#include <SPI.h>
#include <Wire.h>
#include <LittleFS.h>
#include <WebServer.h>
#include <WiFi.h>
#include <ArduinoJson.h>
#include <GxEPD2_BW.h>
#include <Adafruit_Sensor.h>
#include <Adafruit_ADXL343.h>
#include "ss_qr_bitmap.h"
#include "ss_enviro_bitmap.h"
#include "ss_survey_bitmap.h"
#include "ss_resources_bitmap.h"

// ===== Hardware =====
#define EPD_CS   2
#define EPD_DC   3
#define EPD_RST  4
#define EPD_BUSY 43
#define LED_PIN  1

GxEPD2_BW<GxEPD2_420_GDEY042T81, GxEPD2_420_GDEY042T81::HEIGHT> display(GxEPD2_420_GDEY042T81(EPD_CS, EPD_DC, EPD_RST, EPD_BUSY));
TwoWire I2CBus = TwoWire(0);
Adafruit_ADXL343 accel = Adafruit_ADXL343(12345, &I2CBus);

// ===== Wi-Fi / server =====
const char* AP_SSID = "StoryStone";
const char* AP_PASS = nullptr;
WebServer server(80);
bool apActive = false;

// ===== Storage =====
struct Story { uint64_t id; String type; String text; uint64_t ts; };
std::vector<Story> stories;
const char* DB_PATH = "/stories.json";
const size_t MAX_STORIES = 1000;
const size_t MAX_STORY_LENGTH = 200;
const size_t MIN_STORY_LENGTH = 1;
uint64_t epochCounter = 0;

// ===== Page navigation =====
int currentPage = 1;
const int TOTAL_PAGES = 18;
unsigned long stateStartTime = 0;
const unsigned long TIMEOUT_MS = 120000UL; // 2 minutes

// ===== Accelerometer / tap detection =====
float lastX = 0, lastY = 0, lastZ = 0;
const float MOVEMENT_THRESHOLD = 4.0f;           // Normal tap threshold for pages 2+
const float HOMEPAGE_THRESHOLD = 6.0f;          // Firmer tap needed for homepage
unsigned long lastRawTap = 0;
const unsigned long RAW_DEBOUNCE_MS = 500UL;
const unsigned long PAGE_ADVANCE_COOLDOWN_MS = 1350UL;  // 1.5 second cooldown
const unsigned long HOMEPAGE_ADVANCE_COOLDOWN_MS = 1800UL;  // 2 second cooldown after homepage
unsigned long lastPageAdvanceTime = 0;

// ===== Utility =====
uint64_t nowEpoch() { return millis() / 1000ULL; }
uint64_t nextId()  { return (nowEpoch() << 16) | (epochCounter++ & 0xFFFFULL); }

String htmlEscape(const String& input) {
  String output;
  output.reserve(input.length() * 1.2);
  for (size_t i = 0; i < input.length(); i++) {
    char c = input[i];
    switch (c) {
      case '&':  output += "&amp;";  break;
      case '<':  output += "&lt;";   break;
      case '>':  output += "&gt;";   break;
      case '"':  output += "&quot;"; break;
      case '\'': output += "&#39;";  break;
      default:   output += c;        break;
    }
  }
  return output;
}

// ===== LittleFS DB =====
bool loadDB() {
  if (!LittleFS.exists(DB_PATH)) return true;
  File f = LittleFS.open(DB_PATH, "r");
  if (!f) return false;
  size_t size = f.size();
  std::unique_ptr<char[]> buf(new char[size + 1]);
  f.readBytes(buf.get(), size);
  buf[size] = 0;
  f.close();
  DynamicJsonDocument doc(size * 2 + 1024);
  auto err = deserializeJson(doc, buf.get());
  if (err) { Serial.print("DB parse error: "); Serial.println(err.c_str()); return false; }
  JsonArray arr = doc["stories"].as<JsonArray>();
  stories.clear();
  for (JsonObject o : arr) {
    Story s;
    s.id = o["id"].as<uint64_t>();
    s.type = String((const char*)o["type"]);
    s.text = String((const char*)o["text"]);
    s.ts = o["ts"].as<uint64_t>();
    stories.push_back(s);
  }
  Serial.printf("Loaded %u stories\n", (unsigned)stories.size());
  return true;
}

