import SwiftUI
import PDFKit

struct BulletinDetailView: View {
    let bulletin: ChurchBulletin
    @State private var showingPDFViewer = false
    @Environment(\.horizontalSizeClass) private var horizontalSizeClass
    
    var body: some View {
        ScrollView {
            VStack(spacing: 20) {
                // Header Card
                headerCard
                
                // Content Sections
                if !bulletin.sabbathSchool.isEmpty || !bulletin.divineWorship.isEmpty {
                    contentSectionsCard
                }
                
                // Scripture & Sunset Card  
                scriptureAndSunsetCard
                
                // Actions Card
                actionsCard
            }
            .padding()
        }
        .navigationTitle("")
        #if os(iOS)
        .navigationBarTitleDisplayMode(.inline)
        #endif
        .toolbarBackground(.visible, for: .navigationBar)
        .toolbarBackground(.regularMaterial, for: .navigationBar)
        .sheet(isPresented: $showingPDFViewer) {
            if let pdfUrl = bulletin.pdfPath, let url = URL(string: pdfUrl) {
                PDFViewerSheet(url: url, title: bulletin.title)
            }
        }
    }
    
    // MARK: - Header Card
    private var headerCard: some View {
        VStack(alignment: .leading, spacing: 16) {
            // Top section with icon and metadata
            HStack {
                Image(systemName: "doc.text.fill")
                    .font(.system(size: 28))
                    .foregroundStyle(Color(hex: "fb8b23"))
                
                VStack(alignment: .leading, spacing: 4) {
                    Text("Church Bulletin")
                        .font(.caption)
                        .fontWeight(.medium)
                        .padding(.horizontal, 8)
                        .padding(.vertical, 4)
                        .background(.green.opacity(0.1), in: Capsule())
                        .foregroundStyle(.green)
                    
                    Text(bulletin.formattedDate)
                        .font(.caption)
                        .foregroundStyle(.secondary)
                }
                
                Spacer()
                
                if bulletin.pdfPath != nil {
                    Image(systemName: "arrow.down.circle.fill")
                        .font(.title2)
                        .foregroundStyle(.green)
                }
            }
            
            // Title
            Text(bulletin.title)
                .font(.title2)
                .fontWeight(.bold)
                .multilineTextAlignment(.leading)
            
            // Main PDF Action
            if bulletin.pdfPath != nil {
                Button(action: { showingPDFViewer = true }) {
                    HStack {
                        Image(systemName: "doc.text.viewfinder")
                            .font(.title3)
                        
                        Text("View PDF Bulletin")
                            .font(.headline)
                            .fontWeight(.semibold)
                        
                        Spacer()
                        
                        Image(systemName: "arrow.right.circle.fill")
                            .font(.title3)
                    }
                    .foregroundStyle(.white)
                    .padding()
                    .background(Color(hex: "fb8b23"), in: RoundedRectangle(cornerRadius: 12))
                }
                .buttonStyle(.plain)
                .shadow(color: Color(hex: "fb8b23").opacity(0.3), radius: 4, x: 0, y: 2)
            }
        }
        .padding(20)
        .background(.regularMaterial, in: RoundedRectangle(cornerRadius: 16))
        .shadow(color: .black.opacity(0.1), radius: 8, x: 0, y: 4)
    }
    
    // MARK: - Content Sections Card
    private var contentSectionsCard: some View {
        VStack(alignment: .leading, spacing: 20) {
            // Header
            HStack {
                Image(systemName: "list.bullet.clipboard")
                    .font(.title3)
                    .foregroundStyle(Color(hex: "fb8b23"))
                
                Text("Service Order")
                    .font(.headline)
                    .fontWeight(.semibold)
                
