kiwix-apple/SwiftUI/Model/LibraryOperations.swift

//
//  LibraryOperations.swift
//  Kiwix
//
//  Created by Chris Li on 9/12/22.
//  Copyright © 2022 Chris Li. All rights reserved.
//

import CoreData
import os

struct LibraryOperations {
    private init() {}
    
    // MARK: - Open
    
    /// Open a zim file with url
    /// - Parameter url: url of the zim file
    static func open(url: URL) {
        guard let metadata = ZimFileService.getMetaData(url: url),
              let fileURLBookmark = ZimFileService.getBookmarkData(url: url) else { return }
        // open the file
        do {
            try ZimFileService.shared.open(bookmark: fileURLBookmark)
        } catch {
            return
        }
        
        // upsert zim file in the database
        Database.shared.container.performBackgroundTask { context in
            context.mergePolicy = NSMergePolicy.mergeByPropertyObjectTrump
            let predicate = NSPredicate(format: "fileID == %@", metadata.fileID as CVarArg)
            let fetchRequest = ZimFile.fetchRequest(predicate: predicate)
            guard let zimFile = try? context.fetch(fetchRequest).first ?? ZimFile(context: context) else { return }
            LibraryOperations.configureZimFile(zimFile, metadata: metadata)
            zimFile.fileURLBookmark = fileURLBookmark
            zimFile.isMissing = false
            if context.hasChanges { try? context.save() }
        }
    }
    
    /// Reopen zim files from url bookmark data.
    static func reopen() {
        var successCount = 0
        let context = Database.shared.container.viewContext
        let request = ZimFile.fetchRequest(predicate: ZimFile.withFileURLBookmarkPredicate)
        
        guard let zimFiles = try? context.fetch(request) else { return }
        zimFiles.forEach { zimFile in
            guard let data = zimFile.fileURLBookmark else { return }
            do {
                if let data = try ZimFileService.shared.open(bookmark: data) {
                    zimFile.fileURLBookmark = data
                }
                zimFile.isMissing = false
                successCount += 1
            } catch ZimFileOpenError.missing {
                zimFile.isMissing = true
            } catch {
                zimFile.fileURLBookmark = nil
                zimFile.isMissing = false
            }
        }
        if context.hasChanges {
            try? context.save()
        }
        
        os_log("Reopened %d out of %d zim files", log: Log.LibraryOperations, type: .info, successCount, zimFiles.count)
    }
    
    /// Scan a directory and open available zim files inside it
    /// - Parameter url: directory to scan
    static func scanDirectory(_ url: URL) {
        guard let fileURLs = try? FileManager.default.contentsOfDirectory(
            at: url,
            includingPropertiesForKeys: nil,
            options: [.skipsHiddenFiles, .skipsPackageDescendants, .skipsSubdirectoryDescendants]
        ).filter({ $0.pathExtension == "zim"}) else { return }
        os_log("Discovered %d probable zim files.", log: Log.LibraryOperations, type: .info, fileURLs.count)
        for fileURL in fileURLs {
            LibraryOperations.open(url: fileURL)
        }
    }
    
    // MARK: - Configure
    
    /// Configure a zim file object based on its metadata.
    static func configureZimFile(_ zimFile: ZimFile, metadata: ZimFileMetaData) {
        zimFile.articleCount = metadata.articleCount.int64Value
        zimFile.category = metadata.category
        zimFile.created = metadata.creationDate
        zimFile.fileDescription = metadata.fileDescription
        zimFile.fileID = metadata.fileID
        zimFile.flavor = metadata.flavor
        zimFile.hasDetails = metadata.hasDetails
        zimFile.hasPictures = metadata.hasPictures
        zimFile.hasVideos = metadata.hasVideos
        zimFile.languageCode = metadata.languageCode
        zimFile.mediaCount = metadata.mediaCount.int64Value
        zimFile.name = metadata.title
        zimFile.persistentID = metadata.groupIdentifier
        zimFile.requiresServiceWorkers = metadata.requiresServiceWorkers
        zimFile.size = metadata.size.int64Value
        
        // Only overwrite favicon data and url if there is a new value
        if let url = metadata.downloadURL { zimFile.downloadURL = url }
        if let url = metadata.faviconURL { zimFile.faviconURL = url }
    }
    
    //MARK: - Deletion
    
    /// Unlink a zim file from library, and delete the file.
    /// - Parameter zimFile: the zim file to delete
    static func delete(zimFileID: UUID) {
        LibraryOperations.unlink(zimFileID: zimFileID)
    }
    
    /// Unlink a zim file from library, but don't delete the file.
    /// - Parameter zimFile: the zim file to unlink
    static func unlink(zimFileID: UUID) {
        ZimFileService.shared.close(fileID: zimFileID)
        
        Database.shared.container.performBackgroundTask { context in
            context.mergePolicy = NSMergePolicy.mergeByPropertyObjectTrump
            guard let zimFile = try? ZimFile.fetchRequest(fileID: zimFileID).execute().first else { return }
            if zimFile.downloadURL == nil {
                context.delete(zimFile)
            } else {
                zimFile.fileURLBookmark = nil
                zimFile.isMissing = false
            }
            if context.hasChanges { try? context.save() }
        }
    }
}