import AppKit
import SwiftUI

struct ContentView: View {
    @State private var inputURL: URL?
    @State private var outputURL: URL?
    @State private var episodes: [EpisodePlan] = []
    @State private var messages: [ExportMessage] = []
    @State private var overwriteExisting = false
    @State private var isExporting = false

    private var canExport: Bool {
        inputURL != nil && outputURL != nil && !episodes.isEmpty && !isExporting
    }

    var body: some View {
        VStack(spacing: 0) {
            toolbar

            Divider()

            HSplitView {
                VStack(alignment: .leading, spacing: 12) {
                    header
                    episodeTable
                }
                .frame(minWidth: 520)

                VStack(alignment: .leading, spacing: 12) {
                    Text("Protokoll")
                        .font(.headline)
                    messageList
                }
                .frame(minWidth: 280)
                .padding(16)
            }
        }
        .onChange(of: inputURL) { _ in reloadPreview() }
        .onAppear(perform: reloadPreview)
    }

    private var toolbar: some View {
        HStack(spacing: 10) {
            Button {
                chooseFolder(title: "Input-Ordner wählen") { url in
                    inputURL = url
                }
            } label: {
                Label("Input", systemImage: "folder")
            }

            Button {
                chooseFolder(title: "Output-Ordner wählen") { url in
                    outputURL = url
                }
            } label: {
                Label("Output", systemImage: "externaldrive")
            }

            Button {
                reloadPreview()
            } label: {
                Label("Aktualisieren", systemImage: "arrow.clockwise")
            }
            .disabled(inputURL == nil)

            Spacer()

            Toggle("Überschreiben", isOn: $overwriteExisting)
                .toggleStyle(.checkbox)

            Button {
                export()
            } label: {
                Label("Exportieren", systemImage: "square.and.arrow.down")
            }
            .buttonStyle(.borderedProminent)
            .disabled(!canExport)
        }
        .padding(12)
    }

    private var header: some View {
        VStack(alignment: .leading, spacing: 8) {
            Text("TonUINO Export")
                .font(.title2.weight(.semibold))

            VStack(alignment: .leading, spacing: 4) {
                PathRow(label: "Input", url: inputURL)
                PathRow(label: "Output", url: outputURL)
            }

            Text("\(episodes.count) Folgen, \(episodes.reduce(0) { $0 + $1.tracks.count }) Quelldateien")
                .foregroundStyle(.secondary)
        }
        .padding([.horizontal, .top], 16)
    }

    private var episodeTable: some View {
        Table(episodes) {
            TableColumn("Ziel") { episode in
                Text(episode.targetFolderName)
                    .monospacedDigit()
            }
            .width(48)

            TableColumn("Folge") { episode in
                VStack(alignment: .leading, spacing: 2) {
                    Text(episode.sourceName)
                        .lineLimit(1)
                    if !episode.warnings.isEmpty {
                        Text(episode.warnings.joined(separator: " · "))
                            .font(.caption)
                            .foregroundStyle(.orange)
                            .lineLimit(2)
                    }
                }
            }

            TableColumn("Quellen") { episode in
                Text("\(episode.tracks.count)")
                    .monospacedDigit()
            }
            .width(64)

            TableColumn("Zieldatei") { _ in
                Text("001.mp3")
                    .monospacedDigit()
            }
            .width(82)

            TableColumn("Erste Quelle") { episode in
                Text(episode.tracks.first?.source.lastPathComponent ?? "-")
                    .foregroundStyle(.secondary)
                    .lineLimit(1)
            }
        }
        .padding(.horizontal, 16)
        .padding(.bottom, 16)
    }

    private var messageList: some View {
        ScrollView {
            LazyVStack(alignment: .leading, spacing: 8) {
                if messages.isEmpty {
                    Text("Noch kein Export ausgeführt.")
                        .foregroundStyle(.secondary)
                } else {
                    ForEach(messages) { message in
                        HStack(alignment: .top, spacing: 8) {
                            Image(systemName: message.iconName)
                                .foregroundStyle(message.color)
                                .frame(width: 18)
                            Text(message.text)
                                .textSelection(.enabled)
                                .frame(maxWidth: .infinity, alignment: .leading)
                        }
                    }
                }
            }
        }
    }

    private func chooseFolder(title: String, completion: (URL) -> Void) {
        let panel = NSOpenPanel()
        panel.title = title
        panel.canChooseFiles = false
        panel.canChooseDirectories = true
        panel.allowsMultipleSelection = false
        panel.canCreateDirectories = true

        if panel.runModal() == .OK, let url = panel.url {
            completion(url)
        }
    }

    private func reloadPreview() {
        guard let inputURL else {
            episodes = []
            return
        }

        do {
            let scanner = TonUinoScanner(fileManager: .default)
            episodes = try scanner.scan(inputURL: inputURL)
            messages = scannerMessages(for: episodes)
        } catch {
            episodes = []
            messages = [.error("Vorschau fehlgeschlagen: \(error.localizedDescription)")]
        }
    }

    private func scannerMessages(for episodes: [EpisodePlan]) -> [ExportMessage] {
        var result: [ExportMessage] = []

        if episodes.isEmpty {
            result.append(.warning("Keine Unterordner mit Audiodateien gefunden."))
        }

        for episode in episodes where !episode.warnings.isEmpty {
            result.append(.warning("\(episode.sourceName): \(episode.warnings.joined(separator: ", "))"))
        }

        return result
    }

    private func export() {
        guard let outputURL else { return }

        isExporting = true
        messages = [.info("Export gestartet.")]

        DispatchQueue.global(qos: .userInitiated).async {
            let exporter = TonUinoExporter(fileManager: .default)
            let result = exporter.export(
                episodes: episodes,
                outputURL: outputURL,
                overwriteExisting: overwriteExisting
            )

            DispatchQueue.main.async {
                messages = result
                isExporting = false
            }
        }
    }
}

private struct PathRow: View {
    let label: String
    let url: URL?

    var body: some View {
        HStack(alignment: .firstTextBaseline, spacing: 8) {
            Text(label)
                .font(.caption.weight(.semibold))
                .foregroundStyle(.secondary)
                .frame(width: 48, alignment: .leading)
            Text(url?.path(percentEncoded: false) ?? "Nicht gewählt")
                .font(.caption)
                .lineLimit(1)
                .truncationMode(.middle)
                .textSelection(.enabled)
        }
    }
}

struct ExportMessage: Identifiable {
    enum Kind {
        case info
        case warning
        case error
    }

    let id = UUID()
    let kind: Kind
    let text: String

    var iconName: String {
        switch kind {
        case .info: "checkmark.circle"
        case .warning: "exclamationmark.triangle"
        case .error: "xmark.octagon"
        }
    }

    var color: Color {
        switch kind {
        case .info: .green
        case .warning: .orange
        case .error: .red
        }
    }

    static func info(_ text: String) -> ExportMessage {
        ExportMessage(kind: .info, text: text)
    }

    static func warning(_ text: String) -> ExportMessage {
        ExportMessage(kind: .warning, text: text)
    }

    static func error(_ text: String) -> ExportMessage {
        ExportMessage(kind: .error, text: text)
    }
}