session-ios/SessionMessagingKit/Database/Models/Attachment.swift

// Copyright © 2022 Rangeproof Pty Ltd. All rights reserved.

import Foundation
import GRDB
import SessionUtilitiesKit

public struct Attachment: Codable, FetchableRecord, PersistableRecord, TableRecord, ColumnExpressible {
    public static var databaseTableName: String { "attachment" }
    internal static let interactionForeignKey = ForeignKey([Columns.interactionId], to: [Interaction.Columns.id])
    private static let interaction = belongsTo(Interaction.self, using: interactionForeignKey)
    
    public typealias Columns = CodingKeys
    public enum CodingKeys: String, CodingKey, ColumnExpression {
        case interactionId
        case serverId
        case variant
        case state
        case contentType
        case byteCount
        case creationTimestamp
        case sourceFilename
        case downloadUrl
        case width
        case height
        case encryptionKey
        case digest
        case caption
    }
    
    public enum Variant: Int, Codable, DatabaseValueConvertible {
        case standard
        case voiceMessage
    }
    
    public enum State: Int, Codable, DatabaseValueConvertible {
        case pending
        case downloading
        case downloaded
        case uploading
        case uploaded
        case failed
    }
    
    /// The id for the Interaction this attachment belongs to
    public let interactionId: Int64?
    
    /// The id for the attachment returned by the server
    ///
    /// This will be null for attachments which haven’t completed uploading
    ///
    /// **Note:** This value is not unique as multiple SOGS could end up having the same file id
    public let serverId: String?
    
    /// The type of this attachment, used to distinguish logic handling
    public let variant: Variant
    
    /// The current state of the attachment
    public let state: State
    
    /// The MIMEType for the attachment
    public let contentType: String
    
    /// The size of the attachment in bytes
    ///
    /// **Note:** This may be `0` for some legacy attachments
    public let byteCount: UInt
    
    /// Timestamp in seconds since epoch for when this attachment was created
    ///
    /// **Uploaded:** This will be the timestamp the file finished uploading
    /// **Downloaded:** This will be the timestamp the file finished downloading
    /// **Other:** This will be null
    public let creationTimestamp: TimeInterval?
    
    /// Represents the "source" filename sent or received in the protos, not the filename on disk
    public let sourceFilename: String?
    
    /// The url the attachment can be downloaded from, this will be `null` for attachments which haven’t yet been uploaded
    ///
    /// **Note:** The url is a fully constructed url but the clients just extract the id from the end of the url to perform the actual download
    public let downloadUrl: String?
    
    /// The width of the attachment, this will be `null` for non-visual attachment types
    public let width: UInt?
    
    /// The height of the attachment, this will be `null` for non-visual attachment types
    public let height: UInt?
    
    /// The key used to decrypt the attachment
    public let encryptionKey: Data?
    
    /// The computed digest for the attachment (generated from `iv || encrypted data || hmac`)
    public let digest: Data?
    
    /// Caption for the attachment
    public let caption: String?
    
    // MARK: - Relationships
    
    public var interaction: QueryInterfaceRequest<Interaction> {
        request(for: Attachment.interaction)
    }
}