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

import Foundation
import GRDB
import PromiseKit
import SignalCoreKit
import SessionUtilitiesKit
import AVFAudio
import AVFoundation

public struct Attachment: Codable, Identifiable, Equatable, FetchableRecord, PersistableRecord, TableRecord, ColumnExpressible {
    public static var databaseTableName: String { "attachment" }
    internal static let interactionAttachments = belongsTo(InteractionAttachment.self)
    fileprivate static let quote = belongsTo(Quote.self)
    fileprivate static let linkPreview = belongsTo(LinkPreview.self)
    
    public typealias Columns = CodingKeys
    public enum CodingKeys: String, CodingKey, ColumnExpression, CaseIterable {
        case id
        case serverId
        case variant
        case state
        case contentType
        case byteCount
        case creationTimestamp
        case sourceFilename
        case downloadUrl
        case localRelativeFilePath
        case width
        case height
        case duration
        case isValid
        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
    }
    
    /// A unique identifier for the attachment
    public let id: String
    
    /// 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 file path for the attachment relative to the attachments folder
    ///
    /// **Note:** We store this path so that file path generation changes don’t break existing attachments
    public let localRelativeFilePath: 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 number of seconds the attachment plays for (this will only be set for video and audio attachment types)
    public let duration: TimeInterval?
    
    /// A flag indicating whether the attachment data downloaded is valid for it's content type
    public let isValid: Bool
    
    /// 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: - Initialization
    
    public init(
        id: String = UUID().uuidString,
        serverId: String? = nil,
        variant: Variant,
        state: State = .pending,
        contentType: String,
        byteCount: UInt,
        creationTimestamp: TimeInterval? = nil,
        sourceFilename: String? = nil,
        downloadUrl: String? = nil,
        localRelativeFilePath: String? = nil,
        width: UInt? = nil,
        height: UInt? = nil,
        duration: TimeInterval? = nil,
        isValid: Bool = false,
        encryptionKey: Data? = nil,
        digest: Data? = nil,
        caption: String? = nil
    ) {
        self.id = id
        self.serverId = serverId
        self.variant = variant
        self.state = state
        self.contentType = contentType
        self.byteCount = byteCount
        self.creationTimestamp = creationTimestamp
        self.sourceFilename = sourceFilename
        self.downloadUrl = downloadUrl
        self.localRelativeFilePath = localRelativeFilePath
        self.width = width
        self.height = height
        self.duration = duration
        self.isValid = isValid
        self.encryptionKey = encryptionKey
        self.digest = digest
        self.caption = caption
    }
    
    /// This initializer should only be used when converting from either a LinkPreview or a SignalAttachment to an Attachment (prior to upload)
    public init?(
        id: String = UUID().uuidString,
        variant: Variant = .standard,
        contentType: String,
        dataSource: DataSource
    ) {
        guard let originalFilePath: String = Attachment.originalFilePath(id: id, mimeType: contentType, sourceFilename: nil) else {
            return nil
        }
        guard dataSource.write(toPath: originalFilePath) else { return nil }
        
        let imageSize: CGSize? = Attachment.imageSize(
            contentType: contentType,
            originalFilePath: originalFilePath
        )
        let (isValid, duration): (Bool, TimeInterval?) = Attachment.determineValidityAndDuration(
            contentType: contentType,
            originalFilePath: originalFilePath
        )
        
        self.id = id
        self.serverId = nil
        self.variant = variant
        self.state = .pending
        self.contentType = contentType
        self.byteCount = dataSource.dataLength()
        self.creationTimestamp = nil
        self.sourceFilename = nil
        self.downloadUrl = nil
        self.localRelativeFilePath = nil
        self.width = imageSize.map { UInt(floor($0.width)) }
        self.height = imageSize.map { UInt(floor($0.height)) }
        self.duration = duration
        self.isValid = isValid
        self.encryptionKey = nil
        self.digest = nil
        self.caption = nil
    }
}

