Recognise major cities

Refs #31

package.json

@@ -7,6 +7,7 @@
     "@effect/schema": "^0.68.1",
     "@js-temporal/polyfill": "^0.4.4",
     "@observablehq/framework": "^1.9.0",
+    "@vvo/tzdb": "^6.141.0",
     "d3-dsv": "^3.0.1",
     "d3-time-format": "^4.1.0",
     "diacritics": "^1.3.0",

src/lib/Iso3166.ts

@@ -1,4 +1,5 @@
 import { Schema } from '@effect/schema'
+import { rawTimeZones } from '@vvo/tzdb'
 import diacritics from 'diacritics'
 import { Array, Option, type Predicate, String, flow } from 'effect'
 import iso3166 from 'i18n-iso-countries'
@@ -27,6 +28,17 @@ export const guessCountry: (location: string) => Option.Option<Alpha2Code> = flo
           subDivision => subDivision.country,
         ),
       ),
+      Option.orElse(() =>
+        Option.map(
+          Array.findFirst(rawTimeZones, timezone =>
+            Array.some(
+              timezone.mainCities,
+              mainCity => diacritics.remove(location).toLowerCase() === diacritics.remove(mainCity).toLowerCase(),
+            ),
+          ),
+          timeZone => timeZone.countryCode,
+        ),
+      ),
     ),
   ),
   Option.filter(isAlpha2Code),

test/Iso3166.test.ts

@@ -11,9 +11,11 @@ describe('guessCountry', () => {
     ['Czech Republic', 'CZ'],
     ['Czechia', 'CZ'],
     ['GHANA', 'GH'],
+    ['London', 'GB'],
     ['London, Ontario', 'CA'],
     ['London, UK', 'GB'],
     ['London, United Kingdom', 'GB'],
+    ['New York City and Los Angeles', 'US'],
     ['Québec', 'CA'],
     ['Rio de Janeiro, Brazil.', 'BR'],
     ['Sunnyvale, California', 'US'],
@@ -31,9 +33,7 @@ describe('guessCountry', () => {
   test.for([
     'Beijing University of Technology, Beijing 100124, PR China',
     'Fayetteville GA (near Atlanta)',
-    'London',
     'Mars',
-    'New York City and Los Angeles',
     'Southeast Asia',
     'The UK',
   ])("doesn't guess %s", input => {