deltachat-ios/deltachat-ios/Controller/DocumentGalleryController.swift

import UIKit
import DcCore

class DocumentGalleryController: UIViewController {

    private let fileMessageIds: [Int]

    private lazy var tableViews: UITableView = {
        let table = UITableView(frame: .zero, style: .grouped)
        table.register(DocumentGalleryFileCell.self, forCellReuseIdentifier: DocumentGalleryFileCell.reuseIdentifier)
        table.dataSource = self
        table.delegate = self
        table.rowHeight = 60
        return table
    }()

    private lazy var emptyStateView: EmptyStateLabel = {
        let label = EmptyStateLabel()
        label.text = String.localized("tab_docs_empty_hint")
        label.isHidden = true
        return label
    }()


    init(fileMessageIds: [Int]) {
        self.fileMessageIds = fileMessageIds
        super.init(nibName: nil, bundle: nil)
        self.title = String.localized("files")
    }

    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

    // MARK: - lifecycle
    override func viewDidLoad() {
        super.viewDidLoad()
        setupSubviews()
        if fileMessageIds.isEmpty {
            emptyStateView.isHidden = false
        }
    }

    // MARK: - layout
    private func setupSubviews() {
        view.addSubview(tableViews)
        tableViews.translatesAutoresizingMaskIntoConstraints = false
        tableViews.leadingAnchor.constraint(equalTo: view.leadingAnchor, constant: 0).isActive = true
        tableViews.topAnchor.constraint(equalTo: view.topAnchor).isActive = true
        tableViews.trailingAnchor.constraint(equalTo: view.trailingAnchor, constant: 0).isActive = true
        tableViews.bottomAnchor.constraint(equalTo: view.bottomAnchor).isActive = true

        view.addSubview(emptyStateView)
        emptyStateView.translatesAutoresizingMaskIntoConstraints = false
        emptyStateView.leadingAnchor.constraint(equalTo: view.layoutMarginsGuide.leadingAnchor).isActive = true
        emptyStateView.trailingAnchor.constraint(equalTo: view.layoutMarginsGuide.trailingAnchor).isActive = true
        emptyStateView.centerYAnchor.constraint(equalTo: view.safeAreaLayoutGuide.centerYAnchor).isActive = true
        emptyStateView.centerXAnchor.constraint(equalTo: view.safeAreaLayoutGuide.centerXAnchor).isActive = true
    }
}

// MARK: - UITableViewDelegate, UITableViewDataSource
extension DocumentGalleryController: UITableViewDelegate, UITableViewDataSource {
    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return fileMessageIds.count
    }

    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        guard let cell = tableView.dequeueReusableCell(withIdentifier: DocumentGalleryFileCell.reuseIdentifier, for: indexPath) as? DocumentGalleryFileCell else {
            return UITableViewCell()
        }
        let msg = DcMsg(id: fileMessageIds[indexPath.row])
        cell.update(msg: msg)
        return cell
    }

    func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
        let msgId = fileMessageIds[indexPath.row]
        showPreview(msgId: msgId)
        tableView.deselectRow(at: indexPath, animated: false)
    }
}

// MARK: - coordinator
extension DocumentGalleryController {
    func showPreview(msgId: Int) {
        guard let index = fileMessageIds.index(of: msgId) else {
            return
        }
        let previewController = PreviewController(type: .multi(fileMessageIds, index))
        present(previewController, animated: true, completion: nil)
    }
}