import AVFoundation
import DropTwoCore
import SwiftUI

/// Die Dateien als schlichte Tabelle: Standbild mit Ausschnitt · Datei ·
/// wird zu · Status. Klick aufs Standbild öffnet die Ausschnitt-Ansicht.
struct FileListView: View {
    @EnvironmentObject private var coordinator: ConversionCoordinator
    @State private var previewTarget: PreviewTarget?

    var body: some View {
        VStack(spacing: 0) {
            header
            Divider()
            ScrollView {
                LazyVStack(spacing: 0) {
                    ForEach(coordinator.items) { item in
                        FileRow(item: item) {
                            previewTarget = PreviewTarget(itemID: item.id)
                        }
                        Divider().padding(.leading, 16)
                    }
                }
            }
        }
        #if DEBUG
        .onAppear {
            if ProcessInfo.processInfo.environment["DROPTWO_DEBUG_REVIEW"] != nil, let first = coordinator.items.last {
                previewTarget = PreviewTarget(itemID: first.id)
            }
        }
        #endif
        .sheet(item: $previewTarget) { target in
            if let item = coordinator.items.first(where: { $0.id == target.itemID }) {
                ReviewSheet(sourceURL: item.sourceURL, initialPlan: item.cropPlan) { plan in
                    coordinator.setCropPlan(plan, for: item.id)
                }
            }
        }
    }

    private var header: some View {
        HStack(spacing: FileRow.columnSpacing) {
            Color.clear.frame(width: FileRow.thumbnailWidth)
            Text("Datei").frame(maxWidth: .infinity, alignment: .leading)
            Text("wird zu").frame(maxWidth: .infinity, alignment: .leading)
            Text("Ausschnitt").frame(width: FileRow.framingWidth, alignment: .leading)
            Text("Status").frame(width: FileRow.statusWidth, alignment: .leading)
        }
        .font(.system(size: 11))
        .foregroundStyle(.secondary)
        .padding(.horizontal, 16)
        .frame(height: 26)
    }

    private struct PreviewTarget: Identifiable {
        let itemID: UUID
        var id: UUID { itemID }
    }
}

private struct FileRow: View {
    static let thumbnailWidth: CGFloat = 27
    static let statusWidth: CGFloat = 170
    static let framingWidth: CGFloat = 130
    static let columnSpacing: CGFloat = 16

    let item: DropItem
    let onReview: () -> Void

    @EnvironmentObject private var coordinator: ConversionCoordinator
    @State private var thumbnail: CGImage?

    var body: some View {
        HStack(spacing: Self.columnSpacing) {
            Button(action: onReview) {
                CropThumbnail(image: thumbnail, offset: item.cropPlan.keyframes[0].offset, dimmed: item.isMissingFormat)
            }
            .buttonStyle(.plain)
            .help("Ausschnitt prüfen und verschieben")

            Text(item.fileName)
                .lineLimit(1)
                .truncationMode(.middle)
                .frame(maxWidth: .infinity, alignment: .leading)

            targetColumn
                .lineLimit(1)
                .truncationMode(.middle)
                .frame(maxWidth: .infinity, alignment: .leading)

            framingButton
                .frame(width: Self.framingWidth, alignment: .leading)

            statusColumn
                .frame(width: Self.statusWidth, alignment: .leading)
        }
        .font(.system(size: 13))
        .padding(.horizontal, 16)
        .padding(.vertical, 8)
        .background(item.isMissingFormat ? Color.attention.opacity(0.07) : Color.clear)
        .contentShape(Rectangle())
        .contextMenu { contextMenu }
        .task(id: item.sourceURL) { thumbnail = await Self.makeThumbnail(for: item.sourceURL) }
    }

    // MARK: - Spalten

    @ViewBuilder
    private var targetColumn: some View {
        if let target = item.plannedTargetName {
            Text(target).foregroundStyle(.secondary)
        } else {
            switch item.nameOutcome {
            case .skipped:
                Text("ist schon 4:5").foregroundStyle(.secondary)
            case .rejected(.formatSegmentMissing):
                Text("kein Format im Namen").foregroundStyle(Color.attention)
            case .rejected(.finderDuplicate):
                Text("Finder-Duplikat").foregroundStyle(Color.attention)
            case .parsed:
                Text("–").foregroundStyle(.secondary)
            }
        }
    }

