Add PHP port of Etherpad Lite Changeset library with pad writer and reader scripts

bin/etherpad-reader.php

@@ -0,0 +1,282 @@
+#!/usr/bin/env php
+<?php
+
+/**
+ * Etherpad Pad Reader - Proof of Concept
+ *
+ * Connects to an Etherpad pad and listens for changes in an endless loop,
+ * printing each edit (insertions and deletions) to stdout as it arrives.
+ *
+ * Usage:
+ *   php etherpad-reader.php <etherpad-url> <pad-id>
+ *
+ * Example:
+ *   php etherpad-reader.php https://etherpad.example.com my-pad
+ *   php etherpad-reader.php https://demo.etherpad.org test-pad-123
+ *
+ * Press Ctrl+C to stop.
+ */
+
+declare(strict_types=1);
+
+require __DIR__ . '/../vendor/autoload.php';
+
+use ElephantIO\Client as ElephantClient;
+use Gared\EtherScan\Changeset\Changeset;
+use Gared\EtherScan\Changeset\StringIterator;
+use GuzzleHttp\Client as HttpClient;
+use GuzzleHttp\Cookie\CookieJar;
+use GuzzleHttp\RequestOptions;
+
+// ---------------------------------------------------------------------------
+// CLI argument parsing
+// ---------------------------------------------------------------------------
+
+if ($argc < 3) {
+    fwrite(STDERR, "Usage: php etherpad-reader.php <etherpad-url> <pad-id>\n");
+    fwrite(STDERR, "Example: php etherpad-reader.php https://etherpad.example.com my-pad\n");
+    exit(1);
+}
+
+$baseUrl = rtrim($argv[1], '/') . '/';
+$padId   = $argv[2];
+
+echo "=== Etherpad Pad Reader (Proof of Concept) ===\n";
+echo "Server : {$baseUrl}\n";
+echo "Pad    : {$padId}\n";
+echo "Press Ctrl+C to stop.\n\n";
+
+// ---------------------------------------------------------------------------
+// Step 1: Visit the pad URL to obtain a session cookie
+// ---------------------------------------------------------------------------
+
+$cookies = new CookieJar();
+$httpClient = new HttpClient([
+    'timeout' => 10.0,
+    'connect_timeout' => 5.0,
+    RequestOptions::HEADERS => [
+        'User-Agent' => 'EtherpadPadReader/1.0',
+    ],
+    'verify' => false,
+]);
+
+echo "[1/3] 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 !== '' ? $cookieString : '(none)') . "\n\n";
+
+// ---------------------------------------------------------------------------
+// Step 2: Connect via Socket.IO and send CLIENT_READY
+// ---------------------------------------------------------------------------
+
+echo "[2/3] Connecting via Socket.IO...\n";
+
+$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'           => $token,
+    'password'        => null,
+    'protocolVersion' => 2,
+]);
+
+echo "      Connected and CLIENT_READY sent.\n\n";
+
+// ---------------------------------------------------------------------------
+// Step 3: Receive CLIENT_VARS to get initial pad state
+// ---------------------------------------------------------------------------
+
+echo "[3/3] Waiting for CLIENT_VARS...\n";
+
+$currentText = null;
+$currentRev  = null;
+
+while ($result = $socketClient->wait('message', 10)) {
+    if (!is_array($result->data)) {
+        continue;
+    }
+
+    $msg = $result->data;
+
+    if (isset($msg['data']['type']) && $msg['data']['type'] === 'CUSTOM') {
+        continue;
+    }
+
+    $accessStatus = $msg['accessStatus'] ?? null;
+    if ($accessStatus === 'deny') {
+        fwrite(STDERR, "ERROR: Pad access denied. The pad may require authentication.\n");
+        $socketClient->disconnect();
+        exit(1);
+    }
+
+    $type = $msg['type'] ?? null;
+    if ($type !== 'CLIENT_VARS') {
+        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 = $collabClientVars['initialAttributedText']['text'];
+
+    echo "      Initial revision : {$currentRev}\n";
