/*
 * Copyright (C) 2023 by Claudio Cambra <claudio.cambra@nextcloud.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
 * for more details.
 */

import Foundation
import FileProvider
import NextcloudKit
import OSLog

extension FileProviderExtension: NSFileProviderThumbnailing {
    func fetchThumbnails(for itemIdentifiers: [NSFileProviderItemIdentifier],
                         requestedSize size: CGSize,
                         perThumbnailCompletionHandler: @escaping (NSFileProviderItemIdentifier,
                                                                   Data?,
                                                                   Error?) -> Void,
                         completionHandler: @escaping (Error?) -> Void) -> Progress {

        let progress = Progress(totalUnitCount: Int64(itemIdentifiers.count))
        var progressCounter: Int64 = 0

        func finishCurrent() {
            progressCounter += 1

            if progressCounter == progress.totalUnitCount {
                completionHandler(nil)
            }
        }

        for itemIdentifier in itemIdentifiers {
            Logger.fileProviderExtension.debug("Fetching thumbnail for item with identifier:\(itemIdentifier.rawValue, privacy: .public)")
            guard let metadata = NextcloudFilesDatabaseManager.shared.itemMetadataFromFileProviderItemIdentifier(itemIdentifier),
                  let thumbnailUrl = metadata.thumbnailUrl(size: size) else {
                Logger.fileProviderExtension.debug("Did not fetch thumbnail URL")
                finishCurrent()
                continue
            }

            Logger.fileProviderExtension.debug("Fetching thumbnail for file:\(metadata.fileName) at:\(thumbnailUrl.absoluteString, privacy: .public)")

            self.ncKit.getPreview(url: thumbnailUrl) { _, data, error in
                if error == .success && data != nil {
                    perThumbnailCompletionHandler(itemIdentifier, data, nil)
                } else {
                    perThumbnailCompletionHandler(itemIdentifier, nil, NSFileProviderError(.serverUnreachable))
                }
                finishCurrent()
            }
        }

        return progress
    }
}