import Foundation

class RecentFilesManager: ObservableObject {
    static let shared = RecentFilesManager()
    
    @Published var recentFiles: [URL] = []
    
    private let maxRecentFiles = 10
    private let userDefaultsKey = "RecentMarkdownFiles"
    
    private init() {
        loadRecentFiles()
    }
    
    func addRecentFile(_ url: URL) {
        // Remove if already exists to move it to top
        recentFiles.removeAll { $0 == url }
        
        // Add to beginning
        recentFiles.insert(url, at: 0)
        
        // Limit to max count
        if recentFiles.count > maxRecentFiles {
            recentFiles = Array(recentFiles.prefix(maxRecentFiles))
        }
        
        saveRecentFiles()
    }
    
    func removeRecentFile(_ url: URL) {
        recentFiles.removeAll { $0 == url }
        saveRecentFiles()
    }
    
    func clearRecentFiles() {
        recentFiles.removeAll()
        saveRecentFiles()
    }
    
    private func loadRecentFiles() {
        if let data = UserDefaults.standard.data(forKey: userDefaultsKey),
           let urls = try? JSONDecoder().decode([URL].self, from: data) {
            // Filter out files that no longer exist
            recentFiles = urls.filter { FileManager.default.fileExists(atPath: $0.path) }
            
            // Save filtered list back if any files were removed
            if recentFiles.count != urls.count {
                saveRecentFiles()
            }
        }
    }
    
    private func saveRecentFiles() {
        if let data = try? JSONEncoder().encode(recentFiles) {
            UserDefaults.standard.set(data, forKey: userDefaultsKey)
        }
    }
    
    func getDisplayName(for url: URL) -> String {
        return url.lastPathComponent
    }
    
    func getRelativePath(for url: URL) -> String {
        let homeURL = FileManager.default.homeDirectoryForCurrentUser
        if url.path.hasPrefix(homeURL.path) {
            let relativePath = String(url.path.dropFirst(homeURL.path.count))
            return "~" + relativePath
        }
        return url.path
    }
}