189 líneas
8.2 KiB
PHP
189 líneas
8.2 KiB
PHP
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<?php
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// Name of the message buffer file. You have to create it manually with read and write permissions for the webserver.
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$messages_buffer_file = "messages.json";
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// Number of most recent messages kept in the buffer.
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// Note that message list on clients only shows 1000 messages to avoid slowdown (see JavaScript code below).
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$messages_buffer_size = 50;
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// Disabled by default, set to true to enable. Appends each chat messages to a chatlog.txt text file.
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// This log file is uncapped, so you have to clean it form time to time or it can get very large.
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$enable_chatlog = false;
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if ( isset($_POST["content"]) and isset($_POST["name"]) ) {
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// Create the message buffer file if it doesn't exist yet. That way we don't need a setup and it's writable since it
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// was created by the process executing PHP (usually the webserver).
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if ( ! file_exists($messages_buffer_file) )
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touch($messages_buffer_file);
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// Open, lock and read the message buffer file
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$buffer = fopen($messages_buffer_file, "r+b");
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flock($buffer, LOCK_EX);
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$buffer_data = stream_get_contents($buffer);
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// Append new message to the buffer data or start with a message id of 0 if the buffer is empty
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$messages = $buffer_data ? json_decode($buffer_data, true) : [];
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$next_id = (count($messages) > 0) ? $messages[count($messages) - 1]["id"] + 1 : 0;
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$messages[] = [ "id" => $next_id, "time" => time(), "name" => $_POST["name"], "content" => $_POST["content"] ];
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// Remove old messages if necessary to keep the buffer size
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if (count($messages) > $messages_buffer_size)
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$messages = array_slice($messages, count($messages) - $messages_buffer_size);
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// Rewrite and unlock the message file
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ftruncate($buffer, 0);
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rewind($buffer);
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fwrite($buffer, json_encode($messages));
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flock($buffer, LOCK_UN);
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fclose($buffer);
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// Optional: Append message to log file (file appends are atomic)
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if ($enable_chatlog)
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file_put_contents("chatlog.txt", date("Y-m-d H:i:s") . "\t" . strtr($_POST["name"], "\t", " ") . "\t" . strtr($_POST["content"], "\t", " ") . "\n", FILE_APPEND);
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exit();
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}
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?>
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<!DOCTYPE html>
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<meta charset=utf-8>
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<meta name=viewport content="initial-scale=1.0">
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<meta name=author content="Stephan Soller">
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<title>SimpleChat por Altomarketing.com</title>
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<script type=module>
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// Remove the "loading…" list entry
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document.querySelector("ul#messages > li").remove()
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document.querySelector("form").addEventListener("submit", async event => {
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const form = event.target
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const name = form.name.value
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const content = form.content.value
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// Prevent the browsers default action (send form data and show the result page). We just want to send the message without reloading the page.
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event.preventDefault()
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// Only send a new message if it's not empty (also it's ok for the server we don't need to send senseless messages)
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if (name == "" || content == "")
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return
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// Append a "pending" message (a message not yet confirmed from the server) as soon as the POST request is send. The
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// textContent property automatically escapes HTML so no one can harm the client by injecting JavaSript code.
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await fetch(form.action, { method: "POST", body: new URLSearchParams({name, content}) })
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const messageList = document.querySelector("ul#messages")
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const messageElement = messageList.querySelector("template").content.cloneNode(true)
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messageElement.querySelector("small").textContent = name
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messageElement.querySelector("span").textContent = content
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messageList.append(messageElement)
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messageList.scrollTop = messageList.scrollHeight
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form.content.value = ""
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form.content.focus()
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})
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// Poll-function that looks for new messages
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async function poll_for_new_messages() {
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// We want the browser to revalidate the cached messages.json file every time. That is it should send a
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// conditional request with an If-Modified-Since header. This is the default behaviour in Firefox 115.
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// In Chrome 114 it's not. It just uses the cached response without revalidation, thus missing new messages.
