#include <Arduino.h>
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

/* ===================== OLED CONFIG ===================== */
static const int OLED_W = 128;
static const int OLED_H = 64;
static const int OLED_RST = -1;            // обычно -1
static const uint8_t OLED_ADDR = 0x3C;     // чаще всего 0x3C (иногда 0x3D)
Adafruit_SSD1306 oled(OLED_W, OLED_H, &Wire, OLED_RST);
/* ======================================================= */

/* ===================== PIN CONFIG ===================== */
static const uint8_t BTN1_PIN = 16;  // Power
static const uint8_t BTN2_PIN = 17;  // Action/System/Confirm
static const uint8_t BTN3_PIN = 18;  // Nav/History
/* ======================================================= */

/* ===================== TIMING CONFIG ===================== */
static const uint32_t DEBOUNCE_MS   = 45;   // было 35
static const uint32_t DOUBLE_MS     = 420;  // было 320 (главный фикс)
static const uint32_t LONG_MS       = 700;  // было 650 (чуть спокойнее)
static const uint32_t REPEAT_MS     = 220;
static const uint32_t BTN3_ARM_LEFT_MS = 420; // tap -> press&hold to scroll left
/* ========================================================= */

/* ===================== TYPES ===================== */
enum AppState : uint8_t {
  ST_OFF = 0,
  ST_ANSWER,
  ST_CAPTURED,
  ST_SYSTEM_MENU,
  ST_HISTORY_MENU
};

enum BtnEvent : uint8_t {
  EV_NONE = 0,
  EV_CLICK,
  EV_DOUBLE,
  EV_LONG_START,
  EV_LONG_REPEAT,
  EV_LONG_RELEASE
};

struct Btn {
  uint8_t pin = 0;

  bool raw = false;
  bool stable = false;
  bool lastRaw = false;
  bool lastStable = false;

  uint32_t lastDebounceMs = 0;
  uint32_t pressMs = 0;

  bool longFired = false;
  uint32_t lastRepeatMs = 0;

  uint8_t clickCount = 0;
  uint32_t lastClickReleaseMs = 0;
  bool waitingSingle = false;

  // BTN3 special
  uint32_t armLeftUntilMs = 0;
  bool leftModeActive = false;
};
/* ================================================= */

/* ===================== GLOBALS ===================== */
static AppState g_state = ST_OFF;

static const char* ANSWER_OPTIONS[] = { "Option A", "Option B", "Option C" };
static const uint8_t ANSWER_OPT_COUNT = sizeof(ANSWER_OPTIONS) / sizeof(ANSWER_OPTIONS[0]);

static const char* SYS_OPTIONS[] = { "WiFi", "Brightness", "About", "Reset" };
static const uint8_t SYS_OPT_COUNT = sizeof(SYS_OPTIONS) / sizeof(SYS_OPTIONS[0]);

static const char* HIST_ITEMS[] = { "Ans #1", "Ans #2", "Ans #3", "Ans #4" };
static const uint8_t HIST_COUNT = sizeof(HIST_ITEMS) / sizeof(HIST_ITEMS[0]);

static int g_sel = 0;
static int g_answerPage = 0;

static Btn b1, b2, b3;

static char g_lastAction[32] = "BOOT";
/* =================================================== */

/* ===================== HELPERS ===================== */
static void setLastAction(const char* s) {
  strncpy(g_lastAction, s, sizeof(g_lastAction) - 1);
  g_lastAction[sizeof(g_lastAction) - 1] = '\0';
}

static const char* stateToStr(AppState s) {
  switch (s) {
    case ST_OFF: return "OFF";
    case ST_ANSWER: return "ANSWER";
    case ST_CAPTURED: return "CAPTURED";
    case ST_SYSTEM_MENU: return "SYSTEM";
    case ST_HISTORY_MENU: return "HISTORY";
    default: return "?";
  }
}

static void drawOLED() {
  oled.display(); 

  oled.clearDisplay();
  oled.setTextColor(SSD1306_WHITE);

  // Header
  oled.setTextSize(1);
  oled.setCursor(0, 0);
  oled.print("STATE: ");
  oled.print(stateToStr(g_state));

  // Last action
  oled.setCursor(0, 10);
  oled.print("ACT: ");
  oled.print(g_lastAction);