// MARK: - CustomStringConvertible

extension Attachment: CustomStringConvertible {
    public static func description(for variant: Variant, contentType: String, sourceFilename: String?) -> String {
        if MIMETypeUtil.isAudio(contentType) {
            // a missing filename is the legacy way to determine if an audio attachment is
            // a voice note vs. other arbitrary audio attachments.
            if variant == .voiceMessage || sourceFilename == nil || (sourceFilename?.count ?? 0) == 0 {
                return "🎙️ \("ATTACHMENT_TYPE_VOICE_MESSAGE".localized())"
            }
        }
        
        return "\("ATTACHMENT".localized()) \(emoji(for: contentType))"
    }
    
    public static func emoji(for contentType: String) -> String {
        if MIMETypeUtil.isImage(contentType) {
            return "📷"
        }
        else if MIMETypeUtil.isVideo(contentType) {
            return "🎥"
        }
        else if MIMETypeUtil.isAudio(contentType) {
            return "🎧"
        }
        else if MIMETypeUtil.isAnimated(contentType) {
            return "🎡"
        }
        
        return "📎"
    }
    
    public var description: String {
        return Attachment.description(
            for: variant,
            contentType: contentType,
            sourceFilename: sourceFilename
        )
    }
}

// MARK: - Mutation

public extension Attachment {
    func with(
        serverId: String? = nil,
        state: State? = nil,
        creationTimestamp: TimeInterval? = nil,
        downloadUrl: String? = nil,
        localRelativeFilePath: String? = nil,
        encryptionKey: Data? = nil,
        digest: Data? = nil
    ) -> Attachment {
        let (isValid, duration): (Bool, TimeInterval?) = {
            switch (self.state, state) {
                case (_, .downloaded):
                    return Attachment.determineValidityAndDuration(
                        contentType: contentType,
                        originalFilePath: originalFilePath
                    )
                
                // Assume the data is already correct for "uploading" attachments (and don't override it)
                case (.uploading, .failed), (.uploaded, .failed): return (self.isValid, self.duration)
                case (_, .failed): return (false, nil)
                    
                default: return (self.isValid, self.duration)
            }
        }()
        
        return Attachment(
            id: self.id,
            serverId: (serverId ?? self.serverId),
            variant: variant,
            state: (state ?? self.state),
            contentType: contentType,
            byteCount: byteCount,
            creationTimestamp: (creationTimestamp ?? self.creationTimestamp),
            sourceFilename: sourceFilename,
            downloadUrl: (downloadUrl ?? self.downloadUrl),
            localRelativeFilePath: (localRelativeFilePath ?? self.localRelativeFilePath),
            width: width,
            height: height,
            duration: duration,
            isValid: isValid,
            encryptionKey: (encryptionKey ?? self.encryptionKey),
            digest: (digest ?? self.digest),
            caption: self.caption
        )
    }
}

// MARK: - Protobuf

public extension Attachment {
    init(proto: SNProtoAttachmentPointer) {
        func inferContentType(from filename: String?) -> String {
            guard
                let fileName: String = filename,
                let fileExtension: String = URL(string: fileName)?.pathExtension
            else { return OWSMimeTypeApplicationOctetStream }
            
            return (MIMETypeUtil.mimeType(forFileExtension: fileExtension) ?? OWSMimeTypeApplicationOctetStream)
        }
        
        self.id = UUID().uuidString
        self.serverId = "\(proto.id)"
        self.variant = {
            let voiceMessageFlag: Int32 = SNProtoAttachmentPointer.SNProtoAttachmentPointerFlags
                .voiceMessage
                .rawValue
            
            guard proto.hasFlags && ((proto.flags & UInt32(voiceMessageFlag)) > 0) else {
                return .standard
            }
            
            return .voiceMessage
        }()
        self.state = .pending
        self.contentType = (proto.contentType ?? inferContentType(from: proto.fileName))
        self.byteCount = UInt(proto.size)
        self.creationTimestamp = nil
        self.sourceFilename = proto.fileName
        self.downloadUrl = proto.url
        self.localRelativeFilePath = nil
        self.width = (proto.hasWidth && proto.width > 0 ? UInt(proto.width) : nil)
        self.height = (proto.hasHeight && proto.height > 0 ? UInt(proto.height) : nil)
        self.duration = nil         // Needs to be downloaded to be set
        self.isValid = false        // Needs to be downloaded to be set
        self.encryptionKey = proto.key
        self.digest = proto.digest
        self.caption = (proto.hasCaption ? proto.caption : nil)
    }
    
