// Thay WIFI_SSID, WIFI_PASS, SERVER_BASE trước khi nạp.

#include <WiFi.h>
#include <HTTPClient.h>
#include <SPIFFS.h>
#include <ArduinoJson.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1);

const char* WIFI_SSID = "YOUR_SSID"; //thay tên wifi (Tiếng Việt hay có dấu đều được)
const char* WIFI_PASS = "YOUR_PASS"; //thay password wifi
const char* SERVER_BASE = "http://<ip máy tính>:3000"; //thay ip máy tính thành ip máy host server
const char* PLAYER_ENDPOINT = "/player";
const char* LEADERBOARD_ENDPOINT = "/leaderboard.json";

const int btnUpPin = 5;
const int btnDownPin = 2;
const int btnLeftPin = 15;
const int btnRightPin = 4;
const int btnSelectPin = 16;
const int buzzerPin = 18;

#define RIGHT 0
#define UP    1
#define LEFT  2
#define DOWN  3

int score = 0;
int level = 1;
bool isGameOver = false;

struct FOOD { int x; int y; int yes; } food;
struct SNAKE { int x[200]; int y[200]; int node; int dir; } snake;

const char keyMap[][9] = {
  "ABCDEFGH",
  "IJKLMNOP",
  "QRSTUVWX",
  "YZ 0123 "
};
const int K_ROWS = 4, K_COLS = 8;
char nameBuf[17]; int nameLen = 0;
char classBuf[17]; int classLen = 0;

unsigned long lastLeaderboardFetch = 0;
const unsigned long FETCH_INTERVAL = 10000; // 10s

volatile int dirFlag = -1;
volatile bool selectFlag = false;
volatile unsigned long lastISRtime = 0;
const unsigned long ISR_DEBOUNCE = 120;

const uint8_t ele[] PROGMEM = {
  0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff
};
void element(int x, int y) { display.drawBitmap(x, y, ele, 8, 8, 1); }

void IRAM_ATTR isrUp(){ if(millis()-lastISRtime>ISR_DEBOUNCE){ dirFlag = UP; lastISRtime = millis(); } }
void IRAM_ATTR isrDown(){ if(millis()-lastISRtime>ISR_DEBOUNCE){ dirFlag = DOWN; lastISRtime = millis(); } }
void IRAM_ATTR isrLeft(){ if(millis()-lastISRtime>ISR_DEBOUNCE){ dirFlag = LEFT; lastISRtime = millis(); } }
void IRAM_ATTR isrRight(){ if(millis()-lastISRtime>ISR_DEBOUNCE){ dirFlag = RIGHT; lastISRtime = millis(); } }
void IRAM_ATTR isrSelect(){ if(millis()-lastISRtime>ISR_DEBOUNCE){ selectFlag = true; lastISRtime = millis(); } }

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

  pinMode(btnUpPin, INPUT);
  pinMode(btnDownPin, INPUT);
  pinMode(btnLeftPin, INPUT);
  pinMode(btnRightPin, INPUT);
  pinMode(btnSelectPin, INPUT);
  pinMode(buzzerPin, OUTPUT);

  attachInterrupt(digitalPinToInterrupt(btnUpPin), isrUp, FALLING);
  attachInterrupt(digitalPinToInterrupt(btnDownPin), isrDown, FALLING);
  attachInterrupt(digitalPinToInterrupt(btnLeftPin), isrLeft, FALLING);
  attachInterrupt(digitalPinToInterrupt(btnRightPin), isrRight, FALLING);
  attachInterrupt(digitalPinToInterrupt(btnSelectPin), isrSelect, FALLING);

  if (!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
    Serial.println(F("SSD1306 allocation failed"));
    for(;;);
  }
  display.clearDisplay();
  display.display();

  if (!SPIFFS.begin(true)) {
    Serial.println("SPIFFS mount failed");
  } else Serial.println("SPIFFS mounted");

  display.clearDisplay();
  display.setTextSize(1); display.setTextColor(WHITE);
  display.setCursor(0,0); display.println("WiFi connecting...");
  display.display();

  WiFi.begin(WIFI_SSID, WIFI_PASS);
  int cnt = 0;
  while (WiFi.status() != WL_CONNECTED && cnt < 80) {
    delay(100);
    cnt++;
  }

  display.clearDisplay();
  if (WiFi.status() == WL_CONNECTED) {
    display.setCursor(0,0);
    display.print("WiFi OK ");
    display.println(WiFi.localIP());
    Serial.print("WiFi IP: "); Serial.println(WiFi.localIP());
  } else {
    display.setCursor(0,0);
    display.println("WiFi offline");
    Serial.println("WiFi not connected");
  }
  display.display();
  delay(600);
}

void virtualKeyboardInput(char *buf, int &len, const char* title) {
  int r = 0, c = 0;
  bool done = false;
  unsigned long lastDraw = 0;
  buf[0] = 0; len = 0;

