import SwiftUI
import CoreLocation
import WidgetKit

struct ContentView: View {
    @Environment(\.scenePhase) private var scenePhase

    @State private var stations: [FuelStation] = []
    @State private var selectedFuel: FuelType = FuelStore.loadSelectedFuel()
    @State private var sortMode: SortMode = FuelStore.loadSortMode()
    @State private var stationLimit: Int = FuelStore.loadStationLimit()
    @State private var location: Coordinate? = {
        if let loc = FuelStore.loadLocation() { return Coordinate(lat: loc.lat, lng: loc.lng) }
        return nil
    }()
    @State private var isLoading = false
    @State private var statusMessage = ""
    @State private var locationManager = LocationManager()

    private var cheapestPrice: Double? {
        stations.compactMap { $0.prices[selectedFuel] }.min()
    }

    private var displayedStations: [FuelStation] {
        Array(sortedStations.prefix(stationLimit))
    }

    private var sortedStations: [FuelStation] {
        let available = stations.filter { $0.prices[selectedFuel] != nil }
        switch sortMode {
        case .closest:
            guard let location else { return available.sorted { $0.prices[selectedFuel]! < $1.prices[selectedFuel]! } }
            return available.sorted { lhs, rhs in
                // Closest first; price only breaks ties.
                let lDist = lhs.distanceKM(to: location.lat, lng2: location.lng)
                let rDist = rhs.distanceKM(to: location.lat, lng2: location.lng)
                if lDist != rDist { return lDist < rDist }
                return lhs.prices[selectedFuel]! < rhs.prices[selectedFuel]!
            }
        case .cheapest:
            return available.sorted { lhs, rhs in
                // Cheapest first; distance only breaks ties.
                let lPrice = lhs.prices[selectedFuel]!
                let rPrice = rhs.prices[selectedFuel]!
                if lPrice != rPrice { return lPrice < rPrice }
                guard let location else { return false }
                return lhs.distanceKM(to: location.lat, lng2: location.lng) <
                       rhs.distanceKM(to: location.lat, lng2: location.lng)
            }
        }
    }

    var body: some View {
        NavigationStack {
            List {
                Section {
                    Text("\(sortMode == .closest ? "Closest" : "Cheapest") \(selectedFuel.displayName) — tap a station for directions.")
                        .font(.footnote)
                        .foregroundStyle(.secondary)
                }

                Section("Fuel type") {
                    Picker("Fuel type", selection: $selectedFuel) {
                        ForEach(FuelType.allCases) { fuel in
                            Text(fuel.displayName).tag(fuel)
                        }
                    }
                    .pickerStyle(.segmented)
                    .onChange(of: selectedFuel) { _, newValue in
                        FuelStore.saveSelectedFuel(newValue)
                        WidgetCenter.shared.reloadAllTimelines()
                    }
                }

                Section("Stations") {
                    Picker("Sort by", selection: $sortMode) {
                        ForEach(SortMode.allCases) { mode in
                            Text(mode.displayName).tag(mode)
                        }
                    }
                    .pickerStyle(.segmented)
                    .onChange(of: sortMode) { _, newValue in
                        FuelStore.saveSortMode(newValue)
                    }
                    .padding(.vertical, 2)

                    if isLoading {
                        HStack(spacing: 10) {
                            ProgressView()
                            Text("Fetching prices…")
                        }
                    } else if displayedStations.isEmpty {
                        Text("No \(selectedFuel.displayName) stations found.")
                            .foregroundStyle(.secondary)
                    } else {
                        ForEach(Array(displayedStations.enumerated()), id: \.element.id) { index, station in
                            StationRow(
                                station: station,
                                fuel: selectedFuel,
                                location: location,
                                cheapestPrice: cheapestPrice,
                                isTopResult: index == 0
                            )
                        }
                    }

                    if !displayedStations.isEmpty {
                        Divider()
                        Picker("Show", selection: $stationLimit) {
                            ForEach([10, 25, 50, 75, 100], id: \.self) { count in
                                Text("\(count)").tag(count)
                            }
                        }
                        .pickerStyle(.segmented)
                        .onChange(of: stationLimit) { _, newValue in
                            FuelStore.saveStationLimit(newValue)
                        }
                        .padding(.vertical, 2)
                        Text("Showing \(displayedStations.count) of \(sortedStations.count) stations")
                            .font(.caption2)
                            .foregroundStyle(.secondary)
                    }
                }

                Section("Key") {
                    HStack(spacing: 8) {
                        Circle().fill(.green).frame(width: 12, height: 12)
                        Text("Best value — within 1.5p of the cheapest")
                            .font(.caption)
                    }
                    HStack(spacing: 8) {
                        Circle().fill(.orange).frame(width: 12, height: 12)
                        Text("Okay — within 4p of the cheapest")
                            .font(.caption)
                    }
                    HStack(spacing: 8) {
                        Circle().fill(.red).frame(width: 12, height: 12)
                        Text("Pricey — more than 4p over the cheapest")
                            .font(.caption)
                    }
                    HStack(spacing: 8) {
                        Text("TOP")
                            .font(.caption2.bold())
                            .padding(.horizontal, 5)
                            .padding(.vertical, 1)
                            .background(Capsule().fill(.blue.opacity(0.15)))
                            .foregroundStyle(.blue)
                        Text("Top result for the current sort")
                            .font(.caption)
                    }
                }