    func buildProto() -> SNProtoAttachmentPointer? {
        guard let serverId: UInt64 = UInt64(self.serverId ?? "") else { return nil }
        
        let builder = SNProtoAttachmentPointer.builder(id: serverId)
        builder.setContentType(contentType)
        
        if let sourceFilename: String = sourceFilename, !sourceFilename.isEmpty {
            builder.setFileName(sourceFilename)
        }
        
        if let caption: String = self.caption, !caption.isEmpty {
            builder.setCaption(caption)
        }
        
        builder.setSize(UInt32(byteCount))
        builder.setFlags(variant == .voiceMessage ?
            UInt32(SNProtoAttachmentPointer.SNProtoAttachmentPointerFlags.voiceMessage.rawValue) :
            0
        )
        
        if let encryptionKey: Data = encryptionKey, let digest: Data = digest {
            builder.setKey(encryptionKey)
            builder.setDigest(digest)
        }
        
        if
            let width: UInt = self.width,
            let height: UInt = self.height,
            width > 0,
            width < Int.max,
            height > 0,
            height < Int.max
        {
            builder.setWidth(UInt32(width))
            builder.setHeight(UInt32(height))
        }
        
        if let downloadUrl: String = self.downloadUrl {
            builder.setUrl(downloadUrl)
        }
        
        do {
            return try builder.build()
        }
        catch {
            SNLog("Couldn't construct attachment proto from: \(self).")
            return nil
        }
    }
}

// MARK: - GRDB Interactions

public extension Attachment {
    struct DownloadInfo: FetchableRecord, Decodable {
        public let attachmentId: String
        public let interactionId: Int64
    }
    
    static func pendingAttachmentDownloadInfo(for authorId: String) -> SQLRequest<Attachment.DownloadInfo> {
        let attachment: TypedTableAlias<Attachment> = TypedTableAlias()
        let interaction: TypedTableAlias<Interaction> = TypedTableAlias()
        let quote: TypedTableAlias<Quote> = TypedTableAlias()
        let interactionAttachment: TypedTableAlias<InteractionAttachment> = TypedTableAlias()
        let linkPreview: TypedTableAlias<LinkPreview> = TypedTableAlias()
        
        // Note: In GRDB all joins need to run via their "association" system which doesn't support the type
        // of query we have below (a required join based on one of 3 optional joins) so we have to construct
        // the query manually
        return """
            SELECT DISTINCT
                \(attachment[.id]) AS attachmentId,
                \(interaction[.id]) AS interactionId
        
            FROM \(Attachment.self)
            
            JOIN \(Interaction.self) ON
                \(interaction[.authorId]) = \(SQL(sql: ":authorId", arguments: StatementArguments(["authorId": authorId]))) AND (
                    \(interaction[.id]) = \(quote[.interactionId]) OR
                    \(interaction[.id]) = \(interactionAttachment[.interactionId]) OR
                    \(interaction[.linkPreviewUrl]) = \(linkPreview[.url])
                )
            
            LEFT JOIN \(Quote.self) ON \(quote[.attachmentId]) = \(attachment[.id])
            LEFT JOIN \(InteractionAttachment.self) ON \(interactionAttachment[.attachmentId]) = \(attachment[.id])
            LEFT JOIN \(LinkPreview.self) ON
                \(linkPreview[.attachmentId]) = \(attachment[.id]) AND
                \(linkPreview[.variant]) = \(SQL(
                    sql: ":variant",
                    arguments: StatementArguments(["variant": LinkPreview.Variant.standard])
                ))
        
            WHERE
                \(attachment[.variant]) = \(SQL(
                    sql: ":attachmentVariant",
                    arguments: StatementArguments(["attachmentVariant": Attachment.Variant.standard])
                )) AND
                \(attachment[.state]) = \(SQL(
                    sql: ":state",
                    arguments: StatementArguments(["state": Attachment.State.pending])
                ))
        
            ORDER BY interactionId DESC
        """
    }
}

// MARK: - Convenience - Static

public extension Attachment {
    private static let thumbnailDimensionSmall: UInt = 200
    private static let thumbnailDimensionMedium: UInt = 450
    
