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- Move common icon parsing logic into module - Return a "real" icon value during error handling to avoid downstream consumers from trying to use an icon named "false" - Use named regex to parse icon URLs based on API specification
94 lines
3.5 KiB
JavaScript
94 lines
3.5 KiB
JavaScript
/**
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* Parses weather.gov icon URLs and extracts weather condition information
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* Handles both single and dual condition formats according to the weather.gov API spec
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*
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* NOTE: The 'icon' properties are marked as deprecated in the API documentation. This
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* is because it will eventually be replaced with a more generic value that is not a URL.
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*/
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import { debugFlag } from '../utils/debug.mjs';
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/**
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* Parses a weather.gov icon URL and extracts condition and timing information
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* @param {string} iconUrl - Icon URL from weather.gov API (e.g., "/icons/land/day/skc?size=medium")
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* @param {boolean} _isNightTime - Optional override for night time determination
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* @returns {Object} Parsed icon data with conditionIcon, probability, and isNightTime
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*/
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const parseIconUrl = (iconUrl, _isNightTime) => {
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if (!iconUrl) {
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throw new Error('No icon URL provided');
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}
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// Parse icon URL according to API spec: /icons/{set}/{timeOfDay}/{condition}?{params}
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// where {condition} might be single (skc) or dual (tsra_hi,20/rain,50)
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// Each period will have an icon, or two if there is changing weather during that period
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// see https://github.com/weather-gov/api/discussions/557#discussioncomment-9949521
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// (On the weather.gov site, changing conditions results in a "dualImage" forecast icon)
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const iconUrlPattern = /\/icons\/(?<set>\w+)\/(?<timeOfDay>day|night)\/(?<condition>[^?]+)(?:\?(?<params>.*))?$/i;
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const match = iconUrl.match(iconUrlPattern);
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if (!match?.groups) {
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throw new Error(`Unable to parse icon URL format: ${iconUrl}`);
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}
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const { timeOfDay, condition } = match.groups;
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// Determine if it's night time with preference strategy:
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// 1. Primary: use _isNightTime parameter if provided (such as from API's isDaytime property)
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// 2. Secondary: use timeOfDay parsed from URL
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let isNightTime;
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if (_isNightTime !== undefined) {
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isNightTime = _isNightTime;
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} else if (timeOfDay === 'day') {
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isNightTime = false;
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} else if (timeOfDay === 'night') {
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isNightTime = true;
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} else {
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console.warn(`parseIconUrl: unexpected timeOfDay value: ${timeOfDay}`);
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isNightTime = false;
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}
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// Dual conditions can have a probability
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// Examples: "tsra_hi,30/sct", "rain_showers,30/tsra_hi,50", "hot/tsra_hi,70"
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let conditionIcon;
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let probability;
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if (condition.includes('/')) { // Two conditions
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const conditions = condition.split('/');
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const firstCondition = conditions[0] || '';
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const secondCondition = conditions[1] || '';
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const [firstIcon, firstProb] = firstCondition.split(',');
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const [secondIcon, secondProb] = secondCondition.split(',');
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// Default to 100% probability if not specified (high confidence)
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const firstProbability = parseInt(firstProb, 10) || 100;
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const secondProbability = parseInt(secondProb, 10) || 100;
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if (secondIcon !== firstIcon) {
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// When there's more than one condition, use the second condition
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// QUESTION: should the condition with the higher probability determine which one to use?
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// if (firstProbability >= secondProbability) { ... }
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conditionIcon = secondIcon;
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probability = secondProbability;
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if (debugFlag('icons')) {
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console.debug(`2️⃣ Using second condition: '${secondCondition}' instead of first '${firstCondition}'`);
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}
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} else {
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conditionIcon = firstIcon;
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probability = firstProbability;
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}
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} else { // Single condition
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const [name, prob] = condition.split(',');
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conditionIcon = name;
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probability = parseInt(prob, 10) || 100;
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}
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return {
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conditionIcon,
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probability,
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isNightTime,
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};
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};
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export default parseIconUrl;
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