import SwiftUI
import MapKit
import UIKit

/// DEBUG-only explanation of the Best Value numbers for one station. It carries
/// no precise user coordinates and is never persisted.
struct FuelSavingsJourneyDiagnostics {
    let rows: [(label: String, value: String)]
}

/// Detail sheet for a tapped station (when Settings → Tap station = More info).
/// Shows a small map preview, the address, distance from the current location,
/// and a Directions button that opens Apple Maps — the same destination a direct
/// tap would have opened. The station name lives in the sheet header, not in a
/// row.
struct StationDetailView: View {
    let station: FuelStation
    let location: Coordinate?
    let distanceUnit: DistanceUnit
    var fuelSavings: FuelSavingsAvailability? = nil
    var fuelSavingsAmount: FuelSavingsFillAmount = FuelSavingsSettings.defaultPreferredAmount
    var savingsBaselineStationName: String? = nil
    var journeyDiagnostics: FuelSavingsJourneyDiagnostics? = nil
    /// Whether this station is starred for the fuel currently being viewed, and
    /// the toggle that flips it. Passed from the list that opened the sheet, so
    /// the star here and the star on the row are the same fuel-scoped
    /// favourite and cannot drift apart.
    var isFavourite: Bool = false
    var onToggleFavourite: (() -> Void)? = nil
    @Environment(\.dismiss) private var dismiss
    @State private var showingReportIssueConfirmation = false
    /// Transient "Copied" confirmation on the Address row. Cleared by a task so
    /// the caption fades out on its own.
    @State private var showingCopied = false
    @State private var copyResetTask: Task<Void, Never>?

    private let reportIssueURL = URL(string: "https://www.gov.uk/guidance/report-an-error-in-fuel-prices-or-forecourt-details")!

    private var stationCoordinate: CLLocationCoordinate2D {
        CLLocationCoordinate2D(latitude: station.lat, longitude: station.lng)
    }

    /// The row's address text — the same shared line the listing row uses, with
    /// any leading repeat of the station name stripped.
    private var addressLine: String {
        StationAddressLine.display(address: station.address,
                                   postcode: station.postcode,
                                   name: station.name)
    }

    /// The station's postcode, trimmed. Empty means there is nothing to copy and
    /// the Address row stays inert.
    private var postcodeForCopying: String {
        station.postcode.trimmingCharacters(in: .whitespacesAndNewlines)
    }

    /// Opens Apple Maps driving directions — the same destination (and the same
    /// URL) the Directions button below uses, so the map and the button can
    /// never point at two different places.
    private func openDirections() {
        if let url = station.mapsDirectionsURL {
            UIApplication.shared.open(url)
        }
    }

    /// Copies ONLY the postcode, so it can be pasted into another navigation app
    /// without dragging the station name and street along with it. Confirms with
    /// a light haptic and a caption that fades after ~2s.
    private func copyPostcode() {
        let postcode = postcodeForCopying
        guard !postcode.isEmpty else { return }
        UIPasteboard.general.string = postcode
        UINotificationFeedbackGenerator().notificationOccurred(.success)
        withAnimation(.easeInOut(duration: 0.2)) { showingCopied = true }
        copyResetTask?.cancel()
        copyResetTask = Task {
            try? await Task.sleep(nanoseconds: 2_000_000_000)
            guard !Task.isCancelled else { return }
            withAnimation(.easeInOut(duration: 0.3)) { showingCopied = false }
        }
    }