                if !statusMessage.isEmpty {
                    Section("Status") {
                        Text(statusMessage)
                            .font(.caption2)
                            .monospaced()
                            .textSelection(.enabled)
                    }
                }
            }
            .navigationTitle("FuelBoard")
            .toolbar {
                ToolbarItem(placement: .topBarTrailing) {
                    Button {
                        Task { await refresh() }
                    } label: {
                        Image(systemName: "arrow.clockwise")
                    }
                    .disabled(isLoading)
                }
            }
            .onAppear {
                // Request a fresh fix on every launch so "Closest" stays
                // accurate and the widget gets fresh coords.
                locationManager.requestUpdate()
                Task { await refresh() }
            }
            .onChange(of: scenePhase) { _, newPhase in
                if newPhase == .active {
                    // Re-request location on foreground too.
                    locationManager.requestUpdate()
                    Task { await refresh() }
                }
            }
            .onChange(of: locationManager.current) { _, newLocation in
                if let newLocation {
                    location = newLocation
                    FuelStore.saveLocation(lat: newLocation.lat, lng: newLocation.lng)
                    WidgetCenter.shared.reloadAllTimelines()
                    Task { await refresh() }
                }
            }
        }
    }

    private func refresh() async {
        isLoading = true
        defer { isLoading = false }
        do {
            let fetched = try await FuelPriceProvider.active.fetchStations(near: location?.lat, lng: location?.lng, fuel: selectedFuel)
            stations = fetched
            FuelStore.saveStations(fetched)
            WidgetCenter.shared.reloadAllTimelines()
            statusMessage = "Loaded \(fetched.count) stations · \(Date().formatted(date: .omitted, time: .shortened))"
        } catch {
            statusMessage = "Live fetch failed: \(error.localizedDescription). Showing cached/sample data."
            stations = FuelStore.loadStations().isEmpty ? SampleFuelProvider.sampleStations : FuelStore.loadStations()
        }
    }
}

struct StationRow: View {
    let station: FuelStation
    let fuel: FuelType
    let location: Coordinate?
    let cheapestPrice: Double?
    let isTopResult: Bool

    private var ragColor: Color {
        guard let price = station.prices[fuel], let cheapestPrice else { return .gray }
        switch RAGRating.rating(price: price, cheapest: cheapestPrice) {
        case .green: return .green
        case .amber: return .orange
        case .red: return .red
        }
    }

    private var deltaText: String? {
        guard let price = station.prices[fuel], let cheapestPrice else { return nil }
        let delta = price - cheapestPrice
        if delta <= 0.05 { return "best" }
        return String(format: "+%.1fp", delta)
    }

    var body: some View {
        HStack(spacing: 12) {
            // Round brand logo (or generic fuel pump fallback)
            Group {
                if let asset = station.brandImageName {
                    Image(asset)
                        .resizable()
                        .scaledToFit()
                        .padding(5)
                } else {
                    Image(systemName: "fuelpump.fill")
                        .font(.system(size: 22))
                        .foregroundStyle(.white)
                }
            }
            .frame(width: 46, height: 46)
            .background(Circle().fill(.white))
            .clipShape(Circle())
            .overlay(Circle().stroke(Color.primary.opacity(0.08), lineWidth: 1))
            .shadow(color: .black.opacity(0.08), radius: 2, y: 1)

            VStack(alignment: .leading, spacing: 2) {
                HStack(spacing: 6) {
                    Text(station.name)
                        .font(.headline)
                    if isTopResult {
                        Text("TOP")
                            .font(.caption2.bold())
                            .padding(.horizontal, 5)
                            .padding(.vertical, 1)
                            .background(Capsule().fill(.blue.opacity(0.15)))
                            .foregroundStyle(.blue)
                    }
                }
                Text("\(station.address), \(station.postcode)")
                    .font(.caption)
                    .foregroundStyle(.secondary)
                if let location {
                    Text(String(format: "%.1f km away", station.distanceKM(to: location.lat, lng2: location.lng)))
                        .font(.caption2)
                        .foregroundStyle(.secondary)
                }
            }
            Spacer()
            if let price = station.prices[fuel] {
                VStack(alignment: .trailing, spacing: 2) {
                    HStack(spacing: 5) {
                        Circle()
                            .fill(ragColor)
                            .frame(width: 10, height: 10)
                        Text(String(format: "%.1fp", price))
                            .font(.title3.bold())
                    }
                    if let deltaText {
                        Text(deltaText)
                            .font(.caption2.bold())
                            .foregroundStyle(ragColor)
                    }
                }
            }
            Image(systemName: "arrow.triangle.turn.up.right.circle")
                .foregroundStyle(.secondary)
        }
        .contentShape(Rectangle())
        .onTapGesture {
            if let url = station.mapsDirectionsURL {
                UIApplication.shared.open(url)
            }
        }
    }
}

// MARK: - Location manager

@MainActor
final class LocationManager: NSObject, ObservableObject, @preconcurrency CLLocationManagerDelegate {
    @Published var current: Coordinate?
    private let manager = CLLocationManager()

    override init() {
        super.init()
        manager.delegate = self
        manager.desiredAccuracy = kCLLocationAccuracyHundredMeters
    }

    func requestUpdate() {
        switch manager.authorizationStatus {
        case .notDetermined:
            manager.requestWhenInUseAuthorization()
            manager.requestLocation()
        case .authorizedWhenInUse, .authorizedAlways:
            manager.requestLocation()
        default:
            break
        }
    }

    func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
        guard let loc = locations.last else { return }
        current = Coordinate(lat: loc.coordinate.latitude, lng: loc.coordinate.longitude)
    }

    func locationManager(_ manager: CLLocationManager, didFailWithError error: Error) {
        // Ignore — the app still works price-sorted without location.
    }
}