import SwiftUI

struct ContentView: View {
    @EnvironmentObject private var settings: AppSettings
    @StateObject private var coordinator = ConversionCoordinator()
    @State private var showSettings = false
    @State private var isDropTargeted = false

    var body: some View {
        VStack(spacing: 0) {
            if coordinator.items.isEmpty {
                emptyState
            } else {
                FileListView()
            }
            Divider()
            statusBar
        }
        .frame(minWidth: 680, minHeight: 420)
        .navigationTitle("drop.two")
        .toolbar { toolbarContent }
        .overlay {
            if isDropTargeted {
                RoundedRectangle(cornerRadius: 8)
                    .strokeBorder(Color.gold, lineWidth: 2)
                    .padding(4)
                    .allowsHitTesting(false)
            }
        }
        .onDrop(of: [.fileURL], isTargeted: $isDropTargeted) { providers in
            FileImport.loadURLs(from: providers) { coordinator.addFiles($0) }
            return true
        }
        .environmentObject(coordinator)
        #if DEBUG
        // Nur zum Ausprobieren: DROPTWO_DEBUG_FILES="/a.mp4:/b.mov" lädt
        // Dateien beim Start, ohne Dialog.
        .onAppear {
            if let paths = ProcessInfo.processInfo.environment["DROPTWO_DEBUG_FILES"] {
                coordinator.addFiles(paths.split(separator: ":").map { URL(fileURLWithPath: String($0)) })
            }
        }
        #endif
        .sheet(isPresented: $showSettings) {
            SettingsView()
        }
        .alert(
            "Zieldatei existiert bereits",
            isPresented: Binding(
                get: { !coordinator.pendingConflicts.isEmpty },
                set: { isPresented in
                    if !isPresented { coordinator.cancelConflictResolution() }
                }
            )
        ) {
            Button("Überspringen") { coordinator.resolveConflicts(overwrite: false) }
            Button("Ersetzen", role: .destructive) { coordinator.resolveConflicts(overwrite: true) }
            Button("Abbrechen", role: .cancel) { coordinator.cancelConflictResolution() }
        } message: {
            Text(conflictMessage)
        }
    }

    // MARK: - Toolbar

    @ToolbarContentBuilder
    private var toolbarContent: some ToolbarContent {
        ToolbarItemGroup(placement: .primaryAction) {
            Button(action: addFiles) {
                Label("Dateien hinzufügen", systemImage: "plus")
            }
            .help("Videos hinzufügen (⌘O)")
            .keyboardShortcut("o")

            Button(action: chooseTargetFolder) {
                Label {
                    Text(settings.targetFolder?.lastPathComponent ?? String(localized: "Zielordner wählen …"))
                } icon: {
                    Image(systemName: "folder")
                }
                .labelStyle(.titleAndIcon)
            }
            .help(settings.targetFolder.map { "Zielordner: \($0.path)" } ?? String(localized: "Hier entsteht pro Projekt ein Unterordner mit beiden Fassungen."))

            Button("Start", action: start)
                .buttonStyle(ProminentButtonStyle())
                .keyboardShortcut(.defaultAction)
                .disabled(coordinator.items.isEmpty || coordinator.isRunning)
        }
        ToolbarItem(placement: .automatic) {
            Button { showSettings = true } label: {
                Label("Einstellungen", systemImage: "gearshape")
            }
            .help("Einstellungen")
        }
    }

    // MARK: - Leerer Zustand

    /// Kein Symbolbild, keine Box: nur ein Satz. Das ganze Fenster nimmt Dateien an.
    private var emptyState: some View {
        VStack(spacing: 10) {
            Text("9:16-Videos hierher ziehen.")
                .font(.system(size: 22, weight: .medium))
            HStack(spacing: 4) {
                Text("Oder")
                Button("Dateien wählen …", action: addFiles)
                    .buttonStyle(.link)
                    .tint(.gold)
                Text("· Daraus wird je eine 4:5-Fassung im Projektordner.")
            }
            .font(.system(size: 13))
            .foregroundStyle(.secondary)
        }
        .frame(maxWidth: .infinity, maxHeight: .infinity)
    }

    // MARK: - Statusleiste

    private var statusBar: some View {
        HStack(spacing: 6) {
            if coordinator.items.isEmpty {
                Text(settings.targetFolder.map { "Ziel: \($0.path)" } ?? String(localized: "Noch kein Zielordner gewählt."))
                    .foregroundStyle(settings.targetFolder == nil ? Color.attention : .secondary)
            } else {
                Text(summary)
                    .foregroundStyle(.secondary)
                if settings.targetFolder == nil {
                    Text("· Kein Zielordner – wird beim Start abgefragt.")
                        .foregroundStyle(Color.attention)
                }
                let missing = coordinator.itemsMissingFormat
                if missing.count > 1 && !coordinator.isRunning {
                    Text("·").foregroundStyle(.secondary)
                    Button("Bei allen \(missing.count) ohne Format „4x5“ anhängen") {
                        coordinator.setAppendFormat(true, for: missing.map(\.id))
                    }
                    .buttonStyle(.link)
                    .tint(.gold)
                }
            }
            Spacer()
            if !coordinator.items.isEmpty {
                Button("Liste leeren") { coordinator.removeAll() }
                    .buttonStyle(.link)
                    .foregroundStyle(.secondary)
                    .disabled(coordinator.isRunning)
            }
        }
        .font(.system(size: 11))
        .lineLimit(1)
        .padding(.horizontal, 16)
        .frame(height: 28)
        .background(.bar)
    }

    private var summary: String {
        let total = coordinator.items.count
        let done = coordinator.finishedCount
        let files = total == 1 ? String(localized: "1 Datei") : String(localized: "\(total) Dateien")
        if coordinator.isRunning {
            return String(localized: "\(files) · \(done) fertig · rendert …")
        }
        return done > 0
            ? String(localized: "\(files) · \(done) fertig")
            : files
    }

    // MARK: - Aktionen

    private func addFiles() {
        coordinator.addFiles(FileImport.chooseVideos(startingAt: settings.sourceFolder))
    }

    private func chooseTargetFolder() {
        if let url = FolderPicker.choose(startingAt: settings.targetFolder, prompt: String(localized: "Als Zielordner wählen")) {
            settings.setTargetFolder(url)
        }
    }

    private func start() {
        if settings.targetFolder == nil {
            chooseTargetFolder()
        }
        guard let target = settings.targetFolder else { return }
        coordinator.start(targetFolder: target)
    }

    private var conflictMessage: String {
        let names = coordinator.pendingConflicts.map(\.fileName).joined(separator: ", ")
        return "Für folgende Datei(en) existiert die Zieldatei schon: \(names). Ersetzen oder überspringen?"
    }
}