import SwiftUI
import UIKit
import UniformTypeIdentifiers

struct RootView: View {
    @StateObject private var controller = PlayerController()
    @StateObject private var catalogVM = CatalogViewModel()
    @State private var activeModule: Module = .train
    @State private var continuousPlayback = false
    @State private var showImporter = false
    @State private var showFullscreenPlayer = false

    enum Module {
        case train
        case test
    }

    var body: some View {
        ZStack {
            Theme.background.ignoresSafeArea()
            VStack(spacing: 0) {
                header
                moduleTabs
                if activeModule == .train {
                    TrainingView(
                        controller: controller,
                        catalogVM: catalogVM,
                        continuousPlayback: $continuousPlayback,
                        onFullscreen: enterFullscreen
                    )
                } else {
                    TestView(controller: controller, onFullscreen: enterFullscreen)
                }
            }
        }
        .preferredColorScheme(.dark)
        .onAppear {
            catalogVM.controller = controller
            controller.setContinuousPlayback(continuousPlayback)
        }
        .onChange(of: activeModule) { module in
            if module == .train {
                controller.setContinuousPlayback(continuousPlayback)
            } else {
                controller.setContinuousPlayback(true)
            }
        }
        .fileImporter(
            isPresented: $showImporter,
            allowedContentTypes: [.movie],
            allowsMultipleSelection: false
        ) { result in
            if case .success(let urls) = result, let url = urls.first {
                Task {
                    await catalogVM.importVideo(at: url)
                }
            }
        }
        .fullScreenCover(isPresented: $showFullscreenPlayer) {
            FullscreenPlayerView(controller: controller) {
                exitFullscreen()
            }
            .onAppear(perform: enterFullscreen)
        }
    }

    private var header: some View {
        HStack(spacing: 0) {
            VStack(alignment: .leading, spacing: 2) {
                Text("八哥口语")
                    .font(.system(size: 32, weight: .bold))
                    .foregroundColor(.white)
                Text("外语跟读训练神器")
                    .font(.system(size: 15))
                    .foregroundColor(Theme.textMuted)
            }
            Spacer()
            headerButton("导入") {
                showImporter = true
            }
            headerButton("刷新") {
                Task {
                    await catalogVM.load()
                }
            }
        }
        .padding(.horizontal, 18)
        .padding(.top, 8)
        .padding(.bottom, 10)
    }

    private func headerButton(_ label: String, action: @escaping () -> Void) -> some View {
        Button(action: action) {
            Text(label)
                .font(.system(size: 14, weight: .bold))
                .foregroundColor(.white)
                .padding(.horizontal, 14)
                .frame(height: 40)
                .background(Theme.buttonBlue)
                .clipShape(RoundedRectangle(cornerRadius: 8))
        }
        .buttonStyle(.plain)
        .padding(.leading, 8)
    }

    private var moduleTabs: some View {
        HStack(spacing: 0) {
            moduleTab("训练", module: .train)
            moduleTab("测试", module: .test)
        }
        .padding(.horizontal, 16)
        .padding(.bottom, 8)
    }

    private func moduleTab(_ label: String, module: Module) -> some View {
        let selected = activeModule == module
        return Button {
            activeModule = module
        } label: {
            Text(label)
                .font(.system(size: 15, weight: .bold))
                .foregroundColor(selected ? .white : Theme.textMuted)
                .frame(maxWidth: .infinity)
                .frame(height: 38)
                .background(selected ? Theme.buttonBlue : Theme.surface)
                .clipShape(RoundedRectangle(cornerRadius: 8))
        }
        .buttonStyle(.plain)
        .padding(2)
    }

    private func enterFullscreen() {
        AppDelegate.orientationLock = UIDevice.current.userInterfaceIdiom == .pad ? .all : .landscape
        UIViewController.attemptRotationToDeviceOrientation()
        showFullscreenPlayer = true
    }

    private func exitFullscreen() {
        AppDelegate.orientationLock = UIDevice.current.userInterfaceIdiom == .pad ? .all : .portrait
        UIViewController.attemptRotationToDeviceOrientation()
        showFullscreenPlayer = false
    }
}