#include <WiFi.h>
#include <WebServer.h>
#include <Adafruit_NeoPixel.h>
#include <math.h>


// Wi-Fi
// ESP32-C3 / ESP32-S3 only supports 2.4 GHz Wi-Fi.
// Replace these with your router's 2.4 GHz SSID and password.
const char* wifiSsid = "YOUR_2G_WIFI_NAME";
const char* wifiPassword = "YOUR_WIFI_PASSWORD";

// fallback AP
const char* apSsid = "ESP32C3-Light-Test";
const char* apPassword = "12345678";

// LED strip
#ifndef D1
#define D1 3
#endif

const int LED_PIN = D1;
const int NUM_LEDS = 30;  // Match the actual WS2812 strip length

Adafruit_NeoPixel strip(NUM_LEDS, LED_PIN, NEO_GRB + NEO_KHZ800);
WebServer server(80);

bool stationConnected = false;
bool apStarted = false;
bool lightOn = false;
unsigned long lastWifiRetryAt = 0;

constexpr unsigned long WIFI_RETRY_INTERVAL_MS = 30000;

int brightnessValue = 100;  // 0-180，先不要开到255
String colorName = "yellow";

uint8_t currentR = 255;
uint8_t currentG = 180;
uint8_t currentB = 60;

String currentScene = "breathing";
float breathRate = 1.6f;
int breathDepth = 68;

unsigned long lastAnimationFrameAt = 0;

constexpr float MIN_BREATH_RATE = 0.8f;
constexpr float MAX_BREATH_RATE = 3.2f;
constexpr int MIN_BREATH_DEPTH = 20;
constexpr int MAX_BREATH_DEPTH = 100;
constexpr unsigned long ANIMATION_FRAME_MS = 20;



void addCorsHeaders() {
  server.sendHeader("Access-Control-Allow-Origin", "*");
  server.sendHeader("Access-Control-Allow-Methods", "GET, POST, OPTIONS");
  server.sendHeader("Access-Control-Allow-Headers", "*");
}

void handleOptions() {
  addCorsHeaders();
  server.send(204);
}

// =====================================================
// LED functions
// =====================================================

void applyColorFromName(String name) {
  name.toLowerCase();

  if (name == "blue") {
    currentR = 80;
    currentG = 130;
    currentB = 255;
    colorName = "blue";
  } else if (name == "red") {
    currentR = 255;
    currentG = 70;
    currentB = 50;
    colorName = "red";
  } else {
    currentR = 255;
    currentG = 180;
    currentB = 60;
    colorName = "yellow";
  }
}

String normalizeSceneName(String name) {
  name.trim();
  name.toLowerCase();

  if (name == "breath" || name == "breathing" || name == "breathe") {
    return "breathing";
  }

  if (name == "pulse" || name == "pulsing") {
    return "pulse";
  }

  return "static";
}

bool lightNeedsAnimation() {
  return lightOn && brightnessValue > 0 && (currentScene == "breathing" || currentScene == "pulse");
}

void applySceneFromName(String name) {
  currentScene = normalizeSceneName(name);
}

void applyBreathSettingsFromRequest() {
  if (server.hasArg("rate")) {
    breathRate = server.arg("rate").toFloat();
  }

  if (breathRate < MIN_BREATH_RATE) {
    breathRate = MIN_BREATH_RATE;
  } else if (breathRate > MAX_BREATH_RATE) {
    breathRate = MAX_BREATH_RATE;
  }

  if (server.hasArg("depth")) {
    breathDepth = server.arg("depth").toInt();
  }

  if (breathDepth < MIN_BREATH_DEPTH) {
    breathDepth = MIN_BREATH_DEPTH;
  } else if (breathDepth > MAX_BREATH_DEPTH) {
    breathDepth = MAX_BREATH_DEPTH;
  }

  if (server.hasArg("scene")) {
    applySceneFromName(server.arg("scene"));
  }
}

float getSceneScale(unsigned long nowMs) {
  if (currentScene != "breathing" && currentScene != "pulse") {
    return 1.0f;
  }

  float depth = breathDepth / 100.0f;
  float cycleSeconds = breathRate;

  if (currentScene == "pulse") {
    cycleSeconds *= 0.7f;
  }

  if (cycleSeconds < MIN_BREATH_RATE) {
    cycleSeconds = MIN_BREATH_RATE;
  }

  unsigned long cycleMs = (unsigned long)(cycleSeconds * 1000.0f);
  if (cycleMs < 1) {
    cycleMs = 1;
  }

  float progress = (float)(nowMs % cycleMs) / (float)cycleMs;
  float wave = (sin(progress * TWO_PI) + 1.0f) * 0.5f;

  if (currentScene == "pulse") {
    wave = wave * wave;
  }

  return (1.0f - depth) + (depth * wave);
}

void renderLight() {
  if (!lightOn || brightnessValue <= 0) {
    strip.clear();
    strip.show();
    return;
  }

  float scale = (brightnessValue / 180.0f) * getSceneScale(millis());

  int r = (int)(currentR * scale);
  int g = (int)(currentG * scale);
  int b = (int)(currentB * scale);

  if (r < 0) r = 0;
  if (g < 0) g = 0;
  if (b < 0) b = 0;
  if (r > 255) r = 255;
  if (g > 255) g = 255;
  if (b > 255) b = 255;

  for (int i = 0; i < NUM_LEDS; i++) {
    strip.setPixelColor(i, strip.Color((uint8_t)r, (uint8_t)g, (uint8_t)b));
  }

  strip.show();
}

// =====================================================
// API responses
// =====================================================