  while (!done) {
    if (dirFlag != -1) {
      int d = dirFlag; dirFlag = -1;
      if (d == UP) r = (r -1 + K_ROWS) % K_ROWS;
      if (d == DOWN) r = (r +1) % K_ROWS;
      if (d == LEFT) c = (c -1 + K_COLS) % K_COLS;
      if (d == RIGHT) c = (c +1) % K_COLS;
    }

    if (selectFlag) {
      selectFlag = false;
      if (r == 3 && c >= 6) {
        if (c == 6) { if (len > 0) { buf[--len] = 0; tone(buzzerPin, 800); delay(80); noTone(buzzerPin); } }
        else { done = true; tone(buzzerPin, 1200); delay(120); noTone(buzzerPin); }
      } else {
        char ch = keyMap[r][c];
        if (ch != '\0' && len < 15) { buf[len++] = ch; buf[len] = 0; tone(buzzerPin, 1000); delay(80); noTone(buzzerPin); }
      }
    }

    if (millis() - lastDraw > 80) {
      lastDraw = millis();
      display.clearDisplay();
      display.setTextSize(1);
      display.setCursor(0,0); display.print(title);
      display.setCursor(0,8); display.print("Value:"); display.setCursor(50,8); display.print(buf);

      int startY = 20;
      for (int rr=0; rr<K_ROWS; rr++) {
        for (int cc=0; cc<K_COLS; cc++) {
          int cellX = cc*15;
          int cellY = startY + rr*10;
          display.drawRect(cellX, cellY, 14, 9, WHITE);
          char ch = (cc < 8) ? keyMap[rr][cc] : ' ';
          display.setCursor(cellX+2, cellY+1);
          display.print(ch);
        }
      }
      display.setCursor(6*15+2, startY + 3*10 + 1); display.print("<"); // backspace
      display.setCursor(7*15+2, startY + 3*10 + 1); display.print("OK"); // done

      display.drawRect(c*15 -1, startY + r*10 -1, 16, 11, WHITE);
      display.display();
    }
    delay(20);
  }
}

String buildPlayerJson(const char* status) {
  String s = "{\"name\":\"";
  s += String(nameBuf);
  s += "\",\"class\":\"";
  s += String(classBuf);
  s += "\",\"status\":\"";
  s += String(status);
  s += "\",\"score\":";
  s += String(score);
  s += "}";
  return s;
}

void saveLocalLeaderboard(const String &json) {
  File f = SPIFFS.open("/players.json", "w");
  if(!f) { Serial.println("Fail write players.json"); return; }
  f.print(json);
  f.close();
  Serial.println("Saved players.json");
}

String readLocalLeaderboard() {
  if (!SPIFFS.exists("/players.json")) return String("[]");
  File f = SPIFFS.open("/players.json", "r");
  if (!f) return String("[]");
  String s; while(f.available()) s += (char)f.read();
  f.close();
  return s;
}

void sendStatus(const char* status) {
  if (WiFi.status() != WL_CONNECTED) {
    Serial.println("WiFi offline, update local players.json");
    String local = readLocalLeaderboard();
    DynamicJsonDocument doc(16384);
    DeserializationError err = deserializeJson(doc, local);
    if (err) {
      DynamicJsonDocument newDoc(4096);
      JsonArray arr = newDoc.to<JsonArray>();
      JsonObject o = arr.createNestedObject();
      o["name"] = nameBuf; o["class"] = classBuf; o["status"] = status; o["score"] = score; o["updatedAt"] = millis();
      String out; serializeJson(arr, out);
      saveLocalLeaderboard(out);
      return;
    }
    JsonArray arr = doc.as<JsonArray>();
    bool found = false;
    for (JsonObject obj : arr) {
      if (String((const char*)obj["name"]) == String(nameBuf) && String((const char*)obj["class"]) == String(classBuf)) {
        obj["status"] = status; obj["score"] = score; obj["updatedAt"] = millis(); found = true; break;
      }
    }
    if (!found) {
      JsonObject o = arr.createNestedObject();
      o["name"] = nameBuf; o["class"] = classBuf; o["status"] = status; o["score"] = score; o["updatedAt"] = millis();
    }
    String out; serializeJson(arr, out);
    saveLocalLeaderboard(out);
    return;
  }

