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import { getChemicalDb, putChemicalDb } from '@/utils/idbCache';
import { isCAS } from '@/utils/typeGuards/common';
import { Logger } from '@/utils/Logger';
import { getErrorMessage } from '@/helpers/exceptions';
const logger = new Logger('oshaChemicalDb');
/**
* A slimmed OSHA OBIS chemical record. Only the fields the chemical-info dialog shows are kept;
* the ~100 sampling-method / detector-tube fields in the source XML are dropped. Every value is
* optional because OBIS leaves many fields blank.
* @category Science Helpers
* @group Chemical Info
*/
export interface OshaChemical {
/** Display name, with OBIS's trailing `†`/`‡` markers removed. */
name: string;
/** CAS registry number. */
cas?: string;
/** Formula, using Unicode subscripts as OBIS publishes it. */
formula?: string;
/** Alternate names. */
synonyms: string[];
physicalDescription?: string;
molecularWeight?: string;
boilingPoint?: string;
freezingPoint?: string;
flashPoint?: string;
vaporPressure?: string;
specificGravity?: string;
relativeGasDensity?: string;
ionizationPotential?: string;
lowerExplosiveLimit?: string;
upperExplosiveLimit?: string;
/** NFPA 704 health rating (0-4). */
nfpaHealth?: string;
/** NFPA 704 flammability rating (0-4). */
nfpaFire?: string;
/** NFPA 704 instability rating (0-4). */
nfpaReactivity?: string;
/** NFPA 704 special notice, e.g. `W` or `OX`. */
nfpaSpecial?: string;
pelTwa?: string;
pelStel?: string;
pelCeiling?: string;
relTwa?: string;
relStel?: string;
relCeiling?: string;
tlvTwa?: string;
tlvStel?: string;
tlvCeiling?: string;
idlh?: string;
carcinogen?: string;
/** Link to the NIOSH Pocket Guide entry. */
nioshPocketGuideUrl?: string;
/** Link to the NOAA CAMEO Chemicals datasheet. */
cameoUrl?: string;
}
/**
* The single `chemical_db` IndexedDB row.
* @category Science Helpers
* @group Chemical Info
*/
export interface ChemicalDbRecord {
/** Row key; always `"current"`. */
id: string;
/** Epoch milliseconds the dataset was downloaded. */
fetchedAt: number;
/** Slimmed chemical records. */
chemicals: OshaChemical[];
}
/**
* Maps each {@link OshaChemical} field (except `name`/`synonyms`) to its OBIS XML element.
* @source
*/
const FIELD_MAP: ReadonlyArray<readonly [keyof OshaChemical, string]> = [
['cas', 'CASNumber'],
['formula', 'Formula'],
['physicalDescription', 'PhysicalDescription'],
['molecularWeight', 'MolecularWeight'],
['boilingPoint', 'BoilingPoint'],
['freezingPoint', 'FreezingPoint'],
['flashPoint', 'FlashPoint'],
['vaporPressure', 'VaporPressure'],
['specificGravity', 'SpecificGravity'],
['relativeGasDensity', 'RelativeGasDensity'],
['ionizationPotential', 'IonizationPotential'],
['lowerExplosiveLimit', 'LowerExplosiveLimit'],
['upperExplosiveLimit', 'UpperExplosiveLimit'],
['nfpaHealth', 'NFPAHealthRating'],
['nfpaFire', 'NFPAFireRating'],
['nfpaReactivity', 'NFPAReactivityRating'],
['nfpaSpecial', 'NFPASpecialInstruction'],
['pelTwa', 'PELTWAppm'],
['pelStel', 'PELSTELppm'],
['pelCeiling', 'PELCppm'],
['relTwa', 'RELTWAppm'],
['relStel', 'RELSTELppm'],
['relCeiling', 'RELCppm'],
['tlvTwa', 'TLVTWAppm'],
['tlvStel', 'TLVSTELppm'],
['tlvCeiling', 'TLVCppm'],
['idlh', 'IDLHppm'],
['carcinogen', 'Carcinogen'],
['nioshPocketGuideUrl', 'NIOSHpgURL'],
['cameoUrl', 'ERCameoURL'],
];
/**
* Normalizes a chemical name for matching: lowercase, OBIS dagger markers removed, and runs of
* whitespace collapsed.
* @category Science Helpers
* @group Chemical Info
* @param name - A chemical name or synonym.
* @returns The normalized key.
* @example
* ```ts
* normalizeChemicalName('ACETONE†'); // "acetone"
* normalizeChemicalName(' Sodium Hydroxide '); // "sodium hydroxide"
* ```
* @source
*/
export function normalizeChemicalName(name: string): string {
return name.replace(/[†‡]/g, '').replace(/\s+/g, ' ').trim().toLowerCase();
}
/**
* Reads one child element's text from an OBIS `<chemical>` node, stripping embedded HTML.
* @param node - The `<chemical>` element.
* @param tag - The child element name.
* @returns The cleaned text, or undefined when blank.
* @source
*/
function readField(node: Element, tag: string): string | undefined {
const raw = node.getElementsByTagName(tag)[0]?.textContent ?? '';
const text = raw
.replace(/<[^>]*>/g, '')
.replace(/\s+/g, ' ')
.trim();
return text === '' ? undefined : text;
}
/**
* Parses the OBIS `Chemical_DB.xml` document into slimmed records. Records without a name are
* skipped. Requires `DOMParser` (available on extension pages, not in the service worker).
* @category Science Helpers
* @group Chemical Info
* @param xml - The raw XML text.
* @returns The slimmed chemical records.
* @throws When the XML is malformed.
