import Foundation
import UIKit

// MARK: - Download Extensions

extension DownloadTask {
    /// Formatea el tamaño total de la descarga
    var formattedSize: String {
        let formatter = ByteCountFormatter()
        formatter.allowedUnits = [.useBytes, .useKB, .useMB]
        formatter.countStyle = .file
        return formatter.string(fromByteCount: Int64(imageURLs.count * 500_000)) // Estimación de 500KB por imagen
    }

    /// Retorna el tiempo estimado restante
    var estimatedTimeRemaining: String? {
        guard progress > 0 && progress < 1 else { return nil }

        let downloadedPages = Double(imageURLs.count) * progress
        let remainingPages = Double(imageURLs.count) - downloadedPages

        // Estimación: 2 segundos por página
        let estimatedSeconds = remainingPages * 2

        if estimatedSeconds < 60 {
            return "\(Int(estimatedSeconds))s restantes"
        } else {
            let minutes = Int(estimatedSeconds / 60)
            return "\(min)m restantes"
        }
    }
}

extension DownloadManager {
    /// Obtiene estadísticas de descarga
    var downloadStats: DownloadStats {
        let activeCount = activeDownloads.count
        let completedCount = completedDownloads.count
        let failedCount = failedDownloads.count

        return DownloadStats(
            activeDownloads: activeCount,
            completedDownloads: completedCount,
            failedDownloads: failedCount,
            totalProgress: totalProgress
        )
    }

    /// Verifica si hay descargas activas
    var hasActiveDownloads: Bool {
        !activeDownloads.isEmpty
    }

    /// Obtiene el número total de descargas
    var totalDownloads: Int {
        activeDownloads.count + completedDownloads.count + failedDownloads.count
    }
}

// MARK: - Download Stats Model

struct DownloadStats {
    let activeDownloads: Int
    let completedDownloads: Int
    let failedDownloads: Int
    let totalProgress: Double

    var totalDownloads: Int {
        activeDownloads + completedDownloads + failedDownloads
    }

    var successRate: Double {
        guard totalDownloads > 0 else { return 0 }
        return Double(completedDownloads) / Double(totalDownloads)
    }
}

// MARK: - UIImage Extension for Compression

extension UIImage {
    /// Comprime la imagen con una calidad específica
    func compressedData(quality: CGFloat = 0.8) -> Data? {
        return jpegData(compressionQuality: quality)
    }

    /// Redimensiona la imagen a un tamaño máximo
    func resized(maxWidth: CGFloat, maxHeight: CGFloat) -> UIImage? {
        let size = size

        let widthRatio = maxWidth / size.width
        let heightRatio = maxHeight / size.height
        let ratio = min(widthRatio, heightRatio)

        let newSize = CGSize(
            width: size.width * ratio,
            height: size.height * ratio
        )

        UIGraphicsBeginImageContextWithOptions(newSize, false, 1.0)
        draw(in: CGRect(origin: .zero, size: newSize))
        let resizedImage = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()

        return resizedImage
    }

    /// Optimiza la imagen para almacenamiento
    func optimizedForStorage() -> Data? {
        // Redimensionar si es muy grande
        let maxDimension: CGFloat = 2048
        let resized: UIImage

        if size.width > maxDimension || size.height > maxDimension {
            resized = self.resized(maxWidth: maxDimension, maxHeight: maxDimension) ?? self
        } else {
            resized = self
        }

        // Comprimir con calidad balanceada
        return resized.compressedData(quality: 0.75)
    }
}

// MARK: - Notification Names

extension Notification.Name {
    static let downloadDidStart = Notification.Name("downloadDidStart")
    static let downloadDidUpdate = Notification.Name("downloadDidUpdate")
    static let downloadDidComplete = Notification.Name("downloadDidComplete")
    static let downloadDidFail = Notification.Name("downloadDidFail")
    static let downloadDidCancel = Notification.Name("downloadDidCancel")
}

// MARK: - Download Progress Notification

struct DownloadProgressNotification {
    let taskId: String
    let progress: Double
    let downloadedPages: Int
    let totalPages: Int
}

// MARK: - URLSession Extension for Download Tracking

extension URLSession {
    /// Configura una URLSession para descargas con timeout
    static func downloadSession() -> URLSession {
        let configuration = URLSessionConfiguration.default
        configuration.timeoutIntervalForRequest = 30
        configuration.timeoutIntervalForResource = 300
        configuration.requestCachePolicy = .reloadIgnoringLocalCacheData
        return URLSession(configuration: configuration)
    }
}