sendbird-uikit-ios/Sources/View/Common/SBUEmptyView.swift

//
//  SBUEmptyView.swift
//  SendbirdUIKit
//
//  Created by Tez Park on 27/02/2020.
//  Copyright © 2020 Sendbird, Inc. All rights reserved.
//

import UIKit

public protocol SBUEmptyViewDelegate: NSObjectProtocol {
    /// Called when the retry button on the empty view was tapped.
    func didSelectRetry()
}

open class SBUEmptyView: SBUView {
    // MARK: - Properties (Public)
    public var type: EmptyViewType = .none
    public weak var delegate: SBUEmptyViewDelegate?
    public lazy var statusImageView = UIImageView()
    public var statusLabel: UILabel = .init()
    
    @SBUThemeWrapper(theme: SBUTheme.componentTheme)
    public var theme: SBUComponentTheme
    @SBUThemeWrapper(theme: SBUTheme.overlayTheme.componentTheme, setToDefault: true)
    public var overlayTheme: SBUComponentTheme
    
    public lazy var retryButton: UIButton = {
        let theme = self.isOverlay ? self.overlayTheme : self.theme
        let retryButton = UIButton()
         retryButton.setImage(
             SBUIconSetType.iconRefresh.image(
                 with: theme.emptyViewRetryButtonTintColor,
                 to: SBUIconSetType.Metric.defaultIconSize
             ),
             for: .normal
         )
         retryButton.setTitle(SBUStringSet.Retry, for: .normal)
         retryButton.addTarget(self, action: #selector(onClickRetry), for: .touchUpInside)
         return retryButton
     }()
    
    public var isOverlay = false
    
    public var emptyViewTopConstraint: NSLayoutConstraint?

    // MARK: - Properties (Private)
    
    lazy var stackView: UIStackView = {
        let stackView = UIStackView()
        stackView.spacing = 24
        stackView.axis = .vertical
        stackView.alignment = .center
        return stackView
    }()
    
    var topMargin = UIView()
    var bottomMargin = UIView()
    
    // MARK: - Lifecycle
    override public init(frame: CGRect) {
        super.init(frame: frame)
    }
    
    @available(*, unavailable, renamed: "SBUEmptyView.init(frame:)")
    required public init?(coder: NSCoder) {
        super.init(frame: .zero)
    }
    
    public override init() {
        super.init()
    }
    
    open override func setupViews() {
        super.setupViews()
        
        self.stackView.setVStack([
            self.topMargin,
            self.statusImageView,
            self.statusLabel,
            self.retryButton,
            self.bottomMargin
        ])
        self.retryButton.isHidden = true
        self.addSubview(stackView)
        self.isHidden = true
    }
    
    open override func setupLayouts() {
        super.setupLayouts()
        
        self.topMargin.translatesAutoresizingMaskIntoConstraints = false
        self.bottomMargin.translatesAutoresizingMaskIntoConstraints = false
        self.topMargin.heightAnchor.constraint(equalTo: self.bottomMargin.heightAnchor, multiplier: 1.0).isActive = true
        self.topMargin.sbu_constraint_greaterThan(height: 0)
        self.topMargin.sbu_constraint(width: self.frame.width)
        self.bottomMargin.sbu_constraint(width: self.frame.width)
        
        self.stackView.sbu_constraint(equalTo: self, leading: 0, trailing: 0, bottom: 0)
        
        self.statusImageView.setConstraint(width: 60.0, height: 60.0)
        
        self.updateTopAnchorConstraint(constant: 0)
    }
    
    open func updateTopAnchorConstraint(constant: CGFloat) {
        self.emptyViewTopConstraint?.isActive = false
        self.emptyViewTopConstraint = self.stackView.topAnchor.constraint(
            equalTo: self.topAnchor,
            constant: constant
        )
        self.emptyViewTopConstraint?.isActive = true
    }
    
    open override func setupStyles() {
        super.setupStyles()
        
        let theme = self.isOverlay ? self.overlayTheme : self.theme
        
        self.backgroundColor = theme.emptyViewBackgroundColor
        
        self.statusLabel.font = theme.emptyViewStatusFont
        self.statusLabel.textColor = theme.emptyViewStatusTintColor
        self.statusLabel.contentMode = .center
        self.statusLabel.numberOfLines = 0
        self.statusLabel.lineBreakMode = .byWordWrapping

        self.statusImageView.image = self.statusImageView.image?.sbu_with(tintColor: theme.emptyViewStatusTintColor)
         
        self.retryButton.setTitleColor(theme.emptyViewRetryButtonTintColor, for: .normal)
        self.retryButton.titleLabel?.font = theme.emptyViewRetryButtonFont
        self.retryButton.tintColor = theme.emptyViewRetryButtonTintColor
    }
    
