import SwiftUI
import CoreBluetooth

struct Constants {
    static let scbtSvcUuid = "00010F2C-DEAD-BEEF-A455-DEAD69BEEF69";
    static let scbtPetUuid: String = "00010F2D-DEAD-BEEF-A455-DEAD69BEEF69";
}

final class BluetoothManager: NSObject, ObservableObject {
    private var centralManager: CBCentralManager!
    private var tagPerihp: CBPeripheral?
    private var scbtSvc: CBService?
    private var petChar: CBCharacteristic?
	@Published var status = "Starting..."

    override init() {
        super.init()
        centralManager = CBCentralManager(
            delegate: self,
            queue: nil,
            //options: [
            //    CBCentralManagerOptionRestoreIdentifierKey: "DogCollarCentral"
            //]
        )
    }

    func led_on() {
        pet_write(0)
    }

    func led_off() {
        pet_write(1)
    }

    func pet_write(_ value: UInt32) {
        if tagPerihp == nil || petChar == nil {
            status = "Not connected!"
            return
        }

        var lvalue = value
        let data = Data(bytes: &lvalue, count: MemoryLayout<UInt32>.size)
        tagPerihp!.writeValue(data, for: petChar!, type: .withResponse)
    }
}

extension BluetoothManager: CBCentralManagerDelegate, CBPeripheralDelegate {
    func centralManagerDidUpdateState(_ central: CBCentralManager) {
        guard central.state == .poweredOn else {
            status = "Bluetooth OFF"
            return
        }

        let uuid = CBUUID(string: Constants.scbtSvcUuid)
        centralManager.scanForPeripherals(
            withServices: [uuid],
            options: [
                CBCentralManagerScanOptionAllowDuplicatesKey: false
            ]
        )
    }

    // Discovery callback
    func centralManager(
        _ central: CBCentralManager,
        didDiscover peripheral: CBPeripheral,
        advertisementData: [String: Any],
        rssi RSSI: NSNumber
    ) {
        let name = peripheral.name ?? peripheral.identifier.uuidString
        status = "Found \(name)"
        tagPerihp = peripheral
        central.stopScan()
        central.connect(peripheral)
    }

    // Connection callback
    func centralManager(
        _ central: CBCentralManager,
        didConnect peripheral: CBPeripheral
    ) {
        let name = peripheral.name ?? peripheral.identifier.uuidString
        status = "Connected to \(name)"
        let uuid = CBUUID(string: Constants.scbtSvcUuid)
        peripheral.discoverServices([uuid])
        peripheral.delegate = self
    }

    // Connection failure callback
    func centralManager(
        _ central: CBCentralManager,
        didFailToConnect peripheral: CBPeripheral,
        error: Error?
    ) {
        let error2: String
        if (error == nil) { error2 = "unknown" }
        else { error2 = "\(error!)" }
        status = "Failed: \(error2)"

        tagPerihp = nil
        petChar = nil
    }

    // Disconnection callback
    func centralManager(
        _ central: CBCentralManager,
        didDisconnectPeripheral peripheral: CBPeripheral,
        error: Error?
    ) {
        let error2: String
        if (error == nil) { error2 = "unknown" }
        else { error2 = "\(error!)" }
        status = "Disconnected: \(error2)"

        tagPerihp = nil
        petChar = nil
    }

    // Service callback
    func peripheral(
        _ peripheral: CBPeripheral,
        didDiscoverServices error: Error?
    ) {
        guard let services = peripheral.services else { return }

        let svcUUID = CBUUID(string: Constants.scbtSvcUuid)
        let petUUID = CBUUID(string: Constants.scbtPetUuid)

        for service in services {
            if (service.uuid == svcUUID) {
                scbtSvc = service
                peripheral.discoverCharacteristics([petUUID], for: service)
            }
        }

        if scbtSvc == nil {
            status = "Could not find scbt service"
        }
    }

    // Characteristic callback
    func peripheral(
        _ perihperal: CBPeripheral,
        didDiscoverCharacteristicsFor service: CBService,
        error: Error?
    ) {
        if (error != nil) {
            status = "\(error!)"
            return
        }

        guard let characteristics = service.characteristics else { return }
        let scbtPet = CBUUID(string: Constants.scbtPetUuid)

        for characteristic: CBCharacteristic in characteristics {
            if (characteristic.uuid == scbtPet) {
                petChar = characteristic
                status = "Found pet characteristic"
            }
        }

        if petChar == nil {
            status = "Could not find pet characteristic"
        }
    }

    // Characteristic write callback
    func peripheral(
        _ perihperal: CBPeripheral,
        didWriteValueFor characteristic: CBCharacteristic,
        error: (any Error)?
    ) {
        if (error == nil) {
            status = "Write success"
        }
        else {
            status = "Write failed: \(error!)"
        }
    }
}