import HealthKit
import Foundation

@MainActor
class HealthKitService: ObservableObject {
    let healthStore = HKHealthStore()
    @Published var isSyncing = false

    var isAvailable: Bool { HKHealthStore.isHealthDataAvailable() }

    private let typesToRead: Set<HKObjectType> = [
        HKQuantityType(.heartRate),
        HKQuantityType(.restingHeartRate),
        HKQuantityType(.heartRateVariabilitySDNN),
        HKQuantityType(.stepCount),
        HKQuantityType(.activeEnergyBurned),
        HKQuantityType(.oxygenSaturation),
        HKQuantityType(.distanceWalkingRunning),
        HKQuantityType(.respiratoryRate),
        HKCategoryType(.sleepAnalysis),
    ]

    func requestAuthorization() async throws {
        guard isAvailable else { throw HealthKitError.notAvailable }
        try await healthStore.requestAuthorization(toShare: [], read: typesToRead)
    }

    func checkAuthorization(for type: HKObjectType) -> Bool {
        healthStore.authorizationStatus(for: type) == .sharingAuthorized
    }

    // MARK: - Collect All Metrics

    func collectAllMetrics() async -> [[String: Any]] {
        let now = Date()
        let startOfDay = Calendar.current.startOfDay(for: now)
        let predicate = HKQuery.predicateForSamples(withStart: startOfDay, end: now)

        let dateFormatter = DateFormatter()
        dateFormatter.dateFormat = "yyyy-MM-dd HH:mm:ss Z"

        let dateStr = dateFormatter.string(from: startOfDay)

        var metrics: [[String: Any]] = []

        // Step Count
        let steps = await fetchCumulativeSum(.stepCount, unit: .count(), predicate: predicate)
        if steps > 0 {
            metrics.append([
                "name": "step_count",
                "units": "count",
                "data": [["date": dateStr, "qty": steps]]
            ])
        }

        // Resting Heart Rate
        let rhr = await fetchLatestQuantity(.restingHeartRate, unit: HKUnit.count().unitDivided(by: .minute()), predicate: predicate)
        if rhr > 0 {
            metrics.append([
                "name": "resting_heart_rate",
                "units": "bpm",
                "data": [["date": dateStr, "qty": rhr]]
            ])
        }

        // HRV
        let hrvValues = await fetchAllSamples(.heartRateVariabilitySDNN, unit: .secondUnit(with: .milli), predicate: predicate)
        if !hrvValues.isEmpty {
            let hrvData = hrvValues.map { sample -> [String: Any] in
                ["date": dateFormatter.string(from: sample.startDate), "qty": sample.quantity.doubleValue(for: .secondUnit(with: .milli))]
            }
            metrics.append([
                "name": "heart_rate_variability",
                "units": "ms",
                "data": hrvData
            ])
        }

        // Heart Rate
        let hrValues = await fetchAllSamples(.heartRate, unit: HKUnit.count().unitDivided(by: .minute()), predicate: predicate)
        if !hrValues.isEmpty {
            let hrData = hrValues.map { sample -> [String: Any] in
                ["date": dateFormatter.string(from: sample.startDate), "qty": sample.quantity.doubleValue(for: HKUnit.count().unitDivided(by: .minute()))]
            }
            metrics.append([
                "name": "heart_rate",
                "units": "bpm",
                "data": hrData
            ])
        }

        // Active Energy (convert kcal to kJ)
        let energy = await fetchCumulativeSum(.activeEnergyBurned, unit: .kilocalorie(), predicate: predicate)
        if energy > 0 {
            let kJ = energy * 4.184
            metrics.append([
                "name": "active_energy",
                "units": "kJ",
                "data": [["date": dateStr, "qty": kJ]]
            ])
        }

        // Blood Oxygen
        let spo2Values = await fetchAllSamples(.oxygenSaturation, unit: .percent(), predicate: predicate)
        if !spo2Values.isEmpty {
            let spo2Data = spo2Values.map { sample -> [String: Any] in
                ["date": dateFormatter.string(from: sample.startDate), "qty": sample.quantity.doubleValue(for: .percent()) * 100]
            }
            metrics.append([
                "name": "blood_oxygen_saturation",
                "units": "%",
                "data": spo2Data
            ])
        }

