import Foundation
#if canImport(UIKit)
  import UIKit
#endif

struct SettingsRuntime: Equatable {
    let appName: String
    let marketingVersion: String
    let buildVersion: String
    let platform: String
    let systemVersion: String
}

@MainActor
final class SettingsViewModel: ObservableObject {
    @Published private(set) var runtime: SettingsRuntime?
    @Published private(set) var isLoading = false
    @Published var storageLabel = "—"
    @Published var notice: String?
    @Published var errorMessage: String?

    private let store: any LogStore

    init(store: any LogStore) {
        self.store = store
    }

    func refresh() async {
        isLoading = true
        errorMessage = nil

        runtime = SettingsRuntime(
            appName: AppMetadata.name,
            marketingVersion: AppMetadata.marketingVersion,
            buildVersion: AppMetadata.buildVersion,
            platform: "iOS",
            systemVersion: Self.systemVersion()
        )
        await loadStorageLabel()

        isLoading = false
    }

    func clearRuntimeLogs() async -> Int {
        do {
            let removed = try await store.clearRuntimeLogs()
            notice = removed > 0 ? "已清除 \(removed) 条运行日志。" : "没有可清除的运行日志。"
            errorMessage = nil
            await loadStorageLabel()
            return removed
        } catch {
            notice = nil
            errorMessage = "清除运行日志失败。"
            return 0
        }
    }

    private func loadStorageLabel() async {
        do {
            let runtimeCount = try await store.runtimeLogs().count
            let connectionCount = try await store.connectionLogs().count
            storageLabel = "\(runtimeCount) 条运行日志 · \(connectionCount) 条连接日志"
        } catch {
            storageLabel = "—"
            errorMessage = "无法读取本地数据状态。"
        }
    }

    /// 只报对用户有意义的系统版本，不暴露机器标识之类的原始信息。
    private static func systemVersion() -> String {
        #if canImport(UIKit)
          let device = UIDevice.current
          return "\(device.systemName) \(device.systemVersion)"
        #else
          let version = ProcessInfo.processInfo.operatingSystemVersion
          return "iOS \(version.majorVersion).\(version.minorVersion)"
        #endif
    }
}