Add PHP port of Etherpad Lite Changeset library with pad writer script

bin/etherpad-writer.php

@@ -0,0 +1,254 @@
+#!/usr/bin/env php
+<?php
+
+/**
+ * Etherpad Pad Writer - Proof of Concept
+ *
+ * Demonstrates using the Changeset library to connect to an Etherpad instance
+ * and insert "Hello world" in the middle of a pad's existing text.
+ *
+ * Usage:
+ *   php etherpad-writer.php <etherpad-url> <pad-id>
+ *
+ * Example:
+ *   php etherpad-writer.php https://etherpad.example.com my-pad
+ *   php etherpad-writer.php https://demo.etherpad.org test-pad-123
+ */
+
+declare(strict_types=1);
+
+require __DIR__ . '/../vendor/autoload.php';
+
+use ElephantIO\Client as ElephantClient;
+use ElephantIO\Engine\SocketIO;
+use Gared\EtherScan\Changeset\AttributePool;
+use Gared\EtherScan\Changeset\Changeset;
+use GuzzleHttp\Client as HttpClient;
+use GuzzleHttp\Cookie\CookieJar;
+use GuzzleHttp\RequestOptions;
+
+// ---------------------------------------------------------------------------
+// CLI argument parsing
+// ---------------------------------------------------------------------------
+
+if ($argc < 3) {
+    fwrite(STDERR, "Usage: php etherpad-writer.php <etherpad-url> <pad-id>\n");
+    fwrite(STDERR, "Example: php etherpad-writer.php https://etherpad.example.com my-pad\n");
+    exit(1);
+}
+
+$baseUrl = rtrim($argv[1], '/') . '/';
+$padId   = $argv[2];
+$insertText = 'Hello world';
+
+echo "=== Etherpad Pad Writer (Proof of Concept) ===\n";
+echo "Server : {$baseUrl}\n";
+echo "Pad    : {$padId}\n";
+echo "Insert : \"{$insertText}\" at the middle of the current text\n\n";
+
+// ---------------------------------------------------------------------------
+// Step 1: Visit the pad URL to obtain a session cookie
+// ---------------------------------------------------------------------------
+
+$cookies = new CookieJar();
+$httpClient = new HttpClient([
+    'timeout' => 10.0,
+    'connect_timeout' => 5.0,
+    RequestOptions::HEADERS => [
+        'User-Agent' => 'EtherpadPadWriter/1.0',
+    ],
+    'verify' => false,
+]);
+
+echo "[1/4] Fetching pad page to obtain session cookie...\n";
+try {
+    $httpClient->get($baseUrl . 'p/' . $padId, ['cookies' => $cookies]);
+} catch (\Throwable $e) {
+    // Some pads may return non-200 but still set a cookie; continue
+    echo "      (note: HTTP request returned: " . $e->getMessage() . ")\n";
+}
+
+$cookieString = '';
+foreach ($cookies as $cookie) {
+    $cookieString .= $cookie->getName() . '=' . $cookie->getValue() . ';';
+}
+echo "      Cookies: " . ($cookieString !== '' ? $cookieString : '(none)') . "\n\n";
+
+// ---------------------------------------------------------------------------
+// Step 2: Connect via Socket.IO and send CLIENT_READY
+// ---------------------------------------------------------------------------
+
+echo "[2/4] Connecting via Socket.IO...\n";
+
+$token = 't.' . bin2hex(random_bytes(16));
+
+$socketClient = new ElephantClient(
+    ElephantClient::engine(ElephantClient::CLIENT_4X, $baseUrl . 'socket.io/', [
+        'persistent' => false,
+        'context' => [
+            'ssl' => [
+                'verify_peer'      => false,
+                'verify_peer_name' => false,
+            ],
+        ],
+        'headers' => [
+            'Cookie' => $cookieString,
+        ],
+    ])
+);
+
+$socketClient->connect();
+$socketClient->of('/');
+
+$socketClient->emit('message', [
+    'component'       => 'pad',
+    'type'            => 'CLIENT_READY',
+    'padId'           => $padId,
+    'sessionID'       => 'null',
+    'token'           => $token,
+    'password'        => null,
+    'protocolVersion' => 2,
+]);
+
+echo "      Connected and CLIENT_READY sent.\n\n";
+
+// ---------------------------------------------------------------------------
+// Step 3: Wait for CLIENT_VARS to get the current pad state
+// ---------------------------------------------------------------------------
+
+echo "[3/4] Waiting for CLIENT_VARS...\n";
+
+$currentText = null;
+$currentRev  = null;
+$serverApool = null;
+
+while ($result = $socketClient->wait('message', 5)) {
+    if (!is_array($result->data)) {
+        continue;
+    }
+
+    $msg = $result->data;
+
+    // Skip COLLABROOM/CUSTOM messages (e.g. plugin broadcasts)
+    if (isset($msg['data']['type']) && $msg['data']['type'] === 'CUSTOM') {
+        continue;
+    }
+
