//
//  AircraftTrackingViewModel.swift
//  LearnMapKit
//
//  Main ViewModel coordinating all aircraft tracking functionality
//

import Foundation
import Combine
import MapKit
import SwiftUI

@MainActor
class AircraftTrackingViewModel: ObservableObject {

    // MARK: - Published Properties (UI State)
    @Published var aircraft: [Aircraft] = []
    @Published var selectedAircraft: Aircraft?
    @Published var connectionState: DataSourceState = .idle
    @Published var mapRegion: MKCoordinateRegion
    @Published var aircraftCount: Int = 0
    @Published var isLoading: Bool = false
    @Published var errorMessage: String?
    @Published var showingSettings: Bool = false

    // MARK: - Configuration
    @Published var currentConfiguration: AppConfiguration

    // MARK: - Dependencies
    private let configurationManager: ConfigurationManager
    private let aircraftRepository: AircraftRepository
    private var currentDataSource: (any ADSBDataSource)?
    private let dataSourceFactory: DataSourceFactory

    // MARK: - Private Properties
    private var cancellables = Set<AnyCancellable>()

    // MARK: - Initialization
    init(
        configurationManager: ConfigurationManager,
        aircraftRepository: AircraftRepository,
        dataSourceFactory: DataSourceFactory
    ) {
        self.configurationManager = configurationManager
        self.aircraftRepository = aircraftRepository
        self.dataSourceFactory = dataSourceFactory
        self.currentConfiguration = configurationManager.getCurrentConfiguration()

        // Initialize map region from configuration
        let mapSettings = currentConfiguration.mapSettings
        self.mapRegion = MKCoordinateRegion(
            center: mapSettings.defaultCenter,
            span: mapSettings.defaultSpan
        )

        setupBindings()
    }

    // MARK: - Public Interface
    func startTracking() async {
        guard connectionState != .connected && connectionState != .connecting else { return }

        isLoading = true
        errorMessage = nil

        do {
            // Create and configure data source
            currentDataSource = try createDataSource()

            // Start the data source
            try await currentDataSource?.start()

            print("Aircraft tracking started")
        } catch {
            errorMessage = "Failed to start tracking: \(error.localizedDescription)"
            connectionState = .error(error.localizedDescription)
        }

        isLoading = false
    }

    func stopTracking() async {
        await currentDataSource?.stop()
        currentDataSource = nil
        connectionState = .disconnected
    }

    func reconnect() async {
        guard let dataSource = currentDataSource else {
            await startTracking()
            return
        }

        isLoading = true
        do {
            try await dataSource.reconnect()
        } catch {
            errorMessage = "Reconnection failed: \(error.localizedDescription)"
        }
        isLoading = false
    }

    func selectAircraft(_ aircraft: Aircraft?) {
        selectedAircraft = aircraft

        // Center map on selected aircraft
        if let aircraft = aircraft,
           let position = aircraft.position {
            withAnimation(.easeInOut(duration: 0.5)) {
                mapRegion = MKCoordinateRegion(
                    center: CLLocationCoordinate2D(
                        latitude: position.latitude,
                        longitude: position.longitude
                    ),
                    span: MKCoordinateSpan(latitudeDelta: 0.05, longitudeDelta: 0.05)
                )
            }
        }
    }

    func updateConfiguration(_ configuration: AppConfiguration) async {
        // Validate configuration first
        let validation = configurationManager.validateConfiguration(configuration)
        guard validation.isValid else {
            errorMessage = "Invalid configuration: \(validation.errors.joined(separator: ", "))"
            return
        }

        let wasConnected = connectionState == .connected

        // Stop current tracking if running
        if wasConnected {
            await stopTracking()
        }

        // Update configuration
        await configurationManager.updateConfiguration(configuration)

        // Update map region if changed
        let newMapSettings = configuration.mapSettings
        mapRegion = MKCoordinateRegion(
            center: newMapSettings.defaultCenter,
            span: newMapSettings.defaultSpan
        )

        // Restart tracking if it was running
        if wasConnected {
            await startTracking()
        }
    }

    func clearAircraftData() {
        aircraftRepository.clearAll()
        selectedAircraft = nil
    }

    func exportAircraftData() -> String {
        // Export current aircraft data as JSON or CSV
        let encoder = JSONEncoder()
        encoder.dateEncodingStrategy = .iso8601
        encoder.outputFormatting = .prettyPrinted

        do {
            let data = try encoder.encode(aircraft)
            return String(data: data, encoding: .utf8) ?? "Export failed"
        } catch {
            return "Export error: \(error.localizedDescription)"
        }
    }

