import SwiftUI
import UniformTypeIdentifiers
import AppKit

@main
struct MarkdownViewerApp: App {
    @StateObject private var recentFilesManager = RecentFilesManager.shared
    
    var body: some Scene {
        Settings {
            EmptyView()
        }
        .commands {
            CommandGroup(replacing: .newItem) {
                Button("Open Markdown File...") {
                    openMarkdownFile()
                }
                .keyboardShortcut("o", modifiers: .command)
                
                Divider()
                
                Menu("Recent Files") {
                    if recentFilesManager.recentFiles.isEmpty {
                        Text("No Recent Files")
                            .disabled(true)
                    } else {
                        ForEach(recentFilesManager.recentFiles, id: \.self) { url in
                            Button(action: {
                                openRecentFile(url)
                            }) {
                                VStack(alignment: .leading) {
                                    Text(recentFilesManager.getDisplayName(for: url))
                                    Text(recentFilesManager.getRelativePath(for: url))
                                        .font(.caption)
                                        .foregroundColor(.secondary)
                                }
                            }
                        }
                        
                        Divider()
                        
                        Button("Clear Recent Files") {
                            recentFilesManager.clearRecentFiles()
                        }
                    }
                }
            }
        }
    }
    
    private func openMarkdownFile() {
        let panel = NSOpenPanel()
        panel.allowsMultipleSelection = true
        panel.canChooseDirectories = false
        panel.canChooseFiles = true
        panel.allowedContentTypes = [UTType.plainText, UTType(filenameExtension: "md")!]
        
        if panel.runModal() == .OK {
            for url in panel.urls {
                openNewWindow(for: url)
            }
        }
    }
    
    private func openRecentFile(_ url: URL) {
        // Check if file still exists
        guard FileManager.default.fileExists(atPath: url.path) else {
            recentFilesManager.removeRecentFile(url)
            showErrorWindow(message: "File no longer exists", details: url.path)
            return
        }
        
        openNewWindow(for: url)
    }
    
    private func openNewWindow(for url: URL) {
        do {
            let content = try String(contentsOf: url, encoding: .utf8)
            
            // Add to recent files
            recentFilesManager.addRecentFile(url)
            
            let newWindow = NSWindow(
                contentRect: NSRect(x: 0, y: 0, width: 800, height: 600),
                styleMask: [.titled, .closable, .resizable, .miniaturizable],
                backing: .buffered,
                defer: false
            )
            
            newWindow.title = url.lastPathComponent
            newWindow.contentView = NSHostingView(
                rootView: MarkdownDocumentView(
                    content: content,
                    fileName: url.lastPathComponent
                )
            )
            newWindow.center()
            newWindow.makeKeyAndOrderFront(nil)
            
        } catch {
            print("Error reading file: \(error)")
            showErrorWindow(message: "Error loading file", details: error.localizedDescription)
        }
    }
    
    private func showErrorWindow(message: String, details: String) {
        let newWindow = NSWindow(
            contentRect: NSRect(x: 0, y: 0, width: 400, height: 200),
            styleMask: [.titled, .closable],
            backing: .buffered,
            defer: false
        )
        
        newWindow.title = "Error"
        newWindow.contentView = NSHostingView(
            rootView: VStack {
                Image(systemName: "exclamationmark.triangle")
                    .font(.system(size: 40))
                    .foregroundColor(.red)
                Text(message)
                    .font(.headline)
                Text(details)
                    .font(.caption)
                    .foregroundColor(.secondary)
                    .multilineTextAlignment(.center)
            }
            .padding()
        )
        newWindow.center()
        newWindow.makeKeyAndOrderFront(nil)
    }
}