bool saveDB() {
  const size_t capacity = JSON_ARRAY_SIZE(stories.size()) + stories.size() * JSON_OBJECT_SIZE(4) + 8192;
  DynamicJsonDocument doc(capacity);
  JsonArray arr = doc.createNestedArray("stories");
  for (auto &s : stories) {
    JsonObject o = arr.createNestedObject();
    o["id"] = s.id; o["type"] = s.type; o["text"] = s.text; o["ts"] = s.ts;
  }
  File f = LittleFS.open(DB_PATH, "w");
  if (!f) return false;
  serializeJson(doc, f);
  f.close();
  return true;
}

void appendStory(const String &type, const String &text) {
  if (stories.size() >= MAX_STORIES) stories.erase(stories.begin());
  Story s; s.id = nextId(); s.type = type; s.text = text; s.ts = nowEpoch();
  stories.push_back(s);
  saveDB();
}

// ===== Text helpers =====
void drawCenteredText(const char* text, int y, int textSize=2) {
  int16_t tbx,tby; uint16_t tbw,tbh;
  display.setTextSize(textSize);
  display.getTextBounds(text, 0, 0, &tbx, &tby, &tbw, &tbh);
  int16_t x = ((display.width() - tbw) / 2) - tbx;
  display.setCursor(x, y);
  display.print(text);
}

void drawCenteredParagraph(const String &text, int startY, int maxWidth, int lineHeight) {
  display.setTextSize(2);
  
  std::vector<String> lines;
  String currentLine = "";
  String word = "";
  
  for (size_t i = 0; i <= text.length(); ++i) {
    char c = (i < text.length()) ? text[i] : ' ';
    
    if (c == ' ' || c == '\n' || i == text.length()) {
      String testLine = currentLine;
      if (testLine.length() > 0) testLine += " ";
      testLine += word;
      
      int16_t tbx, tby;
      uint16_t tbw, tbh;
      display.getTextBounds(testLine.c_str(), 0, 0, &tbx, &tby, &tbw, &tbh);
      
      if (tbw > maxWidth && currentLine.length() > 0) {
        lines.push_back(currentLine);
        currentLine = word;
      } else {
        currentLine = testLine;
      }
      
      if (c == '\n' || i == text.length()) {
        if (currentLine.length() > 0) {
          lines.push_back(currentLine);
        }
        currentLine = "";
      }
      word = "";
    } else {
      word += c;
    }
  }
  
  int y = startY;
  
  for (const String& line : lines) {
    int16_t tbx, tby;
    uint16_t tbw, tbh;
    display.getTextBounds(line.c_str(), 0, 0, &tbx, &tby, &tbw, &tbh);
    int16_t x = ((display.width() - tbw) / 2) - tbx;
    display.setCursor(x, y);
    display.print(line);
    y += lineHeight;
  }
}

// ===== EPD helpers =====
bool getSrcBit(const unsigned char* bmp, int w, int h, int sx, int sy) {
  int bytesPerLine = (w + 7) / 8;
  int byteIndex = sy * bytesPerLine + (sx / 8);
  unsigned char b = pgm_read_byte(bmp + byteIndex);
  int bit = 7 - (sx % 8);
  return (b >> bit) & 1;
}

void drawScaledBitmap(const unsigned char* src, int srcW, int srcH, int dstX, int dstY, int dstW, int dstH) {
  for (int yy = 0; yy < dstH; ++yy) {
    int sy = (yy * srcH) / dstH;
    for (int xx = 0; xx < dstW; ++xx) {
      int sx = (xx * srcW) / dstW;
      if (getSrcBit(src, srcW, srcH, sx, sy))
        display.drawPixel(dstX + xx, dstY + yy, GxEPD_BLACK);
    }
  }
}

