fix(search): locale-invariant Turkish case folding in every search path (#1640)

Turkish upper and lower case queries now return the same results everywhere a
title can be searched. Lower-casing the dotted capital "İ" (U+0130) leaves a
combining dot behind, so "İnş" and "inş" reached different search arms and
different results.

- Case folding is locale-invariant: `toLowerCase()`, never `toLocaleLowerCase()`,
  which under a Turkish or Azeri OS locale maps ASCII "I" to the dotless "ı".
- The Electron content search composes to NFC and drops the leftover combining
  marks before tokenizing, and its LIKE/GLOB pattern builders additionally spell
  the `'tr'`-locale İ forms, since SQLite LIKE folds only ASCII.
- A shared `foldSearchText` covers every in-memory filter: channel lists, the
  Xtream and Stalker catalogs, category filters, collections, the EPG guide, the
  command palette, sources, the playlist switcher and the download lists.
- Composing before the strip keeps canonically equivalent spellings equal while
  the fold stays accent-sensitive; the Turkish I/ı pair is deliberately left
  alone, as the FTS index does not fold it either.

Covered by a SQLite-backed spec over the real trigram index plus regression
cases in the affected renderer specs.

Closes #609.

Co-Authored-By: Justin Willhite <5132924+thejdubb02@users.noreply.github.com>
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

libs/ui/components/src/lib/channel-list-container/all-channels-view/all-channels-view.component.spec.ts

@@ -91,6 +91,30 @@ describe('AllChannelsViewComponent', () => {
         localStorage.removeItem(ALL_CHANNELS_SORT_STORAGE_KEY);
     });
 
+    it('filters the Turkish dotted capital İ case-insensitively (issue #609)', () => {
+        const turkishChannel = createChannel(
+            'channel-2',
+            'İnşaat Kanalı',
+            'https://example.com/insaat.m3u8'
+        );
+        fixture.componentRef.setInput('channels', [
+            primaryChannel,
+            turkishChannel,
+        ]);
+
+        fixture.componentRef.setInput('searchTerm', 'inş');
+        fixture.detectChanges();
+        expect(component.filteredChannels()).toEqual([turkishChannel]);
+
+        fixture.componentRef.setInput('searchTerm', 'İNŞ');
+        fixture.detectChanges();
+        expect(component.filteredChannels()).toEqual([turkishChannel]);
+
+        fixture.componentRef.setInput('searchTerm', 'news');
+        fixture.detectChanges();
+        expect(component.filteredChannels()).toEqual([primaryChannel]);
+    });
+
     it('defaults to playlist order when no saved sort mode exists', () => {
         expect(component.allChannelsSortMode()).toBe('server');
         expect(component.allChannelsSortLabel()).toBe('Playlist Order');

libs/ui/components/src/lib/channel-list-container/all-channels-view/all-channels-view.component.ts

@@ -21,6 +21,7 @@ import { EpgRuntimeBridgeService } from '@iptvnator/epg/data-access';
 import { SettingsStore } from '@iptvnator/services';
 import { resolveChannelEpgLookupKey } from '@iptvnator/m3u-state';
 import {
+    foldSearchText,
     Channel,
     EpgProgram,
     epgProviderClockMs,
@@ -127,10 +128,12 @@ export class AllChannelsViewComponent {
      * reference when there is no search term, so large lists avoid cloning.
      */
     readonly filteredChannels = computed(() => {
-        const term = this.searchTerm().trim().toLowerCase();
+        const term = foldSearchText(this.searchTerm().trim());
         const channels = this.channels();
         const filteredChannels = term
-            ? channels.filter((ch) => ch.name?.toLowerCase().includes(term))
+            ? channels.filter((ch) =>
+                  foldSearchText(ch.name ?? '').includes(term)
+              )
             : channels;
 
         return sortPlaylistChannelItems(

libs/ui/components/src/lib/channel-list-container/channel-list-container.component.ts

@@ -50,6 +50,7 @@ import {
     SettingsStore,
 } from '@iptvnator/services';
 import {
+    foldSearchText,
     Channel,
     EpgProgram,
     isM3uRecentlyViewedItem,
@@ -217,12 +218,12 @@ export class ChannelListContainerComponent implements OnInit, OnDestroy {
     private readonly routeSearchTerm = queryParamSignal(
         this.route,
         'q',
-        (value) => (value ?? '').trim().toLowerCase()
+        (value) => foldSearchText((value ?? '').trim())
     );
     readonly workspaceSearchTerm = computed(() => {
         const hostTerm = this.searchTerm();
         if (hostTerm !== null) {
-            return hostTerm.trim().toLowerCase();
+            return foldSearchText(hostTerm.trim());
         }
         return this.isWorkspaceLayout ? this.routeSearchTerm() : '';
     });

libs/ui/components/src/lib/channel-list-container/favorites-view/favorites-view.component.ts

@@ -22,6 +22,7 @@ import { EpgRuntimeBridgeService } from '@iptvnator/epg/data-access';
 import { SettingsStore } from '@iptvnator/services';
 import { resolveChannelEpgLookupKey } from '@iptvnator/m3u-state';
 import {
+    foldSearchText,
     Channel,
     EpgProgram,
     epgProviderClockMs,
@@ -97,16 +98,16 @@ export class FavoritesViewComponent {
     );
     readonly filteredFavorites = computed(() => {
         const favorites = this.favorites();
-        const term = this.searchTerm().trim().toLowerCase();
+        const term = foldSearchText(this.searchTerm().trim());
 
         if (!term) {
             return favorites;
         }
 
         return favorites.filter((channel) =>
-            `${channel.name ?? ''} ${channel.group?.title ?? ''}`
-                .toLowerCase()
-                .includes(term)
+            foldSearchText(
+                `${channel.name ?? ''} ${channel.group?.title ?? ''}`
+            ).includes(term)
         );
     });
 

libs/ui/components/src/lib/channel-list-container/groups-view/group-management-dialog/group-management-dialog.component.ts

