() === color.toLowerCase()) || tempNewZonesList.some(nz => nz.color.toLowerCase() === color.toLowerCase())) && attempts < defaultColors.length * 2);
  if (currentGlobalZones.some(z => z.color.toLowerCase() === color.toLowerCase()) || tempNewZonesList.some(nz => nz.color.toLowerCase() === color.toLowerCase())) {
    do {
      color = '#' + Math.floor(Math.random() * 16777215).toString(16).padStart(6, '0');
    } while (currentGlobalZones.some(z => z.color.toLowerCase() === color.toLowerCase()) || tempNewZonesList.some(nz => nz.color.toLowerCase() === color.toLowerCase()));
  }
  return color;
}
```

--------------------------------

### DOM Element References for HexPicker UI Controls

Source: https://github.com/alti3/hexpicker/blob/master/index.html

This snippet lists all the references to HTML elements that serve as UI controls within the HexPicker application. These include buttons for drawing, clearing, creating zones, editing, copying data, and input elements for resolution and file uploads.

```javascript
const drawButton = document.getElementById("drawButton");
const clearButton = document.getElementById("clearButton");
const createZoneButton = document.getElementById("createZoneButton");
const finishEditButton = document.getElementById("finishEditButton");
const copyIdsButton = document.getElementById("copyIdsButton");
const copyGeoButton = document.getElementById("copyGeoButton");
const resolutionSelect = document.getElementById("resolutionSelect");
const hexagonCounter = document.getElementById("hexagonCounter");
const zonesContainer = document.getElementById("zonesContainer");
const exportGeoButton = document.getElementById("exportGeoButton");
const importGeoButton = document.getElementById("importGeoButton");
const geojsonFileInput = document.getElementById("geojsonFile");
const zonesSummaryEl = document.getElementById("zonesSummary");
```

--------------------------------

### Initialize Leaflet Map with H3 Grid in JavaScript

Source: https://context7.com/alti3/hexpicker/llms.txt

Initializes a Leaflet map with H3 hexagonal tessellation for interactive zone management. It uses vanilla JavaScript and the h3-js library to render cells based on the current viewport and allows for interactive selection of hexagons.

```javascript
import * as L from "https://esm.sh/leaflet@1.9.4";
import * as h3 from "https://esm.sh/h3-js@4.1.0";

// Configuration
const DEFAULT_RESOLUTION = 8;
const MAP_CENTER = [32.85, 13.1913];

// Initialize map
const map = L.map("map").setView(MAP_CENTER, 13);
L.tileLayer("https://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png", {
  attribution: "© OpenStreetMap contributors",
}).addTo(map);

// Create layer groups
const cellsLayer = L.layerGroup().addTo(map);
const zoneOutlinesLayer = L.layerGroup().addTo(map);

// Data structures
let h3Resolution = DEFAULT_RESOLUTION;
let drawnCells = new Set();
let cellPolygons = {};
let selectedCells = new Set();

// Draw H3 cells for current viewport
function drawH3Cells() {
  const bounds = map.getBounds();
  const nw = bounds.getNorthWest();
  const se = bounds.getSouthEast();

  const hexagonsToDraw = h3.polygonToCells(
    [
      [nw.lat, nw.lng],
      [se.lat, nw.lng],
      [se.lat, se.lng],
      [nw.lat, se.lng],
    ],
    h3Resolution,
    false
  );

  hexagonsToDraw.forEach((hex) => {
    if (drawnCells.has(hex)) return;

    const coords = h3.cellToBoundary(hex).map(([lat, lng]) => [lat, lng]);
    const polygon = L.polygon(coords, {
      color: "blue",
      weight: 1,
      fillOpacity: 0
    });
    polygon.h3Index = hex;

    // Interactive handlers
    polygon.on("click", function () {
      toggleSelection(this.h3Index, this);
    });

    cellPolygons[hex] = polygon;
    cellsLayer.addLayer(polygon);
    drawnCells.add(hex);
  });
}

// Redraw on map movement
map.on("moveend", drawH3Cells);
drawH3Cells();
```

--------------------------------

### Rendering Zone List in HexPicker UI

Source: https://github.com/alti3/hexpicker/blob/master/index.html

This JavaScript function, `renderZonesList`, is responsible for dynamically populating the `zonesContainer` element with visual representations of created zones. Each zone is displayed with a color swatch, name, hexagon count, and area, and includes controls for editing and deleting.

