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import type { ProfileBand, ProfilePoint } from "./types.js";
export interface OfficialProfileSection {
startDistanceKm: number;
endDistanceKm: number;
startElevation: number;
endElevation: number;
slopePercent: number;
band: ProfileBand;
}
const clamp = (value: number, min: number, max: number) => Math.max(min, Math.min(max, value));
const profileStepSizesM: number[] = [100, 200, 500, 1000];
const displayStepForLength = (lengthM: number): number =>
profileStepSizesM.find((stepM) => Math.ceil(lengthM / stepM) <= 30) || profileStepSizesM[profileStepSizesM.length - 1];
const profileBandForSlope = (slopePercent: number): ProfileBand => {
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: ProfilePoint[], startIndex: number, endIndex: number, stepM: number): OfficialProfileSection[] => {
const startDistanceM = points[startIndex].distanceKm * 1000;
const endDistanceM = points[endIndex].distanceKm * 1000;
const sections: OfficialProfileSection[] = [];
let pointIndex = startIndex;
const elevationAtDistance = (distanceM: number) => {
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;
};
export { displayStepForLength, profileBandForSlope, officialProfileSections };
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