feat(core): add Electron runtime, services, and app composition

src/core/services/subtitle-processing-controller.ts

@@ -0,0 +1,101 @@
+import type { SubtitleData } from '../../types';
+
+export interface SubtitleProcessingControllerDeps {
+  tokenizeSubtitle: (text: string) => Promise<SubtitleData | null>;
+  emitSubtitle: (payload: SubtitleData) => void;
+  logDebug?: (message: string) => void;
+  now?: () => number;
+}
+
+export interface SubtitleProcessingController {
+  onSubtitleChange: (text: string) => void;
+  refreshCurrentSubtitle: (textOverride?: string) => void;
+}
+
+export function createSubtitleProcessingController(
+  deps: SubtitleProcessingControllerDeps,
+): SubtitleProcessingController {
+  let latestText = '';
+  let lastEmittedText = '';
+  let processing = false;
+  let staleDropCount = 0;
+  let refreshRequested = false;
+  const now = deps.now ?? (() => Date.now());
+
+  const processLatest = (): void => {
+    if (processing) {
+      return;
+    }
+
+    processing = true;
+
+    void (async () => {
+      while (true) {
+        const text = latestText;
+        const forceRefresh = refreshRequested;
+        refreshRequested = false;
+        const startedAtMs = now();
+
+        if (!text.trim()) {
+          deps.emitSubtitle({ text, tokens: null });
+          lastEmittedText = text;
+          break;
+        }
+
+        let output: SubtitleData = { text, tokens: null };
+        try {
+          const tokenized = await deps.tokenizeSubtitle(text);
+          if (tokenized) {
+            output = tokenized;
+          }
+        } catch (error) {
+          deps.logDebug?.(`Subtitle tokenization failed: ${(error as Error).message}`);
+        }
+
+        if (latestText !== text) {
+          staleDropCount += 1;
+          deps.logDebug?.(
+            `Dropped stale subtitle tokenization result; dropped=${staleDropCount}, elapsed=${now() - startedAtMs}ms`,
+          );
+          continue;
+        }
+
+        deps.emitSubtitle(output);
+        lastEmittedText = text;
+        deps.logDebug?.(
+          `Subtitle tokenization delivered; elapsed=${now() - startedAtMs}ms, staleDrops=${staleDropCount}`,
+        );
+        break;
+      }
+    })()
+      .catch((error) => {
+        deps.logDebug?.(`Subtitle processing loop failed: ${(error as Error).message}`);
+      })
+      .finally(() => {
+        processing = false;
+        if (refreshRequested || latestText !== lastEmittedText) {
+          processLatest();
+        }
+      });
+  };
+
+  return {
+    onSubtitleChange: (text: string) => {
+      if (text === latestText) {
+        return;
+      }
+      latestText = text;
+      processLatest();
+    },
+    refreshCurrentSubtitle: (textOverride?: string) => {
+      if (typeof textOverride === 'string') {
+        latestText = textOverride;
+      }
+      if (!latestText.trim()) {
+        return;
+      }
+      refreshRequested = true;
+      processLatest();
+    },
+  };
+}