import SwiftUI

struct MainView: View {
  @EnvironmentObject var settings: SettingsManager
  @State private var selectedTab: Int = 0
  @State private var manager = BooruManager(.yandere)

  var body: some View {
    platformSpecificContent
      .environmentObject(settings)
      .environmentObject(manager)
      .onChange(of: settings.preferredBooru) { _, newState in
        updateManager(newState)
      }
      .onChange(of: settings.searchSuggestionsMode) { _, newState in
        if newState != .disabled {
          refreshTags()
        }
      }
      .onChange(of: manager.historyIndex) { _, _ in
        manager.selectedPost = nil
      }
      .onAppear(perform: initializeManager)
  }

  @ViewBuilder private var platformSpecificContent: some View {
    #if os(macOS)
      ContentView(selectedTab: $selectedTab)
    #else
      TabView(selection: $selectedTab) {
        ContentView(selectedTab: $selectedTab)
          .tabItem { Label("Posts", systemImage: "rectangle.stack") }
          .tag(0)

        NavigationStack {
          BookmarksView(selectedTab: $selectedTab)
        }
        .tabItem { Label("Bookmarks", systemImage: "bookmark") }
        .tag(1)

        SettingsView()
          .tabItem { Label("Settings", systemImage: "gear") }
          .tag(2)
      }
    #endif
  }

  private func updateManager(_ provider: BooruProvider) {
    let previousSearchText = manager.searchText

    manager = BooruManager(provider)
    manager.searchText = previousSearchText

    Task {
      refreshTags()

      if manager.searchText.isEmpty {
        manager.fetchPosts()
      } else {
        manager.performSearch(settings: settings)
      }
    }
  }

  private func initializeManager() {
    manager = BooruManager(settings.preferredBooru)

    Task {
      refreshTags()

      if manager.posts.isEmpty {
        manager.fetchPosts()
      }
    }
  }

  private func refreshTags() {
    Task {
      if settings.searchSuggestionsMode != .disabled {
        manager.initializeTags()
      } else {
        manager.updateTagsCacheSize()
      }
    }
  }
}

#Preview {
  #if os(macOS)
    let screenSize = NSScreen.main?.frame.size ?? CGSize(width: 1_920, height: 1_080)
    let heightCoefficient = screenSize.height / 1_080
    let widthCoefficient = screenSize.width / 1_440
  #endif

  MainView()
    .environmentObject(SettingsManager())
    #if os(macOS)
      .frame(
        width: screenSize.width / widthCoefficient,
        height: screenSize.height / heightCoefficient
      )
    #endif
}