  HTTPClient http;
  String url = String(SERVER_BASE) + String(PLAYER_ENDPOINT);
  http.begin(url);
  http.addHeader("Content-Type", "application/json");
  String payload = buildPlayerJson(status);
  int code = http.POST(payload);
  Serial.printf("POST %s -> %d\n", url.c_str(), code);
  http.end();
}

void fetchLeaderboardAndSave() {
  if (WiFi.status() != WL_CONNECTED) return;
  HTTPClient http;
  String url = String(SERVER_BASE) + String(LEADERBOARD_ENDPOINT);
  http.begin(url);
  int code = http.GET();
  if (code == 200) {
    String payload = http.getString();
    // basic JSON validation
    DynamicJsonDocument doc(16384);
    if (deserializeJson(doc, payload) == DeserializationError::Ok) {
      saveLocalLeaderboard(payload);
      Serial.println("Fetched leaderboard saved");
    } else Serial.println("Invalid JSON from leaderboard");
  } else {
    Serial.printf("GET leaderboard code: %d\n", code);
  }
  http.end();
}

void setupGame(){
  randomSeed(analogRead(0));
  food = {40,48,1};
  snake.x[0]=64; snake.y[0]=32; snake.x[1]=56; snake.y[1]=32; snake.node = 2; snake.dir = RIGHT;
  score = 0; level = 1; isGameOver = false;
  generateFood();
}

void generateFood() {
  do {
    food.x = random(0, 16) * 8;
    food.y = (random(0, 7) + 1) * 8;
  } while (isFoodOnSnake());
}

bool isFoodOnSnake() {
  for (int i=0;i<snake.node;i++) if (food.x==snake.x[i] && food.y==snake.y[i]) return true;
  return false;
}

void keyUpdate() {
  if (dirFlag != -1) {
    int d = dirFlag; dirFlag = -1;
    if (d == DOWN && snake.dir != UP) snake.dir = DOWN;
    if (d == RIGHT && snake.dir != LEFT) snake.dir = RIGHT;
    if (d == LEFT && snake.dir != RIGHT) snake.dir = LEFT;
    if (d == UP && snake.dir != DOWN) snake.dir = UP;
  }
}

void snakeGame() {
  switch (snake.dir) {
    case RIGHT: snake.x[0] += 8; if (snake.x[0] > 120) snake.x[0]=0; break;
    case UP: snake.y[0] -= 8; if (snake.y[0] < 0) snake.y[0]=56; break;
    case LEFT: snake.x[0] -= 8; if (snake.x[0] < 0) snake.x[0]=120; break;
    case DOWN: snake.y[0] += 8; if (snake.y[0] > 56) snake.y[0]=0; break;
  }
  if (snake.x[0]==food.x && snake.y[0]==food.y) {
    snake.node++; score += 5; level = score/10 + 1;
    tone(buzzerPin,1000); delay(80); noTone(buzzerPin);
    generateFood();
  }
  for (int i=1;i<snake.node;i++) if (snake.x[0]==snake.x[i] && snake.y[0]==snake.y[i]) isGameOver = true;
  for (int i=snake.node-1;i>0;i--) { snake.x[i]=snake.x[i-1]; snake.y[i]=snake.y[i-1]; }
}

void displaySnake(){ for (int i=0;i<snake.node;i++) element(snake.x[i], snake.y[i]); }

void gameOver() {
  tone(buzzerPin,1500); delay(300); noTone(buzzerPin);
  display.clearDisplay();
  display.setTextSize(2); display.setCursor(10,18); display.println("Game Over");
  display.setTextSize(1); display.setCursor(10,42); display.print("Score: "); display.println(score);
  display.display();

  sendStatus("finished");
  fetchLeaderboardAndSave();
  delay(1000);
  displayLeaderboardFromFile();
  delay(3000);
}

void displayLeaderboardFromFile() {
  String s = readLocalLeaderboard();
  DynamicJsonDocument doc(16384);
  DeserializationError err = deserializeJson(doc, s);
  display.clearDisplay();
  display.setTextSize(1);
  display.setCursor(0,0);
  display.println("Leaderboard:");
  if (err) {
    display.setCursor(0,12); display.println("No data");
    display.display(); return;
  }
  JsonArray arr = doc.as<JsonArray>();
  int y = 12; int maxShow = 6; int idx = 0;
  for (JsonObject obj : arr) {
    if (idx >= maxShow) break;
    const char* nm = obj["name"] | "";
    const char* cl = obj["class"] | "";
    int sc = obj["score"] | 0;
    display.setCursor(0, y); display.print(idx+1); display.print("."); display.print(nm);
    display.setCursor(80, y); display.print(sc);
    y += 9; idx++;
  }
  display.display();
}

void loop() {
  virtualKeyboardInput(nameBuf, nameLen, "Enter name:");
  virtualKeyboardInput(classBuf, classLen, "Enter class:");

  setupGame();
  sendStatus("playing");
  lastLeaderboardFetch = millis();

  while (!isGameOver) {
    display.clearDisplay();
    display.setTextSize(1);
    display.setCursor(0,0); display.print("S:"); display.print(score);
    display.setCursor(64,0); display.print("Lv:"); display.print(level);
    displaySnake();
    element(food.x, food.y);
    display.display();

    keyUpdate();
    snakeGame();

    if (millis() - lastLeaderboardFetch > FETCH_INTERVAL) {
      lastLeaderboardFetch = millis();
      fetchLeaderboardAndSave();
    }

    delay(100);
  }

  gameOver();
  delay(2000);
}