Function computeLandUse

supabase/functions/gee-analytics/index.ts:212–272

(token: string, projectId: string, coords: [number, number][])

// ── Land Use (ESA WorldCover) ────────────────────────────────────

async function computeLandUse(token: string, projectId: string, coords: [number, number][]) {
  const geometry = makeGeometry(coords);

  // Load ESA WorldCover v200
  const collection = {
    functionInvocationValue: {
      functionName: "ImageCollection.load",
      arguments: { id: { constantValue: "ESA/WorldCover/v200" } },
    },
  };
  const image = {
    functionInvocationValue: {
      functionName: "ImageCollection.mosaic",
      arguments: { collection },
    },
  };
  const clipped = {
    functionInvocationValue: {
      functionName: "Image.clip",
      arguments: { input: image, geometry },
    },
  };

  // Use frequencyHistogram reducer to get pixel counts per class
  const histResult = await computeValue(token, projectId, reduceRegion(clipped, geometry, "Reducer.frequencyHistogram", 10));
  console.log("Land use histogram:", JSON.stringify(histResult));

  // ESA WorldCover class codes
  const classNames: Record<string, string> = {
    "10": "Tree cover",
    "20": "Shrubland",
    "30": "Grassland",
    "40": "Cropland",
    "50": "Built-up",
    "60": "Bare/sparse",
    "70": "Snow/ice",
    "80": "Water",
    "90": "Wetland",
    "95": "Mangroves",
    "100": "Moss/lichen",
  };

  // The histogram is in result.Map (the band name)
  const hist = histResult?.result?.Map || histResult?.result?.map || {};
  let total = 0;
  const counts: Record<string, number> = {};
  for (const [classCode, count] of Object.entries(hist)) {
    const n = Number(count);
    total += n;
    const name = classNames[classCode] || `Class ${classCode}`;
    counts[name] = (counts[name] || 0) + n;
  }

  if (total === 0) return null;

  const landUse: Record<string, number> = {};
  for (const [name, count] of Object.entries(counts)) {
    landUse[name] = Math.round((count / total) * 1000) / 10;