void drawInvertedBitmap(const unsigned char* bitmap, int16_t x, int16_t y, int16_t w, int16_t h, uint16_t color) {
  int16_t byteWidth = (w + 7) / 8;
  uint8_t byte = 0;
  for (int16_t j = 0; j < h; j++) {
    for (int16_t i = 0; i < w; i++) {
      if (i & 7) {
        byte <<= 1;
      } else {
        byte = pgm_read_byte(&bitmap[j * byteWidth + i / 8]);
      }
      if (!(byte & 0x80)) {
        display.drawPixel(x + i, y + j, color);
      }
    }
  }
}

// ===== Page Drawing Functions =====
void drawPage1() {
  display.firstPage();
  do {
    display.fillScreen(GxEPD_WHITE);
    display.setTextSize(4);
    drawCenteredText("Welcome to the", 60, 4);
    drawCenteredText("MIT StoryStone!", 110, 4);
    display.setTextSize(3);
    drawCenteredText("Tap to Explore", 200, 3);
  } while(display.nextPage());
  delay(120);
}

void drawPage2() {
  display.firstPage();
  do {
    display.fillScreen(GxEPD_WHITE);
    display.setTextSize(3);
    drawCenteredText("Hello stranger!", 40, 3);
    display.setTextSize(2);
    String para = "Thanks for your willingness to linger here for a moment and explore the object beneath your feet.";
    drawCenteredParagraph(para, 100, display.width() - 40, 28);
    display.setTextSize(2);
    drawCenteredText("-Tap to Continue-", display.height() - 35, 2);
  } while(display.nextPage());
  delay(120);
}

void drawPage3() {
  display.firstPage();
  do {
    display.fillScreen(GxEPD_WHITE);
    display.setTextSize(3);
    drawCenteredText("This is a StoryStone.", 50, 3);
    display.setTextSize(2);
    drawCenteredText("A proof of concept", 110, 2);
    drawCenteredText("for modular, solar powered,", 140, 2);
    drawCenteredText("public interest technology", 170, 2);
    drawCenteredText("that centers the pedestrian.", 200, 2);
    display.setTextSize(2);
    drawCenteredText("-Tap to Continue-", display.height() - 35, 2);
  } while(display.nextPage());
  delay(120);
}

void drawPage4() {
  display.firstPage();
  do {
    display.fillScreen(GxEPD_WHITE);
    display.setTextSize(2);
    String para = "Street bricks and pavers are everywhere. They are a form of modularity in the built environment that rarely invites curiosity or engagement.";
    drawCenteredParagraph(para, 50, display.width() - 40, 28);
    display.setTextSize(2);
    drawCenteredText("But what if they could?", 220, 2);
    display.setTextSize(2);
    drawCenteredText("-Tap to Continue-", display.height() - 35, 2);
  } while(display.nextPage());
  delay(120);
}

void drawPage5() {
  display.firstPage();
  do {
    display.fillScreen(GxEPD_WHITE);
    display.setTextSize(2);
    String para = "What if a brick could be a landmark, a tool for navigating your environment, or a way to learn about the place you're standing?";
    drawCenteredParagraph(para, 60, display.width() - 40, 28);
    display.setTextSize(2);
    drawCenteredText("-Tap to Continue-", display.height() - 35, 2);
  } while(display.nextPage());
  delay(120);
}

void drawPage6() {
  display.firstPage();
  do {
    display.fillScreen(GxEPD_WHITE);
    display.setTextSize(2);
    String para = "What if it held directions or collected data,";
    drawCenteredParagraph(para, 70, display.width() - 40, 28);
    display.setTextSize(2);
    drawCenteredText("or simply offered a moment", 125, 2);
    drawCenteredText("of delight and discovery?", 155, 2);
    display.setTextSize(2);
    drawCenteredText("-Tap to Continue-", display.height() - 35, 2);
  } while(display.nextPage());
  delay(120);
}

