import AppIntents
import SwiftUI

/// Siri / Shortcuts surface for "cheapest [fuel] near me".
///
/// Design (see skill reference `siri-app-intents-scope.md`):
/// - App Intents (iOS 16+), no entitlements/capabilities/Info.plist keys.
/// - Cached-data-first: answers from the full-UK dump saved in the app-group
///   defaults by the normal app fetch, SCOPED to the app's saved search radius
///   (5/10/15 mi) so "near me" really means near me. The dialog ALWAYS labels
///   data age ("as of 6:30 AM") — silent stale answers are a trust killer for
///   fuel prices. The fresh-data path (relay baseURL is LAN-only) is a P0
///   dependency; until it lands, off-LAN answers use whatever the phone
///   last fetched at home.
/// - Location: last-known location fallback (background CoreLocation from a
///   Siri-launched process is slow/unreliable).
/// - Phrases stay literal/boring for App Store review; `\.applicationName`
///   appears in EVERY phrase (iOS 26 metadata-processor requirement —
///   without it the metadata exports ZERO utterances).
/// - Shortcut names match the app (Unleaded / Premium / Diesel); the
///   registered phrases ALSO carry the UK speech variants ("petrol",
///   "super unleaded") so Siri matches how people actually ask. The app UI's
///   FuelType.displayName is untouched.

// MARK: - Fuel parameter

extension FuelType: AppEnum {
    static var typeDisplayRepresentation: TypeDisplayRepresentation = "Fuel"

    static var caseDisplayRepresentations: [FuelType: DisplayRepresentation] = [
        .e10: "Unleaded",
        .e5: "Premium",
        .diesel: "Diesel",
    ]
}

// MARK: - Intent

struct CheapestFuelIntent: AppIntent {
    static var title: LocalizedStringResource = "Cheapest Fuel Near Me"
    static var description = IntentDescription(
        "Finds the cheapest station selling a fuel near you, using the latest cached prices."
    )

    @Parameter(title: "Fuel")
    var fuel: FuelType

    /// Plain construction — Siri resolves the fuel parameter from the
    /// utterance. Defaults to petrol if the parameter is unresolved.
    init() {
        self.fuel = .e10
    }

    /// Fixed-fuel construction for the per-fuel App Shortcuts: the fuel word
    /// becomes literal phrase text so Siri matches "unleaded"/"petrol"/
    /// "diesel" directly instead of resolving the parameter (which was flaky
    /// on-device — "cheapest diesel" matched, "cheapest unleaded" didn't).
    init(fuel: FuelType) {
        self.fuel = fuel
    }

    func perform() async throws -> some IntentResult & ProvidesDialog & ShowsSnippetView & ReturnsValue<String> {
        let stations = FuelStore.loadStations()

        guard !stations.isEmpty else {
            let dialog = "I don't have any price data yet. Open FuelBoard once to download the latest prices, then ask me again."
            return .result(
                value: "No price data yet",
                dialog: IntentDialog(stringLiteral: dialog),
                view: CheapestFuelMessage(text: "No price data yet — open FuelBoard to download prices.")
            )
        }

        guard let coordinate = FuelStore.loadLocationWithDate()?.coordinate else {
            let dialog = "I don't know your location yet. Open FuelBoard and allow location access, then ask me again."
            return .result(
                value: "Location unavailable",
                dialog: IntentDialog(stringLiteral: dialog),
                view: CheapestFuelMessage(text: "Location unavailable — open FuelBoard to share your location.")
            )
        }

        // Scope to the app's saved search radius (5/10/15 mi, default 5) so
        // "near me" really means near me — the UK-wide minimum can be hundreds
        // of miles away.
        let radiusMiles = Double(FuelStore.loadStationLimit())
        guard let station = SiriCheapestLookup.cheapest(
            in: stations,
            fuel: fuel,
            fromLat: coordinate.lat,
            lng: coordinate.lng,
            withinMiles: radiusMiles
        ), let price = station.prices[fuel] else {
            let fuelName = fuel.displayName.lowercased()
            let radiusText = radiusMiles == 1 ? "1 mile" : "\(Int(radiusMiles)) miles"
            return .result(
                value: "No \(fuelName) stations within \(radiusText)",
                dialog: IntentDialog(stringLiteral: "I couldn't find any station selling \(fuelName) within \(radiusText) of you."),
                view: CheapestFuelMessage(text: "No \(fuelName) stations within \(radiusText).")
            )
        }