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// Hence we explicitly tell fetch to revalidate via a conditional request. Because naming things is hard the
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// option to do just that is { cache: "no-cache" }. See https://javascript.info/fetch-api#cache
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// or https://developer.mozilla.org/en-US/docs/Web/HTTP/Caching#force_revalidation
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const response = await fetch("messages.json", { cache: "no-cache" })
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// Do nothing if messages.json wasn't found (doesn't exist yet probably)
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if (!response.ok)
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return
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const messages = await response.json()
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const messageList = document.querySelector("ul#messages")
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const messageTemplate = messageList.querySelector("template").content.querySelector("li")
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// Determine if we should scroll the message list down to the bottom once we inserted all new messages.
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// Only do that if the user already is almost at the bottom (50px at max from it). Otherwise it gets really
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// annoying when the list scrolls down every 2 seconds while you want to read old messages further up. Check the
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// pixel distance before changing the message list. Otherwise the check gets thrown off by removed or new messages.
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const pixelDistanceFromListeBottom = messageList.scrollHeight - messageList.scrollTop - messageList.clientHeight
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const scrollToBottom = (pixelDistanceFromListeBottom < 50)
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// Remove the pending messages from the list (they are replaced by the ones from the server later)
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for (const li of messageList.querySelectorAll("li.pending"))
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li.remove()
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// Get the ID of the last inserted message or start with -1 (so the first message from the server with 0 will
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// automatically be shown).
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const lastMessageId = parseInt(messageList.dataset.lastMessageId ?? "-1")
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// Add a list entry for every incomming message, but only if we not already inserted it (hence the check for
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// the newer ID than the last inserted message).
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for (const msg of messages) {
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if (msg.id > lastMessageId) {
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const date = new Date(msg.time * 1000);
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const messageElement = messageTemplate.cloneNode(true)
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messageElement.classList.remove("pending")
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messageElement.querySelector("small").textContent = Intl.DateTimeFormat(undefined, { dateStyle: "medium", timeStyle: "short" }).format(date) + ": " + msg.name
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messageElement.querySelector("span").textContent = msg.content
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messageList.append(messageElement)
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messageList.dataset.lastMessageId = msg.id
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}
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}
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// Remove all but the last 1000 messages in the list to prevent browser slowdown with extremely large lists
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for (const li of Array.from(messageList.querySelectorAll("li")).slice(0, -1000))
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li.remove()
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// Finally scroll down to the newes messages
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if (scrollToBottom)
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messageList.scrollTop = messageList.scrollHeight - messageList.clientHeight
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}
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// Kick of the poll function and repeat it every two seconds
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poll_for_new_messages()
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setInterval(poll_for_new_messages, 2000)
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</script>
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<style>
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html { margin: 0em; padding: 0; }
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body { height: 100vh; box-sizing: border-box; margin: 0; padding: 2em;
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font-family: sans-serif; font-size: medium; color: #333;
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display: flex; flex-direction: column; gap: 1em; }
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body > h1 { flex: 0 0 auto; }
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body > ul#messages { flex: 1 1 auto; }
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body > form { flex: 0 0 auto; }
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h1 { margin: 0; padding: 0; font-size: 2em; }
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ul#messages { overflow: auto; margin: 0; padding: 0 3px; list-style: none; border: 1px solid gray; }
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ul#messages li { margin: 0.35em 0; padding: 0; }
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ul#messages li small { display: block; font-size: 0.59em; color: gray; }
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ul#messages li.pending { color: #aaa; }
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form { font-size: 1em; margin: 0; padding: 0; }
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form p { margin: 0; padding: 0; display: flex; gap: 0.5em; }
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form p input { font-size: 1em; min-width: 0; }
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form p input[name=name] { flex: 0 1 10em; }
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form p input[name=content] { flex: 1 1 auto; }
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form p button {}
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h1, ul#messages, form { width: 100%; max-width: 40rem; box-sizing: border-box; margin: 0 auto; }
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</style>
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<h1>Simple Chat</h1>
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<ul id=messages>
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<li>loading…</li>
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<template>
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<li class=pending>
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<small>…</small>
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<span>…</span>
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</li>
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</template>
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</ul>
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<form method=post action="<?= htmlentities($_SERVER["PHP_SELF"], ENT_QUOTES | ENT_SUBSTITUTE | ENT_HTML5, "UTF-8") ?>">
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<p>
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<input type=text name=name placeholder="Name" value="Anonymous">
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<input type=text name=content placeholder="Message" autofocus>
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<button>Send</button>
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</p>
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</form>
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