void drawPage7() {
  display.firstPage();
  do {
    display.fillScreen(GxEPD_WHITE);
    display.setTextSize(2);
    String para = "Like an eddy in a river, the StoryStone is an attempt to slow you down, to catch your attention, create meaningful engagement, then return you to the flow of your day.";
    drawCenteredParagraph(para, 50, display.width() - 40, 28);
    display.setTextSize(2);
    drawCenteredText("-Tap to Continue-", display.height() - 35, 2);
  } while(display.nextPage());
  delay(120);
}

void drawPage8() {
  display.firstPage();
  do {
    display.fillScreen(GxEPD_WHITE);
    display.setTextSize(2);
    drawCenteredText("At a place like MIT...", 50, 2);
    display.setTextSize(2);
    String para1 = "Where might a StoryStone or a network of StoryStones belong?";
    drawCenteredParagraph(para1, 90, display.width() - 40, 28);
    String para2 = "What should they say or show? How might they best serve your pedestrian journey?";
    drawCenteredParagraph(para2, 150, display.width() - 40, 28);
    display.setTextSize(2);
    drawCenteredText("-Tap to Continue-", display.height() - 35, 2);
  } while(display.nextPage());
  delay(120);
}

void drawPage9() {
  display.firstPage();
  do {
    display.fillScreen(GxEPD_WHITE);
    display.setTextSize(2);
    String para = "A StoryStone could serve as a wayfinding tool - a point of orientation for hyper-local resources that are accessible by foot...";
    drawCenteredParagraph(para, 60, display.width() - 40, 28);
    display.setTextSize(2);
    drawCenteredText("-Tap to Continue-", display.height() - 35, 2);
  } while(display.nextPage());
  delay(120);
}

void drawPage10() {
  display.firstPage();
  do {
    display.fillScreen(GxEPD_WHITE);
    drawInvertedBitmap(ss_resources_bitmap, 0, 0, display.width(), display.height(), GxEPD_BLACK);
  } while(display.nextPage());
  delay(120);
}

void drawPage11() {
  display.firstPage();
  do {
    display.fillScreen(GxEPD_WHITE);
    display.setTextSize(2);
    String para = "It could sense your surroundings - air quality, temperature, sound - and provide real-time information about the environment...";
    drawCenteredParagraph(para, 60, display.width() - 40, 28);
    display.setTextSize(2);
    drawCenteredText("-Tap to Continue-", display.height() - 35, 2);
  } while(display.nextPage());
  delay(120);
}

void drawPage12() {
  display.firstPage();
  do {
    display.fillScreen(GxEPD_WHITE);
    drawInvertedBitmap(ss_enviro_bitmap, 0, 0, display.width(), display.height(), GxEPD_BLACK);
  } while(display.nextPage());
  delay(120);
}

void drawPage13() {
  display.firstPage();
  do {
    display.fillScreen(GxEPD_WHITE);
    display.setTextSize(2);
    String para = "It could ask questions and gather site-specific data from everyday pedestrian experiences...";
    drawCenteredParagraph(para, 70, display.width() - 40, 28);
    display.setTextSize(2);
    drawCenteredText("-Tap to Continue-", display.height() - 35, 2);
  } while(display.nextPage());
  delay(120);
}

void drawPage14() {
  display.firstPage();
  do {
    display.fillScreen(GxEPD_WHITE);
    drawInvertedBitmap(ss_survey_bitmap, 0, 0, display.width(), display.height(), GxEPD_BLACK);
  } while(display.nextPage());
  delay(120);
}