    // MARK: - Configuration Shortcuts
    func switchToFileMode(filePath: String) async {
        let fileConfig = FileDataSourceConfiguration(filePath: filePath)
        var newConfig = currentConfiguration
        newConfig = AppConfiguration(
            dataSource: fileConfig,
            displaySettings: newConfig.displaySettings,
            mapSettings: newConfig.mapSettings,
            networkSettings: newConfig.networkSettings
        )
        await updateConfiguration(newConfig)
    }

    func switchToNetworkMode(hostname: String, port: Int) async {
        let networkConfig = NetworkDataSourceConfiguration(hostname: hostname, port: port)
        var newConfig = currentConfiguration
        newConfig = AppConfiguration(
            dataSource: networkConfig,
            displaySettings: newConfig.displaySettings,
            mapSettings: newConfig.mapSettings,
            networkSettings: newConfig.networkSettings
        )
        await updateConfiguration(newConfig)
    }

    // MARK: - Private Methods
    private func setupBindings() {
        // Bind configuration updates
        configurationManager.currentConfiguration
            .receive(on: DispatchQueue.main)
            .assign(to: &$currentConfiguration)

        // Bind aircraft updates
        aircraftRepository.aircraftStream
            .receive(on: DispatchQueue.main)
            .assign(to: &$aircraft)

        // Bind aircraft count
        aircraftRepository.aircraftCount
            .receive(on: DispatchQueue.main)
            .assign(to: &$aircraftCount)

        // Update selected aircraft when aircraft list changes
        aircraftRepository.aircraftStream
            .receive(on: DispatchQueue.main)
            .sink { [weak self] aircraft in
                self?.updateSelectedAircraft(from: aircraft)
            }
            .store(in: &cancellables)
    }

    private func createDataSource() throws -> any ADSBDataSource {
        let dataSource = try dataSourceFactory.createDataSource(
            for: currentConfiguration.dataSource
        )

        // Bind data source streams
        dataSource.connectionState
            .receive(on: DispatchQueue.main)
            .assign(to: &$connectionState)

        dataSource.dataStream
            .receive(on: DispatchQueue.main)
            .sink { [weak self] event in
                self?.aircraftRepository.updateAircraft(with: event)
            }
            .store(in: &cancellables)

        return dataSource
    }

    private func updateSelectedAircraft(from aircraftList: [Aircraft]) {
        // Update selected aircraft if it still exists
        if let selected = selectedAircraft {
            selectedAircraft = aircraftList.first { $0.id == selected.id }
        }
    }
}

// MARK: - Data Source Factory
protocol DataSourceFactory {
    func createDataSource(for configuration: DataSourceConfiguration) throws -> any ADSBDataSource
}

class DefaultDataSourceFactory: DataSourceFactory {
    func createDataSource(for configuration: DataSourceConfiguration) throws -> any ADSBDataSource {
        switch configuration.sourceType {
        case .file:
            guard let fileConfig = configuration as? FileDataSourceConfiguration else {
                throw DataSourceFactoryError.invalidConfiguration
            }
            return FileADSBDataSource(configuration: fileConfig)

        case .network:
            guard let networkConfig = configuration as? NetworkDataSourceConfiguration else {
                throw DataSourceFactoryError.invalidConfiguration
            }
            return NetworkADSBDataSource(configuration: networkConfig)

        case .test:
            return TestADSBDataSource(configuration: configuration)
        }
    }
}

enum DataSourceFactoryError: Error {
    case invalidConfiguration
    case unsupportedDataSourceType
}

// MARK: - Test Data Source
class TestADSBDataSource: ADSBDataSource {
    var dataStream: AnyPublisher<ADSBDataEvent, Never> {
        Empty().eraseToAnyPublisher()
    }

    var connectionState: AnyPublisher<DataSourceState, Never> {
        Just(.connected).eraseToAnyPublisher()
    }

    private(set) var configuration: DataSourceConfiguration

    init(configuration: DataSourceConfiguration) {
        self.configuration = configuration
    }

    func configure(with config: DataSourceConfiguration) async {
        self.configuration = config
    }

    func start() async throws {
        // Test implementation
    }

    func stop() async {
        // Test implementation
    }

    func reconnect() async throws {
        // Test implementation
    }
}

// MARK: - Error Handling Extension
extension AircraftTrackingViewModel {
    func handleError(_ error: Error) {
        errorMessage = error.localizedDescription
        connectionState = .error(error.localizedDescription)
    }

    func clearError() {
        errorMessage = nil
        if case .error = connectionState {
            connectionState = .disconnected
        }
    }
}