@@ -15,6 +15,7 @@ import {
 } from '@angular/material/dialog';
 import { MatIconModule } from '@angular/material/icon';
 import { TranslatePipe } from '@ngx-translate/core';
+import { foldSearchText } from '@iptvnator/shared/interfaces';
 
 export interface GroupManagementDialogGroup {
     readonly count: number;
@@ -59,14 +60,14 @@ export class GroupManagementDialogComponent {
     );
 
     readonly filteredGroups = computed(() => {
-        const term = this.searchTerm().trim().toLowerCase();
+        const term = foldSearchText(this.searchTerm().trim());
 
         if (!term) {
             return this.groups();
         }
 
         return this.groups().filter((group) =>
-            group.key.toLowerCase().includes(term)
+            foldSearchText(group.key).includes(term)
         );
     });
 

libs/ui/components/src/lib/channel-list-container/groups-view/groups-view.component.ts

@@ -24,6 +24,7 @@ import { EpgRuntimeBridgeService } from '@iptvnator/epg/data-access';
 import { resolveChannelEpgLookupKey } from '@iptvnator/m3u-state';
 import { SettingsStore } from '@iptvnator/services';
 import {
+    foldSearchText,
     Channel,
     EpgProgram,
     epgProviderClockMs,
@@ -320,7 +321,7 @@ export class GroupsViewComponent {
     });
 
     readonly workspaceFilteredGroups = computed<FilteredGroupView[]>(() => {
-        const term = this.searchTerm().trim().toLowerCase();
+        const term = foldSearchText(this.searchTerm().trim());
         const groups = this.visibleGroups();
 
         if (!term) {
@@ -333,11 +334,11 @@ export class GroupsViewComponent {
         }
 
         return groups.reduce<FilteredGroupView[]>((acc, group) => {
-            const titleMatches = group.key.toLowerCase().includes(term);
+            const titleMatches = foldSearchText(group.key).includes(term);
             const channels = titleMatches
                 ? group.channels
                 : group.channels.filter((channel) =>
-                      `${channel.name ?? ''}`.toLowerCase().includes(term)
+                      foldSearchText(`${channel.name ?? ''}`).includes(term)
                   );
 
             if (channels.length === 0) {
@@ -355,14 +356,16 @@ export class GroupsViewComponent {
     });
 
     readonly filteredGroups = computed<FilteredGroupView[]>(() => {
-        const term = this.localGroupSearchTerm().trim().toLowerCase();
+        const term = foldSearchText(this.localGroupSearchTerm().trim());
         const groups = this.workspaceFilteredGroups();
 
         if (!term) {
             return groups;
         }
 
-        return groups.filter((group) => group.key.toLowerCase().includes(term));
+        return groups.filter((group) =>
+            foldSearchText(group.key).includes(term)
+        );
     });
 
     readonly hasAnyGroups = computed(() => this.allGroups().length > 0);

libs/ui/components/src/lib/channel-list-container/recent-view/recent-view.component.ts

@@ -17,6 +17,7 @@ import { EpgRuntimeBridgeService } from '@iptvnator/epg/data-access';
 import { resolveChannelEpgLookupKey } from '@iptvnator/m3u-state';
 import { SettingsStore } from '@iptvnator/services';
 import {
+    foldSearchText,
     Channel,
     EpgProgram,
     epgProviderClockMs,
@@ -78,16 +79,16 @@ export class RecentViewComponent {
 
     readonly filteredRecentItems = computed(() => {
         const recentItems = this.recentItems();
-        const term = this.searchTerm().trim().toLowerCase();
+        const term = foldSearchText(this.searchTerm().trim());
 
         if (!term) {
             return recentItems;
         }
 
         return recentItems.filter(({ channel }) =>
-            `${channel.name ?? ''} ${channel.group?.title ?? ''}`
-                .toLowerCase()
-                .includes(term)
+            foldSearchText(
+                `${channel.name ?? ''} ${channel.group?.title ?? ''}`
+            ).includes(term)
         );
     });
 

libs/ui/components/src/lib/vod-sources/vod-sources-menu.component.ts

@@ -14,6 +14,7 @@ import {
 } from '@angular/material/slide-toggle';
 import { TranslatePipe } from '@ngx-translate/core';
 import {
+    foldSearchText,
     playlistDisplayLabel,
     VodSourceDescriptor,
     VodSourceMatchKind,
@@ -111,16 +112,16 @@ export class VodSourcesMenuComponent {
 
     /** Sources surviving the search box; what "check all" acts on. */
     private readonly searchedSources = computed(() => {
-        const query = this.filter().trim().toLowerCase();
+        const query = foldSearchText(this.filter().trim());
         const sources = this.sources();
         if (!query || !this.showFilter()) {
             return sources;
         }
 
         return sources.filter((source) =>
-            playlistDisplayLabel(source.playlistName, source.playlistId)
-                .toLowerCase()
-                .includes(query)
+            foldSearchText(
+                playlistDisplayLabel(source.playlistName, source.playlistId)
+            ).includes(query)
         );
     });