import WidgetKit
import SwiftUI
import AppIntents

// FuelBoard widget — petrol stations near you.
//   systemMedium: top 3-4 stations with price + distance, each row opens Maps
//   systemSmall:  single station, whole widget opens Maps
// Taps deep-link to Apple Maps directions (maps://?daddr=). On the Home
// Screen the system either opens Maps directly or delivers the URL to
// FuelBoard, whose onOpenURL forwards it (and also still handles legacy
// fuelboard:// and http://maps.apple.com links from older cached timelines).
//
// CarPlay: this widget is marked as a DISFAVORED location there. Widgets in
// CarPlay can only launch their OWN app, and only when that app is itself a
// CarPlay app (fueling entitlement). FuelBoard is not a CarPlay app, so a
// tap in the car would be a dead interaction — Apple's guidance for widgets
// whose purpose is launching a non-CarPlay app is to disfavor CarPlay: the
// widget stays visible (read-only prices) but interaction is disabled, so
// there is no tap that silently does nothing.
//
// Each widget instance is configured INDEPENDENTLY via its own App Intent
// (long-press → Edit Widget): fuel type (Unleaded/Premium/Diesel) and sort
// (Cheapest/Closest/Favourites). Favourites shows pinned stations for the
// chosen fuel, cheapest-first, with no radius — the Distance picker is hidden
// in that mode. Widgets no longer depend on the app's selected fuel — you can
// place several widgets showing different fuels/orders side by side.
//
// Location flow: the provider requests location itself (async, timeout-bounded).
// On success it caches the fix in the shared store for the app; on failure
// (no permission yet / timeout) it falls back to the app's cached location,
// then to price-only sorting. So the widget is location-driven the moment the
// app has been opened once and permission granted.

struct FuelPriceWidget: Widget {
    let kind = "FuelPriceWidget"

    var body: some WidgetConfiguration {
        // CarPlay: mark as disfavored — FuelBoard is not a CarPlay app, so
        // widget taps there can never launch Maps (Apple only allows a widget
        // to launch its own app in CarPlay, and only CarPlay-enabled apps).
        // Disfavored = read-only in the car, no dead interaction.
        baseConfiguration()
            .disfavoredLocations([.carPlay], for: [.systemSmall])
    }

    private func baseConfiguration() -> some WidgetConfiguration {
        AppIntentConfiguration(
            kind: kind,
            intent: FuelBoardWidgetConfigurationIntent.self,
            provider: FuelPriceTimelineProvider()
        ) { entry in
            FuelPriceWidgetView(entry: entry)
                .containerBackground(for: .widget) {
                    Color(.systemBackground)
                }
        }
        .configurationDisplayName("FuelBoard Prices")
        .description("Fuel prices near you. Configure fuel + sort per widget.")
        .supportedFamilies([.systemSmall, .systemMedium])
    }
}

struct FuelPriceEntry: TimelineEntry {
    let date: Date
    let stations: [FuelStation]   // already filtered + sorted per config
    let fuel: FuelType
    let sort: SortMode            // per-widget: cheapest | closest
    let isFavourites: Bool        // favourites mode: pinned stations, cheapest-first
    let location: Coordinate?
    let locationSource: String    // "live" | "cached" | "none"
    let unit: DistanceUnit        // user's display unit for distances
}

struct FuelPriceTimelineProvider: AppIntentTimelineProvider {
    func placeholder(in context: Context) -> FuelPriceEntry {
        let unit = FuelStore.loadDistanceUnit()
        let sample = SampleFuelProvider.sampleStations
            .filter { $0.prices[.e10] != nil }
            .sorted { $0.prices[.e10]! < $1.prices[.e10]! }
        return FuelPriceEntry(
            date: Date(), stations: Array(sample.prefix(8)),
            fuel: .e10, sort: .cheapest, isFavourites: false,
            location: nil, locationSource: "none", unit: unit
        )
    }

    func snapshot(for configuration: FuelBoardWidgetConfigurationIntent, in context: Context) async -> FuelPriceEntry {
        await makeEntry(configuration: configuration)
    }

    func timeline(
        for configuration: FuelBoardWidgetConfigurationIntent,
        in context: Context
    ) async -> Timeline<FuelPriceEntry> {
        let entry = await makeEntry(configuration: configuration)
        // Short cadence so the widget re-orders around a new location while
        // driving — the provider re-fetches a fresh fix + prices each tick.
        let nextRefresh = Calendar.current.date(byAdding: .minute, value: 5, to: Date())!
        return Timeline(entries: [entry], policy: .after(nextRefresh))
    }

    private func makeEntry(configuration: FuelBoardWidgetConfigurationIntent) async -> FuelPriceEntry {
        // Per-widget config: fuel + sort + distance come from THIS widget instance.
        let fuel = FuelType(rawValue: configuration.fuel.rawValue) ?? .e10
        let isFavourites = configuration.sort == .favourites
        let sort: SortMode = configuration.sort == .closest ? .closest : .cheapest
        let radiusKM = Double(configuration.distance.miles) * 1.60934