void drawPage15() {
  display.firstPage();
  do {
    display.fillScreen(GxEPD_WHITE);
    display.setTextSize(2);
    drawCenteredText("Want to share", 70, 3);
    drawCenteredText("your thoughts?", 100, 3);
    display.setTextSize(2);
    drawCenteredText("The next page opens", 145, 3);
    drawCenteredText("the StoryStone portal.", 175, 3);
    drawCenteredText("-Tap to Continue-", display.height() - 35, 2);
  } while(display.nextPage());
  delay(120);
}

void drawPage16() {
  display.firstPage();
  do {
    display.fillScreen(GxEPD_WHITE);
    display.setTextSize(2);
    String para = "Open the WiFi settings on your phone and connect to the \"StoryStone.\" Then scan the QR code on the next page.";
    drawCenteredParagraph(para, 50, display.width() - 40, 28);
    display.setTextSize(2);
    drawCenteredText("(It may take a few tries!)", 165, 2);
    display.setTextSize(2);
    drawCenteredText("-Tap to Continue-", display.height() - 35, 2);
  } while(display.nextPage());
  delay(120);
}

void drawPage17() {
  const int SRC_W = 200, SRC_H = 200;
  const int DST_W = 180, DST_H = 180;
  int bx = (display.width() - DST_W) / 2;
  int by = 70;

  display.firstPage();
  do {
    display.fillScreen(GxEPD_WHITE);
    display.setTextSize(2);
    drawCenteredText("Scan QR or visit:", 15, 2);
    drawCenteredText("http://192.168.4.1/", 40, 2);
    drawScaledBitmap(ss_qr_bitmap, SRC_W, SRC_H, bx, by, DST_W, DST_H);
    drawCenteredText("-Tap to Continue-", display.height() - 20, 2);
  } while(display.nextPage());
  delay(120);
}

void drawPage18() {
  display.firstPage();
  do {
    display.fillScreen(GxEPD_WHITE);
    display.setTextSize(2);
    String para = "If you wish to collaborate on this project, please feel free to email storystone.project@gmail.com.";
    drawCenteredParagraph(para, 60, display.width() - 40, 28);
    display.setTextSize(2);
    drawCenteredText("Thanks for stopping by!", 210, 2);
    display.setTextSize(2);
    drawCenteredText("-Tap to Return to Homepage-", display.height() - 35, 2);
  } while(display.nextPage());
  delay(120);
}

void drawCurrentPage() {
  switch(currentPage) {
    case 1: drawPage1(); break;
    case 2: drawPage2(); break;
    case 3: drawPage3(); break;
    case 4: drawPage4(); break;
    case 5: drawPage5(); break;
    case 6: drawPage6(); break;
    case 7: drawPage7(); break;
    case 8: drawPage8(); break;
    case 9: drawPage9(); break;
    case 10: drawPage10(); break;
    case 11: drawPage11(); break;
    case 12: drawPage12(); break;
    case 13: drawPage13(); break;
    case 14: drawPage14(); break;
    case 15: drawPage15(); break;
    case 16: drawPage16(); break;
    case 17: drawPage17(); break;
    case 18: drawPage18(); break;
  }
}