    // MARK: - Common
    
    /// This function reloads emptyView.
    /// - Parameter type: Empty view type
    public func reloadData(_ type: EmptyViewType) {
        DispatchQueue.main.async { [weak self] in
            guard let self = self else { return }
            
            self.type = type
            
            self.retryButton.isHidden = (self.type != .error)
            
            self.updateViews()
            
            self.layoutIfNeeded()
            self.updateConstraintsIfNeeded()
        }
    }
    
    /// Override this function to apply a custom type.
    open func updateViews() {
        let theme = self.isOverlay ? self.overlayTheme : self.theme
        var needToHidden = false
        switch self.type {
        case .none:
            self.statusLabel.text = ""
            self.statusImageView.image = nil
            needToHidden = true
        case .noChannels:
            self.statusLabel.text = SBUStringSet.Empty_No_Channels
            self.statusImageView.image = SBUIconSetType.iconChat.image(
                with: theme.emptyViewStatusTintColor,
                to: SBUIconSetType.Metric.iconEmptyView,
                tintAndResize: false
            )
        case .noMessages:
            self.statusLabel.text = SBUStringSet.Empty_No_Messages
            self.statusImageView.image = SBUIconSetType.iconMessage.image(
                with: theme.emptyViewStatusTintColor,
                to: SBUIconSetType.Metric.iconEmptyView,
                tintAndResize: false
            )
        case .noNotifications:
            self.statusLabel.text = SBUStringSet.Empty_No_Notifications
            self.statusImageView.image = SBUIconSetType.iconMessage.image(
                with: theme.emptyViewStatusTintColor,
                to: SBUIconSetType.Metric.iconEmptyView,
                tintAndResize: false
            )
        case .noMembers:
            self.statusLabel.text = SBUStringSet.Empty_No_Users
            self.statusImageView.image = SBUIconSetType.iconMembers.image(
                with: theme.emptyViewStatusTintColor,
                to: SBUIconSetType.Metric.iconEmptyView,
                tintAndResize: false
            )
        case .noMutedMembers:
            self.statusLabel.text = SBUStringSet.Empty_No_Muted_Members
            self.statusImageView.image = SBUIconSetType.iconMute.image(
                with: theme.emptyViewStatusTintColor,
                to: SBUIconSetType.Metric.iconEmptyView,
                tintAndResize: false
            )
        case .noMutedParticipants:
            self.statusLabel.text = SBUStringSet.Empty_No_Muted_Participants
            self.statusImageView.image = SBUIconSetType.iconMute.image(
                with: theme.emptyViewStatusTintColor,
                to: SBUIconSetType.Metric.iconEmptyView,
                tintAndResize: false
            )
        case .noBannedUsers:
            self.statusLabel.text = SBUStringSet.Empty_No_Banned_Users
            self.statusImageView.image = SBUIconSetType.iconBan.image(
                with: theme.emptyViewStatusTintColor,
                to: SBUIconSetType.Metric.iconEmptyView,
                tintAndResize: false
            )
        case .noSearchResults:
            self.statusLabel.text = SBUStringSet.Empty_Search_Result
            self.statusImageView.image = SBUIconSetType.iconSearch.image(
                with: theme.emptyViewStatusTintColor,
                to: SBUIconSetType.Metric.iconEmptyView,
                tintAndResize: false
            )
        case .error:
            self.statusLabel.text = SBUStringSet.Empty_Wrong
            self.statusImageView.image = SBUIconSetType.iconError.image(
                with: theme.emptyViewStatusTintColor,
                to: SBUIconSetType.Metric.iconEmptyView,
                tintAndResize: false
            )
        }
        self.isHidden = needToHidden
    }
    
    // MARK: - Action
    
    /// This function actions when the retry button click.
    /// - Parameter sender: sender
    @objc open func onClickRetry(_ sender: Any) {
        self.delegate?.didSelectRetry()
    }
}