import SwiftUI

struct MainView: View {
  @EnvironmentObject var settings: SettingsManager
  @State private var selectedTab: Int = 0
  @State private var selectedPost: (post: BooruPost?, manager: BooruManager?)

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

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

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

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

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

      manager = BooruManager(provider)
      manager.searchText = previousSearchText

      Task {
        refreshTags()

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

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

      Task {
        refreshTags()

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

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

#Preview {
  MainView()
    .environmentObject(SettingsManager())
    #if os(macOS)
      .frame(width: 736, height: 736)
    #endif
}