```javascript
function renderZonesList() {
    zonesContainer.innerHTML = "";
    zones.forEach((z) => {
        const item = document.createElement("div");
        item.className = "zone-item";
        const left = document.createElement("div");
        left.className = "zone-left";
        const swatch = document.createElement("span");
        swatch.className = "color-swatch";
        swatch.style.background = z.color;
        swatch.title = "Click to change color";
        swatch.addEventListener("click", () => changeZoneColor(z.id));
        const nameWrap = document.createElement("div");
        const nameSpan = document.createElement("div");
        nameSpan.textContent = z.name;
        nameSpan.className = "zone-name";
        const metaSpan = document.createElement("div");
        metaSpan.textContent = `${z.hexagons.size} hex • ${fmtInt(z.area)} m²`;
        metaSpan.className = "zone-meta";
        nameWrap.appendChild(nameSpan);
        nameWrap.appendChild(metaSpan);
        left.appendChild(swatch);
        left.appendChild(nameWrap);
        const actions = document.createElement("div");
        actions.className = "action-btns";
        // Edit button
        const editBtn = document.createElement("button");
        editBtn.className = "edit-btn";
        if (editingZoneId === z.id) {
            editBtn.innerHTML = '<i cl
```

--------------------------------

### Export Zones as GeoJSON

Source: https://github.com/alti3/hexpicker/blob/master/index.html

Generates a GeoJSON FeatureCollection containing all defined zones. Each feature includes zone properties like name, color, hexagon count, and area. It also provides functionality to copy the GeoJSON to the clipboard or trigger a file download.

```javascript
function getGeoJSONForAllZones() {
  const features = zones.map((z) => {
    const multiLngLat = h3.cellsToMultiPolygon(Array.from(z.hexagons), true);
    return {
      type: "Feature",
      geometry: {
        type: "MultiPolygon",
        coordinates: multiLngLat
      },
      properties: {
        zone_name: z.name,
        zone_color: z.color,
        hex_count: z.hexagons.size,
        area_m2: Math.round(z.area),
        h3_resolution: h3Resolution,
      },
    };
  });
  return {
    type: "FeatureCollection",
    features
  };
}
```

```javascript
copyIdsButton.addEventListener("click", () => {
  const payload = zones.map((z) => ({
    zone_name: z.name,
    zone_color: z.color,
    hex_count: z.hexagons.size,
    area_m2: Math.round(z.area),
    zone_cells: Array.from(z.hexagons),
  }));
  navigator.clipboard.writeText(JSON.stringify(payload, null, 2))
    .then(() => alert("Zone cell IDs copied!"));
});
```

```javascript
copyGeoButton.addEventListener("click", () => {
  const geojson = getGeoJSONForAllZones();
  navigator.clipboard.writeText(JSON.stringify(geojson, null, 2))
    .then(() => alert("GeoJSON copied!"));
});
```

```javascript
exportGeoButton.addEventListener("click", () => {
  if (zones.length === 0) return;
  const geojson = getGeoJSONForAllZones();
  const blob = new Blob([JSON.stringify(geojson, null, 2)], {
    type: "application/json"
  });
  const url = URL.createObjectURL(blob);
  const a = document.createElement("a");
  a.href = url;
  a.download = "zones.geojson";
  document.body.appendChild(a);
  a.click();
  document.body.removeChild(a);
  URL.revokeObjectURL(url);
});
```

--------------------------------

### Import GeoJSON Zones with Conflict Resolution (JavaScript)

Source: https://context7.com/alti3/hexpicker/llms.txt

Handles the import of GeoJSON files, including validation, conflict resolution for zone names and colors, and conversion of geometries to H3 cells. It requires the 'h3-js' library for H3 operations and assumes the existence of global variables like 'zones', 'h3Resolution', 'clearAllZones', and DOM elements for file input and import buttons.