                Spacer()
            }
            
            VStack(spacing: 16) {
                if !bulletin.sabbathSchool.isEmpty {
                    ServiceSectionView(
                        title: "Sabbath School",
                        content: bulletin.sabbathSchool,
                        icon: "book.fill",
                        color: .blue
                    )
                }
                
                if !bulletin.divineWorship.isEmpty {
                    ServiceSectionView(
                        title: "Divine Worship",
                        content: bulletin.divineWorship,
                        icon: "hands.sparkles.fill",
                        color: .purple
                    )
                }
            }
        }
        .padding(20)
        .background(.regularMaterial, in: RoundedRectangle(cornerRadius: 16))
        .shadow(color: .black.opacity(0.1), radius: 8, x: 0, y: 4)
    }
    
    // MARK: - Scripture & Sunset Card
    private var scriptureAndSunsetCard: some View {
        VStack(spacing: 16) {
            if !bulletin.scriptureReading.isEmpty {
                ScriptureReadingView(scripture: bulletin.scriptureReading)
            }
            
            SunsetTimeView(sunset: bulletin.sunset)
        }
        .padding(20)
        .background(.regularMaterial, in: RoundedRectangle(cornerRadius: 16))
        .shadow(color: .black.opacity(0.1), radius: 8, x: 0, y: 4)
    }
    
    // MARK: - Actions Card
    private var actionsCard: some View {
        VStack(spacing: 16) {
            HStack {
                Image(systemName: "square.and.arrow.up")
                    .font(.title3)
                    .foregroundStyle(.blue)
                
                Text("Quick Actions")
                    .font(.headline)
                    .fontWeight(.semibold)
                
                Spacer()
            }
            
            HStack(spacing: 12) {
                QuickActionButton(
                    title: "Share",
                    icon: "square.and.arrow.up",
                    color: .blue
                ) {
                    shareBulletin()
                }
                
                if bulletin.pdfPath != nil {
                    QuickActionButton(
                        title: "Download",
                        icon: "arrow.down.circle",
                        color: .green
                    ) {
                        downloadBulletin()
                    }
                }
                
                QuickActionButton(
                    title: "Contact",
                    icon: "phone.fill",
                    color: .orange
                ) {
                    if let url = URL(string: "tel://8608750450") {
                        UIApplication.shared.open(url)
                    }
                }
            }
        }
        .padding(20)
        .background(.regularMaterial, in: RoundedRectangle(cornerRadius: 16))
        .shadow(color: .black.opacity(0.1), radius: 8, x: 0, y: 4)
    }
    
    // MARK: - Helper Functions
    
    private func shareBulletin() {
        var items: [Any] = ["Check out this week's church bulletin: \(bulletin.title)"]
        
        if let pdfPath = bulletin.pdfPath, let url = URL(string: pdfPath) {
            items.append(url)
        }
        
        #if os(iOS)
        let activityVC = UIActivityViewController(activityItems: items, applicationActivities: nil)
        
        if let windowScene = UIApplication.shared.connectedScenes.first as? UIWindowScene,
           let window = windowScene.windows.first {
            window.rootViewController?.present(activityVC, animated: true)
        }
        #endif
    }
    
    private func downloadBulletin() {
        guard let pdfPath = bulletin.pdfPath, let url = URL(string: pdfPath) else { return }
        
        // For remote PDFs, open in Safari which handles downloads properly
        if url.scheme == "http" || url.scheme == "https" {
            UIApplication.shared.open(url)
        }
    }
}

// MARK: - PDF Viewer Sheet

struct PDFViewerSheet: View {
    let url: URL
    let title: String
    @Environment(\.dismiss) private var dismiss
    @State private var isLoading = true
    @State private var error: Error?
    
    var body: some View {
        NavigationStack {
            ZStack {
                if isLoading {
                    VStack(spacing: 16) {
                        ProgressView()
                            .scaleEffect(1.2)
                        
                        Text("Loading PDF...")
                            .font(.subheadline)
                            .foregroundStyle(.secondary)
                    }
                } else if let error = error {
                    VStack(spacing: 16) {
                        Image(systemName: "exclamationmark.triangle")
                            .font(.system(size: 48))
                            .foregroundStyle(.red)
                        
