//
//  VoltraLiveActivityService.swift
//  Voltra
//
//  Service for managing Voltra Live Activities
//

import ActivityKit
import Foundation

// MARK: - Request Types

/// Parameters for creating a Live Activity
public struct CreateActivityRequest {
  /// Unique identifier for the activity (will be generated if nil)
  public let activityId: String?

  /// URL to open when the Live Activity is tapped
  public let deepLinkUrl: String?

  /// UI JSON data
  public let jsonString: String

  /// Optional date when content becomes stale
  public let staleDate: Date?

  /// Score between 0.0 and 1.0 for prioritization (defaults to 0.0)
  public let relevanceScore: Double

  /// Whether to request push token
  public let pushType: PushType?

  /// If true, ends any existing activities with the same name (defaults to true)
  public let endExistingWithSameName: Bool

  public init(
    activityId: String? = nil,
    deepLinkUrl: String? = nil,
    jsonString: String,
    staleDate: Date? = nil,
    relevanceScore: Double = 0.0,
    pushType: PushType? = nil,
    endExistingWithSameName: Bool = true
  ) {
    self.activityId = activityId
    self.deepLinkUrl = deepLinkUrl
    self.jsonString = jsonString
    self.staleDate = staleDate
    self.relevanceScore = relevanceScore
    self.pushType = pushType
    self.endExistingWithSameName = endExistingWithSameName
  }
}

/// Parameters for updating a Live Activity
public struct UpdateActivityRequest {
  /// New UI JSON data
  public let jsonString: String

  /// Optional date when content becomes stale
  public let staleDate: Date?

  /// Score between 0.0 and 1.0 for prioritization (defaults to 0.0)
  public let relevanceScore: Double

  public init(
    jsonString: String,
    staleDate: Date? = nil,
    relevanceScore: Double = 0.0
  ) {
    self.jsonString = jsonString
    self.staleDate = staleDate
    self.relevanceScore = relevanceScore
  }
}

// MARK: - Service

/// Service for managing Voltra Live Activities
public class VoltraLiveActivityService {
  // MARK: - Availability Checks

  /// Check if Live Activities are supported on this OS version
  public static func isSupported() -> Bool {
    guard #available(iOS 16.2, *) else { return false }
    return true
  }

  /// Check if Live Activities are enabled for this app
  public static func areActivitiesEnabled() -> Bool {
    guard #available(iOS 16.2, *) else { return false }
    return ActivityAuthorizationInfo().areActivitiesEnabled
  }

  // MARK: - Query Operations

  /// Find an activity by its name (activityId)
  public func findActivity(byName name: String) -> Activity<VoltraAttributes>? {
    guard Self.isSupported() else { return nil }
    let trimmedName = name.trimmingCharacters(in: .whitespacesAndNewlines)
    return Activity<VoltraAttributes>.activities.first { $0.attributes.name == trimmedName }
  }

  /// Find all activities with the same name
  public func findActivities(byName name: String) -> [Activity<VoltraAttributes>] {
    guard Self.isSupported() else { return [] }
    return Activity<VoltraAttributes>.activities.filter { $0.attributes.name == name }
  }

  /// Get all active Voltra activities
  public func getAllActivities() -> [Activity<VoltraAttributes>] {
    guard Self.isSupported() else { return [] }
    return Array(Activity<VoltraAttributes>.activities)
  }

  /// Get the latest (most recently created) activity
  public func getLatestActivity() -> Activity<VoltraAttributes>? {
    guard Self.isSupported() else { return nil }
    return Activity<VoltraAttributes>.activities.last
  }

  /// Check if an activity with the given name exists
  public func isActivityActive(name: String) -> Bool {
    findActivity(byName: name) != nil
  }

  // MARK: - Create Operations

  /// Create a new Live Activity
  /// - Parameter request: Parameters for creating the activity
  /// - Returns: The created activity's name (activityId)
  /// - Throws: Error if creation fails
  public func createActivity(_ request: CreateActivityRequest) async throws -> String {
    guard Self.isSupported() else {
      throw VoltraLiveActivityError.unsupportedOS
    }
    guard Self.areActivitiesEnabled() else {
      throw VoltraLiveActivityError.liveActivitiesNotEnabled
    }

