import Foundation
import SwiftUI
import UIKit

// MARK: - Environment flag for image export
//
// ImageRenderer can't rasterize Metal-backed `.drawingGroup()` layers (they come
// out blank). Chart views check this flag and skip drawingGroup during export.

private struct ChartImageExportKey: EnvironmentKey {
    static let defaultValue = false
}

extension EnvironmentValues {
    var chartImageExport: Bool {
        get { self[ChartImageExportKey.self] }
        set { self[ChartImageExportKey.self] = newValue }
    }
}

extension View {
    /// GPU-rasterize for scroll performance, except while exporting a share
    /// image (ImageRenderer can't rasterize Metal layers — they come out blank).
    @ViewBuilder
    func chartDrawingGroup(disabledForExport isExporting: Bool) -> some View {
        if isExporting {
            self
        } else {
            drawingGroup()
        }
    }
}

// MARK: - Chart share service
//
// Renders the current chart into a branded card (app mark, KPIs, QR to the App
// Store) and presents the system share sheet. Reuses the QR/App Store plumbing
// from GoalShareService.

@MainActor
final class ChartShareService {
    static let shared = ChartShareService()
    private init() {}

    static let appStoreShareURL = URL(string: "https://apps.apple.com/app/portfolio-journal-tracker/id6757678318?ct=chart_share")!

    func share<Content: View>(title: String, subtitle: String, stats: [ChartStat], @ViewBuilder chart: () -> Content) {
        FirebaseService.shared.logShare(type: "chart")
        guard let windowScene = UIApplication.shared.connectedScenes.first as? UIWindowScene,
              let viewController = windowScene.windows.first?.rootViewController else {
            return
        }

        let card = ChartShareCardView(
            title: title,
            subtitle: subtitle,
            stats: stats,
            qrCodeImage: GoalShareService.generateQRCode(for: Self.appStoreShareURL, size: 200),
            chart: chart()
        )

        let renderer = ImageRenderer(content: card)
        renderer.scale = 3
        renderer.proposedSize = ProposedViewSize(width: 720, height: nil)

        let shareText = String(format: String(localized: "chart_share_text"), title)
            + "\n" + Self.appStoreShareURL.absoluteString

        var items: [Any] = []
        if let image = renderer.uiImage {
            items.append(image)
        }
        items.append(shareText)

        let activityVC = UIActivityViewController(activityItems: items, applicationActivities: nil)
        activityVC.excludedActivityTypes = [.addToReadingList, .assignToContact, .openInIBooks]

        // iPad: activity sheet requires a popover anchor.
        if let popover = activityVC.popoverPresentationController {
            popover.sourceView = viewController.view
            popover.sourceRect = CGRect(
                x: viewController.view.bounds.midX,
                y: viewController.view.bounds.midY,
                width: 0,
                height: 0
            )
            popover.permittedArrowDirections = []
        }

        var presenter = viewController
        while let presented = presenter.presentedViewController {
            presenter = presented
        }
        presenter.present(activityVC, animated: true)
    }
}

// MARK: - Branded card

struct ChartShareCardView<Content: View>: View {
    let title: String
    let subtitle: String
    let stats: [ChartStat]
    let qrCodeImage: UIImage?
    let chart: Content

    private static var dateLabel: String {
        Date().formatted(date: .abbreviated, time: .omitted)
    }

    var body: some View {
        VStack(alignment: .leading, spacing: 18) {
            // Header: brand + chart title
            HStack(spacing: 12) {
                if let brandMark = UIImage(named: "BrandMark") {
                    Image(uiImage: brandMark)
                        .resizable()
                        .scaledToFit()
                        .frame(width: 44, height: 44)
                        .clipShape(RoundedRectangle(cornerRadius: 10))
                }
                VStack(alignment: .leading, spacing: 2) {
                    Text("Portfolio Journal")
                        .font(.headline)
                    Text("\(title) · \(Self.dateLabel)")
                        .font(.subheadline)
                        .foregroundColor(.secondary)
                }
                Spacer()
            }

            chart
                .environment(\.chartImageExport, true)

            if !stats.isEmpty {
                HStack(spacing: 10) {
                    ForEach(stats.indices, id: \.self) { i in
                        VStack(alignment: .leading, spacing: 3) {
                            Text(stats[i].label)
                                .font(.caption2)
                                .foregroundColor(.secondary)
                            Text(stats[i].value)
                                .font(.subheadline.weight(.semibold))
                                .foregroundColor(stats[i].color)
                        }
                        .padding(.horizontal, 12)
                        .padding(.vertical, 8)
                        .background(Color(.systemGray6))
                        .cornerRadius(8)
                    }
                    Spacer()
                }
            }

            Divider()

            // Footer: tagline + QR to the App Store
            HStack(alignment: .center, spacing: 16) {
                VStack(alignment: .leading, spacing: 4) {
                    Text(String(localized: "chart_share_tagline"))
                        .font(.footnote.weight(.medium))
                    Text(verbatim: "portfoliojournal.app")
                        .font(.footnote)
                        .foregroundColor(.appPrimary)
                }
                Spacer()
                if let qrCodeImage {
                    VStack(spacing: 4) {
                        Image(uiImage: qrCodeImage)
                            .resizable()
                            .interpolation(.none)
                            .scaledToFit()
                            .frame(width: 64, height: 64)
                        Text(String(localized: "chart_share_scan"))
                            .font(.caption2)
                            .foregroundColor(.secondary)
                    }
                }
            }
        }
        .padding(24)
        .frame(width: 720)
        .background(Color(.systemBackground))
        .environment(\.colorScheme, .light)
    }
}