        // Walking + Running Distance
        let distance = await fetchCumulativeSum(.distanceWalkingRunning, unit: .meter(), predicate: predicate)
        if distance > 0 {
            metrics.append([
                "name": "walking_running_distance",
                "units": "m",
                "data": [["date": dateStr, "qty": distance]]
            ])
        }

        // Respiratory Rate (дыхание)
        let rrValues = await fetchAllSamples(.respiratoryRate, unit: HKUnit.count().unitDivided(by: .minute()), predicate: predicate)
        if !rrValues.isEmpty {
            let rrData = rrValues.map { sample -> [String: Any] in
                ["date": dateFormatter.string(from: sample.startDate), "qty": sample.quantity.doubleValue(for: HKUnit.count().unitDivided(by: .minute()))]
            }
            metrics.append([
                "name": "respiratory_rate",
                "units": "breaths/min",
                "data": rrData
            ])
        }

        // Sleep Analysis — расширенный диапазон (последние 24 ча��а, чтобы захватить ночной сон)
        let sleepData = await fetchSleepData(dateFormatter: dateFormatter)
        if !sleepData.isEmpty {
            metrics.append([
                "name": "sleep_analysis",
                "units": "hr",
                "data": sleepData
            ])
        }

        return metrics
    }

    // MARK: - Sleep Data Collection

    private func fetchSleepData(dateFormatter: DateFormatter) async -> [[String: Any]] {
        guard let sleepType = HKCategoryType.categoryType(forIdentifier: .sleepAnalysis) else { return [] }

        // Ночной сон: с 18:00 вчера до сейчас (захватывает засыпание вечером + пробуждение утром)
        let now = Date()
        let cal = Calendar.current
        var startComponents = cal.dateComponents([.year, .month, .day], from: now)
        startComponents.hour = 18
        startComponents.minute = 0
        guard let todayEvening = cal.date(from: startComponents),
              let yesterdayEvening = cal.date(byAdding: .day, value: -1, to: todayEvening) else { return [] }
        let sleepStart = now.timeIntervalSince(todayEvening) > 0 ? todayEvening : yesterdayEvening
        let sleepPredicate = HKQuery.predicateForSamples(withStart: sleepStart, end: now)

        return await withCheckedContinuation { cont in
            let sort = NSSortDescriptor(key: HKSampleSortIdentifierStartDate, ascending: true)
            let query = HKSampleQuery(sampleType: sleepType, predicate: sleepPredicate, limit: HKObjectQueryNoLimit, sortDescriptors: [sort]) { _, samples, _ in
                guard let samples = samples as? [HKCategorySample], !samples.isEmpty else {
                    cont.resume(returning: [])
                    return
                }

                // Считаем время по каждой стадии сна в часах
                var deepSeconds = 0.0
                var remSeconds = 0.0
                var coreSeconds = 0.0
                var awakeSeconds = 0.0
                var asleepSeconds = 0.0
                var inBedStart: Date?
                var inBedEnd: Date?

                for sample in samples {
                    let duration = sample.endDate.timeIntervalSince(sample.startDate)

                    switch sample.value {
                    case HKCategoryValueSleepAnalysis.inBed.rawValue:
                        if inBedStart == nil || sample.startDate < inBedStart! { inBedStart = sample.startDate }
                        if inBedEnd == nil || sample.endDate > inBedEnd! { inBedEnd = sample.endDate }
                    case HKCategoryValueSleepAnalysis.asleepDeep.rawValue:
                        deepSeconds += duration
                        asleepSeconds += duration
                    case HKCategoryValueSleepAnalysis.asleepREM.rawValue:
                        remSeconds += duration
                        asleepSeconds += duration
                    case HKCategoryValueSleepAnalysis.asleepCore.rawValue:
                        coreSeconds += duration
                        asleepSeconds += duration
                    case HKCategoryValueSleepAnalysis.asleepUnspecified.rawValue:
                        asleepSeconds += duration
                    case HKCategoryValueSleepAnalysis.awake.rawValue:
                        awakeSeconds += duration
                    default:
                        break
                    }
                }