// ===== AP control =====
void ensureRoutes() {
  server.on("/", [](){
    String html;
    html.reserve(8192);
    html = F("<!DOCTYPE html><html><head><meta name='viewport' content='width=device-width,initial-scale=1'>");
    html += F("<style>body{font-family:Arial;max-width:600px;margin:40px auto;padding:20px;}");
    html += F("h1{color:#333;}textarea{width:100%;height:150px;margin:10px 0;padding:10px;font-size:16px;}");
    html += F("button{background:#007bff;color:white;padding:12px 24px;border:none;border-radius:4px;cursor:pointer;font-size:16px;}");
    html += F("button:hover{background:#0056b3;}.story{background:#f5f5f5;padding:15px;margin:10px 0;border-radius:5px;}");
    html += F(".char-count{text-align:right;color:#999;font-size:14px;margin-top:5px;}</style>");
    html += F("<script>function updateCount(){var t=document.getElementById('story');var c=document.getElementById('count');var wc=document.getElementById('wordcount');");
    html += F("var words=t.value.trim().split(/\\s+/).filter(function(w){return w.length>0;}).length;");
    html += F("c.textContent=t.value.length+'/200 characters';");
    html += F("wc.textContent=words+' words';");
    html += F("c.style.color=t.value.length>200?'red':'#999';");
    html += F("wc.style.color=words>200?'red':'#999';}</script></head><body>");
    html += F("<h1>StoryStone Portal</h1>");
    html += F("<p>Share your thoughts about the StoryStone project or what might improve your pedestrian experiences on campus and elsewhere. (max 200 words):</p>");
    html += F("<form action='/submit' method='POST'>");
    html += F("<textarea id='story' name='story' placeholder='Your story here...' maxlength='200' required oninput='updateCount()'></textarea>");
    html += F("<div class='char-count'><span id='count'>0/200 characters</span> | <span id='wordcount'>0 words</span></div>");
    html += F("<button type='submit'>Submit Story</button></form>");
    html += F("<hr><h2>Recent Stories</h2>");
    int count = 0;
    for(int i = stories.size() - 1; i >= 0 && count < 10; i--, count++) {
      html += "<div class='story'><p>" + htmlEscape(stories[i].text) + "</p></div>";
    }
    html += F("</body></html>");
    server.send(200, "text/html", html);
  });

  server.on("/submit", HTTP_POST, [](){
    if(server.hasArg("story")) {
      String story = server.arg("story");
      story.trim();
      
      story.replace("<", "&lt;");
      story.replace(">", "&gt;");
      
      int wordCount = 0;
      bool inWord = false;
      for (size_t i = 0; i < story.length(); i++) {
        if (isspace(story[i])) {
          inWord = false;
        } else if (!inWord) {
          wordCount++;
          inWord = true;
        }
      }
      
      if (story.length() < MIN_STORY_LENGTH || story.length() > MAX_STORY_LENGTH) {
        server.send(400, "text/plain", "Story must be 1-200 characters");
        return;
      }
      
      if (wordCount > 200) {
        server.send(400, "text/plain", "Story must be 200 words or less");
        return;
      }
      
      appendStory("Public", story);
      String html = F("<!DOCTYPE html><html><head><meta http-equiv='refresh' content='2;url=/'>");
      html += F("<meta name='viewport' content='width=device-width,initial-scale=1'>");
      html += F("<style>body{font-family:Arial;text-align:center;padding:50px;}</style></head><body>");
      html += F("<h1>Thank you!</h1><p>Your story has been saved.</p><p>Redirecting...</p></body></html>");
      server.send(200, "text/html", html);
    } else server.send(400, "text/plain", "Missing story");
  });

  server.on("/download", [](){
    if (!server.authenticate("admin", "storystone")) {
      return server.requestAuthentication();
    }
    File f = LittleFS.open(DB_PATH, "r");
    if (!f) { server.send(404, "text/plain", "No data found"); return; }
    server.streamFile(f, "application/json"); 
    f.close();
  });

  server.on("/admin", [](){
    if (!server.authenticate("admin", "storystone")) {
      return server.requestAuthentication();
    }
    String html = F("<!DOCTYPE html><html><head><meta name='viewport' content='width=device-width,initial-scale=1'>");
    html += F("<style>body{font-family:Arial;max-width:600px;margin:40px auto;padding:20px;}");
    html += F("h1{color:#333;}button{background:#dc3545;color:white;padding:12px 24px;border:none;");
    html += F("border-radius:4px;cursor:pointer;font-size:16px;margin:10px 0;}");
    html += F("button:hover{background:#c82333;}a{display:inline-block;background:#007bff;color:white;");
    html += F("padding:12px 24px;text-decoration:none;border-radius:4px;margin:10px 0;}");
    html += F("a:hover{background:#0056b3;}.info{background:#f0f0f0;padding:15px;border-radius:5px;margin:20px 0;}");
    html += F(".warning{background:#fff3cd;border-left:4px solid #ffc107;padding:15px;margin:20px 0;}</style></head><body>");
    html += F("<h1>Admin Panel</h1>");
    html += F("<div class='info'>");
    html += "<p><strong>Total stories:</strong> " + String(stories.size()) + "/" + String(MAX_STORIES) + "</p>";
    
