import SwiftUI
import FlixyDesign
import FlixyPlayback
import MediaKit

/// Die aufklappbaren technischen Angaben zu einer Datei.
///
/// Zeigt nicht nur, was in der Datei steckt, sondern auch, wie Flixy sie
/// abspielen wird und warum. Bei der Frage „warum ruckelt das" ist das die
/// erste Stelle zum Nachsehen — und in Phase 1, wo es noch kein Transcoding
/// gibt, erklärt es, warum bei manchen Dateien kein Bild-in-Bild angeboten wird.
struct TechnicalDetails: View {
    let media: MediaVersion
    let part: MediaFile
    @Binding var isExpanded: Bool

    private var decision: PlaybackDecision {
        PlaybackDecider().decide(profile: media.profile(file: part), policy: .directPlayOnly)
    }

    var body: some View {
        DisclosureGroup(isExpanded: $isExpanded) {
            VStack(alignment: .leading, spacing: FlixySpacing.snug) {
                row("technical.playbackMethod", playbackMethodLabel)
                if let reason = rationaleLabel {
                    row("technical.reason", reason)
                }

                Divider().overlay(Color.flixySeparator).padding(.vertical, FlixySpacing.tight)

                if let container = part.container { row("technical.container", container.uppercased()) }
                if let codec = media.videoCodec { row("technical.videoCodec", codec.uppercased()) }
                if let width = media.width, let height = media.height {
                    row("technical.resolution", "\(width) × \(height)")
                }
                if let bitrate = media.bitrate {
                    row("technical.bitrate", "\(bitrate / 1000) Mbit/s")
                }
                if let size = part.size {
                    row("technical.size", size.formatted(.byteCount(style: .file)))
                }

                if !part.audioStreams.isEmpty {
                    Divider().overlay(Color.flixySeparator).padding(.vertical, FlixySpacing.tight)
                    ForEach(part.audioStreams) { stream in
                        row("technical.audio", trackLabel(stream))
                    }
                }

                if !part.subtitleStreams.isEmpty {
                    ForEach(part.subtitleStreams) { stream in
                        row("technical.subtitle", trackLabel(stream))
                    }
                }

                if let file = part.file {
                    Divider().overlay(Color.flixySeparator).padding(.vertical, FlixySpacing.tight)
                    VStack(alignment: .leading, spacing: 2) {
                        Text("technical.file")
                            .font(.flixyCaption)
                            .foregroundStyle(Color.flixyTextMuted)
                        Text(file)
                            .font(.system(.caption, design: .monospaced))
                            .foregroundStyle(Color.flixyTextSecondary)
                            .textSelection(.enabled)
                    }
                }
            }
            .padding(.top, FlixySpacing.snug)
        } label: {
            Text("technical.title")
                .font(.flixyRowHeader)
                .foregroundStyle(Color.flixyTextPrimary)
        }
        .tint(Color.flixyTextSecondary)
    }

    private func row(_ label: LocalizedStringKey, _ value: String) -> some View {
        HStack(alignment: .top) {
            Text(label)
                .font(.flixyCaption)
                .foregroundStyle(Color.flixyTextMuted)
            Spacer()
            Text(value)
                .font(.flixyCaption)
                .foregroundStyle(Color.flixyTextSecondary)
                .multilineTextAlignment(.trailing)
        }
    }

    private func trackLabel(_ stream: MediaStream) -> String {
        stream.displayTitle ?? [stream.language, stream.codec?.uppercased()]
            .compactMap(\.self)
            .joined(separator: " · ")
    }

    private var playbackMethodLabel: String {
        switch decision.method {
        case .directPlay(let engine):
            switch engine {
            case .avPlayer: String(localized: "technical.directPlayNative")
            case .vlc: String(localized: "technical.directPlayVLC")
            }
        case .transcode:
            String(localized: "technical.transcode")
        }
    }

    /// Der erste Grund, der gegen den Systemplayer sprach — mehrere
    /// aufzuzählen hilft niemandem, es reicht einer.
    private var rationaleLabel: String? {
        for reason in decision.rationale {
            switch reason {
            case .containerUnsupported(let container):
                return String(localized: "technical.reason.container \(container.uppercased())")
            case .videoCodecUnsupported(let codec):
                return String(localized: "technical.reason.videoCodec \(codec.uppercased())")
            case .audioCodecUnsupported(let codec):
                return String(localized: "technical.reason.audioCodec \(codec.uppercased())")
            case .streamsUnknown:
                return String(localized: "technical.reason.unanalyzed")
            case .qualityChosen:
                return String(localized: "technical.reason.chosen")
            case .nativelySupported, .bitrateExceedsLimit, .transcodingUnavailable:
                continue
            }
        }
        return nil
    }
}