    /// This size is large enough to render full screen
    private static var thumbnailDimensionLarge: UInt = {
        let screenSizePoints: CGSize = UIScreen.main.bounds.size
        let minZoomFactor: CGFloat = UIScreen.main.scale
        
        return UInt(floor(max(screenSizePoints.width, screenSizePoints.height) * minZoomFactor))
    }()
    
    private static var sharedDataAttachmentsDirPath: String = {
        OWSFileSystem.appSharedDataDirectoryPath().appending("/Attachments")
    }()
    
    internal static var attachmentsFolder: String = {
        let attachmentsFolder: String = sharedDataAttachmentsDirPath
        OWSFileSystem.ensureDirectoryExists(attachmentsFolder)
        
        return attachmentsFolder
    }()
    
    private static var thumbnailsFolder: String = {
        let attachmentsFolder: String = sharedDataAttachmentsDirPath
        OWSFileSystem.ensureDirectoryExists(attachmentsFolder)
        
        return attachmentsFolder
    }()
    
    internal static func originalFilePath(id: String, mimeType: String, sourceFilename: String?) -> String? {
        return MIMETypeUtil.filePath(
            forAttachment: id,
            ofMIMEType: mimeType,
            sourceFilename: sourceFilename,
            inFolder: Attachment.attachmentsFolder
        )
    }
    
    internal static func imageSize(contentType: String, originalFilePath: String) -> CGSize? {
        let isVideo: Bool = MIMETypeUtil.isVideo(contentType)
        let isImage: Bool = MIMETypeUtil.isImage(contentType)
        let isAnimated: Bool = MIMETypeUtil.isAnimated(contentType)
        
        guard isVideo || isImage || isAnimated else { return nil }
        
        if isVideo {
            guard OWSMediaUtils.isValidVideo(path: originalFilePath) else { return nil }
            
            return Attachment.videoStillImage(filePath: originalFilePath)?.size
        }
        
        return NSData.imageSize(forFilePath: originalFilePath, mimeType: contentType)
    }
    
    static func videoStillImage(filePath: String) -> UIImage? {
        return try? OWSMediaUtils.thumbnail(
            forVideoAtPath: filePath,
            maxDimension: CGFloat(Attachment.thumbnailDimensionLarge)
        )
    }
    
    internal static func determineValidityAndDuration(contentType: String, originalFilePath: String?) -> (isValid: Bool, duration: TimeInterval?) {
        guard let originalFilePath: String = originalFilePath else { return (false, nil) }
        
        // Process audio attachments
        if MIMETypeUtil.isAudio(contentType) {
            do {
                let audioPlayer: AVAudioPlayer = try AVAudioPlayer(contentsOf: URL(fileURLWithPath: originalFilePath))
                
                return ((audioPlayer.duration > 0), audioPlayer.duration)
            }
            catch {
                switch (error as NSError).code {
                    case Int(kAudioFileInvalidFileError), Int(kAudioFileStreamError_InvalidFile):
                        // Ignore "invalid audio file" errors
                        return (false, nil) // TODO: Confirm this behaviour (previously returned 0)
                        
                    default: return (false, nil)
                }
            }
        }
        
        // Process image attachments
        if MIMETypeUtil.isImage(contentType) {
            return (
                NSData.ows_isValidImage(atPath: originalFilePath, mimeType: contentType),
                nil
            )
        }
        
        // Process video attachments
        if MIMETypeUtil.isVideo(contentType) {
            let videoPlayer: AVPlayer = AVPlayer(url: URL(fileURLWithPath: originalFilePath))
            let durationSeconds: TimeInterval? = videoPlayer.currentItem
                .map { item -> TimeInterval in
                    // Accorting to the CMTime docs "value/timescale = seconds"
                    (TimeInterval(item.duration.value) / TimeInterval(item.duration.timescale))
                }
            
            return (
                OWSMediaUtils.isValidVideo(path: originalFilePath),
                durationSeconds
            )
        }
        
        // Any other attachment types are valid and have no duration
        return (true, nil)
    }
}