                // Если нет inBed, берём из asleep-сэмплов
                if inBedStart == nil {
                    let asleepSamples = samples.filter { $0.value != HKCategoryValueSleepAnalysis.awake.rawValue && $0.value != HKCategoryValueSleepAnalysis.inBed.rawValue }
                    inBedStart = asleepSamples.first?.startDate
                    inBedEnd = asleepSamples.last?.endDate
                }

                let totalSleep = asleepSeconds / 3600.0
                guard totalSleep > 0 else {
                    cont.resume(returning: [])
                    return
                }

                let startOfDay = Calendar.current.startOfDay(for: now)

                // Формат, который ожидает health-webhook API
                var entry: [String: Any] = [
                    "date": dateFormatter.string(from: startOfDay),
                    "totalSleep": round(totalSleep * 1000) / 1000,
                    "deep": round((deepSeconds / 3600.0) * 1000) / 1000,
                    "rem": round((remSeconds / 3600.0) * 1000) / 1000,
                    "core": round((coreSeconds / 3600.0) * 1000) / 1000,
                    "awake": round((awakeSeconds / 3600.0) * 1000) / 1000,
                    "asleep": round(totalSleep * 1000) / 1000,
                    "source": "Apple Watch"
                ]

                if let start = inBedStart {
                    entry["inBedStart"] = dateFormatter.string(from: start)
                    entry["sleepStart"] = dateFormatter.string(from: start)
                }
                if let end = inBedEnd {
                    entry["inBedEnd"] = dateFormatter.string(from: end)
                    entry["sleepEnd"] = dateFormatter.string(from: end)
                }

                cont.resume(returning: [entry])
            }
            self.healthStore.execute(query)
        }
    }

    // MARK: - Send to Server

    func syncToServer(apiKey: String) async throws {
        isSyncing = true
        defer { isSyncing = false }

        guard isAvailable else {
            throw HealthKitError.notAvailable
        }

        try await requestAuthorization()

        let metrics = await collectAllMetrics()
        guard !metrics.isEmpty else {
            throw HealthKitError.noData
        }

        let payload: [String: Any] = [
            "data": [
                "metrics": metrics
            ]
        ]

        let jsonData = try JSONSerialization.data(withJSONObject: payload)

        guard let url = URL(string: "\(HealthAPIService.shared.baseURL)/api/health") else {
            throw HealthKitError.invalidURL
        }

        var request = URLRequest(url: url)
        request.httpMethod = "POST"
        request.setValue("application/json", forHTTPHeaderField: "Content-Type")
        request.setValue(apiKey, forHTTPHeaderField: "X-API-Key")
        request.httpBody = jsonData
        request.timeoutInterval = 30

        let (data, response) = try await URLSession.shared.data(for: request)
        guard let httpResponse = response as? HTTPURLResponse,
              (200...299).contains(httpResponse.statusCode) else {
            let code = (response as? HTTPURLResponse)?.statusCode ?? 0
            let body = String(data: data, encoding: .utf8) ?? ""
            throw HealthKitError.serverError(code, body)
        }
    }

    // MARK: - Helpers

    private func fetchCumulativeSum(_ identifier: HKQuantityTypeIdentifier, unit: HKUnit, predicate: NSPredicate) async -> Double {
        guard let type = HKQuantityType.quantityType(forIdentifier: identifier) else { return 0 }
        return await withCheckedContinuation { cont in
            let query = HKStatisticsQuery(quantityType: type, quantitySamplePredicate: predicate, options: .cumulativeSum) { _, result, _ in
                cont.resume(returning: result?.sumQuantity()?.doubleValue(for: unit) ?? 0)
            }
            healthStore.execute(query)
        }
    }