        // 1) Try a fresh location fix (bounded to a few seconds).
        var location = await WidgetLocationFetcher.shared.currentLocation().map {
            Coordinate(lat: $0.coordinate.latitude, lng: $0.coordinate.longitude)
        }
        var source = "live"

        // 2) Fall back to the app's cached fix.
        if location == nil, let cached = FuelStore.loadLocation() {
            location = cached
            source = "cached"
        }
        if location == nil {
            source = "none"
        }

        // Persist a live fix so the app shows fresh coords on next launch.
        if let location {
            FuelStore.saveLocation(lat: location.lat, lng: location.lng)
        }

        let unit = FuelStore.loadDistanceUnit()

        // 3) Load + order stations per widget mode.
        let ordered: [FuelStation]
        if isFavourites {
            // Favourites: pinned stations for THIS fuel, cheapest-first. Not
            // radius-bound — a favourite in Edinburgh shows on a widget in
            // London. Prices come from the keychain snapshot (the app
            // refreshes favourite prices into keychain after every fetch), or
            // fresher from a focused relay fetch when a favourite happens to
            // be in range.
            let favourites = FuelStore.loadFavourites()
                .filter { $0.fuel == fuel && $0.station.prices[fuel] != nil }
                .map(\.station)
            var refreshed: [FuelStation] = favourites
            if let location,
               let fetched = await Self.fetchFocused(near: location, fuel: fuel, radiusKM: radiusKM) {
                let freshByID = Dictionary(uniqueKeysWithValues: fetched.map { ($0.id, $0) })
                refreshed = favourites.map { freshByID[$0.id] ?? $0 }
            }
            ordered = refreshed.sorted { lhs, rhs in
                let lPrice = lhs.prices[fuel]!
                let rPrice = rhs.prices[fuel]!
                if lPrice != rPrice { return lPrice < rPrice }
                if let location {
                    return lhs.distanceKM(to: location.lat, lng2: location.lng) <
                           rhs.distanceKM(to: location.lat, lng2: location.lng)
                }
                return false
            }
        } else {
            // 3a) Load stations. The widget prefers its OWN focused fetch from the
            // relay so it shows real prices even when the app-group cache isn't
            // shared (SideStore free accounts don't provision the group, which
            // previously left the widget stuck on sample data). Falls back to the
            // shared cache, then to samples.
            var stations: [FuelStation] = []
            if let location {
                if let fetched = await Self.fetchFocused(near: location, fuel: fuel, radiusKM: radiusKM) {
                    stations = fetched
                }
            }
            if stations.isEmpty { stations = FuelStore.loadStations() }
            if stations.isEmpty { stations = SampleFuelProvider.sampleStations }
            if let location {
                // STRICT: cached data fetched around another location must never
                // leak out-of-radius stations into the widget.
                stations = stations.filter {
                    $0.distanceKM(to: location.lat, lng2: location.lng) <= radiusKM
                }
            }
            let filtered = stations.filter { $0.prices[fuel] != nil }
            switch sort {
            case .closest:
                // Nearest first; price only breaks ties.
                ordered = filtered.sorted { lhs, rhs in
                    if let location {
                        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[fuel]! < rhs.prices[fuel]!
                }
            case .cheapest:
                // Cheapest first; distance only breaks ties.
                ordered = filtered.sorted { lhs, rhs in
                    let lPrice = lhs.prices[fuel]!
                    let rPrice = rhs.prices[fuel]!
                    if lPrice != rPrice { return lPrice < rPrice }
                    if let location {
                        return lhs.distanceKM(to: location.lat, lng2: location.lng) <
                               rhs.distanceKM(to: location.lat, lng2: location.lng)
                    }
                    return false
                }
            }
        }

        return FuelPriceEntry(
            date: Date(), stations: Array(ordered.prefix(8)),
            fuel: fuel, sort: sort, isFavourites: isFavourites,
            location: location, locationSource: source,
            unit: unit
        )
    }

