//
//  PhoneReportDetailViewModel.swift
//  QuickLocation
//

import Foundation
import RxSwift
import RxCocoa
import UIKit
import AVFoundation
import SystemConfiguration.CaptiveNetwork
import NetworkExtension
import CoreLocation
import SwiftyUserDefaults

final class PhoneReportDetailViewModel {

    enum ChartMode: Equatable {
        case day
        case week
    }

    struct ChartBar {
        let label: String
        let value: Int
        let isToday: Bool
    }

    struct StatusSnapshot {
        let batteryText: String
        let batteryPercent: Int?
        let isCharging: Bool
        let estimateText: String
        let brightnessText: String
        let volumeText: String
        let wifiText: String
        let deviceText: String
        let storageText: String
        let storageRatio: CGFloat
        let screenTodayText: String
        let unlockTodayText: String
        let usageTodayText: String
        let screenBars: [ChartBar]
        let unlockBars: [ChartBar]

        func replacing(wifiText: String? = nil, volumeText: String? = nil) -> StatusSnapshot {
            StatusSnapshot(
                batteryText: batteryText,
                batteryPercent: batteryPercent,
                isCharging: isCharging,
                estimateText: estimateText,
                brightnessText: brightnessText,
                volumeText: volumeText ?? self.volumeText,
                wifiText: wifiText ?? self.wifiText,
                deviceText: deviceText,
                storageText: storageText,
                storageRatio: storageRatio,
                screenTodayText: screenTodayText,
                unlockTodayText: unlockTodayText,
                usageTodayText: usageTodayText,
                screenBars: screenBars,
                unlockBars: unlockBars
            )
        }
    }

    let members: [GroupMemberModel]
    let selectedMemberId: BehaviorRelay<String>
    let screenMode = BehaviorRelay<ChartMode>(value: .day)
    let unlockMode = BehaviorRelay<ChartMode>(value: .day)
    let snapshot: BehaviorRelay<StatusSnapshot>

    private let disposeBag = DisposeBag()
    private let placeholder = "**"
    private var volumeObservation: NSKeyValueObservation?

    init(members: [GroupMemberModel], selectedUserId: String) {
        UIDevice.current.isBatteryMonitoringEnabled = true
        self.members = members
        self.selectedMemberId = BehaviorRelay(value: selectedUserId)
        self.snapshot = BehaviorRelay(value: Self.emptySnapshot())
        bindInputs()
        refresh(userId: selectedUserId)
    }

    private func bindInputs() {
        selectedMemberId
            .asObservable()
            .skip(1)
            .subscribe(onNext: { [weak self] userId in
                self?.refresh(userId: userId)
            })
            .disposed(by: disposeBag)

        screenMode
            .asObservable()
            .skip(1)
            .subscribe(onNext: { [weak self] _ in
                guard let self else { return }
                self.refresh(userId: self.selectedMemberId.value)
            })
            .disposed(by: disposeBag)

        unlockMode
            .asObservable()
            .skip(1)
            .subscribe(onNext: { [weak self] _ in
                guard let self else { return }
                self.refresh(userId: self.selectedMemberId.value)
            })
            .disposed(by: disposeBag)

        NotificationCenter.default.rx.notification(.unlockCountDidChange)
            .subscribe(onNext: { [weak self] _ in
                guard let self else { return }
                self.refresh(userId: self.selectedMemberId.value)
            })
            .disposed(by: disposeBag)