```javascript
const defaultColors = [
  "#E6194B", "#3CB44B", "#FFE119", "#4363D8", "#F58231",
  "#911EB4", "#46F0F0", "#F032E6", "#BCF60C", "#FABEBE"
];
let defaultColorIndex = 0;
let genericZoneNameCounter = 1;

// Generate unique zone name
function generateUniqueZoneName(currentGlobalZones, tempNewZonesList) {
  let name;
  do {
    name = `Zone ${genericZoneNameCounter++}`;
  } while (
    currentGlobalZones.some(z => z.name.toLowerCase() === name.toLowerCase()) ||
    tempNewZonesList.some(nz => nz.name.toLowerCase() === name.toLowerCase())
  );
  return name;
}

// Generate unique zone color
function generateUniqueZoneColor(currentGlobalZones, tempNewZonesList) {
  let color;
  let attempts = 0;

  do {
    color = defaultColors[defaultColorIndex % defaultColors.length];
    defaultColorIndex++;
    attempts++;
  } while (
    (currentGlobalZones.some(z => z.color.toLowerCase() === color.toLowerCase()) ||
     tempNewZonesList.some(nz => nz.color.toLowerCase() === color.toLowerCase())) &&
    attempts < defaultColors.length * 2
  );

  // Fallback to random color if all defaults are taken
  if (currentGlobalZones.some(z => z.color.toLowerCase() === color.toLowerCase()) ||
      tempNewZonesList.some(nz => nz.color.toLowerCase() === color.toLowerCase())) {
    do {
      color = '#' + Math.floor(Math.random() * 16777215).toString(16).padStart(6, '0');
    } while (
      currentGlobalZones.some(z => z.color.toLowerCase() === color.toLowerCase()) ||
      tempNewZonesList.some(nz => nz.color.toLowerCase() === color.toLowerCase())
    );
  }

  return color;
}

// Import handler
document.getElementById("importGeoButton").addEventListener("click", () => {
  document.getElementById("geojsonFile").click();
});

document.getElementById("geojsonFile").addEventListener("change", (event) => {
  const file = event.target.files[0];
  if (!file) return;

  const reader = new FileReader();
  reader.onload = (e) => {
    try {
      const geojsonData = JSON.parse(e.target.result);

      // Validate structure
      if (geojsonData.type !== "FeatureCollection" ||
          !Array.isArray(geojsonData.features)) {
        throw new Error("Invalid GeoJSON: Must be a FeatureCollection");
      }

      if (geojsonData.features.length === 0) {
        alert("No features found in GeoJSON");
        return;
      }

      // Check resolution mismatch
      const importResolution = geojsonData.features[0]?.properties?.h3_resolution;
      if (importResolution !== undefined && importResolution !== h3Resolution) {
        if (!confirm(
          `GeoJSON has resolution ${importResolution}, current is ${h3Resolution}. Continue?`
        )) {
          return;
        }
      }

      // Clear existing zones if present
      if (zones.length > 0) {
        if (!confirm("Importing will clear all existing zones. Continue?")) {
          return;
        }
        clearAllZones();
      }

      const importedZonesBatch = [];
      let importedCellCount = 0;

      // Process each feature
      for (const feature of geojsonData.features) {
        if (feature.type !== "Feature" ||
            feature.geometry?.type !== "MultiPolygon") {
          console.warn("Skipping invalid feature:", feature);
          continue;
        }

        // Get or generate zone name
        let zoneName = feature.properties?.zone_name;
        if (!zoneName || String(zoneName).trim() === "") {
          zoneName = generateUniqueZoneName(zones, importedZonesBatch);
        } else {
          zoneName = String(zoneName).trim();
          if (zones.some(z => z.name.toLowerCase() === zoneName.toLowerCase()) ||
              importedZonesBatch.some(nz => nz.name.toLowerCase() === zoneName.toLowerCase())) {
            zoneName = generateUniqueZoneName(zones, importedZonesBatch);
          }
        }