        let distanceKM = station.distanceKM(to: coordinate.lat, lng2: coordinate.lng)
        let distanceText = FuelStore.loadDistanceUnit().format(distanceKM)
        let priceText = String(format: "£%.3f", price / 100)
        let freshness = SiriCheapestLookup.freshnessLabel(
            updated: FuelStore.loadDataUpdated(),
            lastRefresh: FuelStore.loadLastRefresh()
        )
        let summary = "\(station.name): \(priceText), \(distanceText)"
        let freshnessClause = freshness.isEmpty ? "" : " — prices \(freshness)"
        let dialog = "The cheapest \(fuel.displayName.lowercased()) near you is \(station.name) at \(priceText), \(distanceText) away\(freshnessClause)."

        return .result(
            value: summary,
            dialog: IntentDialog(stringLiteral: dialog),
            view: CheapestFuelCard(
                stationName: station.name,
                fuelName: fuel.displayName,
                price: priceText,
                distance: distanceText,
                freshness: freshness
            )
        )
    }
}

// MARK: - Directions intent

/// Opens Apple Maps with turn-by-turn directions to the cheapest station
/// selling `fuel` within the saved search radius. Shares the exact same
/// radius-scoped lookup as `CheapestFuelIntent`; the only difference is the
/// result — it hands off to Maps instead of speaking the price.
struct DirectionsToCheapestFuelIntent: AppIntent {
    static var title: LocalizedStringResource = "Directions to Cheapest Fuel Near Me"
    static var description = IntentDescription(
        "Opens Apple Maps directions to the cheapest station selling a fuel near you, using the latest cached prices."
    )

    @Parameter(title: "Fuel")
    var fuel: FuelType

    init() {
        self.fuel = .e10
    }

    init(fuel: FuelType) {
        self.fuel = fuel
    }

    func perform() async throws -> some IntentResult & OpensIntent {
        let stations = FuelStore.loadStations()

        guard !stations.isEmpty else {
            throw DirectionsError("I don't have any price data yet. Open FuelBoard once to download the latest prices, then ask me again.")
        }

        guard let coordinate = FuelStore.loadLocationWithDate()?.coordinate else {
            throw DirectionsError("I don't know your location yet. Open FuelBoard and allow location access, then ask me again.")
        }

        let radiusMiles = Double(FuelStore.loadStationLimit())
        guard let station = SiriCheapestLookup.cheapest(
            in: stations,
            fuel: fuel,
            fromLat: coordinate.lat,
            lng: coordinate.lng,
            withinMiles: radiusMiles
        ) else {
            let fuelName = fuel.displayName.lowercased()
            let radiusText = radiusMiles == 1 ? "1 mile" : "\(Int(radiusMiles)) miles"
            throw DirectionsError("I couldn't find any station selling \(fuelName) within \(radiusText) of you.")
        }

        let url = SiriCheapestLookup.mapsURL(latitude: station.lat, longitude: station.lng)
        return .result(opensIntent: OpenURLIntent(url))
    }
}

/// Localized error thrown when directions can't be produced (no data, no
/// location, or no station within the radius). Siri presents the message
/// directly.
private struct DirectionsError: LocalizedError {
    let message: String
    init(_ message: String) { self.message = message }
    var errorDescription: String? { message }
}

// MARK: - Snippets

/// Price card shown in Shortcuts / Siri results.
struct CheapestFuelCard: View {
    let stationName: String
    let fuelName: String
    let price: String
    let distance: String
    let freshness: String

    var body: some View {
        HStack(spacing: 14) {
            Image(systemName: "fuelpump.fill")
                .font(.title2)
                .foregroundStyle(.tint)
            VStack(alignment: .leading, spacing: 2) {
                Text(stationName)
                    .font(.headline)
                    .lineLimit(1)
                Text("\(fuelName) · \(distance)")
                    .font(.subheadline)
                    .foregroundStyle(.secondary)
                if !freshness.isEmpty {
                    Text(freshness)
                        .font(.caption)
                        .foregroundStyle(.tertiary)
                }
            }
            Spacer(minLength: 8)
            Text(price)
                .font(.title2.bold())
                .monospacedDigit()
        }
        .padding(12)
    }
}