        // 与系统状态栏同步：电量 / 充电状态变化时刷新
        let batteryCenter = NotificationCenter.default
        Observable.merge(
            batteryCenter.rx.notification(UIDevice.batteryLevelDidChangeNotification),
            batteryCenter.rx.notification(UIDevice.batteryStateDidChangeNotification)
        )
        .observe(on: MainScheduler.instance)
        .subscribe(onNext: { [weak self] _ in
            guard let self else { return }
            guard self.selectedMemberId.value == AppContextManager.shared.userId else { return }
            self.refresh(userId: self.selectedMemberId.value)
        })
        .disposed(by: disposeBag)

        observeSystemVolume()
    }

    private func observeSystemVolume() {
        let session = AVAudioSession.sharedInstance()
        try? session.setActive(true)
        volumeObservation = session.observe(\.outputVolume, options: [.new]) { [weak self] _, _ in
            DispatchQueue.main.async {
                guard let self else { return }
                guard self.selectedMemberId.value == AppContextManager.shared.userId else { return }
                let volume = Self.volumeText() ?? self.placeholder
                self.snapshot.accept(self.snapshot.value.replacing(volumeText: volume))
            }
        }
    }

    private func refresh(userId: String) {
        let isSelf = userId == AppContextManager.shared.userId
        let member = members.first { $0.user_id == userId }

        if isSelf {
            snapshot.accept(makeSelfSnapshot())
        } else {
            snapshot.accept(makeOtherSnapshot(member: member))
        }
    }

    private func makeSelfSnapshot() -> StatusSnapshot {
        let mgr = UnlockCountManager.shared
        let batteryPercent = UIDevice.batteryPercent
        let isCharging = UIDevice.isBatteryCharging
        let screenSec = mgr.todayScreenTimeSeconds
        let unlock = mgr.todayCount
        let usage = mgr.todayAppUsageCount

        let batteryText = batteryPercent.map { "\($0)%" } ?? placeholder
        let brightnessText = Self.brightnessText() ?? placeholder
        let volumeText = Self.volumeText() ?? placeholder
        let wifiText = Self.wifiSSID() ?? placeholder
        let storageText = Self.storageText() ?? placeholder
        let storageRatio = Self.storageRatio() ?? 0
        let screenTodayText = screenSec > 0 ? Self.formatDuration(screenSec) : placeholder
        let screenBars = Self.screenBars(from: mgr, mode: screenMode.value)
        let unlockBars = Self.unlockBars(unlock: unlock, mode: unlockMode.value)

        // 异步补拉 SSID（iOS 14+），成功后再刷新一次
        Self.fetchWifiSSIDAsync { [weak self] ssid in
            guard let self, let ssid, !ssid.isEmpty else { return }
            guard self.selectedMemberId.value == AppContextManager.shared.userId else { return }
            let current = self.snapshot.value
            guard current.wifiText != ssid else { return }
            self.snapshot.accept(current.replacing(wifiText: ssid))
        }

        return StatusSnapshot(
            batteryText: batteryText,
            batteryPercent: batteryPercent,
            isCharging: isCharging,
            estimateText: placeholder,
            brightnessText: brightnessText,
            volumeText: volumeText,
            wifiText: wifiText,
            deviceText: UIDevice.modelName,
            storageText: storageText,
            storageRatio: storageRatio,
            screenTodayText: screenTodayText,
            unlockTodayText: "\(unlock)",
            usageTodayText: "\(usage)",
            screenBars: screenBars,
            unlockBars: unlockBars
        )
    }

    private func makeOtherSnapshot(member: GroupMemberModel?) -> StatusSnapshot {
        let battery = Int(member?.battery.int ?? 0)
        let hasBattery = battery > 0
        return StatusSnapshot(
            batteryText: hasBattery ? "\(battery)%" : placeholder,
            batteryPercent: hasBattery ? battery : nil,
            isCharging: false,
            estimateText: placeholder,
            brightnessText: placeholder,
            volumeText: placeholder,
            wifiText: placeholder,
            deviceText: placeholder,
            storageText: placeholder,
            storageRatio: 0,
            screenTodayText: placeholder,
            unlockTodayText: placeholder,
            usageTodayText: placeholder,
            screenBars: [],
            unlockBars: []
        )
    }

