import SwiftUI

struct YouTubeImportView: View {
    let folderNumber: Int
    let onComplete: () -> Void
    @EnvironmentObject private var app: AppModel
    @Environment(\.dismiss) private var dismiss
    @State private var urlText = ""
    @State private var video: YouTubeVideoInfo?
    @State private var splitByChapters = false
    @State private var isInspecting = false
    @State private var isImporting = false
    @State private var imported = false
    @State private var errorMessage: String?

    private var chapters: [YouTubeChapter] { video?.usableChapters ?? [] }

    var body: some View {
        VStack(alignment: .leading, spacing: 16) {
            VStack(alignment: .leading, spacing: 4) {
                Text("YouTube-Audio importieren").font(.title2.bold())
                Text("Ziel: Ordner \(String(format: "%02d", folderNumber))")
                    .foregroundStyle(.secondary)
            }

            HStack {
                TextField("https://www.youtube.com/watch?v=…", text: $urlText)
                    .textFieldStyle(.roundedBorder)
                    .onSubmit { inspectVideo() }
                    .onChange(of: urlText) { _ in video = nil; imported = false; errorMessage = nil }
                Button("Video prüfen", systemImage: "magnifyingglass") { inspectVideo() }
                    .disabled(isInspecting || isImporting || urlText.trimmingCharacters(in: .whitespacesAndNewlines).isEmpty)
            }

            if isInspecting {
                ProgressView("YouTube-Video wird analysiert…")
            } else if let video {
                VStack(alignment: .leading, spacing: 10) {
                    VStack(alignment: .leading, spacing: 3) {
                        Text(video.title).font(.headline).lineLimit(2)
                        Text([video.artist.isEmpty ? nil : video.artist, durationText(video.duration)].compactMap { $0 }.joined(separator: " · "))
                            .font(.caption).foregroundStyle(.secondary)
                    }
                    Picker("Importart", selection: $splitByChapters) {
                        Text("Gesamtes Video als eine MP3").tag(false)
                        Text("Einzeldatei je Kapitel (\(chapters.count))").tag(true).disabled(chapters.isEmpty)
                    }
                    if chapters.isEmpty {
                        Text("Keine Kapitel gefunden. Das Video kann als eine Datei importiert werden.")
                            .font(.caption).foregroundStyle(.secondary)
                    } else {
                        VStack(alignment: .leading, spacing: 4) {
                            Text("Kapitelvorschau").font(.subheadline.weight(.semibold))
                            ForEach(Array(chapters.indices.prefix(6)), id: \.self) { index in
                                let chapter = chapters[index]
                                HStack(spacing: 8) {
                                    Text(String(format: "%02d", index + 1)).foregroundStyle(.secondary).monospacedDigit()
                                    Text(chapter.title?.isEmpty == false ? chapter.title! : "Kapitel \(index + 1)").lineLimit(1)
                                    Spacer()
                                    Text(durationText((chapter.end ?? video.duration).map { $0 - chapter.start }))
                                        .foregroundStyle(.secondary).monospacedDigit()
                                }.font(.caption)
                            }
                            if chapters.count > 6 { Text("und \(chapters.count - 6) weitere Kapitel…").font(.caption).foregroundStyle(.secondary) }
                        }
                        .padding(12)
                        .background(.quaternary.opacity(0.35), in: RoundedRectangle(cornerRadius: 8))
                    }
                }
            }

            if isImporting {
                ProgressView("Audio wird heruntergeladen, konvertiert und importiert…")
            } else if let errorMessage {
                Label(errorMessage, systemImage: "exclamationmark.triangle.fill")
                    .font(.callout).foregroundStyle(.red).fixedSize(horizontal: false, vertical: true)
            } else if imported {
                Label("Audio wurde in Ordner \(String(format: "%02d", folderNumber)) importiert.", systemImage: "checkmark.circle.fill")
                    .foregroundStyle(.green)
            }

            Spacer(minLength: 0)
            HStack {
                Text("yt-dlp lädt die Audiospur; FFmpeg erstellt MP3-Dateien mit Titel- und Interpret-Tags.")
                    .font(.caption).foregroundStyle(.secondary).frame(maxWidth: .infinity, alignment: .leading)
                Button("Schließen") { dismiss() }.keyboardShortcut(.cancelAction)
                Button("Importieren", systemImage: "arrow.down.to.line") { importVideo() }
                    .buttonStyle(.borderedProminent)
                    .disabled(video == nil || isInspecting || isImporting || (splitByChapters && chapters.isEmpty))
            }
        }
        .padding(22)
        .frame(width: 640, height: 540)
    }

    private func inspectVideo() {
        let value = urlText.trimmingCharacters(in: .whitespacesAndNewlines)
        guard !value.isEmpty else { return }
        isInspecting = true; errorMessage = nil; imported = false
        Task {
            do {
                let result = try await Task.detached(priority: .userInitiated) { try YouTubeImportService.inspect(value) }.value
                video = result
                splitByChapters = false
                isInspecting = false
            } catch {
                errorMessage = error.localizedDescription
                isInspecting = false
            }
        }
    }

    private func importVideo() {
        guard let video else { return }
        isImporting = true; errorMessage = nil; imported = false
        Task {
            do {
                try await app.library.importYouTube(video, splitByChapters: splitByChapters, to: folderNumber)
                isImporting = false; imported = true
                app.status = "YouTube-Audio in Ordner \(String(format: "%02d", folderNumber)) importiert"
                onComplete()
            } catch {
                isImporting = false; errorMessage = error.localizedDescription
            }
        }
    }

    private func durationText(_ seconds: Double?) -> String {
        guard let seconds, seconds.isFinite, seconds >= 0 else { return "" }
        let total = Int(seconds.rounded())
        return total >= 3600 ? String(format: "%d:%02d:%02d", total / 3600, (total / 60) % 60, total % 60) : String(format: "%d:%02d", total / 60, total % 60)
    }
}