// ============================================================
// ESP32 Serial Logger
// Hardware: ESP-WROOM-32D DevKitC V4
//
// Arduino IDE Settings:
//   Board: "ESP32 Dev Module"
//   Upload Speed: 921600
//   CPU Frequency: 240MHz (WiFi/BT)
//   Flash Frequency: 80MHz
//   Flash Mode: QIO
//   Flash Size: 4MB (32Mb)
//   Partition Scheme: "Huge APP (3MB No OTA/1MB SPIFFS)"
//   PSRAM: Disabled
//
// Required Libraries:
//   1. WebSocketsServer by Links2004
//      (Install: Library Manager -> "WebSockets" by Markus Sattler)
//   2. ArduinoJson by Benoit Blanchon v6.x
//      (Install: Library Manager -> "ArduinoJson")
//   3. SD (built-in)
//   4. SPI (built-in)
//
// Pin Assignments:
//   UART2 TX: GPIO17 | UART2 RX: GPIO16
//   SD CLK: GPIO14 | SD MISO: GPIO26 | SD MOSI: GPIO13 | SD CS: GPIO15
// ============================================================

#include <Arduino.h>
#include <WiFi.h>
#include <esp_wifi.h>
#include <WebServer.h>
#include <WebSocketsServer.h>
#include <ArduinoJson.h>
#include <SPI.h>
#include <SD.h>
#include <freertos/FreeRTOS.h>
#include <freertos/task.h>
#include <freertos/queue.h>
#include <freertos/semphr.h>
#include <sys/time.h>
#include <time.h>

#include "config.h"
#include "serial_task.h"
#include "sdcard_task.h"
#include "web_task.h"

// ============================================================
// NTP Time Sync Task
// Only works in STA mode (internet required)
// In AP mode, time is synced from browser via WebSocket
// ============================================================
void ntpSyncTask(void *param) {
  Serial.println("[Task] NTP Sync started");

  // Only attempt NTP if connected to external WiFi (STA mode)
  if (WiFi.getMode() == WIFI_AP) {
    Serial.println("[NTP] AP mode - skipping NTP, waiting for browser time sync");
    // In AP mode, just keep task alive for potential future use
    while (true) {
      vTaskDelay(pdMS_TO_TICKS(60000));
    }
  }

  // STA mode - try NTP
  configTime(NTP_GMT_OFFSET, NTP_DAYLIGHT_OFFSET, NTP_SERVER);

  struct tm timeinfo;
  int retries = 0;
  while (!getLocalTime(&timeinfo) && retries < 5) {
    Serial.println("[NTP] Waiting for time sync...");
    vTaskDelay(pdMS_TO_TICKS(1000));
    retries++;
  }

  if (getLocalTime(&timeinfo)) {
    Serial.printf("[NTP] Synced: %04d-%02d-%02d %02d:%02d:%02d\n",
      timeinfo.tm_year + 1900, timeinfo.tm_mon + 1, timeinfo.tm_mday,
      timeinfo.tm_hour, timeinfo.tm_min, timeinfo.tm_sec);
  } else {
    Serial.println("[NTP] Failed - will use browser time when client connects");
  }

  // Periodic re-sync every 1 hour
  while (true) {
    vTaskDelay(pdMS_TO_TICKS(3600000));
    configTime(NTP_GMT_OFFSET, NTP_DAYLIGHT_OFFSET, NTP_SERVER);
    Serial.println("[NTP] Time re-synced");
  }
}

// ============================================================
// WiFi Connection (STA + fallback AP mode)
// ============================================================
void wifiConnect() {
  Serial.println("[WiFi] Connecting to: " + String(WIFI_SSID));

  WiFi.mode(WIFI_STA);
  WiFi.begin(WIFI_SSID, WIFI_PASSWORD);
  WiFi.setSleep(false);

  unsigned long startTime = millis();
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
    if (millis() - startTime > WIFI_CONNECT_TIMEOUT) {
      Serial.println("\n[WiFi] STA failed! Starting AP mode...");
      WiFi.mode(WIFI_AP);
      WiFi.softAP(WIFI_AP_SSID, WIFI_AP_PASSWORD);
      Serial.println("[WiFi] AP SSID: " + String(WIFI_AP_SSID));
      Serial.println("[WiFi] AP IP: " + WiFi.softAPIP().toString());
      return;
    }
  }

  Serial.println();
  Serial.println("[WiFi] Connected! IP: " + WiFi.localIP().toString());
  Serial.println("[WiFi] RSSI: " + String(WiFi.RSSI()) + " dBm");
}

// ============================================================
// Setup
// ============================================================
void setup() {
  Serial.begin(115200);
  delay(1000);

  Serial.println("============================================");
  Serial.println("  ESP32 Serial Logger v1.0");
  Serial.println("  ESP-WROOM-32D DevKitC V4");
  Serial.println("============================================");
  Serial.printf("  Free Heap: %d bytes\n", ESP.getFreeHeap());
  Serial.printf("  CPU Freq: %d MHz\n", getCpuFrequencyMhz());
  Serial.println("============================================");

  // 1. WiFi
  wifiConnect();

  // 2. NTP (STA mode only) + Browser time sync (AP mode)
  xTaskCreatePinnedToCore(ntpSyncTask, "NTP", TASK_STACK_NTP,
    NULL, TASK_PRIORITY_NTP, NULL, 0);
  if (WiFi.getMode() != WIFI_AP) {
    delay(2000);  // Brief wait for NTP only in STA mode
  } else {
    Serial.println("[Time] AP mode: time will sync from browser on first connect");
  }

  // 3. SD Card
  sdTaskInit();

  // 4. Serial2 UART
  serialTaskInit();

  // 5. Web Server + WebSocket
  webTaskInit();

  Serial.println("============================================");
  Serial.println("  All tasks started!");
  Serial.printf("  Free Heap: %d bytes\n", ESP.getFreeHeap());

  String ip = (WiFi.getMode() == WIFI_AP) ?
    WiFi.softAPIP().toString() : WiFi.localIP().toString();
  Serial.println("  URL: http://" + ip);
  Serial.println("============================================");
  Serial.println("\n  Task Layout:");
  Serial.println("  Core 1: SerialRX(5), SerialTX(4)");
  Serial.println("  Core 0: SDLog(3), WebBC(2), NTP(1)");
  Serial.println("  Loop  : server.handleClient()");
  Serial.println("  Time  : NTP(STA) or Browser sync(AP)");
  Serial.println("============================================\n");
}

// ============================================================
// Loop - handles HTTP requests (must be on main loop)
// ============================================================
void loop() {
  server.handleClient();
  vTaskDelay(pdMS_TO_TICKS(2));

  // Periodic status report (30s)
  static unsigned long lastReport = 0;
  if (millis() - lastReport > 30000) {
    lastReport = millis();
    Serial.printf("[SYS] Heap: %d | MinHeap: %d | SD: %s | WS: %d clients\n",
      ESP.getFreeHeap(),
      ESP.getMinFreeHeap(),
      sdCardPresent() ? "OK" : "FAIL",
      webSocket.connectedClients());
  }
}