package main

import (
	"fmt"
	"log"
	"math/rand"
	"time"

	"ble_simulator/internal/ble"
	"ble_simulator/internal/device"

	"tinygo.org/x/bluetooth"
)

func main() {
	log.Println("[INFO] BLE Simulator v1.0")

	adapter := bluetooth.DefaultAdapter
	must("enable BLE", adapter.Enable())

	// Connection handler
	adapter.SetConnectHandler(func(dev bluetooth.Device, connected bool) {
		if connected {
			log.Printf("[CONN] Client Connected: %s", dev.Address.String())
		} else {
			log.Println("[CONN] Client Disconnected")
		}
	})

	// Setup device state and service
	state := device.NewDeviceState()
	notifyChar, err := ble.SetupService(adapter, state)
	must("add service", err)

	// Configure advertising
	adv := adapter.DefaultAdvertisement()
	must("configure adv", adv.Configure(bluetooth.AdvertisementOptions{
		LocalName:    "GO_SIMULATOR",
		ServiceUUIDs: []bluetooth.UUID{ble.ServiceUUID},
	}))

	must("start advertising", adv.Start())

	log.Println("[INFO] Advertising as GO_SIMULATOR...")
	log.Println("[INFO] Using Nordic UART Service (NUS) UUIDs")
	log.Println("[INFO] Service UUID: 6e400001-b5a3-f393-e0a9-e50e24dcca9e")
	log.Println("[INFO] Command Char: 6e400002-b5a3-f393-e0a9-e50e24dcca9e (Write/RX)")
	log.Println("[INFO] Notify Char:  6e400003-b5a3-f393-e0a9-e50e24dcca9e (Notify/TX)")
	log.Println("[INFO] Waiting for connections...")

	// Start notification loop (500ms heartbeat with sensor data)
	go notificationLoop(notifyChar, state)

	// Block forever
	select {}
}

func notificationLoop(char *bluetooth.Characteristic, state *device.DeviceState) {
	ticker := time.NewTicker(500 * time.Millisecond)
	for range ticker.C {
		value := state.GetSensorValue()
		// Add small jitter for realism (-10 to +10)
		jitter := rand.Intn(21) - 10
		msg := fmt.Sprintf("SENSOR:%d", value+jitter)

		_, err := char.Write([]byte(msg + "\n"))
		if err != nil {
			// Silently ignore write errors (no subscribers)
			continue
		}
		log.Printf("[TX] Sending: %s", msg)
	}
}

func must(action string, err error) {
	if err != nil {
		log.Fatalf("Failed to %s: %v", action, err)
	}
}