    /// One focused fetch from the relay around the widget's location — small
    /// response (radius + limit 500), bounded so a dead relay can't stall the
    /// timeline. Returns nil on any failure so callers fall back to cache.
    private static func fetchFocused(near location: Coordinate, fuel: FuelType, radiusKM: Double) async -> [FuelStation]? {
        var components = URLComponents(
            url: RelayFuelProvider().baseURL.appendingPathComponent("api/v1/stations"),
            resolvingAgainstBaseURL: false
        )!
        components.queryItems = [
            URLQueryItem(name: "fuel", value: fuel.rawValue),
            URLQueryItem(name: "lat", value: String(location.lat)),
            URLQueryItem(name: "lng", value: String(location.lng)),
            URLQueryItem(name: "radius", value: String(radiusKM)),
            URLQueryItem(name: "limit", value: "500"),
        ]
        var request = URLRequest(url: components.url!)
        request.timeoutInterval = 5
        do {
            let (data, response) = try await URLSession.shared.data(for: request)
            guard let http = response as? HTTPURLResponse, http.statusCode == 200 else { return nil }
            return try? FuelPriceProvider.decodeStations(from: data)
        } catch {
            return nil
        }
    }
}

struct FuelPriceWidgetView: View {
    @Environment(\.widgetFamily) private var family
    let entry: FuelPriceEntry

    var body: some View {
        Group {
            if entry.stations.isEmpty {
                VStack(spacing: 6) {
                    Image(systemName: entry.isFavourites ? "star" : "fuelpump")
                        .font(.title2)
                        .foregroundStyle(.secondary)
                    Text(entry.isFavourites
                         ? "No favourite \(entry.fuel.displayName) stations"
                         : "No \(entry.fuel.displayName) stations")
                        .font(.caption2)
                        .foregroundStyle(.secondary)
                }
            } else if family == .systemSmall {
                singleStation
            } else {
                stationList
            }
        }
    }

    private var heading: String {
        if entry.isFavourites { return "Favourite \(entry.fuel.displayName)" }
        return entry.sort == .closest
            ? "Closest \(entry.fuel.displayName)"
            : "Cheapest \(entry.fuel.displayName)"
    }

    private var singleStation: some View {
        let station = entry.stations[0]
        return VStack(alignment: .leading, spacing: 6) {
            HStack {
                Image(systemName: "fuelpump.fill")
                    .foregroundStyle(.green)
                Text(heading)
                    .font(.caption2)
                    .foregroundStyle(.secondary)
            }
            Text(station.name)
                .font(.headline)
                .lineLimit(1)
            if let price = station.prices[entry.fuel] {
                Text(String(format: "£%.3f", price / 100))
                    .font(.system(size: 26, weight: .bold).monospaced())
                    .foregroundStyle(.green)
            }
            if let location = entry.location {
                Text(entry.unit.format(station.distanceKM(to: location.lat, lng2: location.lng)) + " away")
                    .font(.caption2)
                    .foregroundStyle(.secondary)
            } else {
                Text("Tap for directions")
                    .font(.caption2)
                    .foregroundStyle(.secondary)
            }
        }
        .frame(maxWidth: .infinity, maxHeight: .infinity, alignment: .leading)
        .widgetURL(station.widgetDirectionsURL)
    }

    /// How many station rows each family can fit: medium widgets are short
    /// (158pt) so 3 rows is the safe cap; large/extraLarge have ~2× the height
    /// and fit 5 compact rows. Small widgets use singleStation instead.
    private var maxRows: Int {
        switch family {
        case .systemMedium: return 3
        default: return 5
        }
    }

    private var stationList: some View {
        let cheapest = entry.stations.compactMap { $0.prices[entry.fuel] }.min()
        return VStack(alignment: .leading, spacing: 6) {
            HStack {
                Image(systemName: "fuelpump.fill")
                    .foregroundStyle(.green)
                Text(heading)
                    .font(.caption2)
                    .foregroundStyle(.secondary)
                Spacer()
                Text(entry.isFavourites ? "cheapest first"
                     : (entry.locationSource == "none" ? "by price" : "near you"))
                    .font(.caption2)
                    .foregroundStyle(.secondary)
            }
            ForEach(entry.stations.prefix(maxRows)) { station in
                Link(destination: station.widgetDirectionsURL ?? URL(string: "maps://")!) {
                    HStack(spacing: 8) {
                        Text(station.name)
                            .font(.caption.weight(.semibold))
                            .lineLimit(1)
                        if let location = entry.location {
                            Text(entry.unit.format(station.distanceKM(to: location.lat, lng2: location.lng)))
                                .font(.caption2)
                                .foregroundStyle(.secondary)
                        }
                        Spacer()
                        if let price = station.prices[entry.fuel] {
                            HStack(spacing: 4) {
                                Circle()
                                    .fill(ragColor(for: price, cheapest: cheapest))
                                    .frame(width: 6, height: 6)
                                Text(String(format: "£%.3f", price / 100))
                                    .font(.caption.weight(.bold).monospaced())
                                    .foregroundStyle(.primary)
                            }
                        }
                    }
                }
                .buttonStyle(.plain)
            }
            Spacer(minLength: 0)
        }
        .frame(maxWidth: .infinity, maxHeight: .infinity, alignment: .topLeading)
    }

    private func ragColor(for price: Double, cheapest: Double?) -> Color {
        guard let cheapest else { return .gray }
        switch RAGRating.rating(price: price, cheapest: cheapest) {
        case .green: return .green
        case .amber: return .orange
        case .red: return .red
        }
    }
}