//
 /*
  * SwiftFin is subject to the terms of the Mozilla Public
  * License, v2.0. If a copy of the MPL was not distributed with this
  * file, you can obtain one at https://mozilla.org/MPL/2.0/.
  *
  * Copyright 2021 Aiden Vigue & Jellyfin Contributors
  */

import Foundation
import SwiftUI
import SwiftUICollection


struct LiveTVChannelsView: View {
    @EnvironmentObject var programsRouter: LiveTVChannelsCoordinator.Router
    @StateObject var viewModel = LiveTVChannelsViewModel()
    
    var body: some View {
        if viewModel.isLoading == true {
            ProgressView()
        } else if !viewModel.rows.isEmpty {
            CollectionView(rows: viewModel.rows) { section, env in
                return createGridLayout()
            } cell: { indexPath, cell in
                makeCellView(indexPath: indexPath, cell: cell)
            } supplementaryView: { _, indexPath in
                EmptyView()
                .accessibilityIdentifier("\(indexPath.section).\(indexPath.row)")
            }
            .frame(maxWidth: .infinity, maxHeight: .infinity)
            .ignoresSafeArea()
            
        } else {
            VStack {
                Text("No results.")
                Button {
                    print("movieLibraries reload")
                } label: {
                    Text("Reload")
                }
            }
        }
    }
    
    @ViewBuilder func makeCellView(indexPath: IndexPath, cell: LiveTVChannelRowCell) -> some View {
        GeometryReader { _ in
            if let item = cell.item,
               let channel = item.channel{
                if channel.type != "Folder" {
                    Button {
                    } label: {
                        LiveTVChannelItemElement(channel: channel, program: item.program)
                    }
                    .buttonStyle(PlainNavigationLinkButtonStyle())
                }
            }
        }
    }
    
    private func createGridLayout() -> NSCollectionLayoutSection {
        // I don't know why tvOS has a margin on the sides of a collection view
        // But it does, even with contentInset = .zero and ignoreSafeArea. 
        let sideMargin = CGFloat(30)
        let itemWidth = (UIScreen.main.bounds.width / 4) - (sideMargin *  2)
        let itemSize = NSCollectionLayoutSize(widthDimension: .absolute(itemWidth),
                                              heightDimension: .absolute(itemWidth))
        let item = NSCollectionLayoutItem(layoutSize: itemSize)
        item.edgeSpacing = .init(
            leading: .fixed(8),
            top: .fixed(8),
            trailing: .fixed(8),
            bottom: .fixed(8)
        )
        
        
        let groupSize = NSCollectionLayoutSize(widthDimension: .fractionalWidth(1.0),
                                               heightDimension:  .absolute(itemWidth))
        let group = NSCollectionLayoutGroup.horizontal(layoutSize: groupSize,
                                                       subitems: [item])
        group.edgeSpacing = .init(
            leading: .fixed(0),
            top: .fixed(16),
            trailing: .fixed(0),
            bottom: .fixed(16)
        )
        group.contentInsets = .zero
        
        
        let section = NSCollectionLayoutSection(group: group)
        section.contentInsets = .zero

        return section
    }
    
}