    File f = LittleFS.open(DB_PATH, "r");
    if (f) {
      html += "<p><strong>Database size:</strong> " + String(f.size()) + " bytes</p>";
      f.close();
    }
    html += F("</div>");
    
    if (stories.size() > 800) {
      html += F("<div class='warning'><strong>Warning:</strong> Storage is over 80% full. Consider downloading and clearing old stories.</div>");
    }
    
    html += F("<a href='/download'>Download All Stories (JSON)</a><br>");
    html += F("<a href='/view_all'>View All Stories</a><br><br>");
    html += F("<form action='/admin_clear' method='POST' onsubmit='return confirm(\"Are you sure you want to delete all stories? This cannot be undone.\")'>");
    html += F("<button type='submit'>Clear All Stories</button></form>");
    html += F("<br><a href='/'>Back to Portal</a>");
    html += F("</body></html>");
    server.send(200, "text/html", html);
  });

  server.on("/view_all", [](){
    if (!server.authenticate("admin", "storystone")) {
      return server.requestAuthentication();
    }
    String html = F("<!DOCTYPE html><html><head><meta name='viewport' content='width=device-width,initial-scale=1'>");
    html += F("<style>body{font-family:Arial;max-width:800px;margin:40px auto;padding:20px;}");
    html += F("h1{color:#333;}.story{background:#f5f5f5;padding:15px;margin:10px 0;border-radius:5px;border-left:4px solid #007bff;}");
    html += F(".story-meta{color:#666;font-size:12px;margin-top:10px;}a{color:#007bff;}</style></head><body>");
    html += F("<h1>All Stories</h1>");
    html += "<p>Total: " + String(stories.size()) + " stories</p>";
    html += F("<a href='/admin'>← Back to Admin</a><hr>");
    
    for(int i = stories.size() - 1; i >= 0; i--) {
      html += "<div class='story'>";
      html += "<p>" + htmlEscape(stories[i].text) + "</p>";
      html += "<div class='story-meta'>ID: " + String((unsigned long)stories[i].id);
      html += " | Time: " + String((unsigned long)stories[i].ts) + "</div>";
      html += "</div>";
    }
    html += F("</body></html>");
    server.send(200, "text/html", html);
  });

  server.on("/admin_clear", HTTP_POST, [](){
    if (!server.authenticate("admin", "storystone")) {
      return server.requestAuthentication();
    }
    stories.clear(); 
    saveDB();
    String html = F("<!DOCTYPE html><html><head><meta http-equiv='refresh' content='2;url=/admin'>");
    html += F("<meta name='viewport' content='width=device-width,initial-scale=1'>");
    html += F("<style>body{font-family:Arial;text-align:center;padding:50px;}</style></head><body>");
    html += F("<h1>Success</h1><p>All stories cleared.</p><p>Redirecting...</p></body></html>");
    server.send(200, "text/html", html);
  });
}

void startAPIfNeeded() {
  if (apActive) return;
  WiFi.softAP(AP_SSID);
  ensureRoutes();
  server.begin();
  apActive = true;
  Serial.println("AP started");
}

void stopAPIfActive() {
  if (!apActive) return;
  server.stop();
  WiFi.softAPdisconnect(true);
  apActive = false;
  Serial.println("AP stopped");
}

void advancePage() {
  int oldPage = currentPage;
  currentPage++;
  if (currentPage > TOTAL_PAGES) currentPage = 1;