    private static func emptySnapshot() -> StatusSnapshot {
        StatusSnapshot(
            batteryText: "**",
            batteryPercent: nil,
            isCharging: false,
            estimateText: "**",
            brightnessText: "**",
            volumeText: "**",
            wifiText: "**",
            deviceText: "**",
            storageText: "**",
            storageRatio: 0,
            screenTodayText: "**",
            unlockTodayText: "**",
            usageTodayText: "**",
            screenBars: [],
            unlockBars: []
        )
    }

    private static func formatDuration(_ seconds: Int) -> String {
        let hours = seconds / 3600
        let minutes = (seconds % 3600) / 60
        if hours > 0 { return minutes > 0 ? "\(hours)h \(minutes)m" : "\(hours)h" }
        return "\(minutes)m"
    }

    private static func brightnessText() -> String? {
        let value = UIScreen.main.brightness
        guard value >= 0 else { return nil }
        return "\(Int(value * 100))%"
    }

    private static func volumeText() -> String? {
        let session = AVAudioSession.sharedInstance()
        do {
            try session.setActive(true)
        } catch {
            // 激活失败仍尝试读取当前值
        }
        let volume = session.outputVolume
        guard volume >= 0 else { return nil }
        return "\(Int((volume * 100).rounded()))%"
    }

    private static func hasLocationPermissionForWifi() -> Bool {
        let status = CLLocationManager.authorizationStatus()
        switch status {
        case .authorizedAlways, .authorizedWhenInUse:
            return true
        default:
            return false
        }
    }

    private static func wifiSSID() -> String? {
        guard hasLocationPermissionForWifi() else { return nil }
        guard let interfaces = CNCopySupportedInterfaces() as? [String] else { return nil }
        for name in interfaces {
            if let info = CNCopyCurrentNetworkInfo(name as CFString) as? [String: Any],
               let ssid = info[kCNNetworkInfoKeySSID as String] as? String,
               !ssid.isEmpty {
                return ssid
            }
        }
        return nil
    }

    /// iOS 14+ 异步获取当前 Wi‑Fi SSID（需定位权限 + Access Wi‑Fi Information）
    private static func fetchWifiSSIDAsync(completion: @escaping (String?) -> Void) {
        guard hasLocationPermissionForWifi() else {
            completion(nil)
            return
        }
        if #available(iOS 14.0, *) {
            NEHotspotNetwork.fetchCurrent { network in
                DispatchQueue.main.async {
                    let ssid = network?.ssid
                    completion((ssid?.isEmpty == false) ? ssid : nil)
                }
            }
        } else {
            completion(wifiSSID())
        }
    }

    /// 与「设置 → 通用 → iPhone 存储空间」一致：十进制 GB + ImportantUsage 可用容量
    private static func storageBytes() -> (used: Int64, total: Int64)? {
        let url = URL(fileURLWithPath: NSHomeDirectory())
        let keys: Set<URLResourceKey> = [
            .volumeTotalCapacityKey,
            .volumeAvailableCapacityForImportantUsageKey
        ]
        guard
            let values = try? url.resourceValues(forKeys: keys),
            let total = values.volumeTotalCapacity,
            let available = values.volumeAvailableCapacityForImportantUsage,
            total > 0
        else { return nil }
        let used = max(0, Int64(total) - available)
        return (used, Int64(total))
    }

    private static func formatStorageGB(_ bytes: Int64, fractionDigits: Int) -> String {
        // Settings 使用十进制（1GB = 1e9），128G 机型会显示约 128GB 而非 119GB
        let gb = Double(bytes) / 1_000_000_000
        return String(format: "%.\(fractionDigits)fGB", gb)
    }

    private static func storageText() -> String? {
        guard let info = storageBytes() else { return nil }
        let usedText = formatStorageGB(info.used, fractionDigits: 1)
        let totalText = formatStorageGB(info.total, fractionDigits: 0)
        return "\(usedText)/\(totalText)"
    }

    private static func storageRatio() -> CGFloat? {
        guard let info = storageBytes(), info.total > 0 else { return nil }
        return CGFloat(Double(info.used) / Double(info.total))
    }

