import SwiftUI
import WidgetKit

// Shared widget rendering — compiled by BOTH the widget extension and the
// app target. The app uses it for the in-app widget preview screen (launch
// arg `-widgets`); the widget extension uses it for real timelines.
// WidgetKit is available to the app target, so WidgetFamily is fine here.
// NOTE: FuelBoardTests only symlinks specific Shared files, so this file is
// NOT compiled by the SPM test target (it needs WidgetKit).

// Fuel colour wheel — mirrors the app's palette in StationsView.swift
// (FuelType.tintColor): green = unleaded (#30D158), yellow = premium
// (#FFD60A), cyan = diesel (#64D2FF). Lives here because both the widget and
// the app preview need it; Shared/FuelStore.swift stays Foundation-only.
// (Previously a private extension in the widget target — deleted on the move.)
private extension FuelType {
    var fuelColor: Color {
        switch self {
        case .e10: return Color(red: 48/255.0, green: 209/255.0, blue: 88/255.0)      // #30D158
        case .e5: return Color(red: 255/255.0, green: 214/255.0, blue: 10/255.0)      // #FFD60A
        case .diesel: return Color(red: 100/255.0, green: 210/255.0, blue: 255/255.0) // #64D2FF
        }
    }
}

/// Plain data (no WidgetKit types) so both the widget and the app preview can
/// construct entries. The widget's `FuelPriceEntry: TimelineEntry` wraps this.
struct FuelPriceWidgetEntryData {
    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
}

/// The widget face, parameterised by family so the app can preview it.
/// `isWidget` controls WidgetKit-only chrome (widgetURL / Link rows) — in-app
/// previews pass false.
struct FuelPriceWidgetContent: View {
    let entry: FuelPriceWidgetEntryData
    let family: WidgetFamily
    var isWidget = true

    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(entry.fuel.fuelColor)
                Text(heading)
                    .font(.caption2)
                    .foregroundStyle(.secondary)
            }
            Text(station.name)
                .font(.headline)
                .lineLimit(1)
            if let price = station.prices[entry.fuel] {
                FuelStore.priceTextAttributed(price, size: 26, weight: .bold, color: .green)
            }
            if let location = entry.location {
                Text(entry.unit.format(FuelStore.displayDistanceKM(station: station, userLat: location.lat, userLng: location.lng)) + " away")
                    .font(.caption2)
                    .foregroundStyle(.secondary)
            } else {
                Text("Tap for directions")
                    .font(.caption2)
                    .foregroundStyle(.secondary)
            }
        }
        .frame(maxWidth: .infinity, maxHeight: .infinity, alignment: .leading)
        .modifier(WidgetURLModifier(url: isWidget ? station.tapDestinationURL : nil))
    }

    /// 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(entry.fuel.fuelColor)
                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
                if isWidget {
                    Link(destination: station.tapDestinationURL ?? URL(string: "maps://")!) {
                        row(station, cheapest: cheapest)
                    }
                    .buttonStyle(.plain)
                } else {
                    row(station, cheapest: cheapest)
                }
            }
            Spacer(minLength: 0)
        }
        .frame(maxWidth: .infinity, maxHeight: .infinity, alignment: .topLeading)
    }

    private func row(_ station: FuelStation, cheapest: Double?) -> some View {
        HStack(spacing: 8) {
            Text(station.name)
                .font(.caption.weight(.semibold))
                .lineLimit(1)
            if let location = entry.location {
                Text(entry.unit.format(FuelStore.displayDistanceKM(station: station, userLat: location.lat, userLng: 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)
                    FuelStore.priceTextAttributed(price, size: 12, weight: .bold)
                }
            }
        }
    }

    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
        }
    }
}

/// Applies widgetURL only when a URL is given (WidgetKit-only modifier).
private struct WidgetURLModifier: ViewModifier {
    let url: URL?
    func body(content: Content) -> some View {
        if let url {
            content.widgetURL(url)
        } else {
            content
        }
    }
}