import WidgetKit
import SwiftUI

// FuelBoard widget — cheapest petrol stations near you.
//   systemMedium: top 4 stations with price + distance, each row opens Maps
//   systemSmall:  single cheapest station, whole widget opens Maps
// Taps deep-link to Apple Maps directions (http://maps.apple.com/?daddr=).
// Note: on the home screen Link opens Maps directly. Inside CarPlay the widget
// renders but can't launch Maps (widgets can only launch their own CarPlay app).

struct FuelPriceWidget: Widget {
    let kind = "FuelPriceWidget"

    var body: some WidgetConfiguration {
        StaticConfiguration(kind: kind, provider: FuelPriceProvider2()) { entry in
            FuelPriceWidgetView(entry: entry)
                .containerBackground(for: .widget) {
                    Color(.systemBackground)
                }
        }
        .configurationDisplayName("FuelBoard Prices")
        .description("The cheapest fuel near you. Tap a station for directions.")
        .supportedFamilies([.systemSmall, .systemMedium])
    }
}

struct FuelPriceEntry: TimelineEntry {
    let date: Date
    let stations: [FuelStation]   // already filtered + sorted for the selected fuel
    let fuel: FuelType
    let location: (lat: Double, lng: Double)?
}

struct FuelPriceProvider2: TimelineProvider {
    func placeholder(in context: Context) -> FuelPriceEntry {
        let fuel = FuelStore.loadSelectedFuel()
        let sample = SampleFuelProvider.sampleStations
            .filter { $0.prices[fuel] != nil }
            .sorted { $0.prices[fuel]! < $1.prices[fuel]! }
        return FuelPriceEntry(date: Date(), stations: Array(sample.prefix(4)), fuel: fuel, location: nil)
    }

    func getSnapshot(in context: Context, completion: @escaping (FuelPriceEntry) -> Void) {
        completion(makeEntry())
    }

    func getTimeline(in context: Context, completion: @escaping (Timeline<FuelPriceEntry>) -> Void) {
        let entry = makeEntry()
        let nextRefresh = Calendar.current.date(byAdding: .minute, value: 15, to: Date())!
        completion(Timeline(entries: [entry], policy: .after(nextRefresh)))
    }

    private func makeEntry() -> FuelPriceEntry {
        let fuel = FuelStore.loadSelectedFuel()
        let location = FuelStore.loadLocation().map { (lat: $0.lat, lng: $0.lng) }
        var stations = FuelStore.loadStations()
        if stations.isEmpty { stations = SampleFuelProvider.sampleStations }
        let filtered = stations.filter { $0.prices[fuel] != nil }
        let sorted: [FuelStation]
        if let location {
            sorted = filtered.sorted { lhs, rhs in
                let lScore = lhs.distanceKM(to: location.lat, lng2: location.lng) * 0.4 + lhs.prices[fuel]! * 0.001
                let rScore = rhs.distanceKM(to: location.lat, lng2: location.lng) * 0.4 + rhs.prices[fuel]! * 0.001
                return lScore < rScore
            }
        } else {
            sorted = filtered.sorted { $0.prices[fuel]! < $1.prices[fuel]! }
        }
        return FuelPriceEntry(date: Date(), stations: Array(sorted.prefix(4)), fuel: fuel, location: location)
    }
}

struct FuelPriceWidgetView: View {
    let entry: FuelPriceEntry

    var body: some View {
        Group {
            if entry.stations.isEmpty {
                VStack(spacing: 6) {
                    Image(systemName: "fuelpump")
                        .font(.title2)
                        .foregroundStyle(.secondary)
                    Text("No \(entry.fuel.displayName) stations")
                        .font(.caption2)
                        .foregroundStyle(.secondary)
                }
            } else if entry.stations.count == 1 || UIDevice.current.userInterfaceIdiom == .pad {
                singleCheapest
            } else {
                stationList
            }
        }
    }

    private var singleCheapest: some View {
        let station = entry.stations[0]
        return VStack(alignment: .leading, spacing: 6) {
            HStack {
                Image(systemName: "fuelpump.fill")
                    .foregroundStyle(.green)
                Text("Cheapest \(entry.fuel.displayName)")
                    .font(.caption2)
                    .foregroundStyle(.secondary)
            }
            Text(station.brand)
                .font(.headline)
                .lineLimit(1)
            if let price = station.prices[entry.fuel] {
                Text(String(format: "%.1fp", price))
                    .font(.system(size: 28, weight: .bold))
                    .foregroundStyle(.green)
            }
            if let location = entry.location {
                Text(String(format: "%.1f km away", station.distanceKM(to: location.lat, lng2: location.lng)))
                    .font(.caption2)
                    .foregroundStyle(.secondary)
            }
            Text("Tap for directions")
                .font(.caption2)
                .foregroundStyle(.secondary)
        }
        .frame(maxWidth: .infinity, maxHeight: .infinity, alignment: .leading)
        .widgetURL(station.mapsDirectionsURL)
    }

    private var stationList: some View {
        VStack(alignment: .leading, spacing: 6) {
            HStack {
                Image(systemName: "fuelpump.fill")
                    .foregroundStyle(.green)
                Text("Cheapest \(entry.fuel.displayName)")
                    .font(.caption2)
                    .foregroundStyle(.secondary)
                Spacer()
                Text("Tap → Maps")
                    .font(.caption2)
                    .foregroundStyle(.secondary)
            }
            ForEach(entry.stations.prefix(3)) { station in
                Link(destination: station.mapsDirectionsURL ?? URL(string: "http://maps.apple.com")!) {
                    HStack(spacing: 8) {
                        Text(station.brand)
                            .font(.caption.weight(.semibold))
                            .lineLimit(1)
                        if let location = entry.location {
                            Text(String(format: "%.1f km", station.distanceKM(to: location.lat, lng2: location.lng)))
                                .font(.caption2)
                                .foregroundStyle(.secondary)
                        }
                        Spacer()
                        if let price = station.prices[entry.fuel] {
                            Text(String(format: "%.1fp", price))
                                .font(.caption.weight(.bold))
                                .foregroundStyle(.green)
                        }
                    }
                }
                .buttonStyle(.plain)
            }
            Spacer(minLength: 0)
        }
        .frame(maxWidth: .infinity, maxHeight: .infinity, alignment: .topLeading)
    }
}