Add google uule query param support for regional search

google/search_test.go

@@ -133,6 +133,68 @@ func TestBuildSearchURL(t *testing.T) {
 				}
 			},
 		},
+		{
+			name: "curated city region resolves to canonical google uule without country market",
+			query: core.Query{
+				Text:   "weather",
+				Region: "New York",
+				Filter: true,
+			},
+			check: func(t *testing.T, params url.Values, host string) {
+				t.Helper()
+				if host != "www.google.com" {
+					t.Fatalf("unexpected host: %s", host)
+				}
+				// "New York" resolves to the exact Google canonical name
+				// "New York,New York,United States", which is what Google
+				// actually honors (a bare city name is ignored).
+				if got := params.Get("uule"); got != "w+CAIQICIfTmV3IFlvcmssTmV3IFlvcmssVW5pdGVkIFN0YXRlcw==" {
+					t.Fatalf("unexpected uule value: %q", got)
+				}
+				if got := params.Get("gl"); got != "" {
+					t.Fatalf("city region should not set gl, got %q", got)
+				}
+			},
+		},
+		{
+			name: "bare city Berlin resolves to canonical google uule",
+			query: core.Query{
+				Text:   "weather",
+				Region: "Berlin",
+				Filter: true,
+			},
+			check: func(t *testing.T, params url.Values, host string) {
+				t.Helper()
+				// region=Berlin -> "Berlin,Berlin,Germany" canonical, which is
+				// the form Google honors. A bare "Berlin" UULE is ignored.
+				if got := params.Get("uule"); got != "w+CAIQICIVQmVybGluLEJlcmxpbixHZXJtYW55" {
+					t.Fatalf("unexpected uule value: %q", got)
+				}
+				if got := params.Get("gl"); got != "" {
+					t.Fatalf("city region should not set gl, got %q", got)
+				}
+			},
+		},
+		{
+			name: "numeric yandex region does not set google market",
+			query: core.Query{
+				Text:   "weather",
+				Region: "213",
+				Filter: true,
+			},
+			check: func(t *testing.T, params url.Values, host string) {
+				t.Helper()
+				if host != "www.google.com" {
+					t.Fatalf("unexpected host: %s", host)
+				}
+				if got := params.Get("gl"); got != "" {
+					t.Fatalf("numeric region should not set gl, got %q", got)
+				}
+				if got := params.Get("uule"); got != "" {
+					t.Fatalf("numeric region should not set uule, got %q", got)
+				}
+			},
+		},
 		{
 			name: "site and filetype without text",
 			query: core.Query{

google/url.go

@@ -1,6 +1,7 @@
 package google
 
 import (
+	"encoding/base64"
 	"errors"
 	"fmt"
 	"net/url"
@@ -225,6 +226,10 @@ var googleDefaultCountryByLanguage = map[string]string{
 	"ko": "kr",
 }
 
+const googleUULEPrefix = "w+CAIQICI"
+
+var googleUULELengthAlphabet = []byte("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_")
+
 // BuildURL builds a Google web search URL from Query fields.
 // It returns an error when the resulting query text is empty or invalid.
 func BuildURL(q core.Query) (string, error) {
@@ -289,6 +294,9 @@ func BuildURL(q core.Query) (string, error) {
 	if locale.country != "" {
 		params.Add("gl", locale.country)
 	}
+	if uule := googleUULE(q.Region); uule != "" {
+		params.Add("uule", uule)
+	}
 	if locale.language != "" {
 		params.Add("hl", locale.language)
 		params.Add("lr", "lang_"+locale.language)
@@ -355,6 +363,9 @@ func BuildImageURL(q core.Query) (string, error) {
 	if locale.country != "" {
 		params.Add("gl", locale.country)
 	}
+	if uule := googleUULE(q.Region); uule != "" {
+		params.Add("uule", uule)
+	}
 	if locale.language != "" {
 		params.Add("hl", locale.language)
 		params.Add("lr", "lang_"+locale.language)
@@ -420,6 +431,43 @@ func googleDomain(locale googleLocaleParams) string {
 	return GoogleDomains[""]
 }
 
+// googleUULE builds a Google UULE v1 value for a region hint.
+//
+// UULE only takes effect when the encoded string is an exact Google geotargets
+// canonical name; a bare free-text city is silently ignored by Google. We
+// therefore resolve the region first (core.ResolveRegion) and encode the
+// resolved canonical name when one is found. Country-level hints intentionally
+// produce no UULE — those are conveyed via gl= instead.
+func googleUULE(region string) string {
+	target := core.ResolveRegion(region)
+	canonical := target.GoogleCanonical
+	if canonical == "" {
+		// No resolved canonical name. A bare country code (e.g. "DE") or a
+		// numeric Yandex lr ID must not become a UULE; both are handled
+		// elsewhere (gl=) or are not applicable to Google.
+		if target.Country != "" || target.YandexLR != "" {
+			return ""
+		}
+		// Best-effort: encode the raw free-text region. This may be ignored by
+		// Google if it isn't a canonical name, matching prior behavior.
+		canonical = strings.TrimSpace(region)
+	}
+	if canonical == "" {
+		return ""
+	}
+	return encodeGoogleUULE(canonical)
+}
+
+// encodeGoogleUULE encodes a canonical location name into a UULE v1 value:
+// a fixed prefix, a single length-tag character, then base64(name).
+func encodeGoogleUULE(canonical string) string {
+	length := len([]rune(canonical))
+	if length <= 0 || length >= len(googleUULELengthAlphabet) {
+		return ""
+	}
+	return googleUULEPrefix + string(googleUULELengthAlphabet[length]) + base64.StdEncoding.EncodeToString([]byte(canonical))
+}
+
 // SourceImage contains parsed Google image metadata extracted from result links.
 type SourceImage struct {
 	PageURL     string