KNMI MCP Server

/** * Copyright 2025 David Stotijn * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ /** * Location resolver for converting location names to KNMI grid identifiers. * Based on the KNMI iOS app GridDefinition approach. * @see https://gitlab.com/KNMI-OSS/KNMI-App/knmi-app-ios/-/blob/35a30d8543995b8f297612341b24d5f7f7e8a366/KNMI/SharedLibrary/Sources/GridDefinition/GridDefinition.swift */ import residencesData from "./residences.json" with { type: "json" }; export interface LocationPoint { id: string; name: string; normalised: string; coordinates: [number, number]; // [longitude, latitude] disambiguator: string; } /** * KNMI Grid Definition parameters (from iOS app). */ const KNMI_GRID = { southWest: { lat: 50.7, lon: 3.2 }, northEast: { lat: 53.6, lon: 7.4 }, steps: { lat: 35, lon: 30 }, prefix: "A", direction: "NWCR", // NorthWestColumnRow projection: "epsg4326", }; /** * Convert latitude/longitude coordinates to a grid identifier using KNMI's exact algorithm. * Based on GridDefinition.swift from KNMI iOS app. */ function coordinatesToGridId(lat: number, lon: number): string { const { southWest, northEast, steps, prefix, direction } = KNMI_GRID; // Check if coordinate is within grid bounds const withinBounds = direction === "NWCR" ? lat > southWest.lat && lat <= northEast.lat && lon >= southWest.lon && lon < northEast.lon : lat >= southWest.lat && lat < northEast.lat && lon >= southWest.lon && lon < northEast.lon; if (!withinBounds) { throw new Error( `Coordinate (${lat}, ${lon}) is outside the KNMI grid bounds`, ); } // Calculate multipliers const latitudeMultiplier = steps.lat / (northEast.lat - southWest.lat); const longitudeMultiplier = steps.lon / (northEast.lon - southWest.lon); let cellNumber: number; if (direction === "NWCR") { // NorthWestColumnRow: Cell 0 is in the north west corner // First counting from North to South, then going West to East const latitudeCell = Math.floor( (northEast.lat - lat) * latitudeMultiplier, ); const longitudeCell = Math.floor( (lon - southWest.lon) * longitudeMultiplier, ); cellNumber = latitudeCell + longitudeCell * steps.lat; } else { // SouthWestColumnRow: Cell 0 is in the south west corner // First counting from South to North, then going West to East const latitudeCell = Math.floor( (lat - southWest.lat) * latitudeMultiplier, ); const longitudeCell = Math.floor( (lon - southWest.lon) * longitudeMultiplier, ); cellNumber = latitudeCell + longitudeCell * steps.lat; } return `${prefix}${cellNumber}`; } /** * Normalize location name for searching. */ function normalizeLocationName(name: string): string { return name .toLowerCase() .replace(/[^a-z0-9\s]/g, "") .replace(/\s+/g, "") .trim(); } /** * Resolve location name to grid identifier. */ export async function resolveLocation(location: string): Promise<string> { const normalizedInput = normalizeLocationName(location); // Search for exact name match first for (const residence of residencesData as LocationPoint[]) { if ( residence.normalised === normalizedInput || normalizeLocationName(residence.name) === normalizedInput ) { const [lon, lat] = residence.coordinates; return coordinatesToGridId(lat, lon); } } // Search for partial matches const partialMatches: Array<{ residence: LocationPoint; score: number }> = []; for (const residence of residencesData as LocationPoint[]) { const residenceNormalized = residence.normalised; const nameNormalized = normalizeLocationName(residence.name); // Calculate match score let score = 0; if ( residenceNormalized.includes(normalizedInput) || normalizedInput.includes(residenceNormalized) ) { score += 0.8; } if ( nameNormalized.includes(normalizedInput) || normalizedInput.includes(nameNormalized) ) { score += 0.6; } // Check disambiguator (province/region) const disambiguatorNormalized = normalizeLocationName( residence.disambiguator, ); if ( disambiguatorNormalized.includes(normalizedInput) || normalizedInput.includes(disambiguatorNormalized) ) { score += 0.3; } if (score > 0) { partialMatches.push({ residence, score }); } } if (partialMatches.length === 0) { throw new Error( `Location not found: ${location}. Please try a more specific location name.`, ); } // Sort by score and return the best match partialMatches.sort((a, b) => b.score - a.score); const bestMatch = partialMatches[0]; if (!bestMatch) { throw new Error( `Location not found: ${location}. Please try a more specific location name.`, ); } const [lon, lat] = bestMatch.residence.coordinates; return coordinatesToGridId(lat, lon); }