* @example
* ```ts
* parseOshaXml('<chemical_db><chemical><Analyte>ACETONE</Analyte><CASNumber>67-64-1</CASNumber></chemical></chemical_db>');
* // [{ name: "ACETONE", cas: "67-64-1", synonyms: [] }]
* ```
* @source
*/
export function parseOshaXml(xml: string): OshaChemical[] {
const doc = new DOMParser().parseFromString(xml, 'text/xml');
if (doc.getElementsByTagName('parsererror').length > 0) {
throw new Error('Malformed OSHA OBIS XML');
}
const chemicals: OshaChemical[] = [];
for (const node of Array.from(doc.getElementsByTagName('chemical'))) {
const analyte = readField(node, 'Analyte');
if (analyte === undefined) continue;
const chemical: OshaChemical = {
name: analyte.replace(/[†‡]/g, '').trim(),
synonyms: (readField(node, 'Synonyms') ?? '')
.split(';')
.map((synonym) => synonym.trim())
.filter((synonym) => synonym !== ''),
};
for (const [field, tag] of FIELD_MAP) {
const raw = readField(node, tag);
if (raw === undefined) continue;
// OBIS publishes links without a scheme.
const value = tag.endsWith('URL') && !/^https?:\/\//.test(raw) ? `https://${raw}` : raw;
Object.assign(chemical, { [field]: value });
}
chemicals.push(chemical);
}
return chemicals;
}
/**
* Lookup indexes over the loaded dataset.
* @source
*/
interface OshaIndex {
byCas: Map<string, OshaChemical>;
byName: Map<string, OshaChemical>;
/** Normalized name → sorted-token key, for word-order-insensitive matches. */
byTokens: Map<string, OshaChemical>;
}
let indexPromise: Promise<OshaIndex | undefined> | undefined;
/**
* Builds the in-memory lookup indexes for a dataset.
* @param chemicals - The chemical records.
* @returns The indexes.
* @source
*/
function buildIndex(chemicals: OshaChemical[]): OshaIndex {
const index: OshaIndex = { byCas: new Map(), byName: new Map(), byTokens: new Map() };
for (const chemical of chemicals) {
if (chemical.cas !== undefined) index.byCas.set(chemical.cas, chemical);
for (const name of [chemical.name, ...chemical.synonyms]) {
const key = normalizeChemicalName(name);
if (!index.byName.has(key)) index.byName.set(key, chemical);
const tokenKey = key.split(' ').sort().join(' ');
if (!index.byTokens.has(tokenKey)) index.byTokens.set(tokenKey, chemical);
}
}
return index;
}
/**
* Loads the OBIS dataset from IndexedDB, downloading and caching it when missing or older than
* `chemicalDb.ttlDays`. The download is abandoned after `chemicalDb.fetchTimeoutMs`, and a stale copy is
* still used when the refresh fails or times out. The result is memoized
* for the page's lifetime.
* @category Science Helpers
* @group Chemical Info
* @returns The lookup index, or undefined when no copy is cached and the download failed.
* @example
* ```ts
* const index = await loadOshaIndex();
* ```
* @source
*/
function loadOshaIndex(): Promise<OshaIndex | undefined> {
indexPromise ??= (async () => {
const cached = await getChemicalDb();
const ttlMs = chemicalDb.ttlDays * 24 * 60 * 60 * 1000;
if (cached !== undefined && Date.now() - cached.fetchedAt < ttlMs) {
return buildIndex(cached.chemicals);
}
try {
// The signal also covers reading the body, so a stalled download can't hang the dialog.
const response = await fetch(chemicalDb.url, {
signal: AbortSignal.timeout(chemicalDb.fetchTimeoutMs),
});
if (!response.ok) throw new Error(`OSHA OBIS responded ${response.status}`);
const chemicals = parseOshaXml(await response.text());
await putChemicalDb(chemicals, Date.now());
return buildIndex(chemicals);
} catch (error) {
logger.error(`Failed to download OSHA OBIS chemical DB: ${getErrorMessage(error)}`, {
error,
});
return cached === undefined ? undefined : buildIndex(cached.chemicals);
}
})();
// Don't memoize a failure; let the next open retry.
void indexPromise.then((index) => {
if (index === undefined) indexPromise = undefined;
});
return indexPromise;
}
/**
* Looks a searched term up in the OSHA OBIS dataset by CAS number, exact name/synonym, or the
* same words in any order (so "hydroxide sodium" still finds "sodium hydroxide").
* @category Science Helpers
* @group Chemical Info
* @param term - A chemical name or CAS number.
* @returns The matching record, or undefined when OBIS has none or is unavailable.
* @example
* ```ts
* await lookupOshaChemical('67-64-1'); // { name: "ACETONE", nfpaHealth: "1", ... }
* await lookupOshaChemical('hydroxide sodium'); // { name: "SODIUM HYDROXIDE", ... }
* ```
* @source
*/
export async function lookupOshaChemical(term: string): Promise<OshaChemical | undefined> {
const index = await loadOshaIndex();
if (index === undefined) return undefined;
const trimmed = term.trim();
if (isCAS(trimmed)) return index.byCas.get(trimmed);
const key = normalizeChemicalName(trimmed);
return index.byName.get(key) ?? index.byTokens.get(key.split(' ').sort().join(' '));
}
/**
* Clears the memoized index so the next lookup reloads from storage. Test helper.
* @category Science Helpers
* @group Chemical Info
* @example
* ```ts
* resetOshaIndex();
* ```
* @source
*/
export function resetOshaIndex(): void {
indexPromise = undefined;
}
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