    private static func screenBars(from mgr: UnlockCountManager, mode: ChartMode) -> [ChartBar] {
        let byDay = Defaults[\.screenTimeByDay]
        let todayValue = mgr.todayScreenTimeSeconds
        switch mode {
        case .day:
            return dayBars(byDay: byDay, todayValue: todayValue, labelStyle: .monthDaySlash)
        case .week:
            return weekBars(byDay: byDay, todayValue: todayValue)
        }
    }

    private static func unlockBars(unlock: Int, mode: ChartMode) -> [ChartBar] {
        var byDay = Defaults[\.unlockCountByDay]
        let todayKey = dayKey(for: Date())
        byDay[todayKey] = unlock
        switch mode {
        case .day:
            return dayBars(byDay: byDay, todayValue: unlock, labelStyle: .monthDay)
        case .week:
            return weekBars(byDay: byDay, todayValue: unlock)
        }
    }

    private enum DayLabelStyle {
        case monthDaySlash // 08/04
        case monthDay      // 8/4
    }

    private static func dayKey(for date: Date) -> String {
        let formatter = DateFormatter()
        formatter.locale = Locale(identifier: "en_US_POSIX")
        formatter.calendar = Calendar.current
        formatter.timeZone = TimeZone.current
        formatter.dateFormat = "yyyy-MM-dd"
        return formatter.string(from: date)
    }

    private static func dayBars(
        byDay: [String: Int],
        todayValue: Int,
        labelStyle: DayLabelStyle
    ) -> [ChartBar] {
        let calendar = Calendar.current
        let today = calendar.startOfDay(for: Date())
        let labelFormatter = DateFormatter()
        labelFormatter.locale = Locale(identifier: "en_US_POSIX")
        switch labelStyle {
        case .monthDaySlash:
            labelFormatter.dateFormat = "MM/dd"
        case .monthDay:
            labelFormatter.dateFormat = "M/d"
        }

        return (0..<7).map { offset -> ChartBar in
            let dayOffset = offset - 6
            let date = calendar.date(byAdding: .day, value: dayOffset, to: today) ?? today
            let key = dayKey(for: date)
            let isToday = dayOffset == 0
            let value = isToday ? todayValue : (byDay[key] ?? 0)
            return ChartBar(
                label: labelFormatter.string(from: date),
                value: value,
                isToday: isToday
            )
        }
    }

    /// 近 7 周：每周一根柱，值为该周内按日数据之和；label 为周起始日 M/d
    private static func weekBars(byDay: [String: Int], todayValue: Int) -> [ChartBar] {
        let calendar = Calendar.current
        let today = calendar.startOfDay(for: Date())
        guard let currentWeek = calendar.dateInterval(of: .weekOfYear, for: today) else {
            return dayBars(byDay: byDay, todayValue: todayValue, labelStyle: .monthDay)
        }
        let labelFormatter = DateFormatter()
        labelFormatter.locale = Locale(identifier: "en_US_POSIX")
        labelFormatter.dateFormat = "M/d"
        let todayKey = dayKey(for: today)

        return (0..<7).map { offset -> ChartBar in
            let weekOffset = offset - 6
            let weekStart = calendar.date(byAdding: .weekOfYear, value: weekOffset, to: currentWeek.start)
                ?? currentWeek.start
            let weekInterval = calendar.dateInterval(of: .weekOfYear, for: weekStart)
                ?? DateInterval(start: weekStart, duration: 7 * 24 * 3600)

            var sum = 0
            var cursor = weekInterval.start
            while cursor < weekInterval.end {
                let key = dayKey(for: cursor)
                if key == todayKey {
                    sum += todayValue
                } else {
                    sum += byDay[key] ?? 0
                }
                guard let next = calendar.date(byAdding: .day, value: 1, to: cursor) else { break }
                cursor = next
            }

            return ChartBar(
                label: labelFormatter.string(from: weekInterval.start),
                value: sum,
                isToday: weekOffset == 0
            )
        }
    }
}