import UIKit

/// Asks where ipx is. Shown on first run, and again whenever the address needs changing.
final class ServerSetupViewController: UIViewController, UITextFieldDelegate {
    var onSave: ((URL) -> Void)?

    private let field = UITextField()
    private let note = UILabel()
    private let first: Bool

    /// The first run has nothing to go back to, so it gets no Cancel.
    init(first: Bool) {
        self.first = first
        super.init(nibName: nil, bundle: nil)
    }
    required init?(coder: NSCoder) { fatalError("not from a storyboard") }

    override func viewDidLoad() {
        super.viewDidLoad()
        view.backgroundColor = .systemBackground
        title = first ? "Where is ipx?" : "Server"

        navigationItem.rightBarButtonItem = UIBarButtonItem(
            title: "Save", style: .done, target: self, action: #selector(save))
        if !first {
            navigationItem.leftBarButtonItem = UIBarButtonItem(
                title: "Cancel", style: .plain, target: self, action: #selector(cancel))
        }

        let blurb = UILabel()
        blurb.text = "The address of your ipx server. Sign in on the page that follows; the app plays "
            + "what you are signed in to."
        blurb.numberOfLines = 0
        blurb.font = .preferredFont(forTextStyle: .subheadline)
        blurb.textColor = .secondaryLabel

        field.text = ServerSettings.base?.absoluteString ?? ServerSettings.suggestion
        field.placeholder = ServerSettings.suggestion
        field.borderStyle = .roundedRect
        field.keyboardType = .URL
        field.textContentType = .URL
        field.autocapitalizationType = .none
        field.autocorrectionType = .no
        field.spellCheckingType = .no
        field.clearButtonMode = .whileEditing
        field.returnKeyType = .done
        field.delegate = self
        field.addTarget(self, action: #selector(edited), for: .editingChanged)

        note.numberOfLines = 0
        note.font = .preferredFont(forTextStyle: .footnote)
        note.textColor = .secondaryLabel

        let stack = UIStackView(arrangedSubviews: [blurb, field, note])
        stack.axis = .vertical
        stack.spacing = 12
        stack.translatesAutoresizingMaskIntoConstraints = false
        view.addSubview(stack)
        NSLayoutConstraint.activate([
            stack.topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.topAnchor, constant: 24),
            stack.leadingAnchor.constraint(equalTo: view.leadingAnchor, constant: 20),
            stack.trailingAnchor.constraint(equalTo: view.trailingAnchor, constant: -20),
        ])
        edited()
    }

    override func viewDidAppear(_ animated: Bool) {
        super.viewDidAppear(animated)
        field.becomeFirstResponder()
    }

    func textFieldShouldReturn(_ textField: UITextField) -> Bool { save(); return true }

    /// Says what is wrong while it is still being typed, rather than after a failed load.
    @objc private func edited() {
        let typed = field.text ?? ""
        guard let url = ServerSettings.parse(typed) else {
            note.text = typed.isEmpty ? "" : "That is not a web address."
            note.textColor = .secondaryLabel
            navigationItem.rightBarButtonItem?.isEnabled = false
            return
        }
        navigationItem.rightBarButtonItem?.isEnabled = true
        if url.scheme == "http" && !ServerSettings.isLocal(url) {
            // Saying so here beats a blocked request later that reads like the server is down.
            note.text = "Plain HTTP is only allowed on your own network. This address will not load."
            note.textColor = .systemOrange
        } else if url.scheme == "http" {
            note.text = "On your own network, so plain HTTP is fine."
            note.textColor = .secondaryLabel
        } else {
            note.text = "Will open \(url.absoluteString)"
            note.textColor = .secondaryLabel
        }
    }

    @objc private func save() {
        guard let url = ServerSettings.parse(field.text ?? "") else { return }
        ServerSettings.base = url
        field.resignFirstResponder()
        onSave?(url)
    }

    @objc private func cancel() { dismiss(animated: true) }
}