        // Get or generate zone color
        let zoneColor = feature.properties?.zone_color;
        const HEX_COLOR_REGEX = /^#(?:[0-9a-fA-F]{3}|[0-9a-fA-F]{6}|[0-9a-fA-F]{8})$/;
        if (!zoneColor || !HEX_COLOR_REGEX.test(zoneColor)) {
          zoneColor = generateUniqueZoneColor(zones, importedZonesBatch);
        } else if (
          zones.some(z => z.color.toLowerCase() === zoneColor.toLowerCase()) ||
          importedZonesBatch.some(nz => nz.color.toLowerCase() === zoneColor.toLowerCase())
        ) {
          zoneColor = generateUniqueZoneColor(zones, importedZonesBatch);
        }

        // Convert geometry to H3 cells
        const zoneH3Cells = new Set();
        for (const polygonGeoJsonCoords of feature.geometry.coordinates) {
          if (polygonGeoJsonCoords?.[0]?.length >= 3) {
            try {
              const cellsFromPolygon = h3.polygonToCells(
                polygonGeoJsonCoords,
                h3Resolution,
                true
              );
              cellsFromPolygon.forEach(cell => {

```

--------------------------------

### Utility Functions for HexPicker: Formatting and Validation

Source: https://github.com/alti3/hexpicker/blob/master/index.html

This code block defines utility functions for the HexPicker project, including number formatting, area computation using h3-js, and hexadecimal color validation. These functions are essential for data processing and UI feedback.

```javascript
// -------- Utility --------
const fmtInt = (v) => v.toLocaleString(undefined, { maximumFractionDigits: 0 });

const computeArea = (hexSet) => {
    let total = 0;
    hexSet.forEach((h) => (total += h3.cellArea(h, "m2")));
    return total;
};

const isValidHexColor = (c) => HEX_COLOR_REGEX.test(c);
```

--------------------------------

### Create Zone Action Buttons - JavaScript

Source: https://github.com/alti3/hexpicker/blob/master/index.html

This code creates action buttons (Edit, Rename, Locate, Delete) for each zone. Each button is associated with a specific zone ID and triggers a corresponding action when clicked. The buttons' disabled state is managed based on whether a zone is currently being edited.

```javascript
// Edit button
const editBtn = document.createElement("button");
editBtn.className = "edit-btn";
editBtn.title = editingZoneId === z.id ? 'Editing…' : "Edit Zone";
editBtn.innerHTML = editingZoneId === z.id ? '<i class="fas fa-pencil-alt"></i> Editing…' : '<i class="fas fa-pencil-alt"></i>';
editBtn.classList.add("edit-active");

if (editingZoneId !== null && editingZoneId !== z.id) {
    editBtn.disabled = true;
} else {
    editBtn.disabled = false;
    editBtn.title = "Edit Zone";
}

editBtn.addEventListener("click", () => toggleEditZone(z.id));

// Rename button
const renameBtn = document.createElement("button");
renameBtn.className = "rename-btn";
renameBtn.innerHTML = '<i class="fas fa-font"></i>';
renameBtn.title = "Rename Zone";
renameBtn.disabled = editingZoneId !== null && editingZoneId !== z.id;
renameBtn.addEventListener("click", () => renameZone(z.id));

// Center/locate button
const locateBtn = document.createElement("button");
locateBtn.className = "locate-btn";
locateBtn.innerHTML = '<i class="fas fa-crosshairs"></i>';
locateBtn.title = "Center map on zone";
locateBtn.disabled = editingZoneId !== null && editingZoneId !== z.id;
locateBtn.addEventListener("click", () => zoomToZone(z.id));

// Delete button
const deleteBtn = document.createElement("button");
deleteBtn.innerHTML = '<i class="fas fa-trash-alt"></i>';
deleteBtn.title = "Delete Zone";
deleteBtn.className = "delete-btn";
deleteBtn.disabled = editingZoneId !== null;
deleteBtn.addEventListener("click", () => deleteZone(z.id));

actions.appendChild(editBtn);
actions.appendChild(renameBtn);
actions.appendChild(locateBtn);
actions.appendChild(deleteBtn);
```

--------------------------------

### Export Zones to GeoJSON in JavaScript

Source: https://context7.com/alti3/hexpicker/llms.txt

Generates a GeoJSON FeatureCollection from defined zones, including geometry and properties. Provides functionality to copy the GeoJSON to the clipboard or download it as a file. Depends on the H3 library and browser Clipboard API.