String makeStateJson() {
  const bool wifiConnected = WiFi.status() == WL_CONNECTED;
  String ipText = wifiConnected ? WiFi.localIP().toString() : WiFi.softAPIP().toString();

  String json = "{";
  json += "\"connected\":" + String(wifiConnected ? "true" : "false") + ",";
  json += "\"apActive\":" + String(apStarted ? "true" : "false") + ",";
  json += "\"ip\":\"" + ipText + "\",";
  json += "\"mode\":\"" + String(wifiConnected ? "STA" : "AP") + "\",";
  json += "\"lightOn\":" + String(lightOn ? "true" : "false") + ",";
  json += "\"brightness\":" + String(brightnessValue) + ",";
  json += "\"color\":\"" + colorName + "\",";
  json += "\"scene\":\"" + currentScene + "\",";
  json += "\"breath_rate\":" + String(breathRate, 1) + ",";
  json += "\"breathRate\":" + String(breathRate, 1) + ",";
  json += "\"breath_depth\":" + String(breathDepth) + ",";
  json += "\"breathDepth\":" + String(breathDepth) + ",";
  json += "\"numLeds\":" + String(NUM_LEDS);
  json += "}";

  return json;
}

void sendJson(String json) {
  addCorsHeaders();
  server.send(200, "application/json", json);
}

// =====================================================
// API routes
// =====================================================

void handleRoot() {
  addCorsHeaders();

  String html = "";
  html += "<!doctype html><html><head>";
  html += "<meta charset='UTF-8'>";
  html += "<meta name='viewport' content='width=device-width, initial-scale=1.0'>";
  html += "<title>ESP32-C3 Light API</title>";
  html += "<style>";
  html += "body{font-family:Arial,sans-serif;background:#f6f8fb;color:#1f2937;padding:30px;}";
  html += ".card{max-width:620px;background:white;padding:24px;border-radius:16px;box-shadow:0 16px 36px rgba(15,23,42,.12);}";
  html += "a{display:inline-block;margin:6px;padding:12px 18px;background:#5f84d8;color:white;border-radius:999px;text-decoration:none;font-weight:bold;}";
  html += ".gray{background:#94a3b8;}";
  html += "</style></head><body>";
  html += "<main class='card'>";
  html += "<h1>ESP32-C3 Light API</h1>";
  html += "<p>This page is hosted by ESP32-C3. Your local designed webpage can call the API below.</p>";
  html += "<p><b>API:</b></p>";
  html += "<p>/api/on / /api/off / /api/toggle / /api/state</p>";
  html += "<p>/api/brightness?value=120</p>";
  html += "<p>/api/color?name=yellow | blue | red</p>";
  html += "<p>/api/scene?name=static | breathing | pulse</p>";
  html += "<p>/api/breath?rate=1.6&depth=68&scene=breathing</p>";
  html += "<a href='/api/on'>ON</a>";
  html += "<a class='gray' href='/api/off'>OFF</a>";
  html += "<a href='/api/toggle'>TOGGLE</a>";
  html += "<a href='/api/color?name=yellow'>YELLOW</a>";
  html += "<a href='/api/color?name=blue'>BLUE</a>";
  html += "<a href='/api/color?name=red'>RED</a>";
  html += "<a class='gray' href='/api/brightness?value=40'>LOW</a>";
  html += "<a href='/api/brightness?value=120'>MID</a>";
  html += "<a href='/api/brightness?value=180'>HIGH</a>";
  html += "<a class='gray' href='/api/scene?name=static'>STATIC</a>";
  html += "<a href='/api/scene?name=breathing'>BREATH</a>";
  html += "<a class='gray' href='/api/scene?name=pulse'>PULSE</a>";
  html += "<pre>" + makeStateJson() + "</pre>";
  html += "</main></body></html>";

  server.send(200, "text/html", html);
}

void handleState() {
  Serial.println("[API] STATE requested");
  sendJson(makeStateJson());
}

void handleOn() {
  lightOn = true;
  renderLight();

  Serial.println("[API] Light ON");
  sendJson(makeStateJson());
}

void handleOff() {
  lightOn = false;
  renderLight();

  Serial.println("[API] Light OFF");
  sendJson(makeStateJson());
}

void handleToggle() {
  lightOn = !lightOn;
  renderLight();