  // Body
  oled.setCursor(0, 24);
  if (g_state == ST_OFF) {
    oled.print("BTN1: Power ON");
  } else if (g_state == ST_ANSWER) {
    oled.print("page=");
    oled.print(g_answerPage);
    oled.setCursor(0, 34);
    oled.print("sel=");
    oled.print(g_sel);
    oled.print(" ");
    oled.print(ANSWER_OPTIONS[g_sel]);
    oled.setCursor(0, 48);
    oled.print("B2=CAP  B3=SEL");
  } else if (g_state == ST_CAPTURED) {
    oled.print("Photo ready (stub)");
    oled.setCursor(0, 34);
    oled.print("B2 click=SEND");
    oled.setCursor(0, 44);
    oled.print("B2 hold=CANCEL");
  } else if (g_state == ST_SYSTEM_MENU) {
    oled.print("sel=");
    oled.print(g_sel);
    oled.setCursor(0, 34);
    oled.print(SYS_OPTIONS[g_sel]);
    oled.setCursor(0, 48);
    oled.print("B3=NEXT  B2=OK");
  } else if (g_state == ST_HISTORY_MENU) {
    oled.print("sel=");
    oled.print(g_sel);
    oled.setCursor(0, 34);
    oled.print(HIST_ITEMS[g_sel]);
    oled.setCursor(0, 48);
    oled.print("B3=NEXT  B2=OK");
  }

  oled.display();
}

static void setState(AppState next) {
  if (g_state == next) return;
  if (next == ST_ANSWER || next == ST_SYSTEM_MENU || next == ST_HISTORY_MENU || next == ST_CAPTURED) {
    g_sel = 0;
  }
  g_state = next;
  drawOLED();
}

static bool readPressed(uint8_t pin) {
  return (digitalRead(pin) == LOW);
}

static BtnEvent updateButton(Btn &b) {
  const uint32_t now = millis();
  b.raw = readPressed(b.pin);

  if (b.raw != b.lastRaw) {
    b.lastDebounceMs = now;
    b.lastRaw = b.raw;
  }
  if ((now - b.lastDebounceMs) >= DEBOUNCE_MS) {
    b.stable = b.raw;
  }

  // stable edge
  if (b.stable != b.lastStable) {
    b.lastStable = b.stable;
    if (b.stable) {
      b.pressMs = now;
      b.longFired = false;
      b.lastRepeatMs = now;
    } else {
      if (b.longFired) return EV_LONG_RELEASE;

      b.clickCount++;
      b.lastClickReleaseMs = now;
      b.waitingSingle = true;
    }
  }

  if (b.stable) {
    const uint32_t held = now - b.pressMs;
    if (!b.longFired && held >= LONG_MS) {
      b.longFired = true;
      return EV_LONG_START;
    }
    if (b.longFired && (now - b.lastRepeatMs) >= REPEAT_MS) {
      b.lastRepeatMs = now;
      return EV_LONG_REPEAT;
    }
  }

  if (b.waitingSingle) {
    if (b.clickCount >= 2) {
      b.clickCount = 0;
      b.waitingSingle = false;
      return EV_DOUBLE;
    }
    if ((now - b.lastClickReleaseMs) > DOUBLE_MS) {
      b.clickCount = 0;
      b.waitingSingle = false;
      return EV_CLICK;
    }
  }

  return EV_NONE;
}

/* ===================== ACTIONS (STUBS) ===================== */
static void powerToggle() {
  if (g_state == ST_OFF) {
    setLastAction("Power ON");
    setState(ST_ANSWER);
  } else {
    setLastAction("Power OFF");
    setState(ST_OFF);
  }
}

static void captureStub() {
  setLastAction("YA SFOTKAL");
  setState(ST_CAPTURED);
}

static void sendStub() {
  setLastAction("OTPRAVIL");
  setState(ST_ANSWER);
}

static void cancelStub() {
  setLastAction("OTMENA");
  setState(ST_ANSWER);
}

static void confirmStub() {
  setLastAction("CONFIRM");
  drawOLED();
}

static void cycleSel(uint8_t maxCount) {
  if (!maxCount) return;
  g_sel = (g_sel + 1) % maxCount;
  setLastAction("SEL NEXT");
  drawOLED();
}

static void toggleSystemMenu() {
  if (g_state == ST_SYSTEM_MENU) {
    setLastAction("SYS CLOSE");
    setState(ST_ANSWER);
  } else {
    setLastAction("SYS OPEN");
    setState(ST_SYSTEM_MENU);
  }
}

static void toggleHistoryMenu() {
  if (g_state == ST_HISTORY_MENU) {
    setLastAction("HIST CLOSE");
    setState(ST_ANSWER);
  } else {
    setLastAction("HIST OPEN");
    setState(ST_HISTORY_MENU);
  }
}

static void scrollRight() {
  g_answerPage++;
  setLastAction("SCROLL R");
  drawOLED();
}

static void scrollLeft() {
  g_answerPage--;
  setLastAction("SCROLL L");
  drawOLED();
}

