import AppKit
import VoiceCatCore

// UserPickerSheet — a modal sheet for picking one user from the list of all connected server
// users. Used by the "Messages → New Private Message…" menu item so the user can start a PM
// with anyone on the server, not just the current channel. Mirrors the Windows client's
// `UserPickerDialog` (clients/windows/VoiceCat.App/Forms/UserPickerDialog.cs), adapted to the
// Mac sheet pattern used by the rest of the macOS client (InputSheet, MoveUserSheet, etc.).

final class UserPickerSheet: NSViewController, NSTableViewDataSource, NSTableViewDelegate {

    /// Called with the selected user's ID, or `nil` if the user cancelled.
    var onComplete: ((UInt32?) -> Void)?

    private let users: [User]
    private let tableView = NSTableView()
    private var okButton: NSButton?
    private var selectedRow: Int = -1

    init(users: [User]) {
        self.users = users
        super.init(nibName: nil, bundle: nil)
    }

    required init?(coder: NSCoder) { fatalError() }

    override func loadView() {
        view = NSView(frame: NSRect(x: 0, y: 0, width: 300, height: 320))
    }

    override func viewDidLoad() {
        super.viewDidLoad()
        buildUI()
    }

    // MARK: - UI

    private func buildUI() {
        let titleLabel = NSTextField(labelWithString: "Select a user:")
        titleLabel.font = .boldSystemFont(ofSize: 13)
        titleLabel.setAccessibilityLabel("Select a user")

        let col = NSTableColumn(identifier: NSUserInterfaceItemIdentifier("user"))
        tableView.addTableColumn(col)
        tableView.headerView = nil
        tableView.dataSource = self
        tableView.delegate = self
        tableView.doubleAction = #selector(okClicked)
        tableView.target = self
        tableView.setAccessibilityLabel("User list")

        let scroll = NSScrollView()
        scroll.documentView = tableView
        scroll.hasVerticalScroller = true
        scroll.borderType = .bezelBorder
        scroll.translatesAutoresizingMaskIntoConstraints = false

        let cancelButton = NSButton(title: "Cancel", target: self, action: #selector(cancelClicked))
        cancelButton.bezelStyle = .rounded

        let okButton = NSButton(title: "OK", target: self, action: #selector(okClicked))
        okButton.bezelStyle = .rounded
        okButton.keyEquivalent = "\r"
        okButton.isEnabled = false
        self.okButton = okButton

        let buttonRow = NSStackView(views: [NSView(), cancelButton, okButton])
        buttonRow.orientation = .horizontal
        buttonRow.spacing = 8

        let stack = NSStackView(views: [titleLabel, scroll, buttonRow])
        stack.orientation = .vertical
        stack.spacing = 8
        stack.edgeInsets = NSEdgeInsets(top: 16, left: 16, bottom: 16, right: 16)
        stack.translatesAutoresizingMaskIntoConstraints = false
        view.addSubview(stack)
        NSLayoutConstraint.activate([
            stack.topAnchor.constraint(equalTo: view.topAnchor),
            stack.leadingAnchor.constraint(equalTo: view.leadingAnchor),
            stack.trailingAnchor.constraint(equalTo: view.trailingAnchor),
            stack.bottomAnchor.constraint(equalTo: view.bottomAnchor),
        ])
    }

    override func viewDidAppear() {
        super.viewDidAppear()
        if users.count == 1 {
            tableView.selectRowIndexes(IndexSet(integer: 0), byExtendingSelection: false)
        }
    }

    // MARK: - Actions

    @objc private func okClicked() {
        guard selectedRow >= 0, selectedRow < users.count else { return }
        let userId = users[selectedRow].id
        dismiss(nil)
        onComplete?(userId)
    }

    @objc private func cancelClicked() {
        dismiss(nil)
        onComplete?(nil)
    }

    // MARK: - NSTableViewDataSource / Delegate

    func numberOfRows(in tableView: NSTableView) -> Int { users.count }

    func tableView(_ tableView: NSTableView, viewFor tableColumn: NSTableColumn?, row: Int) -> NSView? {
        let id = NSUserInterfaceItemIdentifier("userCell")
        let cell = tableView.makeView(withIdentifier: id, owner: nil) as? NSTableCellView
                   ?? makeCellView(identifier: id)
        cell.textField?.stringValue = users[row].nickname
        return cell
    }

    func tableViewSelectionDidChange(_ notification: Notification) {
        selectedRow = tableView.selectedRow
        okButton?.isEnabled = selectedRow >= 0
    }

    private func makeCellView(identifier: NSUserInterfaceItemIdentifier) -> NSTableCellView {
        let cell = NSTableCellView()
        cell.identifier = identifier
        let tf = NSTextField(labelWithString: "")
        tf.translatesAutoresizingMaskIntoConstraints = false
        cell.addSubview(tf)
        cell.textField = tf
        NSLayoutConstraint.activate([
            tf.leadingAnchor.constraint(equalTo: cell.leadingAnchor, constant: 4),
            tf.trailingAnchor.constraint(equalTo: cell.trailingAnchor, constant: -4),
            tf.centerYAnchor.constraint(equalTo: cell.centerYAnchor),
        ])
        return cell
    }
}