// FuelBoardLiveActivityView.swift — renders the FuelBoard Live Activity.
//
// Lives in the widget extension (the standard host for ActivityConfiguration).
// Shows the cheapest station for the pinned fuel within the app's chosen
// radius. Tapping anywhere opens Apple Maps directions to that station.
//
// ADAPTIVE LAYOUT: ActivityConfiguration shares ONE content view across the
// Lock Screen, banner, and the CarPlay small slot — there is no per-platform
// closure. So this view provides two layouts and lets ViewThatFits pick by
// available width:
//   • richBody  — the full three-column design (glyph · fuel+station · price),
//                 wins wherever there's Lock Screen width (it carries an
//                 explicit minWidth so it can never be squeezed into the car).
//   • compactBody — a minimal price-strip (glyph+fuel+price, station caption
//                 below) that wins in the CarPlay/Apple Watch Smart Stack
//                 small slot.

import ActivityKit
import SwiftUI
import WidgetKit

/// The Live Activity itself — registered in the widget bundle alongside the
/// regular price widget. No CarPlay entitlement involved: this renders on the
/// Lock Screen, Dynamic Island, and the car display (CarPlay Ultra, iOS 26+).
/// `.supplementalActivityFamilies([.small])` makes it eligible for the car's
/// small Live Activity slot — display-only there (FuelBoard is not a
/// CarPlay-enabled app, so car-side taps can't launch anything).
struct FuelBoardLiveActivity: Widget {
    var body: some WidgetConfiguration {
        ActivityConfiguration(for: FuelBoardLiveActivityAttributes.self) { context in
            // Lock Screen / banner / CarPlay small slot presentation
            FuelBoardLiveActivityView(context: context)
        } dynamicIsland: { context in
            DynamicIsland {
                DynamicIslandExpandedRegion(.leading) {
                    FuelBoardLiveActivityCompactView(context: context)
                }
                DynamicIslandExpandedRegion(.trailing) {
                    FuelBoardLiveActivityPriceView(context: context)
                }
                DynamicIslandExpandedRegion(.bottom) {
                    FuelBoardLiveActivityStationView(context: context)
                }
            } compactLeading: {
                Image(systemName: "fuelpump.fill")
                    .foregroundStyle(.green)
            } compactTrailing: {
                FuelBoardLiveActivityPriceView(context: context)
            } minimal: {
                Text(context.state.priceText)
                    .font(.caption2.bold().monospacedDigit())
            }
        }
        .supplementalActivityFamilies([.small])
    }
}

/// Lock Screen / banner / CarPlay body — adaptive.
private struct FuelBoardLiveActivityView: View {
    let context: ActivityViewContext<FuelBoardLiveActivityAttributes>

    var body: some View {
        Link(destination: context.state.mapsURL) {
            ViewThatFits(in: .horizontal) {
                // rich first — wins on full-width Lock Screen / banner
                richBody
                    // CarPlay / Watch small slot is far narrower than this,
                    // so ViewThatFits reliably falls through to compactBody.
                    .frame(minWidth: 280)
                // compact fallback — the car's small supplemental slot
                compactBody
            }
        }
    }

    /// Full three-column design (unchanged): brand glyph · fuel+station · price.
    private var richBody: some View {
        HStack(spacing: 12) {
            // LEFT — station brand glyph
            Image(systemName: "fuelpump.circle.fill")
                .font(.system(size: 32))
                .foregroundStyle(.green, .white)
                .frame(width: 40, height: 40)

            // MIDDLE — fuel + station
            VStack(alignment: .leading, spacing: 2) {
                Text("Cheapest \(context.state.fuel.displayName)")
                    .font(.headline)
                Text("\(context.state.stationName) · \(context.state.distanceText)")
                    .font(.subheadline)
                    .foregroundStyle(.secondary)
                    .lineLimit(1)
            }
            .frame(maxWidth: .infinity, alignment: .leading)

            // RIGHT — price
            VStack(alignment: .trailing, spacing: 2) {
                FuelStore.priceTextAttributed(context.state.pricePence,
                                               style: context.state.priceDisplayStyle,
                                               size: 22, weight: .bold)
                Text("Tap for directions")
                    .font(.caption2)
                    .foregroundStyle(.secondary)
            }
        }
        .padding()
    }

    /// Minimal strip for the small CarPlay / Watch Smart Stack slot:
    /// glyph + fuel left, bold price right, truncated station below.
    private var compactBody: some View {
        VStack(alignment: .leading, spacing: 3) {
            HStack(spacing: 5) {
                Image(systemName: "fuelpump.fill")
                    .font(.caption2)
                    .foregroundStyle(.green)
                Text(context.state.fuel.displayName)
                    .font(.caption2.weight(.semibold))
                    .lineLimit(1)
                Spacer(minLength: 4)
                FuelStore.priceTextAttributed(context.state.pricePence,
                                               style: context.state.priceDisplayStyle,
                                               size: 15, weight: .bold)
                    .lineLimit(1)
            }
            Text("\(context.state.stationName) · \(context.state.distanceText)")
                .font(.system(size: 9))
                .foregroundStyle(.secondary)
                .lineLimit(1)
        }
        .padding(8)
    }
}

/// Dynamic Island expanded regions + compact trailing — price only.
private struct FuelBoardLiveActivityPriceView: View {
    let context: ActivityViewContext<FuelBoardLiveActivityAttributes>

    var body: some View {
        FuelStore.priceTextAttributed(context.state.pricePence,
                                      style: context.state.priceDisplayStyle,
                                      size: 17, weight: .bold)
    }
}

/// Dynamic Island expanded — fuel + station name.
private struct FuelBoardLiveActivityCompactView: View {
    let context: ActivityViewContext<FuelBoardLiveActivityAttributes>

    var body: some View {
        VStack(alignment: .leading, spacing: 2) {
            Text("Cheapest \(context.state.fuel.displayName)")
                .font(.caption2)
                .foregroundStyle(.secondary)
            Text(context.state.stationName)
                .font(.caption.bold())
                .lineLimit(1)
        }
    }
}

/// Dynamic Island expanded bottom — station + distance.
private struct FuelBoardLiveActivityStationView: View {
    let context: ActivityViewContext<FuelBoardLiveActivityAttributes>

    var body: some View {
        Text("\(context.state.stationName) · \(context.state.distanceText)")
            .font(.caption)
            .lineLimit(1)
    }
}

// MARK: - ContentState display helpers

extension FuelBoardLiveActivityAttributes.ContentState {
    /// Display distance using the user's chosen unit (miles default).
    var distanceText: String {
        FuelStore.loadDistanceUnit().format(distanceKM)
    }

    /// Price string from pence, in the user's chosen display style
    /// (station sign "129.9" or pounds "£1.29⁹/L"). Uses the style captured
    /// in the state at push time.
    var priceText: String {
        FuelStore.priceText(pricePence, style: priceDisplayStyle)
    }

    /// Apple Maps directions URL to the pinned station.
    var mapsURL: URL {
        URL(string: "maps://?daddr=\(lat),\(lng)&t=d")!
    }
}