import Foundation

class GIFStorageService {
    static let shared = GIFStorageService()
    
    private let userDefaults = UserDefaults(suiteName: "group.gifcollector")
    private let savedGIFsKey = "savedGIFs"
    private let pendingGIFsKey = "pendingGIFs"
    
    private init() {
        // Make sure the shared UserDefaults exists
        if userDefaults == nil {
            print("Error: Could not create UserDefaults with app group")
        }
        
        // Process any pending GIFs from the Share Extension
        checkForSharedGIFs()
    }
    
    func saveGIF(data: Data, fromURL urlString: String, completion: @escaping (GIF?) -> Void) {
        // First store the GIF data to disk
        guard let localPath = GIFFileManager.shared.storeGIF(data: data, fromURL: urlString) else {
            completion(nil)
            return
        }
        
        // Create and save the GIF model
        let gif = GIF(localFilePath: localPath, originalURL: urlString)
        
        var savedGIFs = fetchGIFs()
        
        // Don't save duplicates of the same URL
        if !savedGIFs.contains(where: { $0.originalURL == urlString }) {
            savedGIFs.append(gif)
            saveToUserDefaults(gifs: savedGIFs)
        }
        
        // Perform cleanup if needed
        GIFFileManager.shared.performStorageCleanupIfNeeded()
        
        completion(gif)
    }
    
    func fetchGIFs() -> [GIF] {
        guard let data = userDefaults?.data(forKey: savedGIFsKey),
              let gifs = try? JSONDecoder().decode([GIF].self, from: data) else {
            return []
        }
        
        // Filter out any GIFs whose files no longer exist
        let validGIFs = gifs.filter { GIFFileManager.shared.fileExists(at: $0.localFilePath) }
        
        // If we filtered any out, save the updated list
        if validGIFs.count != gifs.count {
            saveToUserDefaults(gifs: validGIFs)
        }
        
        return validGIFs.sorted(by: { $0.createdAt > $1.createdAt })
    }
    
    func deleteGIF(with id: UUID) {
        var savedGIFs = fetchGIFs()
        
        // Find the GIF to delete
        if let gifToDelete = savedGIFs.first(where: { $0.id == id }) {
            // Delete the file from storage
            GIFFileManager.shared.deleteGIF(at: gifToDelete.localFilePath)
            
            // Remove from the list
            savedGIFs.removeAll(where: { $0.id == id })
            saveToUserDefaults(gifs: savedGIFs)
        }
    }
    
    func clearAllGIFs() {
        // Delete all GIF files
        fetchGIFs().forEach { gif in
            GIFFileManager.shared.deleteGIF(at: gif.localFilePath)
        }
        
        // Clear the list
        saveToUserDefaults(gifs: [])
    }
    
    private func saveToUserDefaults(gifs: [GIF]) {
        guard let data = try? JSONEncoder().encode(gifs) else { return }
        userDefaults?.set(data, forKey: savedGIFsKey)
    }
    
    func getGIFData(for gif: GIF) -> Data? {
        return GIFFileManager.shared.loadGIFData(from: gif.localFilePath)
    }
    
    // MARK: - Share Extension Integration
    
    func checkForSharedGIFs() {
        guard let pendingGIFsData = userDefaults?.array(forKey: pendingGIFsKey) as? [[String: Any]] else {
            return
        }
        
        guard !pendingGIFsData.isEmpty else {
            return
        }
        
        var savedGIFs = fetchGIFs()
        var newGIFsAdded = false
        
        for gifInfo in pendingGIFsData {
            if let localFilePath = gifInfo["localFilePath"] as? String,
               let originalURL = gifInfo["originalURL"] as? String,
               let createdAt = gifInfo["createdAt"] as? TimeInterval {
                
                // Create a GIF object
                let gif = GIF(
                    localFilePath: localFilePath,
                    originalURL: originalURL
                )
                
                // Don't add duplicates
                if !savedGIFs.contains(where: { $0.localFilePath == localFilePath }) {
                    savedGIFs.append(gif)
                    newGIFsAdded = true
                }
            }
        }
        
        // Save updated GIFs list and clear pending ones
        if newGIFsAdded {
            saveToUserDefaults(gifs: savedGIFs)
        }
        
        // Clear pending GIFs
        userDefaults?.removeObject(forKey: pendingGIFsKey)
    }
}