/* ===================== ROUTING (YOUR RULES) ===================== */
static void handleBtn1(BtnEvent ev) {
  if (ev == EV_CLICK) powerToggle();
}

static void handleBtn2(BtnEvent ev) {
  if (g_state == ST_OFF) return;

  // BTN2 double: toggle system menu (open from ANSWER, close from SYSTEM)
if (ev == EV_DOUBLE) {
  if (g_state == ST_ANSWER || g_state == ST_SYSTEM_MENU) {
    toggleSystemMenu();
  }
  return;
}

  // BTN2 hold: only in CAPTURED cancel
  if (ev == EV_LONG_START) {
    if (g_state == ST_CAPTURED) cancelStub();
    return;
  }

  // BTN2 click:
  if (ev == EV_CLICK) {
    if (g_state == ST_ANSWER) captureStub();
    else if (g_state == ST_CAPTURED) sendStub();
    else if (g_state == ST_SYSTEM_MENU || g_state == ST_HISTORY_MENU) confirmStub();
    return;
  }
}

static void handleBtn3(BtnEvent ev) {
  if (g_state == ST_OFF) return;

  // BTN3 double: toggle history menu (open from ANSWER, close from HISTORY)
if (ev == EV_DOUBLE) {
  if (g_state == ST_ANSWER || g_state == ST_HISTORY_MENU) {
    toggleHistoryMenu();
  }
  return;
}

  // BTN3 click: in system/history switch variants; also allowed "everywhere" if ты хочешь
  if (ev == EV_CLICK) {
    if (g_state == ST_SYSTEM_MENU) cycleSel(SYS_OPT_COUNT);
    else if (g_state == ST_HISTORY_MENU) cycleSel(HIST_COUNT);
    else if (g_state == ST_ANSWER) {
      // по твоему прошлому ТЗ: click везде может переключать варианты,
      // но если тебе нужно, чтобы в ANSWER click не трогал выбор — скажешь.
      cycleSel(ANSWER_OPT_COUNT);
      // arm left gesture
      b3.armLeftUntilMs = millis() + BTN3_ARM_LEFT_MS;
      b3.leftModeActive = false;
    }
    return;
  }

  // BTN3 hold: only in ANSWER scroll right; tap->hold scroll left
  if (g_state == ST_ANSWER) {
    if (ev == EV_LONG_START) {
      uint32_t now = millis();
      if (now <= b3.armLeftUntilMs) {
        b3.leftModeActive = true;
        scrollLeft();
      } else {
        b3.leftModeActive = false;
        scrollRight();
      }
      return;
    }
    if (ev == EV_LONG_REPEAT) {
      if (b3.leftModeActive) scrollLeft();
      else scrollRight();
      return;
    }
  }
}

/* ===================== SETUP/LOOP ===================== */
void setup() {
  Serial.begin(115200);

  pinMode(BTN1_PIN, INPUT_PULLUP);
  pinMode(BTN2_PIN, INPUT_PULLUP);
  pinMode(BTN3_PIN, INPUT_PULLUP);

  b1.pin = BTN1_PIN;
  b2.pin = BTN2_PIN;
  b3.pin = BTN3_PIN;

  // I2C init (ESP32 defaults: SDA=21, SCL=22)
  Wire.begin(21, 22);

  if (!oled.begin(SSD1306_SWITCHCAPVCC, OLED_ADDR)) {
    // если экран не найден, просто пишем в Serial и зависаем
    Serial.println("SSD1306 init failed");
    while (true) delay(100);
  }

  oled.clearDisplay();
  oled.display();

  setLastAction("BOOT");
  setState(ST_OFF);
}

void loop() {
  BtnEvent e1 = updateButton(b1);
  BtnEvent e2 = updateButton(b2);
  BtnEvent e3 = updateButton(b3);

  if (e1 != EV_NONE) handleBtn1(e1);
  if (e2 != EV_NONE) handleBtn2(e2);
  if (e3 != EV_NONE) handleBtn3(e3);
}