                        Text("Error Loading PDF")
                            .font(.headline)
                            .fontWeight(.semibold)
                        
                        Text(error.localizedDescription)
                            .font(.subheadline)
                            .foregroundStyle(.secondary)
                            .multilineTextAlignment(.center)
                        
                        Button("Try Again") {
                            loadPDF()
                        }
                        .buttonStyle(.borderedProminent)
                    }
                    .padding()
                } else {
                    PDFKitView(url: url, isLoading: $isLoading, error: $error)
                }
            }
            .navigationTitle(title)
            #if os(iOS)
            .navigationBarTitleDisplayMode(.inline)
            #endif
            .toolbar {
                ToolbarItem(placement: .navigationBarLeading) {
                    Button("Done") {
                        dismiss()
                    }
                }
                
                ToolbarItem(placement: .navigationBarTrailing) {
                    Menu {
                        Button {
                            // Share PDF
                        } label: {
                            Label("Share", systemImage: "square.and.arrow.up")
                        }
                        
                        Button {
                            // Download PDF
                        } label: {
                            Label("Download", systemImage: "arrow.down.circle")
                        }
                        
                        Button {
                            // Print PDF
                        } label: {
                            Label("Print", systemImage: "printer")
                        }
                    } label: {
                        Image(systemName: "ellipsis.circle")
                    }
                }
            }
        }
        .onAppear {
            loadPDF()
        }
    }
    
    private func loadPDF() {
        isLoading = true
        error = nil
        
        // Simulate loading or implement actual PDF loading logic
        DispatchQueue.main.asyncAfter(deadline: .now() + 1) {
            isLoading = false
        }
    }
}

// MARK: - PDFKit View

struct PDFKitView: UIViewRepresentable {
    let url: URL
    @Binding var isLoading: Bool
    @Binding var error: Error?
    
    func makeUIView(context: Context) -> PDFView {
        let pdfView = PDFView()
        pdfView.autoScales = true
        pdfView.displayMode = .singlePageContinuous
        pdfView.displayDirection = .vertical
        #if os(iOS)
        pdfView.backgroundColor = .systemBackground
        #else
        pdfView.backgroundColor = .black
        #endif
        
        // Load PDF
        loadPDF(into: pdfView)
        
        return pdfView
    }
    
    func updateUIView(_ uiView: PDFView, context: Context) {
        // Update if needed
    }
    
    private func loadPDF(into pdfView: PDFView) {
        Task {
            do {
                let (data, _) = try await URLSession.shared.data(from: url)
                
                await MainActor.run {
                    if let pdfDocument = PDFDocument(data: data) {
                        pdfView.document = pdfDocument
                        self.isLoading = false
                    } else {
                        self.error = URLError(.cannotDecodeContentData)
                        self.isLoading = false
                    }
                }
            } catch {
                await MainActor.run {
                    self.error = error
                    self.isLoading = false
                }
            }
        }
    }
}

// MARK: - Supporting View Components

struct ServiceSectionView: View {
    let title: String
    let content: String
    let icon: String
    let color: Color
    
    var body: some View {
        VStack(alignment: .leading, spacing: 12) {
            HStack(spacing: 8) {
                Image(systemName: icon)
                    .font(.subheadline)
                    .foregroundStyle(color)
                
                Text(title)
                    .font(.subheadline)
                    .fontWeight(.semibold)
                    .foregroundStyle(color)
                