    private func fetchLatestQuantity(_ identifier: HKQuantityTypeIdentifier, unit: HKUnit, predicate: NSPredicate) async -> Double {
        guard let type = HKQuantityType.quantityType(forIdentifier: identifier) else { return 0 }
        return await withCheckedContinuation { cont in
            let sort = NSSortDescriptor(key: HKSampleSortIdentifierStartDate, ascending: false)
            let query = HKSampleQuery(sampleType: type, predicate: predicate, limit: 1, sortDescriptors: [sort]) { _, samples, _ in
                let value = (samples?.first as? HKQuantitySample)?.quantity.doubleValue(for: unit) ?? 0
                cont.resume(returning: value)
            }
            healthStore.execute(query)
        }
    }

    private func fetchAllSamples(_ identifier: HKQuantityTypeIdentifier, unit: HKUnit, predicate: NSPredicate) async -> [HKQuantitySample] {
        guard let type = HKQuantityType.quantityType(forIdentifier: identifier) else { return [] }
        return await withCheckedContinuation { cont in
            let sort = NSSortDescriptor(key: HKSampleSortIdentifierStartDate, ascending: true)
            let query = HKSampleQuery(sampleType: type, predicate: predicate, limit: HKObjectQueryNoLimit, sortDescriptors: [sort]) { _, samples, _ in
                cont.resume(returning: (samples as? [HKQuantitySample]) ?? [])
            }
            healthStore.execute(query)
        }
    }

    // MARK: - Sleep Segments (timeline)

    func fetchSleepSegments() async -> [SleepSegment] {
        guard let sleepType = HKCategoryType.categoryType(forIdentifier: .sleepAnalysis) else { return [] }
        let now = Date()
        let cal = Calendar.current
        var startComp = cal.dateComponents([.year, .month, .day], from: now)
        startComp.hour = 18
        guard let todayEvening = cal.date(from: startComp),
              let yesterdayEvening = cal.date(byAdding: .day, value: -1, to: todayEvening) else { return [] }
        let sleepStart = now.timeIntervalSince(todayEvening) > 0 ? todayEvening : yesterdayEvening
        let predicate = HKQuery.predicateForSamples(withStart: sleepStart, end: now)

        return await withCheckedContinuation { cont in
            let sort = NSSortDescriptor(key: HKSampleSortIdentifierStartDate, ascending: true)
            let query = HKSampleQuery(sampleType: sleepType, predicate: predicate, limit: HKObjectQueryNoLimit, sortDescriptors: [sort]) { _, samples, _ in
                guard let samples = samples as? [HKCategorySample] else {
                    cont.resume(returning: [])
                    return
                }

                let segments: [SleepSegment] = samples.compactMap { sample in
                    let phase: SleepPhaseType?
                    switch sample.value {
                    case HKCategoryValueSleepAnalysis.asleepDeep.rawValue: phase = .deep
                    case HKCategoryValueSleepAnalysis.asleepREM.rawValue: phase = .rem
                    case HKCategoryValueSleepAnalysis.asleepCore.rawValue: phase = .core
                    case HKCategoryValueSleepAnalysis.asleepUnspecified.rawValue: phase = .core
                    case HKCategoryValueSleepAnalysis.awake.rawValue: phase = .awake
                    default: phase = nil
                    }
                    guard let p = phase else { return nil }
                    return SleepSegment(phase: p, start: sample.startDate, end: sample.endDate)
                }
                cont.resume(returning: segments)
            }
            self.healthStore.execute(query)
        }
    }
}

// MARK: - Errors

enum HealthKitError: Error, LocalizedError {
    case notAvailable
    case noData
    case invalidURL
    case serverError(Int, String)

    var errorDescription: String? {
        switch self {
        case .notAvailable: return "HealthKit недоступен на этом устройстве"
        case .noData: return "Нет данных HealthKit за сегодня. Убедитесь, что Apple Watch синхронизированы"
        case .invalidURL: return "Неверный URL сервера"
        case .serverError(let code, let body): return "Ошибка сервера (\(code)): \(body.prefix(100))"
        }
    }
}