import SwiftUI
import CoreLocation


struct RoutePreviewView: View {

    private let iconSize: CGFloat = 150

    @ObservedObject
    var file: FileResource

    @State
    var overview: RouteOverview?

    @State
    var message: String?

    @State
    var elevation: [ElevationSample] = []

    var body: some View {
        VStack {
            Image(systemSymbol: .map)
                .resizable()
                .aspectRatio(contentMode:.fit)
                .frame(width: iconSize)
            if let message {
                Text(message)
                    .font(.title)
            } else if let overview {
                if let start = overview.start {
                    if let end = overview.end {
                        Text("\(start.formatted()) - \(end.formatted()) (\(overview.duration.timeString))")
                    } else {
                        Text(start.formatted())
                    }
                }
                Text(String(format: "%.2f km (%.0f m ascended)", overview.distance / 1000, overview.ascendedElevation))
                Text("\(Int(overview.energy)) kcal")
                if !elevation.isEmpty {
                    ElevationGraph(samples: elevation)
                        .frame(width: 500, height: 200)
                        .padding()
                }
            } else {
                Text("Loading route overview...")
                    .font(.title)
                ProgressView()
                    .progressViewStyle(.circular)
            }
        }
        .foregroundStyle(.secondary)
        .onAppear { loadOverview() }
    }

    private func loadOverview() {
        guard overview == nil && message == nil else {
            return
        }
        Task {
            guard let data = file.dataContent() else {
                DispatchQueue.main.async {
                    self.message = "Failed to get file data"
                }
                return
            }
            let route: WorkoutData
            do {
                route = try WorkoutData(data: data)
            } catch {
                DispatchQueue.main.async {
                    self.message = "Failed to decode route: \(error)"
                }
                return
            }

            let overview = route.overview

            let elevations = route.locations.map { ElevationSample(timestamp: $0.timestamp, altitude: $0.altitude) }

            DispatchQueue.main.async {
                self.overview = overview
                self.elevation = elevations
            }
        }
    }
}