    // Generate activityId if not provided
    let finalActivityId = request.activityId?.trimmingCharacters(in: .whitespacesAndNewlines).isEmpty == false
      ? request.activityId!.trimmingCharacters(in: .whitespacesAndNewlines)
      : UUID().uuidString

    // End existing activities with the same name if requested
    if request.endExistingWithSameName {
      try await endActivities(byName: finalActivityId)
    }

    // Create attributes and initial state
    let attributes = VoltraAttributes(name: finalActivityId, deepLinkUrl: request.deepLinkUrl)
    let initialState = try VoltraAttributes.ContentState(uiJsonData: request.jsonString)

    // Request the activity
    let activity = try Activity.request(
      attributes: attributes,
      content: .init(
        state: initialState,
        staleDate: request.staleDate,
        relevanceScore: request.relevanceScore
      ),
      pushType: request.pushType
    )

    return finalActivityId
  }

  // MARK: - Update Operations

  /// Update an existing Live Activity
  /// - Parameters:
  ///   - activity: The activity to update
  ///   - request: Parameters for updating the activity
  /// - Throws: Error if update fails
  public func updateActivity(
    _ activity: Activity<VoltraAttributes>,
    request: UpdateActivityRequest
  ) async throws {
    guard Self.isSupported() else {
      throw VoltraLiveActivityError.unsupportedOS
    }

    let newState = try VoltraAttributes.ContentState(uiJsonData: request.jsonString)
    await activity.update(
      ActivityContent(
        state: newState,
        staleDate: request.staleDate,
        relevanceScore: request.relevanceScore
      )
    )
  }

  /// Update an activity by name
  /// - Parameters:
  ///   - name: The activity name (activityId)
  ///   - request: Parameters for updating the activity
  /// - Throws: Error if activity not found or update fails
  public func updateActivity(
    byName name: String,
    request: UpdateActivityRequest
  ) async throws {
    guard let activity = findActivity(byName: name) else {
      throw VoltraLiveActivityError.notFound
    }
    try await updateActivity(activity, request: request)
  }

  // MARK: - End Operations

  /// End a specific activity
  /// - Parameter activity: The activity to end
  /// - Parameter dismissalPolicy: How the activity should be dismissed
  public func endActivity(
    _ activity: Activity<VoltraAttributes>,
    dismissalPolicy: ActivityUIDismissalPolicy = .immediate
  ) async {
    guard Self.isSupported() else { return }
    await activity.end(
      ActivityContent(state: activity.content.state, staleDate: nil),
      dismissalPolicy: dismissalPolicy
    )
  }

  /// End an activity by name
  /// - Parameter name: The activity name (activityId)
  /// - Parameter dismissalPolicy: How the activity should be dismissed
  /// - Throws: Error if activity not found
  public func endActivity(
    byName name: String,
    dismissalPolicy: ActivityUIDismissalPolicy = .immediate
  ) async throws {
    guard let activity = findActivity(byName: name) else {
      throw VoltraLiveActivityError.notFound
    }
    await endActivity(activity, dismissalPolicy: dismissalPolicy)
  }

  /// End all activities with the same name
  /// - Parameter name: The activity name (activityId)
  public func endActivities(byName name: String) async throws {
    guard Self.isSupported() else { return }
    let activities = findActivities(byName: name)
    for activity in activities {
      await endActivity(activity)
    }
  }

  /// End all Voltra Live Activities
  public func endAllActivities() async {
    guard Self.isSupported() else { return }
    let activities = getAllActivities()
    for activity in activities {
      await endActivity(activity)
    }
  }
}

// MARK: - Errors

public enum VoltraLiveActivityError: Error {
  case unsupportedOS
  case notFound
  case liveActivitiesNotEnabled
}