                Spacer()
            }
            
            HymnTextView(text: content)
                .padding(.leading, 4)
        }
        .padding(16)
        .background(color.opacity(0.05), in: RoundedRectangle(cornerRadius: 12))
    }
}

struct ScriptureReadingView: View {
    let scripture: String
    
    private func parseScripture(_ text: String) -> [ScriptureVerse] {
        // Use the Rust implementation for consistent scripture parsing
        let jsonString = formatScriptureTextJson(scriptureText: text)
        guard let data = jsonString.data(using: .utf8),
              let scriptureSection = try? JSONDecoder().decode([ScriptureSection].self, from: data) else {
            // Fallback to original numbered verse parsing if Rust parsing fails
            return parseNumberedVerses(text)
        }
        
        var verses: [ScriptureVerse] = []
        
        for section in scriptureSection {
            // If we have both verse and reference, add them separately  
            if !section.reference.isEmpty {
                verses.append(ScriptureVerse(number: nil, text: section.verse))
                verses.append(ScriptureVerse(number: nil, text: section.reference))
            } else {
                // Single verse or text without reference
                verses.append(ScriptureVerse(number: nil, text: section.verse))
            }
        }
        
        // If still no verses found, fallback
        if verses.isEmpty {
            verses.append(ScriptureVerse(number: nil, text: text.trimmingCharacters(in: .whitespacesAndNewlines)))
        }
        
        return verses
    }
    
    private func parseNumberedVerses(_ text: String) -> [ScriptureVerse] {
        // Fallback: Check for numbered verses like "1. text" or "1 text"
        let lines = text.components(separatedBy: .newlines)
            .map { $0.trimmingCharacters(in: .whitespacesAndNewlines) }
            .filter { !$0.isEmpty }
        
        var verses: [ScriptureVerse] = []
        
        for line in lines {
            // Check if line starts with a number
            if let firstChar = line.first, firstChar.isNumber {
                let components = line.components(separatedBy: CharacterSet(charactersIn: ". "))
                if components.count > 1,
                   let number = Int(components[0]),
                   components.count > 1 {
                    let text = components.dropFirst().joined(separator: " ").trimmingCharacters(in: .whitespacesAndNewlines)
                    if !text.isEmpty {
                        verses.append(ScriptureVerse(number: number, text: text))
                        continue
                    }
                }
            }
            
            // Add as regular text
            verses.append(ScriptureVerse(number: nil, text: line))
        }
        
        // If no verses found, treat as single verse
        if verses.isEmpty {
            verses.append(ScriptureVerse(number: nil, text: text.trimmingCharacters(in: .whitespacesAndNewlines)))
        }
        
        return verses
    }
    
    var body: some View {
        let verses = parseScripture(scripture)
        
        VStack(alignment: .leading, spacing: 16) {
            // Header with enhanced styling
            HStack(spacing: 8) {
                ZStack {
                    Circle()
                        .fill(.indigo.opacity(0.15))
                        .frame(width: 28, height: 28)
                    
                    Image(systemName: "book.closed.fill")
                        .font(.caption)
                        .foregroundStyle(.indigo)
                }
                
                Text("Scripture Reading")
                    .font(.subheadline)
                    .fontWeight(.semibold)
                    .foregroundStyle(.indigo)
                
                Spacer()
                
                // Verse count indicator for multiple verses
                if verses.count > 1 {
                    Text("\(verses.count) verses")
                        .font(.caption2)
                        .padding(.horizontal, 8)
                        .padding(.vertical, 3)
                        .background(.indigo.opacity(0.1), in: Capsule())
                        .foregroundStyle(.indigo)
                }
            }
            
            // Verses with enhanced styling
            VStack(spacing: verses.count > 1 ? 12 : 8) {
                ForEach(Array(verses.enumerated()), id: \.offset) { index, verse in
                    VStack(alignment: .leading, spacing: 6) {
                        if let number = verse.number {
                            HStack(spacing: 8) {
                                // Verse number badge
                                Text("\(number)")
                                    .font(.caption)
                                    .fontWeight(.bold)
                                    .foregroundStyle(.white)
                                    .frame(width: 20, height: 20)
                                    .background(.indigo, in: Circle())
                                