+    // The CLIENT_VARS message carries access status
+    $accessStatus = $msg['accessStatus'] ?? null;
+    if ($accessStatus === 'deny') {
+        fwrite(STDERR, "ERROR: Pad access denied. The pad may require authentication.\n");
+        $socketClient->disconnect();
+        exit(1);
+    }
+
+    // CLIENT_VARS message: {type:'CLIENT_VARS', data: clientVars}
+    $type = $msg['type'] ?? null;
+    if ($type !== 'CLIENT_VARS') {
+        // Not CLIENT_VARS yet, keep waiting
+        continue;
+    }
+
+    $clientVars       = $msg['data'];
+    $collabClientVars = $clientVars['collab_client_vars'] ?? null;
+
+    if ($collabClientVars === null) {
+        fwrite(STDERR, "ERROR: Unexpected CLIENT_VARS structure (missing collab_client_vars).\n");
+        $socketClient->disconnect();
+        exit(1);
+    }
+
+    $currentRev  = (int) $collabClientVars['rev'];
+    $currentText = $collabClientVars['initialAttributedText']['text'];
+    $serverApool = $collabClientVars['apool']; // {numToAttrib: {...}, nextNum: N}
+
+    echo "      Current revision : {$currentRev}\n";
+    echo "      Current text     : " . json_encode($currentText) . "\n";
+    break;
+}
+
+if ($currentText === null || $currentRev === null || $serverApool === null) {
+    fwrite(STDERR, "ERROR: Did not receive CLIENT_VARS within timeout.\n");
+    $socketClient->disconnect();
+    exit(1);
+}
+
+// ---------------------------------------------------------------------------
+// Step 4: Build a changeset that inserts text in the middle, then send it
+// ---------------------------------------------------------------------------
+
+echo "\n[4/4] Building and sending changeset...\n";
+
+// Etherpad pads always end with "\n". The text we receive will look like "some text\n".
+// We want to insert "Hello world" in the middle of the textual content
+// (i.e., halfway through the characters, not counting the final newline).
+
+$textLength = strlen($currentText); // includes trailing "\n"
+
+// Find the insertion point: middle of the text (before the trailing newline)
+$contentLength    = max(0, $textLength - 1); // exclude trailing "\n"
+$insertionPoint   = (int) ($contentLength / 2);
+
+echo "      Text length      : {$textLength} chars\n";
+echo "      Insertion point  : position {$insertionPoint}\n";
+
+// Reconstruct the server's attribute pool so we can pass it to moveOpsToNewPool if needed.
+// For a simple plain-text insertion with no attributes, we use an empty local pool.
+$localPool = new AttributePool();
+
+// Build the changeset: keep the first half, insert the new text, keep the rest.
+$changeset = Changeset::makeSplice($currentText, $insertionPoint, 0, $insertText);
+
+echo "      Changeset        : {$changeset}\n";
+
+// Verify the changeset applies correctly (sanity check)
+$resultText = Changeset::applyToText($changeset, $currentText);
+echo "      Resulting text   : " . json_encode($resultText) . "\n";
+
+// Send the USER_CHANGES message wrapped in COLLABROOM
+$socketClient->emit('message', [
+    'type'      => 'COLLABROOM',
+    'component' => 'pad',
+    'data'      => [
+        'type'      => 'USER_CHANGES',
+        'baseRev'   => $currentRev,
+        'changeset' => $changeset,
+        'apool'     => $localPool->toJsonable(),
+    ],
+]);
+
+echo "      USER_CHANGES sent.\n";
+
+// Wait for ACCEPT_COMMIT confirmation
+$accepted = false;
+while ($result = $socketClient->wait('message', 5)) {
+    if (!is_array($result->data)) {
+        continue;
+    }
+    $msg  = $result->data;
+    $type = $msg['data']['type'] ?? null;
+
+    if ($type === 'ACCEPT_COMMIT') {
+        $newRev = $msg['data']['newRev'] ?? '?';
+        echo "      ACCEPT_COMMIT received! New revision: {$newRev}\n";
+        $accepted = true;
+        break;
+    }
+
+    // Handle disconnect/error response
+    if (isset($msg['disconnect'])) {
+        fwrite(STDERR, "ERROR: Server rejected changeset: " . $msg['disconnect'] . "\n");
+        $socketClient->disconnect();
+        exit(1);
+    }
+}
+
+$socketClient->disconnect();
+
+if ($accepted) {
+    echo "\n✓ Success! \"{$insertText}\" was inserted at position {$insertionPoint} in pad '{$padId}'.\n";
+} else {
+    fwrite(STDERR, "\nWARNING: Changeset was sent but no ACCEPT_COMMIT was received within timeout.\n");
+    fwrite(STDERR, "The change may have been applied; check the pad manually.\n");
+    exit(2);
+}