// MARK: - Convenience

extension Attachment {
    public enum ThumbnailSize {
        case small
        case medium
        case large
        
        var dimension: UInt {
            switch self {
                case .small: return Attachment.thumbnailDimensionSmall
                case .medium: return Attachment.thumbnailDimensionMedium
                case .large: return Attachment.thumbnailDimensionLarge
            }
        }
    }
    
    public var originalFilePath: String? {
        return Attachment.originalFilePath(
            id: self.id,
            mimeType: self.contentType,
            sourceFilename: self.sourceFilename
        )
    }
    
    var thumbnailsDirPath: String {
        // Thumbnails are written to the caches directory, so that iOS can
        // remove them if necessary
        return "\(OWSFileSystem.cachesDirectoryPath())/\(id)-thumbnails"
    }
    
    var originalImage: UIImage? {
        guard let originalFilePath: String = originalFilePath else { return nil }
        
        if isVideo {
            return Attachment.videoStillImage(filePath: originalFilePath)
        }
        
        guard isImage || isAnimated else { return nil }
        guard isValid else { return nil }
        
        return UIImage(contentsOfFile: originalFilePath)
    }
    
    public var isImage: Bool { MIMETypeUtil.isImage(contentType) }
    public var isVideo: Bool { MIMETypeUtil.isVideo(contentType) }
    public var isAnimated: Bool { MIMETypeUtil.isAnimated(contentType) }
    public var isAudio: Bool { MIMETypeUtil.isAudio(contentType) }
    
    public var isVisualMedia: Bool { isImage || isVideo || isAnimated }
    
    public func readDataFromFile() throws -> Data? {
        guard let filePath: String = Attachment.originalFilePath(id: self.id, mimeType: self.contentType, sourceFilename: self.sourceFilename) else {
            return nil
        }
        
        return try Data(contentsOf: URL(fileURLWithPath: filePath))
    }
    
    public func thumbnailPath(for dimensions: UInt) -> String {
        return "\(thumbnailsDirPath)/thumbnail-\(dimensions).jpg"
    }
    
    private func loadThumbnail(with dimensions: UInt, success: @escaping (UIImage) -> (), failure: @escaping () -> ()) {
        guard let width: UInt = self.width, let height: UInt = self.height, width > 1, height > 1 else {
            failure()
            return
        }
        
        // There's no point in generating a thumbnail if the original is smaller than the
        // thumbnail size
        if width < dimensions || height < dimensions {
            guard let image: UIImage = originalImage else {
                failure()
                return
            }
            
            success(image)
            return
        }
        
        let thumbnailPath = thumbnailPath(for: dimensions)
        
        if FileManager.default.fileExists(atPath: thumbnailPath) {
            guard let image: UIImage = UIImage(contentsOfFile: thumbnailPath) else {
                failure()
                return
            }
            
            success(image)
            return
        }
        
        OWSThumbnailService.shared.ensureThumbnail(
            for: self,
            dimensions: dimensions,
            success: { loadedThumbnail in success(loadedThumbnail.image) },
            failure: { _ in failure() }
        )
    }
    
    public func thumbnail(size: ThumbnailSize, success: @escaping (UIImage) -> (), failure: @escaping () -> ()) {
        loadThumbnail(with: size.dimension, success: success, failure: failure)
    }
    
    func thumbnailSync(size: ThumbnailSize) -> UIImage? {
        guard isVideo || isImage || isAnimated else { return nil }
        
        let semaphore: DispatchSemaphore = DispatchSemaphore(value: 0)
        var image: UIImage?
        
        thumbnail(
            size: size,
            success: { loadedImage in
                image = loadedImage
                semaphore.signal()
            },
            failure: { semaphore.signal() }
        )

        // Wait up to 5 seconds for the thumbnail to be loaded
        _ = semaphore.wait(timeout: .now() + .seconds(5))
        
        return image
    }
    
    public func cloneAsThumbnail() -> Attachment {
        fatalError("TODO: Add this back")
    }
    
    public func write(data: Data) throws -> Bool {
        guard let originalFilePath: String = originalFilePath else { return false }

        try data.write(to: URL(fileURLWithPath: originalFilePath))
        
        return true
    }
}