//
//  HealthKitHelper.swift
//  Werkout_ios
//
//  Created by Trey Tartt on 8/13/23.
//

import Foundation
import HealthKit
import SharedCore

struct HealthKitWorkoutData {
    var caloriesBurned: Double?
    var minHeartRate: Double?
    var maxHeartRate: Double?
    var avgHeartRate: Double?
}

class HealthKitHelper {
    private let runtimeReporter = RuntimeReporter.shared
    let healthStore = HKHealthStore()

    func getDetails(forHealthKitUUID uuid: UUID, completion: @escaping ((HealthKitWorkoutData?) -> Void)) {
        runtimeReporter.recordInfo("Fetching HealthKit workout details", metadata: ["uuid": uuid.uuidString])

        let query = HKSampleQuery(sampleType: HKWorkoutType.workoutType(),
                                  predicate: HKQuery.predicateForObject(with: uuid),
                                  limit: 1,
                                  sortDescriptors: nil)
        { [weak self] (_, results, error) -> Void in
            guard let self else {
                DispatchQueue.main.async {
                    completion(nil)
                }
                return
            }

            if let queryError = error {
                self.runtimeReporter.recordError(
                    "Failed querying HealthKit workout",
                    metadata: ["error": queryError.localizedDescription]
                )
                DispatchQueue.main.async {
                    completion(nil)
                }
                return
            }

            guard let workout = results?.compactMap({ $0 as? HKWorkout }).first else {
                self.runtimeReporter.recordWarning("No HealthKit workout found for UUID", metadata: ["uuid": uuid.uuidString])
                DispatchQueue.main.async {
                    completion(nil)
                }
                return
            }

            self.collectDetails(forWorkout: workout, completion: completion)
        }

        healthStore.execute(query)
    }

    private func collectDetails(forWorkout workout: HKWorkout, completion: @escaping ((HealthKitWorkoutData?) -> Void)) {
        let aggregateQueue = DispatchQueue(label: "com.werkout.healthkit.aggregate")
        var workoutData = HealthKitWorkoutData(
            caloriesBurned: nil,
            minHeartRate: nil,
            maxHeartRate: nil,
            avgHeartRate: nil
        )

        let group = DispatchGroup()
        group.enter()
        getTotalBurned(forWorkout: workout) { calories in
            aggregateQueue.async {
                workoutData.caloriesBurned = calories
                group.leave()
            }
        }

        group.enter()
        getHeartRateStuff(forWorkout: workout) { heartRateData in
            aggregateQueue.async {
                workoutData.minHeartRate = heartRateData?.minHeartRate
                workoutData.maxHeartRate = heartRateData?.maxHeartRate
                workoutData.avgHeartRate = heartRateData?.avgHeartRate
                group.leave()
            }
        }

        group.notify(queue: .main) {
            let hasValues = workoutData.caloriesBurned != nil ||
                workoutData.minHeartRate != nil ||
                workoutData.maxHeartRate != nil ||
                workoutData.avgHeartRate != nil

            completion(hasValues ? workoutData : nil)
        }
    }

    private func getHeartRateStuff(forWorkout workout: HKWorkout, completion: @escaping ((HealthKitWorkoutData?) -> Void)) {
        guard let heartType = HKQuantityType.quantityType(forIdentifier: .heartRate) else {
            completion(nil)
            return
        }

        let heartPredicate = HKQuery.predicateForSamples(withStart: workout.startDate,
                                                         end: workout.endDate,
                                                         options: HKQueryOptions.strictEndDate)

        let heartQuery = HKStatisticsQuery(quantityType: heartType,
                                           quantitySamplePredicate: heartPredicate,
                                           options: [.discreteAverage, .discreteMin, .discreteMax],
                                           completionHandler: { [weak self] (_, result, error) -> Void in
            if let error {
                self?.runtimeReporter.recordError(
                    "Failed querying HealthKit heart rate stats",
                    metadata: ["error": error.localizedDescription]
                )
                completion(nil)
                return
            }

            guard let result,
                  let minValue = result.minimumQuantity(),
                  let maxValue = result.maximumQuantity(),
                  let avgValue = result.averageQuantity() else {
                completion(nil)
                return
            }

            let unit = HKUnit(from: "count/min")
            let data = HealthKitWorkoutData(
                caloriesBurned: nil,
                minHeartRate: minValue.doubleValue(for: unit),
                maxHeartRate: maxValue.doubleValue(for: unit),
                avgHeartRate: avgValue.doubleValue(for: unit)
            )
            completion(data)
        })
        healthStore.execute(heartQuery)
    }

    private func getTotalBurned(forWorkout workout: HKWorkout, completion: @escaping ((Double?) -> Void)) {
        guard let calType = HKQuantityType.quantityType(forIdentifier: .activeEnergyBurned) else {
            completion(nil)
            return
        }

        let calPredicate = HKQuery.predicateForSamples(withStart: workout.startDate,
                                                       end: workout.endDate,
                                                       options: HKQueryOptions.strictEndDate)

        let calQuery = HKStatisticsQuery(quantityType: calType,
                                         quantitySamplePredicate: calPredicate,
                                         options: [.cumulativeSum],
                                         completionHandler: { [weak self] (_, result, error) -> Void in
            if let error {
                self?.runtimeReporter.recordError(
                    "Failed querying HealthKit calories",
                    metadata: ["error": error.localizedDescription]
                )
                completion(nil)
                return
            }

            completion(result?.sumQuantity()?.doubleValue(for: HKUnit.kilocalorie()))
        })
        healthStore.execute(calQuery)
    }
}