1 files changed, 81 insertions, 0 deletions
diff --git a/ext/bg/js/clipboard-monitor.js b/ext/bg/js/clipboard-monitor.js
new file mode 100644
index 00000000..c2f41385
--- /dev/null
+++ b/ext/bg/js/clipboard-monitor.js
@@ -0,0 +1,81 @@
+/*
+ * Copyright (C) 2020  Alex Yatskov <alex@foosoft.net>
+ * Author: Alex Yatskov <alex@foosoft.net>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+/*global apiClipboardGet, jpIsStringPartiallyJapanese*/
+
+class ClipboardMonitor {
+    constructor() {
+        this.timerId = null;
+        this.timerToken = null;
+        this.interval = 250;
+        this.previousText = null;
+    }
+
+    onClipboardText(_text) {
+        throw new Error('Override me');
+    }
+
+    start() {
+        this.stop();
+
+        // The token below is used as a unique identifier to ensure that a new clipboard monitor
+        // hasn't been started during the await call. The check below the await apiClipboardGet()
+        // call will exit early if the reference has changed.
+        const token = {};
+        const intervalCallback = async () => {
+            this.timerId = null;
+
+            let text = null;
+            try {
+                text = await apiClipboardGet();
+            } catch (e) {
+                // NOP
+            }
+            if (this.timerToken !== token) { return; }
+
+            if (
+                typeof text === 'string' &&
+                (text = text.trim()).length > 0 &&
+                text !== this.previousText
+            ) {
+                this.previousText = text;
+                if (jpIsStringPartiallyJapanese(text)) {
+                    this.onClipboardText(text);
+                }
+            }
+
+            this.timerId = setTimeout(intervalCallback, this.interval);
+        };
+
+        this.timerToken = token;
+
+        intervalCallback();
+    }
+
+    stop() {
+        this.timerToken = null;
+        if (this.timerId !== null) {
+            clearTimeout(this.timerId);
+            this.timerId = null;
+        }
+    }
+
+    setPreviousText(text) {
+        this.previousText = text;
+    }
+}