HealthContentView.swift

//
//  ContentView.swift
//  SwiftUI-HealtKit-Sample
//
//  Created by Shawn Frank on 30/11/2024.
//

import SwiftUI
import HealthKit

struct ContentView: View {
    @StateObject private var stepCounter = StepCounter()

    var body: some View {
        VStack {
            Text("Steps Today")
                .font(.title)
                .padding()

            if let steps = stepCounter.steps {
                Text("\(steps)")
                    .font(.largeTitle)
                    .bold()
                    .padding()
            } else {
                Text("Loading...")
                    .font(.headline)
                    .padding()
            }
        }
        .onAppear {
            stepCounter.requestAuthorization()
        }
    }
}

class StepCounter: ObservableObject {
    private var healthStore = HKHealthStore()
    @Published var steps: Int?

    func requestAuthorization() {
        // Check if HealthKit is available
        guard HKHealthStore.isHealthDataAvailable() else {
            print("HealthKit is not available on this device.")
            return
        }

        let stepType = HKQuantityType.quantityType(forIdentifier: .stepCount)!

        healthStore.requestAuthorization(toShare: [], read: [stepType]) { success, error in
            if success {
                self.fetchSteps()
            } else if let error = error {
                print("Authorization failed: \(error.localizedDescription)")
            }
        }
    }

    func fetchSteps() {
        let stepType = HKQuantityType.quantityType(forIdentifier: .stepCount)!
        let startOfDay = Calendar.current.startOfDay(for: Date())
        let predicate = HKQuery.predicateForSamples(withStart: startOfDay, end: Date(), options: .strictStartDate)

        let query = HKStatisticsQuery(quantityType: stepType, quantitySamplePredicate: predicate, options: .cumulativeSum) { _, result, error in
            guard let result = result, let sum = result.sumQuantity() else {
                print("Failed to fetch steps: \(String(describing: error?.localizedDescription))")
                DispatchQueue.main.async {
                    self.steps = nil
                }
                return
            }

            let stepCount = Int(sum.doubleValue(for: HKUnit.count()))
            DispatchQueue.main.async {
                self.steps = stepCount
            }
        }

        healthStore.execute(query)
    }
}