```javascript
// Generate GeoJSON for all zones
function getGeoJSONForAllZones() {
  const features = zones.map((zone) => {
    const multiLngLat = h3.cellsToMultiPolygon(
      Array.from(zone.hexagons),
      true
    );

    return {
      type: "Feature",
      geometry: {
        type: "MultiPolygon",
        coordinates: multiLngLat
      },
      properties: {
        zone_name: zone.name,
        zone_color: zone.color,
        hex_count: zone.hexagons.size,
        area_m2: Math.round(zone.area),
        h3_resolution: h3Resolution,
      },
    };
  });

  return {
    type: "FeatureCollection",
    features
  };
}

// Copy to clipboard
document.getElementById("copyGeoButton").addEventListener("click", () => {
  const geojson = getGeoJSONForAllZones();
  navigator.clipboard.writeText(JSON.stringify(geojson, null, 2))
    .then(() => alert("GeoJSON copied to clipboard"));
});

// Download as file
document.getElementById("exportGeoButton").addEventListener("click", () => {
  if (zones.length === 0) return;

  const geojson = getGeoJSONForAllZones();
  const blob = new Blob(
    [JSON.stringify(geojson, null, 2)],
    { type: "application/json" }
  );
  const url = URL.createObjectURL(blob);
  const a = document.createElement("a");
  a.href = url;
  a.download = "zones.geojson";
  document.body.appendChild(a);
  a.click();
  document.body.removeChild(a);
  URL.revokeObjectURL(url);
});

// Example output structure:
/*
{
  "type": "FeatureCollection",
  "features": [
    {
      "type": "Feature",
      "geometry": {
        "type": "MultiPolygon",
        "coordinates": [[[ 
          [13.1234, 32.8567],
          [13.1245, 32.8578],
          [13.1256, 32.8589]
        ]]]
      },
      "properties": {
        "zone_name": "Downtown",
        "zone_color": "#ff0000",
        "hex_count": 45,
        "area_m2": 125678,
        "h3_resolution": 8
      }
    }
  ]
}
*/
```

--------------------------------

### Populating Resolution Dropdown in HexPicker

Source: https://github.com/alti3/hexpicker/blob/master/index.html

This JavaScript code iterates from 0 to 15 to create and append 'option' elements to a 'resolutionSelect' dropdown. It sets the default selected option to the 'DEFAULT_RESOLUTION'.

```javascript
// Populate resolution dropdown
for (let r = 0; r <= 15; r++) {
    const opt = document.createElement("option");
    opt.value = r.toString();
    opt.textContent = `Resolution ${r}`;
    if (r === DEFAULT_RESOLUTION) opt.selected = true;
    resolutionSelect.appendChild(opt);
}
```

--------------------------------

### Import GeoJSON Zones

Source: https://github.com/alti3/hexpicker/blob/master/index.html

Handles the import of GeoJSON files to create new zones. It triggers a file input dialog and processes the selected file. This functionality is disabled if a zone is currently being edited.

```javascript
importGeoButton.addEventListener("click", () => {
  if (editingZoneId !== null) {
    alert("Please finish editing the current zone before importing.");
    return;
  }
  geojsonFileInput.click();
});
```

```javascript
geojsonFileInput.addEventListener("change", (event) => {
  const file = event.target.files[0];
  if (!file) return;
  c
```

--------------------------------

### HexPicker UI Update Functions: Counters and Buttons

Source: https://github.com/alti3/hexpicker/blob/master/index.html

This section contains JavaScript functions designed to update the HexPicker user interface. It includes functions to update the hexagon counter, enable/disable control buttons based on selection or zone data, and render a summary of created zones.