                                // Verse text with elegant styling
                                Text(verse.text)
                                    .font(.body)
                                    .fontWeight(.medium)
                                    .foregroundStyle(.primary)
                                    .multilineTextAlignment(.leading)
                            }
                        } else {
                            // Single verse or paragraph without numbering
                            HStack(alignment: .top, spacing: 8) {
                                // Decorative quote mark or bullet
                                if verses.count == 1 {
                                    Image(systemName: "quote.opening")
                                        .font(.caption)
                                        .foregroundStyle(.indigo.opacity(0.6))
                                        .padding(.top, 2)
                                } else {
                                    Circle()
                                        .fill(.indigo.opacity(0.4))
                                        .frame(width: 4, height: 4)
                                        .padding(.top, 8)
                                }
                                
                                Text(verse.text)
                                    .font(.body)
                                    .fontWeight(.medium)
                                    .foregroundStyle(.primary)
                                    .multilineTextAlignment(.leading)
                            }
                        }
                    }
                    .padding(.leading, 4)
                    
                    // Separator between verses (except last one)
                    if index < verses.count - 1 {
                        HStack {
                            Spacer()
                            Rectangle()
                                .fill(.indigo.opacity(0.2))
                                .frame(width: 30, height: 1)
                            Spacer()
                        }
                    }
                }
            }
        }
        .padding(20)
        .background(.indigo.opacity(0.03), in: RoundedRectangle(cornerRadius: 16))
        .overlay(
            RoundedRectangle(cornerRadius: 16)
                .strokeBorder(.indigo.opacity(0.15), lineWidth: 1.5)
        )
        .shadow(color: .indigo.opacity(0.1), radius: 4, x: 0, y: 2)
    }
}

// MARK: - Scripture Verse Model
struct ScriptureVerse {
    let number: Int?
    let text: String
}

struct SunsetTimeView: View {
    let sunset: String
    
    var body: some View {
        HStack(spacing: 12) {
            Image(systemName: "sunset.fill")
                .font(.title3)
                .foregroundStyle(.orange)
            
            VStack(alignment: .leading, spacing: 2) {
                Text("Sabbath Ends")
                    .font(.caption)
                    .foregroundStyle(.secondary)
                
                Text(sunset)
                    .font(.headline)
                    .fontWeight(.semibold)
            }
            
            Spacer()
            
            Image(systemName: "clock.fill")
                .font(.title3)
                .foregroundStyle(.orange.opacity(0.6))
        }
        .padding(16)
        .background(.orange.opacity(0.05), in: RoundedRectangle(cornerRadius: 12))
    }
}

struct QuickActionButton: View {
    let title: String
    let icon: String
    let color: Color
    let action: () -> Void
    
    var body: some View {
        Button(action: action) {
            VStack(spacing: 8) {
                Image(systemName: icon)
                    .font(.title2)
                    .foregroundStyle(color)
                
                Text(title)
                    .font(.caption)
                    .fontWeight(.medium)
                    .multilineTextAlignment(.center)
            }
            .frame(maxWidth: .infinity)
            .padding(.vertical, 16)
            .background(color.opacity(0.1), in: RoundedRectangle(cornerRadius: 12))
        }
        .buttonStyle(.plain)
    }
}

// MARK: - Hymn Text View with Clickable Hymn Numbers

struct HymnTextView: View {
    let text: String
    
    private func parseTextWithHymns(_ text: String) -> [(text: String, isHymn: Bool, hymnNumber: Int?)] {
        var result: [(text: String, isHymn: Bool, hymnNumber: Int?)] = []
        let hymnPattern = #"(?:Hymn(?:al)?\s+(?:#\s*)?|#\s*)(\d+)(?:\s+["""]([^"""]*)[""])?.*"#
        
        guard let regex = try? NSRegularExpression(pattern: hymnPattern, options: [.caseInsensitive]) else {
            return [(text: text, isHymn: false, hymnNumber: nil)]
        }
        
        let nsText = text as NSString
        let matches = regex.matches(in: text, range: NSRange(location: 0, length: nsText.length))
        
        if matches.isEmpty {
            return [(text: text, isHymn: false, hymnNumber: nil)]
        }
        
        var lastIndex = 0
        
        for match in matches {
            // Add text before the hymn match
            if match.range.location > lastIndex {
                let textBefore = nsText.substring(with: NSRange(location: lastIndex, length: match.range.location - lastIndex))
                if !textBefore.isEmpty {
                    result.append((text: textBefore, isHymn: false, hymnNumber: nil))
                }
            }
            
