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// SPDX-License-Identifier: LGPL-3.0-or-later
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// Copyright 2016-2026 Hristo Gochkov, Mathieu Carbou, Emil Muratov, Will Miles
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//
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// Shows how to serve a static and dynamic template
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//
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#include <Arduino.h>
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#if defined(ESP32) || defined(LIBRETINY)
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#include <AsyncTCP.h>
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#include <WiFi.h>
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#elif defined(ESP8266)
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#include <ESP8266WiFi.h>
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#include <ESPAsyncTCP.h>
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#elif defined(TARGET_RP2040) || defined(TARGET_RP2350) || defined(PICO_RP2040) || defined(PICO_RP2350)
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#include <RPAsyncTCP.h>
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#include <WiFi.h>
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#endif
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#include <ESPAsyncWebServer.h>
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#include <LittleFS.h>
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static AsyncWebServer server(80);
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static const char *htmlContent PROGMEM = R"(
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<!DOCTYPE html>
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<html>
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<body>
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    <h1>Hello, %USER%</h1>
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</body>
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</html>
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)";
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static const size_t htmlContentLength = strlen_P(htmlContent);
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// Variables used for dynamic cacheable template
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static unsigned uptimeInMinutes = 0;
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static AsyncStaticWebHandler *uptimeHandler = nullptr;
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// Utility function for performing that update
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static void setUptimeInMinutes(unsigned t) {
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  uptimeInMinutes = t;
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  // Update caching header with a new value as well
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  if (uptimeHandler) {
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    uptimeHandler->setLastModified();
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  }
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}
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void setup() {
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  Serial.begin(115200);
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#if ASYNCWEBSERVER_WIFI_SUPPORTED
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  WiFi.mode(WIFI_AP);
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  WiFi.softAP("esp-captive");
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#endif
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#ifdef ESP32
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  LittleFS.begin(true);
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#else
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  LittleFS.begin();
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#endif
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  {
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    File f = LittleFS.open("/template.html", "w");
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    assert(f);
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    f.print(htmlContent);
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    f.close();
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  }
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  // Serve the static template file
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  //
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  // This call will have caching headers automatically added as it is a static file.
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  //
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  // curl -v http://192.168.4.1/template.html
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  server.serveStatic("/template.html", LittleFS, "/template.html");
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  // Serve a template with dynamic content
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  //
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  // serveStatic recognizes that template processing is in use, and will not automatically
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  // add caching headers.
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  //
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  // curl -v http://192.168.4.1/dynamic.html
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  server.serveStatic("/dynamic.html", LittleFS, "/template.html").setTemplateProcessor([](const String &var) -> String {
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    if (var == "USER") {
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      return String("Bob ") + millis();
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    }
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    return asyncsrv::emptyString;
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  });
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  // Serve a static template with a template processor
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  //
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  // By explicitly calling setLastModified() on the handler object, we enable
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  // sending the caching headers, even when a template is in use.
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  // This pattern should never be used with template data that can change.
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  // Example below: USER never changes.
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  //
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  // curl -v http://192.168.4.1/index.html
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  server.serveStatic("/index.html", LittleFS, "/template.html")
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    .setTemplateProcessor([](const String &var) -> String {
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      if (var == "USER") {
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        return "Bob";
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      }
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      return asyncsrv::emptyString;
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    })
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    .setLastModified("Sun, 28 Sep 2025 01:02:03 GMT");
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  // Serve a template with dynamic content *and* caching
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  //
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  // The data used in this template is updated in loop().  loop() is then responsible
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  // for calling setLastModified() on the handler object to notify any caches that
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  // the data has changed.
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  //
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  // curl -v http://192.168.4.1/uptime.html
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  uptimeHandler = &server.serveStatic("/uptime.html", LittleFS, "/template.html").setTemplateProcessor([](const String &var) -> String {
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    if (var == "USER") {
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      return String("Bob ") + uptimeInMinutes + " minutes";
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    }
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    return asyncsrv::emptyString;
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  });
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  // Serve a template with dynamic content based on user request
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  //
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  // In this case, the template is served via a callback request.  Data from the request
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  // is used to generate the template callback.
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  //
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  // curl -v -G -d "USER=Bob" http://192.168.4.1/user_request.html
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  server.on("/user_request.html", HTTP_GET, [](AsyncWebServerRequest *request) {
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    request->send(LittleFS, "/template.html", "text/html", false, [=](const String &var) -> String {
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      if (var == "USER") {
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        const AsyncWebParameter *param = request->getParam("USER");
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        if (param) {
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          return param->value();
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        }
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      }
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      return asyncsrv::emptyString;
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    });
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  });
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  server.begin();
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}
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// not needed
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void loop() {
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  delay(100);
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  // Compute uptime
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  unsigned currentUptimeInMinutes = millis() / (60 * 1000);
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  if (currentUptimeInMinutes != uptimeInMinutes) {
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    setUptimeInMinutes(currentUptimeInMinutes);
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  }
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}