  Serial.print("[API] Light TOGGLE -> ");
  Serial.println(lightOn ? "ON" : "OFF");

  sendJson(makeStateJson());
}

void handleBrightness() {
  if (server.hasArg("value")) {
    brightnessValue = server.arg("value").toInt();
    brightnessValue = constrain(brightnessValue, 0, 180);
  }

  renderLight();

  Serial.print("[API] Brightness -> ");
  Serial.println(brightnessValue);

  sendJson(makeStateJson());
}

void handleColor() {
  if (server.hasArg("name")) {
    applyColorFromName(server.arg("name"));
  }

  renderLight();

  Serial.print("[API] Color -> ");
  Serial.println(colorName);

  sendJson(makeStateJson());
}

void handleScene() {
  if (server.hasArg("name")) {
    applySceneFromName(server.arg("name"));
  }

  renderLight();

  Serial.print("[API] Scene -> ");
  Serial.println(currentScene);

  sendJson(makeStateJson());
}

void handleBreath() {
  applyBreathSettingsFromRequest();

  renderLight();

  Serial.print("[API] Breath -> scene=");
  Serial.print(currentScene);
  Serial.print(", rate=");
  Serial.print(breathRate, 1);
  Serial.print("s, depth=");
  Serial.println(breathDepth);

  sendJson(makeStateJson());
}

void handleNotFound() {
  addCorsHeaders();
  server.send(404, "application/json", "{\"error\":\"not_found\"}");
}

// =====================================================
// Wi-Fi
// =====================================================

void startAP() {
  if (apStarted) {
    return;
  }

  WiFi.softAP(apSsid, apPassword);
  apStarted = true;

  Serial.println();
  Serial.println("Fallback AP started.");
  Serial.print("AP SSID: ");
  Serial.println(apSsid);
  Serial.print("AP Password: ");
  Serial.println(apPassword);
  Serial.print("Open browser: http://");
  Serial.println(WiFi.softAPIP());
}

void connectWiFi() {
  WiFi.persistent(false);
  WiFi.setAutoReconnect(true);
  WiFi.mode(WIFI_AP_STA);

  startAP();
  WiFi.begin(wifiSsid, wifiPassword);
  lastWifiRetryAt = millis();

  Serial.println();
  Serial.print("Connecting to Wi-Fi: ");
  Serial.println(wifiSsid);
}

void monitorWiFi() {
  if (WiFi.status() == WL_CONNECTED) {
    if (!stationConnected) {
      stationConnected = true;
      Serial.println();
      Serial.println("Wi-Fi connected.");
      Serial.print("Open browser: http://");
      Serial.println(WiFi.localIP());
    }
    return;
  }

  if (stationConnected) {
    stationConnected = false;
    Serial.println();
    Serial.println("Wi-Fi disconnected. AP fallback stays available.");
  }

  if (millis() - lastWifiRetryAt >= WIFI_RETRY_INTERVAL_MS) {
    lastWifiRetryAt = millis();
    Serial.println("Retrying Wi-Fi...");
    WiFi.begin(wifiSsid, wifiPassword);
  }
}

// =====================================================
// Setup / Loop
// =====================================================

void setup() {
  Serial.begin(115200);
  delay(500);

  Serial.println();
  Serial.println("====================================");
  Serial.println("XIAO ESP32-C3 Light API Test");
  Serial.println("Local webpage -> ESP32-C3 -> LED strip");
  Serial.println("No WebSocket yet.");
  Serial.println("====================================");

  strip.begin();
  strip.clear();
  strip.setBrightness(255);
  strip.show();

  applyColorFromName(colorName);
  renderLight();

  connectWiFi();

  server.on("/", HTTP_GET, handleRoot);

  server.on("/api/state", HTTP_GET, handleState);
  server.on("/api/on", HTTP_GET, handleOn);
  server.on("/api/off", HTTP_GET, handleOff);
  server.on("/api/toggle", HTTP_GET, handleToggle);
  server.on("/api/brightness", HTTP_GET, handleBrightness);
  server.on("/api/color", HTTP_GET, handleColor);
  server.on("/api/scene", HTTP_GET, handleScene);
  server.on("/api/breath", HTTP_GET, handleBreath);

  server.on("/api/state", HTTP_OPTIONS, handleOptions);
  server.on("/api/on", HTTP_OPTIONS, handleOptions);
  server.on("/api/off", HTTP_OPTIONS, handleOptions);
  server.on("/api/toggle", HTTP_OPTIONS, handleOptions);
  server.on("/api/brightness", HTTP_OPTIONS, handleOptions);
  server.on("/api/color", HTTP_OPTIONS, handleOptions);
  server.on("/api/scene", HTTP_OPTIONS, handleOptions);
  server.on("/api/breath", HTTP_OPTIONS, handleOptions);

  server.onNotFound(handleNotFound);

  server.begin();
  Serial.println("HTTP API server started.");
}

void loop() {
  monitorWiFi();
  server.handleClient();

  if (lightNeedsAnimation() && millis() - lastAnimationFrameAt >= ANIMATION_FRAME_MS) {
    lastAnimationFrameAt = millis();
    renderLight();
  }
}