```javascript
function updateHexagonCounter() {
    hexagonCounter.textContent = `Selected Hexagons: ${selectedCells.size}`;
    clearButton.disabled = selectedCells.size === 0;
    createZoneButton.disabled = selectedCells.size === 0;
}

function updateCopyButtons() {
    const disabled = zones.length === 0;
    copyIdsButton.disabled = disabled;
    copyGeoButton.disabled = disabled;
    exportGeoButton.disabled = disabled;
}

function updateZonesSummary() {
    if (zones.length === 0) {
        zonesSummaryEl.innerHTML = "";
        zonesSummaryEl.style.display = "none";
        return;
    }
    let totalHexagons = 0;
    let totalArea = 0;
    zones.forEach(zone => {
        totalHexagons += zone.hexagons.size;
        totalArea += zone.area;
    });
    zonesSummaryEl.innerHTML = ` <strong>Total Zones:</strong> ${zones.length}<br> <strong>Total Hexagons:</strong> ${fmtInt(totalHexagons)}<br> <strong>Total Area:</strong> ${fmtInt(totalArea)} m² `;
    zonesSummaryEl.style.display = "block";
}
```

--------------------------------

### Center Map on Zone (JavaScript)

Source: https://context7.com/alti3/hexpicker/llms.txt

Provides a function to zoom the map view to fit a specific zone's geographic bounds. It prioritizes using pre-defined outline polygons and falls back to calculating bounds from H3 cell boundaries if outlines are not available. Requires Leaflet and H3 libraries.

```javascript
// Zoom to zone's bounding box
function zoomToZone(zoneId) {
  const zone = zones.find((z) => z.id === zoneId);
  if (!zone) return;

  // Ensure outlines exist for bounds calculation
  if (!zone.outlinePolys || zone.outlinePolys.length === 0) {
    const multiLngLat = h3.cellsToMultiPolygon(
      Array.from(zone.hexagons),
      true
    );
    zone.outlinePolys = [];
    multiLngLat.forEach((polyLngLat) => {
      const latlngs = polyLngLat.map((ringLngLat) =>
        ringLngLat.map(([lng, lat]) => [lat, lng])
      );
      const outline = L.polygon(latlngs, {
        color: zone.color,
        weight: 3,
        fillOpacity: 0,
        interactive: false
      });
      zoneOutlinesLayer.addLayer(outline);
      zone.outlinePolys.push(outline);
    });
  }

  // Calculate combined bounds from all outline polygons
  let combinedBounds = null;
  if (zone.outlinePolys && zone.outlinePolys.length) {
    zone.outlinePolys.forEach((poly) => {
      const b = poly.getBounds();
      if (!combinedBounds) {
        combinedBounds = L.latLngBounds(
          b.getSouthWest(),
          b.getNorthEast()
        );
      } else {
        combinedBounds.extend(b);
      }
    });
  } else {
    // Fallback: compute bounds from cell boundaries
    const latlngs = [];
    zone.hexagons.forEach((hex) => {
      const boundary = h3.cellToBoundary(hex);
      boundary.forEach(([lat, lng]) => latlngs.push([lat, lng]));
    });
    if (latlngs.length) {
      combinedBounds = L.latLngBounds(
        latlngs.map(([lat, lng]) => L.latLng(lat, lng))
      );
    }
  }

  if (combinedBounds) {
    map.fitBounds(combinedBounds, { padding: [40, 40] });
  }
}

// Usage with button click
document.querySelector(".locate-btn").addEventListener("click", () => {
  zoomToZone(targetZoneId);
});

```

--------------------------------

### Apply Zone Styling Function

Source: https://github.com/alti3/hexpicker/blob/master/index.html

Applies visual styling to a hexagon polygon based on its assigned zone. Sets the fill opacity and color for the polygon, and resets the border weight to zero to integrate it visually into the zone.

```javascript
function applyZoneStyle(polygon, zone) {
  polygon.setStyle({
    fillOpacity: 0.5,
    fillColor: zone.color,
    weight: 0
  });
}
```