// File created from SimpleUserProfileExample
// $ createScreen.sh Room/UserSuggestion UserSuggestion
// 
// Copyright 2021 New Vector Ltd
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//

import SwiftUI

@available(iOS 14.0, *)
struct UserSuggestionList: View {
    private struct Constants {
        static let rowHeight: CGFloat = 60.0
        static let maxHeight: CGFloat = 300.0
        static let listItemPadding: CGFloat = 4.0
    }

    // MARK: - Properties
    
    // MARK: Private
    
    @Environment(\.theme) private var theme: ThemeSwiftUI
    
    // MARK: Public
    
    @ObservedObject var viewModel: UserSuggestionViewModel.Context
    
    var body: some View {
        BackgroundView {
            List(viewModel.viewState.items) { item in
                Button {
                    viewModel.send(viewAction: .selectedItem(item))
                } label: {
                    UserSuggestionListItem(
                        avatar: item.avatar,
                        displayName: item.displayName,
                        userId: item.id
                    )
                    .padding([.top, .bottom], Constants.listItemPadding)
                }
            }
            .listStyle(PlainListStyle())
            .environment(\.defaultMinListRowHeight, Constants.rowHeight)
            .frame(height: min(Constants.maxHeight, Constants.rowHeight * CGFloat(viewModel.viewState.items.count)))
            .id(UUID()) // Rebuild the whole list on item changes. Fixes performance issues.
        }
    }
}

@available(iOS 14.0, *)
private struct BackgroundView<Content: View>: View {
    
    var content: () -> Content
    
    @Environment(\.theme) private var theme: ThemeSwiftUI
    private let shadowRadius: CGFloat = 20.0
    
    init(@ViewBuilder content: @escaping () -> Content) {
        self.content = content
    }
    
    var body: some View {
        content()
            .background(theme.colors.background)
            .clipShape(RoundedCornerShape(radius: shadowRadius, corners: [.topLeft, .topRight]))
            .shadow(color: .black.opacity(0.20), radius: 20.0, x: 0.0, y: 3.0)
            .mask(Rectangle().padding(.init(top: -(shadowRadius * 2), leading: 0.0, bottom: 0.0, trailing: 0.0)))
            .edgesIgnoringSafeArea(.all)
    }
}

// MARK: - Previews

@available(iOS 14.0, *)
struct UserSuggestion_Previews: PreviewProvider {
    static let stateRenderer = MockUserSuggestionScreenState.stateRenderer
    static var previews: some View {
        stateRenderer.screenGroup()
    }
}