Add a built in reader page with a clipboard hook

reader.js

@@ -0,0 +1,74 @@
+function toggle()
+{
+    browser.runtime.sendMessage({type:"toggle"});
+}
+
+browser.contextMenus.create({
+    id: "nazeka-toggle",
+    title: "Toggle Nazeka",
+    contexts: ["all"],
+    onclick: toggle
+});
+
+function might_have_japanese(text)
+{
+    for(let char of text)
+        if(char && char.length > 0 && char.codePointAt(0) > 0x2E80)
+            return true;
+    return false;
+}
+
+function update(text)
+{
+    if(!might_have_japanese(text))
+        return;
+    
+    let target = document.body;
+    let newnode = document.createElement("p");
+    newnode.textContent = text;
+    
+    target.insertBefore(newnode, document.querySelector("#helptext"));
+}
+
+let text_previous = "";
+function cycle_text(text)
+{
+    if(text != "" && text != text_previous)
+        update(text);
+    text_previous = text;
+}
+
+window.addEventListener("load", () =>
+{
+    document.querySelector("#nazeka-paste-target").addEventListener("paste", (event) =>
+    {
+        // skip event if there's no plaintext; thanks github.com/kmltml/clipboard-inserter
+        let text = event.clipboardData.getData("text/plain");
+        if(text !== "")
+            cycle_text(text);
+        
+        event.preventDefault();
+    })
+});
+
+function checkpaste()
+{
+    let target = document.querySelector("#nazeka-paste-target");
+    
+    target.parentNode.style.visibility = "visible";
+    
+    target.textContent = "";
+    target.focus();
+    document.execCommand("paste");
+    
+    target.parentNode.style.visibility = "hidden";
+}
+
+let interval = 250;
+
+setInterval(checkpaste, interval);
+
+var executing = browser.tabs.executeScript({
+    file: "/texthook.js",
+    allFrames: true
+});