  Serial.print("ADVANCE: Page ");
  Serial.print(oldPage);
  Serial.print(" -> Page ");
  Serial.println(currentPage);

  if (currentPage >= 15 && currentPage <= 18) startAPIfNeeded();
  else stopAPIfActive();

  drawCurrentPage();
  
  stateStartTime = millis();
  lastPageAdvanceTime = millis();
}

// ===== Main loop =====
void loop() {
  unsigned long now = millis();

  sensors_event_t ev;
  accel.getEvent(&ev);
  float movement = abs(ev.acceleration.x - lastX) + abs(ev.acceleration.y - lastY) + abs(ev.acceleration.z - lastZ);
  lastX = ev.acceleration.x; lastY = ev.acceleration.y; lastZ = ev.acceleration.z;

  // Use different thresholds for homepage vs other pages
  float currentThreshold = (currentPage == 1) ? HOMEPAGE_THRESHOLD : MOVEMENT_THRESHOLD;

  if (movement > currentThreshold) {
    if (now - lastRawTap > RAW_DEBOUNCE_MS) {
      lastRawTap = now;
      
      Serial.print("TAP detected (movement: ");
      Serial.print(movement);
      Serial.print(") at ");
      Serial.print(now);
      Serial.print(" | Page: ");
      Serial.println(currentPage);

      // Determine which cooldown to use
      unsigned long requiredCooldown = (currentPage == 2) ? HOMEPAGE_ADVANCE_COOLDOWN_MS : PAGE_ADVANCE_COOLDOWN_MS;
      unsigned long timeSinceLastAdvance = now - lastPageAdvanceTime;
      
      if (timeSinceLastAdvance > requiredCooldown) {
        Serial.printf("Advancing from page %d (cooldown satisfied: %lu ms)\n", currentPage, timeSinceLastAdvance);
        advancePage();
        
        // Clear accelerometer buffer after advancing
        if (currentPage == 2) {
          delay(100);
          for (int i = 0; i < 5; i++) {
            sensors_event_t clearEv;
            accel.getEvent(&clearEv);
            lastX = clearEv.acceleration.x;
            lastY = clearEv.acceleration.y;
            lastZ = clearEv.acceleration.z;
            delay(20);
          }
        }
      } else {
        Serial.printf("Cooldown active on page %d, ignoring tap (%lu ms remaining)\n", currentPage, requiredCooldown - timeSinceLastAdvance);
      }
    }
  }

  // Timeout check - return to homepage after 2 minutes of inactivity
  if (currentPage != 1 && stateStartTime > 0) {
    unsigned long timeDiff = now - stateStartTime;
    if (timeDiff < 0x80000000UL && timeDiff > TIMEOUT_MS) {
      Serial.println("TIMEOUT - returning to page 1");
      currentPage = 1;
      stopAPIfActive();
      drawCurrentPage();
      stateStartTime = 0;
    }
  }

  if (apActive) server.handleClient();

  delay(30);
}

// ===== Setup =====
void setup() {
  Serial.begin(115200);
  pinMode(LED_PIN, INPUT);
  SPI.begin(7, -1, 9, EPD_CS);
  display.init(115200, true, 2, false);
  display.setRotation(0);
  display.setTextColor(GxEPD_BLACK);
  display.setFullWindow();

  I2CBus.begin(5,6);
  if (!accel.begin(0x1D)) { Serial.println("ADXL343 not detected!"); while(1) delay(1000); }

  sensors_event_t ev;
  accel.getEvent(&ev);
  lastX = ev.acceleration.x; lastY = ev.acceleration.y; lastZ = ev.acceleration.z;

  if (!LittleFS.begin(true)) { Serial.println("LittleFS mount failed"); }
  loadDB();

  currentPage = 1;
  drawCurrentPage();
  stateStartTime = 0;
  Serial.println("Setup complete - Single tap navigation active");
}