            // Add hymn match
            let hymnText = nsText.substring(with: match.range)
            let hymnNumber = Int(nsText.substring(with: match.range(at: 1))) ?? 0
            result.append((text: hymnText, isHymn: true, hymnNumber: hymnNumber))
            
            lastIndex = match.range.location + match.range.length
        }
        
        // Add remaining text after the last match
        if lastIndex < nsText.length {
            let remainingText = nsText.substring(from: lastIndex)
            if !remainingText.isEmpty {
                result.append((text: remainingText, isHymn: false, hymnNumber: nil))
            }
        }
        
        return result
    }
    
    var body: some View {
        let parsedText = parseTextWithHymns(text)
        
        if parsedText.count == 1 && !parsedText[0].isHymn {
            // No hymns found, just show regular text
            Text(text)
                .font(.body)
        } else {
            // Mix of text and hymn numbers
            VStack(alignment: .leading, spacing: 8) {
                ForEach(Array(parsedText.enumerated()), id: \.offset) { _, segment in
                    if segment.isHymn, let hymnNumber = segment.hymnNumber {
                        Button(action: {
                            openHymnInAdventistHymnarium(hymnNumber)
                        }) {
                            HStack(spacing: 6) {
                                Image(systemName: "music.note")
                                    .foregroundStyle(.blue)
                                    .font(.caption)
                                
                                Text(segment.text)
                                    .font(.body)
                                    .foregroundStyle(.blue)
                            }
                            .padding(.horizontal, 8)
                            .padding(.vertical, 4)
                            .background(
                                RoundedRectangle(cornerRadius: 6)
                                    .fill(.blue.opacity(0.1))
                            )
                        }
                        .buttonStyle(.plain)
                    } else {
                        Text(segment.text)
                            .font(.body)
                    }
                }
            }
        }
    }
    
    private func openHymnInAdventistHymnarium(_ number: Int) {
        // Try to open Adventist Hymnarium app first
        let hymnAppURL = URL(string: "adventisthymnarium://hymn?number=\(number)")
        let appStoreURL = URL(string: "https://apps.apple.com/us/app/adventist-hymnarium/id6738877733")
        
        if let hymnAppURL = hymnAppURL, UIApplication.shared.canOpenURL(hymnAppURL) {
            // Open in Adventist Hymnarium app
            UIApplication.shared.open(hymnAppURL)
        } else if let appStoreURL = appStoreURL {
            // Offer to download the app
            let alert = UIAlertController(
                title: "Open in Adventist Hymnarium",
                message: "Download the Adventist Hymnarium app to view Hymn #\(number)?",
                preferredStyle: .alert
            )
            
            alert.addAction(UIAlertAction(title: "Download App", style: .default) { _ in
                UIApplication.shared.open(appStoreURL)
            })
            
            alert.addAction(UIAlertAction(title: "Cancel", style: .cancel))
            
            if let windowScene = UIApplication.shared.connectedScenes.first as? UIWindowScene,
               let window = windowScene.windows.first,
               let rootViewController = window.rootViewController {
                rootViewController.present(alert, animated: true)
            }
        }
    }
}

#Preview {
    NavigationStack {
        BulletinDetailView(bulletin: ChurchBulletin(
            id: "1",
            title: "January 11, 2025",
            date: "Saturday, January 11, 2025",
            sabbathSchool: "The Beatitudes - Part 3",
            divineWorship: "Blessed Are Those Who Hunger",
            scriptureReading: "Matthew 5:1-12",
            sunset: "5:47 PM",
            pdfPath: "https://example.com/bulletin.pdf",
            coverImage: nil,
            isActive: true
        ))
    }
}