Tusker/Tusker/Models/CompositionAttachment.swift

//
//  CompositionAttachment.swift
//  Tusker
//
//  Created by Shadowfacts on 3/14/20.
//  Copyright © 2020 Shadowfacts. All rights reserved.
//

import Foundation
import UIKit
import UniformTypeIdentifiers

final class CompositionAttachment: NSObject, Codable, ObservableObject {
    static let typeIdentifier = "space.vaccor.Tusker.composition-attachment"
    
    let id: UUID
    @Published var data: CompositionAttachmentData
    @Published var attachmentDescription: String
    
    init(data: CompositionAttachmentData, description: String = "") {
        self.id = UUID()
        self.data = data
        self.attachmentDescription = description
    }
    
    init(from decoder: Decoder) throws {
        let container = try decoder.container(keyedBy: CodingKeys.self)
        
        self.id = try container.decode(UUID.self, forKey: .id)
        self.data = try container.decode(CompositionAttachmentData.self, forKey: .data)
        self.attachmentDescription = try container.decode(String.self, forKey: .attachmentDescription)
    }
    
    func encode(to encoder: Encoder) throws {
        var container = encoder.container(keyedBy: CodingKeys.self)
        
        try container.encode(id, forKey: .id)
        try container.encode(data, forKey: .data)
        try container.encode(attachmentDescription, forKey: .attachmentDescription)
    }
    
    static func ==(lhs: CompositionAttachment, rhs: CompositionAttachment) -> Bool {
        return lhs.id == rhs.id
    }
    
    enum CodingKeys: String, CodingKey {
        case id
        case data
        case attachmentDescription
    }
}

extension CompositionAttachment: Identifiable {}

private let imageType = UTType.image.identifier
private let mp4Type = UTType.mpeg4Movie.identifier
private let quickTimeType = UTType.quickTimeMovie.identifier
private let dataType = UTType.data.identifier
private let gifType = UTType.gif.identifier

extension CompositionAttachment: NSItemProviderWriting {
    static var writableTypeIdentifiersForItemProvider: [String] {
        [typeIdentifier]
    }
    
    func loadData(withTypeIdentifier typeIdentifier: String, forItemProviderCompletionHandler completionHandler: @escaping (Data?, Error?) -> Void) -> Progress? {
        if typeIdentifier == CompositionAttachment.typeIdentifier {
            do {
                completionHandler(try PropertyListEncoder().encode(self), nil)
            } catch {
                completionHandler(nil, error)
            }
        } else {
            completionHandler(nil, ItemProviderError.incompatibleTypeIdentifier)
        }
        return nil
    }
    
    enum ItemProviderError: Error {
        case incompatibleTypeIdentifier

        var localizedDescription: String {
            switch self {
            case .incompatibleTypeIdentifier:
                return "Cannot provide data for given type"
            }
        }
    }
}

extension CompositionAttachment: NSItemProviderReading {
    static var readableTypeIdentifiersForItemProvider: [String] {
        // todo: is there a better way of handling movies than manually adding all possible UTI types?
        // just using kUTTypeMovie doesn't work, because we need the actually type in order to get the file extension
        // without the file extension, getting the thumbnail and exporting the video for attachment upload fails
        [typeIdentifier] + UIImage.readableTypeIdentifiersForItemProvider + [mp4Type, quickTimeType] + NSURL.readableTypeIdentifiersForItemProvider
    }
    
    static func object(withItemProviderData data: Data, typeIdentifier: String) throws -> CompositionAttachment {
        if typeIdentifier == CompositionAttachment.typeIdentifier {
            return try PropertyListDecoder().decode(CompositionAttachment.self, from: data)
        } else if typeIdentifier == gifType {
            return CompositionAttachment(data: .gif(data))
        } else if UIImage.readableTypeIdentifiersForItemProvider.contains(typeIdentifier), let image = try? UIImage.object(withItemProviderData: data, typeIdentifier: typeIdentifier) {
            return CompositionAttachment(data: .image(image))
        } else if let type = UTType(typeIdentifier), type == .mpeg4Movie || type == .quickTimeMovie {
            let temporaryDirectoryURL = URL(fileURLWithPath: NSTemporaryDirectory(), isDirectory: true)
            let temporaryFileName = ProcessInfo().globallyUniqueString
            let fileExt = type.preferredFilenameExtension!
            let temporaryFileURL = temporaryDirectoryURL.appendingPathComponent(temporaryFileName).appendingPathExtension(fileExt)
            try data.write(to: temporaryFileURL)
            return CompositionAttachment(data: .video(temporaryFileURL))
        } else if NSURL.readableTypeIdentifiersForItemProvider.contains(typeIdentifier), let url = try? NSURL.object(withItemProviderData: data, typeIdentifier: typeIdentifier) as URL {
            return CompositionAttachment(data: .video(url))
        } else {
            throw ItemProviderError.incompatibleTypeIdentifier
        }
    }
}