/// Fallback message card for the no-data / no-location / no-station cases.
struct CheapestFuelMessage: View {
    let text: String

    var body: some View {
        HStack(spacing: 10) {
            Image(systemName: "info.circle")
                .foregroundStyle(.secondary)
            Text(text)
                .font(.subheadline)
        }
        .padding(12)
    }
}

// MARK: - App Shortcuts

struct FuelBoardShortcuts: AppShortcutsProvider {
    static var appShortcuts: [AppShortcut] {
        // Generic parameterized shortcut — matches whatever fuel word Siri
        // resolves. Parameter resolution is flaky on-device ("cheapest diesel"
        // matched, "cheapest unleaded" didn't), which is why the fixed-fuel
        // entries below carry the fuel word as LITERAL phrase text.
        AppShortcut(
            intent: CheapestFuelIntent(),
            phrases: [
                "Ask \(.applicationName) what's the cheapest \(\.$fuel) near me",
            ],
            shortTitle: "Cheapest Fuel",
            systemImageName: "fuelpump"
        )

        AppShortcut(
            intent: CheapestFuelIntent(fuel: .e10),
            phrases: [
                "Ask \(.applicationName) for the cheapest unleaded near me",
                "Ask \(.applicationName) for the cheapest petrol near me",
                "Find the cheapest petrol near me \(.applicationName)",
                "Find the cheapest unleaded near me \(.applicationName)",
            ],
            shortTitle: "Cheapest Unleaded",
            systemImageName: "fuelpump"
        )

        AppShortcut(
            intent: CheapestFuelIntent(fuel: .e5),
            phrases: [
                "Ask \(.applicationName) for the cheapest premium near me",
                "Ask \(.applicationName) for the cheapest super unleaded near me",
                "Find the cheapest super unleaded near me \(.applicationName)",
            ],
            shortTitle: "Cheapest Premium",
            systemImageName: "fuelpump"
        )

        AppShortcut(
            intent: CheapestFuelIntent(fuel: .diesel),
            phrases: [
                "Ask \(.applicationName) for the cheapest diesel near me",
                "Find the cheapest diesel near me \(.applicationName)",
                "Cheapest diesel near me \(.applicationName)",
            ],
            shortTitle: "Cheapest Diesel",
            systemImageName: "fuelpump"
        )

        // Directions — separate intent so the price queries stay answer-only
        // and only the explicit directions query hands off to Apple Maps.
        // Phrases use direction verbs ("directions to", "get directions") to
        // stay distinct from the price shortcut phrases.
        AppShortcut(
            intent: DirectionsToCheapestFuelIntent(),
            phrases: [
                "Ask \(.applicationName) for directions to the cheapest \(\.$fuel) near me",
            ],
            shortTitle: "Directions to Cheapest Fuel",
            systemImageName: "map"
        )

        AppShortcut(
            intent: DirectionsToCheapestFuelIntent(fuel: .e10),
            phrases: [
                "Ask \(.applicationName) for directions to the cheapest unleaded near me",
                "Get directions to the cheapest petrol near me \(.applicationName)",
            ],
            shortTitle: "Directions to Cheapest Unleaded",
            systemImageName: "map"
        )

        AppShortcut(
            intent: DirectionsToCheapestFuelIntent(fuel: .e5),
            phrases: [
                "Ask \(.applicationName) for directions to the cheapest premium near me",
                "Get directions to the cheapest super unleaded near me \(.applicationName)",
            ],
            shortTitle: "Directions to Cheapest Premium",
            systemImageName: "map"
        )

        AppShortcut(
            intent: DirectionsToCheapestFuelIntent(fuel: .diesel),
            phrases: [
                "Ask \(.applicationName) for directions to the cheapest diesel near me",
                "Get directions to the cheapest diesel near me \(.applicationName)",
            ],
            shortTitle: "Directions to Cheapest Diesel",
            systemImageName: "map"
        )
    }
}