//
//  HealthManager.swift
//  FitnessApp
//
//  Created by Matt Bruce on 12/20/24.
//

import Foundation
import HealthKit

extension Date {
    static var startOfDay: Date {
        let calendar = Calendar.current
        return calendar.startOfDay(for: Date())
    }
}

class HealthManager {
    
    static let shared = HealthManager()
    
    let healthStore = HKHealthStore()
    
    private init () {
        Task {
            do {
                try await requestHealthKitAccess()
            } catch {
                
            }
        }
    }
    
    func requestHealthKitAccess() async throws {
        let calories = HKQuantityType(.activeEnergyBurned)
        let exercise = HKQuantityType(.appleExerciseTime)
        let stand = HKCategoryType(.appleStandHour)
        
        let healthTypes: Set = [calories, exercise, stand]

        try await healthStore.requestAuthorization(toShare: [], read: healthTypes)
    }

    func fetchTodayCaloriesBurned(completion: @escaping(Result<Double, Error>) -> Void) {
        guard HKHealthStore.isHealthDataAvailable() else {
            completion(.failure(NSError(domain: "HealthManager", code: -2, userInfo: [NSLocalizedDescriptionKey: "Health data unavailable"])))
            return
        }

        let calories = HKQuantityType(.activeEnergyBurned)
        let predicate = HKQuery.predicateForSamples(withStart: .startOfDay, end: Date())

        let query = HKStatisticsQuery(quantityType: calories, quantitySamplePredicate: predicate) { _, results, error in
            if let error = error {
                completion(.failure(error))
                return
            }

            if let quantity = results?.sumQuantity() {
                let caloriesBurned = quantity.doubleValue(for: .kilocalorie())
                completion(.success(caloriesBurned))
            } else {
                completion(.failure(NSError(domain: "HealthManager", code: -3, userInfo: [NSLocalizedDescriptionKey: "No data found for today's calories"])))
            }
        }
        healthStore.execute(query)
    }
    
    func fetchTodayExerciseTime(completion: @escaping(Result<Double, Error>) -> Void) {
        guard HKHealthStore.isHealthDataAvailable() else {
            completion(.failure(NSError(domain: "HealthManager", code: -2, userInfo: [NSLocalizedDescriptionKey: "Health data unavailable"])))
            return
        }
        
        let exercise = HKQuantityType(.appleExerciseTime)
        let predicate = HKQuery.predicateForSamples(withStart: .startOfDay, end: Date())
        
        let query = HKStatisticsQuery(quantityType: exercise, quantitySamplePredicate: predicate) { _, results, error in
            if let error = error {
                completion(.failure(error))
                return
            }

            if let quantity = results?.sumQuantity() {
                let exerciseTime = quantity.doubleValue(for: .minute())
                completion(.success(exerciseTime))
            } else {
                completion(.failure(NSError(domain: "HealthManager", code: -3, userInfo: [NSLocalizedDescriptionKey: "No exercise time data found for today."])))
            }
        }
        healthStore.execute(query)
    }

    func fetchTodayStandHours(completion: @escaping(Result<Double, Error>) -> Void) {
        guard HKHealthStore.isHealthDataAvailable() else {
            completion(.failure(NSError(domain: "HealthManager", code: -2, userInfo: [NSLocalizedDescriptionKey: "Health data unavailable"])))
            return
        }
        
        let stand = HKCategoryType(.appleStandHour)
        let predicate = HKQuery.predicateForSamples(withStart: .startOfDay, end: Date())
        
        let query = HKSampleQuery(sampleType: stand, predicate: predicate, limit: HKObjectQueryNoLimit, sortDescriptors: nil) { _, results, error in
            if let error = error {
                completion(.failure(error))
                return
            }
            
            guard let samples = results as? [HKCategorySample], !samples.isEmpty else {
                completion(.failure(NSError(domain: "HealthManager", code: -3, userInfo: [NSLocalizedDescriptionKey: "No stand data found for today."])))
                return
            }
            
            // Count stand hours
            let standHours = samples.filter { $0.value == HKCategoryValueAppleStandHour.stood.rawValue }.count
            completion(.success(Double(standHours)))
        }
        
        healthStore.execute(query)
    }
}