#include <WiFi.h>
#include <HTTPClient.h>
#include <ArduinoJson.h>

// WiFi credentials
const char* ssid = "Wokwi-GUEST";
const char* password = "";

// Backend API configuration - Using ngrok URL
const char* backendUrl = "https://sentinellike-meaghan-gaspingly.ngrok-free.dev";
String sessionId = "d343b7fb-fad8-419c-b499-6d9b95e3632f";

String inputBuffer = "";

void setup() {
  Serial.begin(115200);
  delay(1000);
  
  connectWiFi();
  delay(2000);
  
  startSession("TROLLEY_01");
  
  Serial.println("\n=== Smart Trolley Barcode Scanner ===");
  Serial.println("Enter product barcode and press Enter:");
  Serial.println("\nSample barcodes:");
  Serial.println("  8901234567890 - Milk (1L) - ₹65");
  Serial.println("  8901234567891 - Bread (White) - ₹45");
  Serial.println("  8901234567892 - Rice (5kg) - ₹350");
  Serial.println("  8901234567893 - Cooking Oil (1L) - ₹180");
  Serial.println("  8901234567894 - Sugar (1kg) - ₹55");
  Serial.println("=====================================\n");
}

void loop() {
  while (Serial.available()) {
    char c = Serial.read();
    
    if (c == '\n' || c == '\r') {
      if (inputBuffer.length() > 0) {
        Serial.println("\n📦 Scanning barcode: " + inputBuffer);
        
        if (sessionId.length() > 0) {
          sendBarcodeToBackend(inputBuffer);
        } else {
          Serial.println("❌ Error: No active session!");
        }
        
        inputBuffer = "";
        Serial.println("\nEnter next barcode:");
      }
    } else {
      inputBuffer += c;
    }
  }
  
  delay(10);
}

void connectWiFi() {
  Serial.println("🔌 Connecting to WiFi...");
  WiFi.begin(ssid, password);
  
  int attempts = 0;
  while (WiFi.status() != WL_CONNECTED && attempts < 20) {
    delay(500);
    Serial.print(".");
    attempts++;
  }
  
  if (WiFi.status() == WL_CONNECTED) {
    Serial.println("\n✅ WiFi connected!");
    Serial.print("📡 ESP32 IP: ");
    Serial.println(WiFi.localIP());
  } else {
    Serial.println("\n❌ WiFi connection failed!");
  }
}

void startSession(String trolleyId) {
  if (WiFi.status() != WL_CONNECTED) {
    Serial.println("❌ WiFi not connected!");
    return;
  }
  
  Serial.println("\n🛒 Starting session for " + trolleyId + "...");
  
  HTTPClient http;
  String url = String(backendUrl) + "/api/session/start";
  
  Serial.println("📡 Connecting to: " + url);
  
  http.begin(url);
  http.addHeader("Content-Type", "application/json");
  http.setTimeout(15000);
  
  StaticJsonDocument<100> jsonDoc;
  jsonDoc["trolley_id"] = trolleyId;
  
  String jsonString;
  serializeJson(jsonDoc, jsonString);
  
  int httpResponseCode = http.POST(jsonString);
  
  if (httpResponseCode > 0) {
    String response = http.getString();
    Serial.println("✅ Response code: " + String(httpResponseCode));
    
    StaticJsonDocument<512> responseDoc;
    DeserializationError error = deserializeJson(responseDoc, response);
    
    if (!error) {
      sessionId = responseDoc["session_id"].as<String>();
      Serial.println("🆔 Session ID: " + sessionId);
      Serial.println("✅ Session started successfully!\n");
    } else {
      Serial.println("⚠️  JSON parse error");
      Serial.println("Response: " + response);
    }
  } else {
    Serial.println("❌ Connection failed! Code: " + String(httpResponseCode));
    Serial.println("   Make sure:");
    Serial.println("   1. Django server is running");
    Serial.println("   2. ngrok tunnel is active");
    Serial.println("   3. URL is correct");
  }
  
  http.end();
}

void sendBarcodeToBackend(String barcode) {
  if (WiFi.status() != WL_CONNECTED) {
    Serial.println("❌ WiFi not connected!");
    return;
  }
  
  HTTPClient http;
  String url = String(backendUrl) + "/api/cart/scan";
  
  http.begin(url);
  http.addHeader("Content-Type", "application/json");
  http.setTimeout(15000);
  
  StaticJsonDocument<200> jsonDoc;
  jsonDoc["session_id"] = sessionId;
  jsonDoc["barcode"] = barcode;
  
  String jsonString;
  serializeJson(jsonDoc, jsonString);
  
  Serial.println("📤 Sending: " + jsonString);
  
  int httpResponseCode = http.POST(jsonString);
  
  if (httpResponseCode > 0) {
    String response = http.getString();
    Serial.println("📥 Response code: " + String(httpResponseCode));
    
    StaticJsonDocument<512> responseDoc;
    DeserializationError error = deserializeJson(responseDoc, response);
    
    if (!error && httpResponseCode == 200) {
      const char* productName = responseDoc["product"]["name"];
      const char* price = responseDoc["product"]["price"];
      int quantity = responseDoc["quantity"];
      const char* subtotal = responseDoc["subtotal"];
      const char* action = responseDoc["action"];
      
      Serial.println("\n✅ SUCCESS!");
      Serial.println("   🏷️  Product: " + String(productName));
      Serial.println("   💰 Price: ₹" + String(price));
      Serial.println("   📦 Quantity: " + String(quantity));
      Serial.println("   💵 Subtotal: ₹" + String(subtotal));
      Serial.println("   🎬 Action: " + String(action));
    } else {
      Serial.println("❌ Response: " + response);
    }
  } else {
    Serial.println("❌ HTTP Error: " + String(httpResponseCode));
  }
  
  http.end();
}