import Foundation
import AppKit

final class ImageReader {

    /// The content folder where the input data is stored
    let contentFolder: URL

    private let fileUpdates: FileUpdateChecker

    let runDataFolder: URL

    init(in input: URL, runFolder: URL, fileUpdates: FileUpdateChecker) {
        self.contentFolder = input
        self.runDataFolder = runFolder
        self.fileUpdates = fileUpdates
    }

    var numberOfFilesLoaded: Int {
        fileUpdates.numberOfFilesLoaded
    }

    var numberOfFilesAccessed: Int {
        fileUpdates.numberOfFilesAccessed
    }

    func loadData() -> FileUpdateChecker.LoadResult {
        fileUpdates.loadPreviousRun(from: runDataFolder)
    }

    func writeDetectedFileChangesToDisk() -> String? {
        fileUpdates.writeDetectedFileChanges(to: runDataFolder)
    }

    func imageHasChanged(at path: String) -> Bool {
        fileUpdates.fileHasChanged(at: path)
    }

    func getImage(atPath path: String) -> NSImage? {
        guard let data = getData(atPath: path) else {
            // TODO: log.error("Failed to load file", source: path)
            return nil
        }
        guard let image = NSImage(data: data) else {
            // TODO: log.error("Failed to read image", source: path)
            return nil
        }
        return image
    }

    private func getData(atPath path: String) -> Data? {
        let url = contentFolder.appendingPathComponent(path)
        guard url.exists else {
            return nil
        }
        do {
            let data = try Data(contentsOf: url)
            fileUpdates.didLoad(data, at: path)
            return data
        } catch {
            // TODO: log.error("Failed to read data: \(error)", source: path)
            return nil
        }
    }

}