    var body: some View {
        NavigationStack {
            List {
                Section {
                    // Tapping anywhere on the map opens the same Apple Maps
                    // directions the Directions button below opens.
                    //
                    // The tap target is an OVERLAY Button laid ON TOP of the
                    // Map, not a Button wrapping it. A Map runs its own UIKit
                    // view, and inside a List row the wrapped-Map form left the
                    // card untappable — the touch never reached the button. An
                    // overlay sits above the map, owns an explicit rounded-rect
                    // content shape, and cannot be intercepted by MapKit. The
                    // Map itself stays non-interactive: it is a preview, not
                    // something to pan.
                    Map(position: .constant(.region(MKCoordinateRegion(
                        center: stationCoordinate,
                        span: MKCoordinateSpan(latitudeDelta: 0.02, longitudeDelta: 0.02)
                    )))) {
                        Marker(station.name, coordinate: stationCoordinate)
                            .tint(.red)
                    }
                    .frame(height: 180)
                    .clipShape(RoundedRectangle(cornerRadius: 12))
                    .allowsHitTesting(false)
                    .overlay {
                        Button {
                            openDirections()
                        } label: {
                            Color.clear
                                .contentShape(RoundedRectangle(cornerRadius: 12))
                        }
                        .buttonStyle(.plain)
                        .accessibilityLabel(String(localized: "Directions to \(station.name)",
                                                   comment: "Accessibility label for the tappable map preview in the More info sheet"))
                        .accessibilityHint(String(localized: "Opens Apple Maps with driving directions",
                                                  comment: "Accessibility hint for the tappable map preview in the More info sheet"))
                    }
                // The map, the address, the distance, any notices and the two
                // station actions all share ONE card. The list's own row
                // hairlines separate them (inset, the same line that already
                // separates Address from Distance), so no hand-rolled Divider is
                // needed — adding one would double the line.
                    // The station name is NOT repeated here: the sheet header
                    // (navigationTitle, inline) already shows it, and the address
                    // line below has any leading repeat of the name stripped, so
                    // a "Name" row only said it twice.
                    //
                    // The whole row is a copy control: it puts JUST the postcode
                    // on the clipboard so it can be pasted into another
                    // navigation app. The copy glyph and its "Copied"
                    // confirmation share a SECOND line that is always there, so
                    // the confirmation can never reflow the address above it.
                    Button {
                        copyPostcode()
                    } label: {
                        VStack(alignment: .leading, spacing: 6) {
                            HStack(alignment: .firstTextBaseline, spacing: 8) {
                                Text("Address")
                                Spacer(minLength: 8)
                                Text(addressLine)
                                    .multilineTextAlignment(.trailing)
                                    .foregroundStyle(.secondary)
                            }
                            HStack(spacing: 4) {
                                Spacer(minLength: 0)
                                if showingCopied {
                                    Text("Copied")
                                        .foregroundStyle(.green)
                                        .transition(.opacity)
                                }
                                Image(systemName: showingCopied ? "checkmark" : "doc.on.doc")
                                    .foregroundStyle(showingCopied ? Color.green : Color.secondary)
                            }
                            .font(.footnote.weight(.semibold))
                        }
                    }
                    .buttonStyle(.plain)
                    .disabled(postcodeForCopying.isEmpty)
                    .accessibilityLabel(String(localized: "Address: \(addressLine)",
                                               comment: "Accessibility label for the address row in the More info sheet"))
                    .accessibilityHint(postcodeForCopying.isEmpty
                        ? ""
                        : String(localized: "Copies the postcode",
                                 comment: "Accessibility hint for the address row in the More info sheet"))
                    if let location {
                        let distance = FuelStore.stationDistanceDisplay(
                            station: station, userLat: location.lat, userLng: location.lng
                        )
                        LabeledContent("Distance", value: distance.labelWithReturn(unit: distanceUnit))
                            .monospacedDigit()
                    }
                    ForEach(StationNotice.notices(for: station)) { notice in
                        Label(notice.title, systemImage: notice.symbolName)
                            .font(.subheadline.weight(.semibold))
                            .foregroundStyle(.orange)
                            .padding(.horizontal, 10)
                            .padding(.vertical, 6)
                            .background(Capsule().fill(Color.orange.opacity(0.14)))
                    }
                    // The two station actions are the LAST row of the card: half
                    // the width each, on one line, below Address and Distance.
                    HStack(spacing: 12) {
                        Button {
                            openDirections()
                        } label: {
                            Label("Directions", systemImage: "arrow.triangle.turn.up.right.diamond.fill")
                                .frame(maxWidth: .infinity)
                        }
                        Button(role: .destructive) {
                            showingReportIssueConfirmation = true
                        } label: {
                            Label("Report issue", systemImage: "exclamationmark.bubble.fill")
                                .frame(maxWidth: .infinity)
                        }
                    }
                    // REQUIRED: with the default button style a `List` row has ONE
                    // row-wide tap target, so two buttons in the same row BOTH fire
                    // on any tap inside the row (tapping Directions also showed the
                    // report-issue alert and vice versa). `.borderless` gives each
                    // button its own hit area — the half-row frame above.
                    .buttonStyle(.borderless)
                }
                // Only shown while Fuel Savings backs it. `fuelSavings` is nil
                // when the feature is off — `savingsLookup` returns nil when it
                // is not configured — so the heading cannot be left dangling
                // over an empty section.
                if let fuelSavings {
                    Section {
                        FuelSavingsSummaryView(
                            availability: fuelSavings,
                            amount: fuelSavingsAmount,
                            baselineStationName: savingsBaselineStationName,
                            distanceUnit: distanceUnit
                        )
                    } header: {
                        Text("Best Value")
                    }
                }

#if DEBUG
                if let journeyDiagnostics {
                    Section("Best Value Diagnostics") {
                        ForEach(journeyDiagnostics.rows, id: \.label) { row in
                            LabeledContent(row.label, value: row.value)
                                .font(.caption)
                                .monospacedDigit()
                        }
                    }
                }
#endif

            }
            .navigationTitle(station.name)
            .navigationBarTitleDisplayMode(.inline)
            .alert("Report an error?", isPresented: $showingReportIssueConfirmation) {
                Button("Cancel", role: .cancel) { }
                Button("Report") {
                    UIApplication.shared.open(reportIssueURL)
                }
            } message: {
                Text("Are you sure you want to report an error in fuel prices or forecourt details? This will open in your chosen browser.")
            }
            .toolbar {
                ToolbarItem(placement: .cancellationAction) {
                    Button("Done") { dismiss() }
                }
                ToolbarItem(placement: .confirmationAction) {
                    Button {
                        onToggleFavourite?()
                    } label: {
                        Image(systemName: isFavourite ? "star.fill" : "star")
                    }
                    .tint(isFavourite ? Color.yellow : nil)
                    .disabled(onToggleFavourite == nil)
                    .accessibilityLabel(
                        isFavourite
                            ? String(localized: "Remove from favourites", comment: "Unstar a station from the More info sheet")
                            : String(localized: "Add to favourites", comment: "Star a station from the More info sheet")
                    )
                }
            }
            // The "Copied" fade-out task must not outlive the sheet.
            .onDisappear { copyResetTask?.cancel() }
#if DEBUG
            // QA hook: `-qaCopyPostcode` runs the REAL copy on open, so the
            // clipboard value (read back with `xcrun simctl pbpaste`) and the
            // "Copied" confirmation can be verified without a tap — simctl
            // cannot drive taps into the Simulator.
            .task {
                guard ProcessInfo.processInfo.arguments.contains("-qaCopyPostcode") else { return }
                copyPostcode()
            }
#endif
        }
    }
}