1 files changed, 47 insertions, 0 deletions
diff --git a/web/static/official-climb-profile-logic.js b/web/static/official-climb-profile-logic.js
new file mode 100644
index 0000000..c84960b
--- /dev/null
+++ b/web/static/official-climb-profile-logic.js
@@ -0,0 +1,47 @@
+(() => {
+  const clamp = (value, min, max) => Math.max(min, Math.min(max, value));
+  const profileStepSizesM = [100, 200, 500, 1000];
+  const displayStepForLength = (lengthM) => profileStepSizesM.find((stepM) => Math.ceil(lengthM / stepM) <= 30) || profileStepSizesM[profileStepSizesM.length - 1];
+  const profileBandForSlope = (slopePercent) => {
+    if (slopePercent < 0) return "downhill";
+    if (slopePercent < 3) return "0-3";
+    if (slopePercent < 6) return "3-6";
+    if (slopePercent < 9) return "6-9";
+    if (slopePercent < 12) return "9-12";
+    return "12-plus";
+  };
+  const officialProfileSections = (points, startIndex, endIndex, stepM) => {
+    const startDistanceM = points[startIndex].distanceKm * 1000;
+    const endDistanceM = points[endIndex].distanceKm * 1000;
+    const sections = [];
+    let pointIndex = startIndex;
+    const elevationAtDistance = (distanceM) => {
+      while (pointIndex < endIndex - 1 && points[pointIndex + 1].distanceKm * 1000 < distanceM) pointIndex++;
+      const nextIndex = Math.min(pointIndex + 1, endIndex);
+      const first = points[pointIndex];
+      const next = points[nextIndex];
+      const distanceSpan = next.distanceKm * 1000 - first.distanceKm * 1000;
+      if (distanceSpan <= 0) return first.elevationM;
+      const fraction = (distanceM - first.distanceKm * 1000) / distanceSpan;
+      return first.elevationM + clamp(fraction, 0, 1) * (next.elevationM - first.elevationM);
+    };
+    for (let sectionStartM = startDistanceM; sectionStartM < endDistanceM; sectionStartM += stepM) {
+      const sectionEndM = Math.min(sectionStartM + stepM, endDistanceM);
+      const startElevation = elevationAtDistance(sectionStartM);
+      const endElevation = elevationAtDistance(sectionEndM);
+      const slopePercent = (endElevation - startElevation) / (sectionEndM - sectionStartM) * 100;
+      sections.push({
+        startDistanceKm: sectionStartM / 1000,
+        endDistanceKm: sectionEndM / 1000,
+        startElevation,
+        endElevation,
+        slopePercent,
+        band: profileBandForSlope(slopePercent),
+      });
+    }
+    return sections;
+  };
+  const api = { displayStepForLength, profileBandForSlope, officialProfileSections };
+  if (typeof module !== "undefined" && module.exports) module.exports = api;
+  else window.OfficialClimbProfileLogic = api;
+})();