import Foundation

/// Eine Datei auf der Platte des Servers.
///
/// Plex schachtelt hier zweifach: ein Titel hat mehrere `Media` (dieselbe
/// Fassung in 4K und 1080p), und jedes `Media` hat `Part` (ein Film, der auf
/// zwei Dateien verteilt ist). Für die Wiedergabe zählt der `Part` — er trägt
/// den Pfad.
public struct PlexPart: Sendable, Equatable, Codable, Identifiable {
    public let id: Int
    /// Der Pfad, unter dem die Datei abrufbar ist.
    public let key: String
    public let container: String?
    public let size: Int64?
    public let duration: Int?
    public let file: String?
    public let streams: [PlexStream]

    private enum CodingKeys: String, CodingKey {
        case id, key, container, size, duration, file
        // Plex schreibt verschachtelte Sammlungen groß.
        case streams = "Stream"
    }

    public init(
        id: Int,
        key: String,
        container: String? = nil,
        size: Int64? = nil,
        duration: Int? = nil,
        file: String? = nil,
        streams: [PlexStream] = []
    ) {
        self.id = id
        self.key = key
        self.container = container
        self.size = size
        self.duration = duration
        self.file = file
        self.streams = streams
    }

    public init(from decoder: any Decoder) throws {
        let container = try decoder.container(keyedBy: CodingKeys.self)
        self.id = try container.decode(Int.self, forKey: .id)
        self.key = try container.decode(String.self, forKey: .key)
        self.container = try container.decodeIfPresent(String.self, forKey: .container)
        self.size = try container.decodeIfPresent(Int64.self, forKey: .size)
        self.duration = try container.decodeIfPresent(Int.self, forKey: .duration)
        self.file = try container.decodeIfPresent(String.self, forKey: .file)
        // Fehlt die Spurenliste, ist die Datei noch nicht analysiert. Das ist
        // kein Fehler — es heißt nur, dass wir nicht über DirectPlay
        // entscheiden können und im Zweifel transcodieren lassen.
        self.streams = try container.decodeIfPresent([PlexStream].self, forKey: .streams) ?? []
    }

    public var videoStream: PlexStream? { streams.first { $0.kind == .video } }
    public var audioStreams: [PlexStream] { streams.filter { $0.kind == .audio } }
    public var subtitleStreams: [PlexStream] { streams.filter { $0.kind == .subtitle } }
    /// Die Tonspur, die der Server als aktiv meldet — sonst die erste.
    public var selectedAudioStream: PlexStream? {
        audioStreams.first { $0.isSelected } ?? audioStreams.first
    }
}

/// Eine Fassung eines Titels.
public struct PlexMedia: Sendable, Equatable, Codable, Identifiable {
    public let id: Int
    public let container: String?
    public let videoCodec: String?
    public let audioCodec: String?
    /// Plex meldet hier Werte wie `"1080"`, `"4k"` oder `"sd"` — keine Zahl.
    public let videoResolution: String?
    public let videoProfile: String?
    /// In Kilobit pro Sekunde.
    public let bitrate: Int?
    public let width: Int?
    public let height: Int?
    public let audioChannels: Int?
    public let duration: Int?
    public let parts: [PlexPart]

    private enum CodingKeys: String, CodingKey {
        case id, container, videoCodec, audioCodec, videoResolution, videoProfile
        case bitrate, width, height, audioChannels, duration
        case parts = "Part"
    }

    public init(
        id: Int,
        container: String? = nil,
        videoCodec: String? = nil,
        audioCodec: String? = nil,
        videoResolution: String? = nil,
        videoProfile: String? = nil,
        bitrate: Int? = nil,
        width: Int? = nil,
        height: Int? = nil,
        audioChannels: Int? = nil,
        duration: Int? = nil,
        parts: [PlexPart] = []
    ) {
        self.id = id
        self.container = container
        self.videoCodec = videoCodec
        self.audioCodec = audioCodec
        self.videoResolution = videoResolution
        self.videoProfile = videoProfile
        self.bitrate = bitrate
        self.width = width
        self.height = height
        self.audioChannels = audioChannels
        self.duration = duration
        self.parts = parts
    }

    public init(from decoder: any Decoder) throws {
        let container = try decoder.container(keyedBy: CodingKeys.self)
        self.id = try container.decode(Int.self, forKey: .id)
        self.container = try container.decodeIfPresent(String.self, forKey: .container)
        self.videoCodec = try container.decodeIfPresent(String.self, forKey: .videoCodec)
        self.audioCodec = try container.decodeIfPresent(String.self, forKey: .audioCodec)
        self.videoResolution = try container.decodeIfPresent(String.self, forKey: .videoResolution)
        self.videoProfile = try container.decodeIfPresent(String.self, forKey: .videoProfile)
        self.bitrate = try container.decodeIfPresent(Int.self, forKey: .bitrate)
        self.width = try container.decodeIfPresent(Int.self, forKey: .width)
        self.height = try container.decodeIfPresent(Int.self, forKey: .height)
        self.audioChannels = try container.decodeIfPresent(Int.self, forKey: .audioChannels)
        self.duration = try container.decodeIfPresent(Int.self, forKey: .duration)
        self.parts = try container.decodeIfPresent([PlexPart].self, forKey: .parts) ?? []
    }

    /// Eine kurze Beschreibung für die Versionsauswahl auf der Detailseite,
    /// etwa „4K · HEVC · 38,2 Mbit/s".
    public var qualityLabel: String {
        var pieces: [String] = []
        if let videoResolution { pieces.append(videoResolution.uppercased()) }
        if let videoCodec { pieces.append(videoCodec.uppercased()) }
        if let bitrate { pieces.append("\(bitrate / 1000) Mbit/s") }
        return pieces.joined(separator: " · ")
    }
}