import Foundation
import CoreBluetooth

/// Beacon type detected by service UUID or name
enum BeaconType: String {
    case kbeacon = "KBeacon"
    case dxsmart = "DX-Smart"
    case bluecharm = "BlueCharm"
    case unknown = "Unknown"
}

/// A discovered BLE beacon that can be provisioned
struct DiscoveredBeacon: Identifiable {
    let id: UUID  // CoreBluetooth peripheral identifier
    let peripheral: CBPeripheral
    let name: String
    let type: BeaconType
    var rssi: Int
    var lastSeen: Date

    var displayName: String {
        if name.isEmpty {
            return id.uuidString.prefix(8) + "..."
        }
        return name
    }
}

/// Scans for BLE beacons that can be configured (KBeacon and BlueCharm)
class BLEBeaconScanner: NSObject, ObservableObject {

    // KBeacon config service
    static let KBEACON_SERVICE = CBUUID(string: "0000FFE0-0000-1000-8000-00805F9B34FB")
    // BlueCharm config service
    static let BLUECHARM_SERVICE = CBUUID(string: "0000FFF0-0000-1000-8000-00805F9B34FB")

    @Published var isScanning = false
    @Published var discoveredBeacons: [DiscoveredBeacon] = []
    @Published var bluetoothState: CBManagerState = .unknown

    private var centralManager: CBCentralManager!
    private var scanTimer: Timer?

    override init() {
        super.init()
        centralManager = CBCentralManager(delegate: self, queue: .main)
    }

    /// Start scanning for configurable beacons
    func startScanning() {
        guard centralManager.state == .poweredOn else {
            NSLog("BLEBeaconScanner: Bluetooth not ready, state=\(centralManager.state.rawValue)")
            return
        }

        NSLog("BLEBeaconScanner: Starting scan for configurable beacons")
        discoveredBeacons.removeAll()
        isScanning = true

        // Scan for devices advertising our config services
        // Note: We scan for all devices and filter by service after connection
        // because some beacons don't advertise their config service UUID
        centralManager.scanForPeripherals(
            withServices: nil,  // Scan all - we'll filter by name/characteristics
            options: [CBCentralManagerScanOptionAllowDuplicatesKey: true]
        )

        // Auto-stop after 1 second (beacons advertise every ~200ms so 1s is plenty)
        scanTimer?.invalidate()
        scanTimer = Timer.scheduledTimer(withTimeInterval: 1.0, repeats: false) { [weak self] _ in
            self?.stopScanning()
        }
    }

    /// Stop scanning
    func stopScanning() {
        NSLog("BLEBeaconScanner: Stopping scan, found \(discoveredBeacons.count) beacons")
        centralManager.stopScan()
        isScanning = false
        scanTimer?.invalidate()
        scanTimer = nil
    }

    /// Check if Bluetooth is available
    var isBluetoothReady: Bool {
        centralManager.state == .poweredOn
    }
}

// MARK: - CBCentralManagerDelegate

extension BLEBeaconScanner: CBCentralManagerDelegate {

    func centralManagerDidUpdateState(_ central: CBCentralManager) {
        bluetoothState = central.state
        NSLog("BLEBeaconScanner: Bluetooth state changed to \(central.state.rawValue)")

        if central.state == .poweredOn && isScanning {
            // Resume scanning if we were trying to scan
            startScanning()
        }
    }

    func centralManager(_ central: CBCentralManager, didDiscover peripheral: CBPeripheral,
                        advertisementData: [String: Any], rssi RSSI: NSNumber) {

        let rssiValue = RSSI.intValue
        guard rssiValue > -70 && rssiValue < 0 else { return }  // Only show nearby devices

        let name = peripheral.name ?? advertisementData[CBAdvertisementDataLocalNameKey] as? String ?? ""
        let nameUpper = name.uppercased()

        // Best-effort type hint from advertised services OR device name
        // Note: Some DX-Smart beacons don't advertise FFE0 in scan response, so also filter by name
        var beaconType: BeaconType = .unknown
        if let serviceUUIDs = advertisementData[CBAdvertisementDataServiceUUIDsKey] as? [CBUUID] {
            if serviceUUIDs.contains(BLEBeaconScanner.KBEACON_SERVICE) {
                beaconType = .dxsmart
            } else if serviceUUIDs.contains(BLEBeaconScanner.BLUECHARM_SERVICE) {
                beaconType = .bluecharm
            }
        }

        // Also detect DX-Smart by name pattern (some beacons don't advertise FFE0)
        if beaconType == .unknown && (nameUpper.contains("DX") || nameUpper.contains("SMART")) {
            beaconType = .dxsmart
        }

        // Update or add beacon
        if let index = discoveredBeacons.firstIndex(where: { $0.id == peripheral.identifier }) {
            discoveredBeacons[index].rssi = rssiValue
            discoveredBeacons[index].lastSeen = Date()
        } else {
            let beacon = DiscoveredBeacon(
                id: peripheral.identifier,
                peripheral: peripheral,
                name: name,
                type: beaconType,
                rssi: rssiValue,
                lastSeen: Date()
            )
            discoveredBeacons.append(beacon)
            NSLog("BLEBeaconScanner: Discovered \(beaconType.rawValue) beacon: \(name) RSSI=\(rssiValue)")
        }

        // Sort by RSSI (strongest first)
        discoveredBeacons.sort { $0.rssi > $1.rssi }
    }
}