CurrencyRowContainerView.swift

//
//  CurrencyRowData.swift
//  CurrencyRowData
//
//  Created by Andrew Morgan on 26/08/2021.
//

import SwiftUI
import RealmSwift

struct CurrencyRowContainerView: View {
    @ObservedResults(Rate.self) var rates
    
    var isBase = false
    let baseSymbol: String
    @Binding var baseAmount: Double
    let symbol: String
    var refreshToggle: Bool
    var action: (_: String) -> Void = {_ in }
    
    @State private var previousToggle = false
    
    var rate: Rate? {
        rates.where { $0.query.from == baseSymbol && $0.query.to == symbol }.first
    }
    
    var body: some View {
        if let rate = rate {
            HStack {
                CurrencyRowDataView(rate: rate, isBase: isBase, baseAmount: $baseAmount, action: action)
                if refreshToggle != previousToggle {
                    Image(systemName: "arrow.clockwise.icloud")
                        .onAppear(perform: refreshData)
                }
            }
        } else {
            Text("Loading Data...")
                .onAppear(perform: loadData)
        }
    }
    
    private func refreshData() {
        guard let url = URL(string: "https://api.exchangerate.host/convert?from=\(baseSymbol)&to=\(symbol)") else {
            print("Invalid URL")
            previousToggle = refreshToggle
            return
        }
        
        let request = URLRequest(url: url)
        URLSession.shared.dataTask(with: request) { data, response, error in
            guard let data = data else {
                print("Error fetching data: \(error?.localizedDescription ?? "Unknown error")")
                DispatchQueue.main.async { previousToggle = refreshToggle }
                return
            }
            if let decodedResponse = try? JSONDecoder().decode(Rate.self, from: data) {
                DispatchQueue.main.async {
                    if let existingRate = rate {
                        do {
                            let realm = try Realm()
                            try realm.write() {
                                guard let thawedrate = existingRate.thaw() else {
                                    print("Couldn't thaw existingRate")
                                    return
                                }
                                thawedrate.date = decodedResponse.date
                                thawedrate.result = decodedResponse.result
                            }
                        } catch {
                            print("Unable to update existing rate in Realm")
                        }
                    }
                    previousToggle = refreshToggle
                }
            } else {
                print("No data received")
                DispatchQueue.main.async { previousToggle = refreshToggle }
            }
        }
        .resume()
    }
    
    private func loadData() {
        guard let url = URL(string: "https://api.exchangerate.host/convert?from=\(baseSymbol)&to=\(symbol)") else {
            print("Invalid URL")
            return
        }
        let request = URLRequest(url: url)
        print("Network request: \(url.description)")
        URLSession.shared.dataTask(with: request) { data, response, error in
            guard let data = data else {
                print("Error fetching data: \(error?.localizedDescription ?? "Unknown error")")
                return
            }
            if let decodedResponse = try? JSONDecoder().decode(Rate.self, from: data) {
                DispatchQueue.main.async {
                    $rates.append(decodedResponse)
                }
            } else {
                print("No data received")
            }
        }
        .resume()
    }
}

struct CurrencyRowData_Previews: PreviewProvider {
    static var previews: some View {
        CurrencyRowContainerView(baseSymbol: "GBP",
                                 baseAmount: .constant(1.0),
                                 symbol: "USD",
                                 refreshToggle: false)
    }
}