+    echo "      Initial text     : " . json_encode($currentText) . "\n\n";
+    break;
+}
+
+if ($currentText === null || $currentRev === null) {
+    fwrite(STDERR, "ERROR: Did not receive CLIENT_VARS within timeout.\n");
+    $socketClient->disconnect();
+    exit(1);
+}
+
+// ---------------------------------------------------------------------------
+// Endless loop: listen for NEW_CHANGES and print diffs
+// ---------------------------------------------------------------------------
+
+echo "Listening for changes (Ctrl+C to stop)...\n";
+echo str_repeat('-', 60) . "\n";
+
+// Handle Ctrl+C (SIGINT) and SIGTERM gracefully
+$running = true;
+if (function_exists('pcntl_signal')) {
+    pcntl_signal(SIGINT, static function () use (&$running): void {
+        echo "\nStopping...\n";
+        $running = false;
+    });
+    pcntl_signal(SIGTERM, static function () use (&$running): void {
+        $running = false;
+    });
+}
+
+while ($running) {
+    if (function_exists('pcntl_signal_dispatch')) {
+        pcntl_signal_dispatch();
+    }
+    $result = $socketClient->wait('message', 30);
+
+    if ($result === null) {
+        // No message within the poll window — send a keepalive and continue
+        echo "[" . date('H:i:s') . "] (no changes, still listening...)\n";
+        continue;
+    }
+
+    if (!is_array($result->data)) {
+        continue;
+    }
+
+    $msg = $result->data;
+
+    // Only handle COLLABROOM messages
+    if (($msg['type'] ?? null) !== 'COLLABROOM') {
+        continue;
+    }
+
+    $data     = $msg['data'] ?? [];
+    $dataType = $data['type'] ?? null;
+
+    if ($dataType !== 'NEW_CHANGES') {
+        continue;
+    }
+
+    $newRev    = (int) ($data['newRev'] ?? ($currentRev + 1));
+    $changeset = $data['changeset'] ?? '';
+    $author    = $data['author'] ?? 'unknown';
+
+    if ($changeset === '') {
+        continue;
+    }
+
+    // Apply the changeset to the current text to get the new text
+    $newText = Changeset::applyToText($changeset, $currentText);
+
+    // Parse the ops to extract what was inserted and what was deleted
+    $unpacked  = Changeset::unpack($changeset);
+    $strIter   = new StringIterator($currentText);
+    $charBank  = $unpacked['charBank'];
+    $bankPos   = 0;
+
+    $insertions = [];
+    $deletions  = [];
+
+    foreach (Changeset::deserializeOps($unpacked['ops']) as $op) {
+        switch ($op->opcode) {
+            case '=':
+                $strIter->skip($op->chars);
+                break;
+            case '-':
+                $deletions[] = $strIter->take($op->chars);
+                break;
+            case '+':
+                $insertions[] = mb_substr($charBank, $bankPos, $op->chars, 'UTF-8');
+                $bankPos += $op->chars;
+                break;
+        }
+    }
+
+    // Print the change summary
+    echo sprintf(
+        "[%s] rev %d → %d (author: %s)\n",
+        date('H:i:s'),
+        $currentRev,
+        $newRev,
+        $author !== '' ? $author : 'unknown'
+    );
+
+    foreach ($deletions as $deleted) {
+        $display = str_replace("\n", "↵", $deleted);
+        echo "  - \033[31m{$display}\033[0m\n";
+    }
+    foreach ($insertions as $inserted) {
+        $display = str_replace("\n", "↵", $inserted);
+        echo "  + \033[32m{$display}\033[0m\n";
+    }
+
+    if ($insertions === [] && $deletions === []) {
+        echo "  (attribute-only change)\n";
+    }
+
+    echo "  New text: " . json_encode($newText) . "\n";
+    echo str_repeat('-', 60) . "\n";
+
+    // Advance state
+    $currentText = $newText;
+    $currentRev  = $newRev;
+}