    @ViewBuilder
    private var statusColumn: some View {
        switch item.status {
        case .waiting:
            if item.isMissingFormat && !coordinator.isRunning {
                Button("„4x5“ anhängen") { coordinator.setAppendFormat(true, for: [item.id]) }
                    .controlSize(.small)
                    .help(appendHelp)
            } else if item.plannedTargetName == nil {
                Text("wird übersprungen").foregroundStyle(.secondary)
            } else {
                Text("wartet").foregroundStyle(.secondary)
            }
        case .running(let progress):
            HStack(spacing: 8) {
                Text("rendert \(Int(progress * 100)) %")
                    .monospacedDigit()
                    .foregroundStyle(Color.gold)
                ProgressView(value: progress)
                    .progressViewStyle(.linear)
                    .tint(.gold)
                    .frame(width: 60)
            }
        case .succeeded(let destination):
            HStack(spacing: 4) {
                Text("fertig ·")
                Button("im Finder") { NSWorkspace.shared.activateFileViewerSelecting([destination]) }
                    .buttonStyle(.link)
                    .tint(.gold)
            }
        case .skipped(let reason):
            Text(reason.errorDescription ?? "übersprungen").foregroundStyle(.secondary).help(reason.errorDescription ?? "")
        case .skippedByUser(let reason):
            Text("übersprungen").foregroundStyle(.secondary).help(reason)
        case .rejected(let reason):
            Text(reason.errorDescription ?? "abgelehnt").foregroundStyle(Color.attention).help(reason.errorDescription ?? "")
        case .failed(let message):
            Text(message).foregroundStyle(Color.attention).help(message)
        }
    }

    @ViewBuilder
    private var contextMenu: some View {
        Button("Ausschnitt anpassen …", action: onReview)
        if item.isMissingFormat {
            Button("„4x5“ an den Namen anhängen") { coordinator.setAppendFormat(true, for: [item.id]) }
        }
        if case .succeeded(let destination) = item.status {
            Button("Im Finder zeigen") { NSWorkspace.shared.activateFileViewerSelecting([destination]) }
        }
        Divider()
        Button("Aus der Liste entfernen") { coordinator.remove(item.id) }
            .disabled(coordinator.isRunning)
    }

    private var appendHelp: String {
        guard let preview = FileNameParser.appendingTargetFormat(to: item.fileName) else { return "" }
        return "Ergibt „\(preview.projectName)/\(ConversionPipeline.mp4Name(preview.targetFileName))“"
    }

    /// Zeigt, wie der Ausschnitt steht, und öffnet ihn — derselbe Weg wie
    /// der Klick aufs Standbild, nur als sichtbarer Knopf.
    private var framingButton: some View {
        Button(action: onReview) {
            Label(framingText, systemImage: "crop")
        }
        .controlSize(.small)
        .tint(item.cropPlan.isDefault ? nil : .gold)
        .foregroundStyle(item.cropPlan.isDefault ? Color.primary : Color.gold)
        .help("Ausschnitt prüfen und verschieben")
    }

    private var framingText: String {
        let plan = item.cropPlan
        if plan.keyframes.count > 1 {
            return String(localized: "\(plan.keyframes.count) Positionen")
        }
        switch plan.keyframes[0].offset {
        case 0: return String(localized: "mittig")
        case ..<0: return String(localized: "weiter oben")
        default: return String(localized: "weiter unten")
        }
    }

    private static func makeThumbnail(for url: URL) async -> CGImage? {
        let generator = AVAssetImageGenerator(asset: AVURLAsset(url: url))
        generator.appliesPreferredTrackTransform = true
        generator.maximumSize = CGSize(width: 120, height: 120)
        let time = CMTime(seconds: 0.5, preferredTimescale: 600)
        return await withCheckedContinuation { continuation in
            generator.generateCGImagesAsynchronously(forTimes: [NSValue(time: time)]) { _, image, _, _, _ in
                continuation.resume(returning: image)
            }
        }
    }
}

/// Mini-Standbild im 9:16-Format mit dem 4:5-Rahmen an seiner Position.
private struct CropThumbnail: View {
    let image: CGImage?
    let offset: CGFloat
    var dimmed = false

    private let size = CGSize(width: 27, height: 48)

    var body: some View {
        let reference = CGSize(width: 1080, height: 1920)
        let rect = CropEngine.cropRect(forSourceSize: reference, offset: offset)
        let scale = size.height / reference.height
        ZStack(alignment: .top) {
            Rectangle().fill(Color.secondary.opacity(0.2))
            if let image {
                Image(decorative: image, scale: 1)
                    .resizable()
                    .aspectRatio(contentMode: .fill)
                    .frame(width: size.width, height: size.height)
            }
            // Abgedunkelt, was wegfällt; Goldrahmen, was bleibt.
            VStack(spacing: 0) {
                Rectangle().fill(Color.black.opacity(0.5)).frame(height: rect.minY * scale)
                Rectangle()
                    .strokeBorder(Color.gold.opacity(dimmed ? 0.5 : 1), lineWidth: 1.5)
                    .frame(height: rect.height * scale)
                Rectangle().fill(Color.black.opacity(0.5))
            }
        }
        .frame(width: size.width, height: size.height)
        .clipShape(RoundedRectangle(cornerRadius: 2))
    }
}