import Cocoa

@NSApplicationMain
class AppDelegate: NSObject, NSApplicationDelegate {

    @IBOutlet weak var window: NSWindow!
    @IBOutlet weak var view: NSView!

    lazy var outline: NSOutlineView = {
        let v = NSOutlineView()

        v.dataSource = self
        v.delegate = self

        let col = NSTableColumn()
        v.outlineTableColumn = col
        v.addTableColumn(col)

        v.headerView = nil

//        v.autosaveExpandedItems = true
//        v.autosaveName = "outline"

        v.selectionHighlightStyle = .sourceList
        v.backgroundColor = .clear
        v.rowSizeStyle = NSTableView.RowSizeStyle.default
        v.allowsMultipleSelection = true
        v.allowsEmptySelection = true

        return v

    }()


    let items: [Item] = [
        Item(name: "a", children: [
            Item(name: "aa", children: [
                Item(name: "aaa", children: []),
                Item(name: "aab", children: [
                    Item(name: "aaba", children: []),
                ]),
            ]),
            Item(name: "ab", children: []),
            Item(name: "ac", children: []),
        ]),
        Item(name: "b", children: [
            Item(name: "ba", children: []),
        ]),
    ]


    func applicationDidFinishLaunching(_ aNotification: Notification) {

        self.view.addSubview(self.outline)
        self.outline.translatesAutoresizingMaskIntoConstraints = false
        self.outline.topAnchor.constraint(equalTo: view.topAnchor).isActive = true
        self.outline.bottomAnchor.constraint(equalTo: view.bottomAnchor).isActive = true
        self.outline.leadingAnchor.constraint(equalTo: view.leadingAnchor).isActive = true
        self.outline.trailingAnchor.constraint(equalTo: view.trailingAnchor).isActive = true

        self.outline.heightAnchor.constraint(equalToConstant: 400).isActive = true
        self.outline.widthAnchor.constraint(equalToConstant: 400).isActive = true

        self.outline.dataSource = self
        self.outline.delegate = self
        self.outline.reloadData()
        self.outline.sizeLastColumnToFit()

    }


}

class Item: NSObject {
    let name: String
    let children: [Item]

    init(name: String, children: [Item]) {
        self.name = name
        self.children = children
    }

}

extension AppDelegate: NSOutlineViewDataSource {


    func outlineView(_ outlineView: NSOutlineView, numberOfChildrenOfItem item: Any?) -> Int {
        guard let item = item as? Item else { return items.count }

        return item.children.count
    }

    func outlineView(_ outlineView: NSOutlineView, child index: Int, ofItem item: Any?) -> Any {
        guard let item = item as? Item else { return items[index] }

        return item.children[index]
    }

    func outlineView(_ outlineView: NSOutlineView, isItemExpandable item: Any) -> Bool {
        guard let item = item as? Item else { return false }

        return !item.children.isEmpty
    }

    func outlineView(_ outlineView: NSOutlineView, objectValueFor tableColumn: NSTableColumn?, byItem item: Any?) -> Any? {
        return item
    }


}

extension AppDelegate: NSOutlineViewDelegate {

    func outlineView(_ outlineView: NSOutlineView, isGroupItem item: Any) -> Bool {
        return false
    }

    func outlineView(_ outlineView: NSOutlineView, shouldCollapseItem item: Any) -> Bool {
        guard let item = item as? Item else { return false }
        print("should collapse", item.name)
        return !item.children.isEmpty
    }

    func outlineView(_ outlineView: NSOutlineView, willDisplayCell cell: Any, for tableColumn: NSTableColumn?, item: Any) {

        guard let item = item as? Item else { return }
        guard let cell = cell as? NSCell else { return }

        cell.title = item.name

    }

    func outlineView(_ outlineView: NSOutlineView, viewFor tableColumn: NSTableColumn?, item: Any) -> NSView? {
        guard let i = item as? Item else { return nil }
        let v = NSView(frame: NSZeroRect)
        v.addSubview(NSTextField(labelWithString: i.name))
        return v
    }

    func outlineView(_ outlineView: NSOutlineView, persistentObjectForItem item: Any?) -> Any? {
        return item
    }

    func outlineView(_ outlineView: NSOutlineView, itemForPersistentObject object: Any) -> Any? {
        return object
    }

    func outlineViewItemDidCollapse(_ notification: Notification) {
        guard let item = notification.userInfo?["NSObject"] as? Item else {
            return
        }

        let isExpanded = self.outline.isItemExpanded(item)
        let isParentExpanded = self.outline.parent(forItem: item).map(self.outline.isItemExpanded)

        print("DELEGATE DID COLLAPSE", item.name, isExpanded, isParentExpanded)
    }

    func outlineViewItemDidExpand(_ notification: Notification) {
        guard let item = notification.userInfo?["NSObject"] as? Item else {
            return
        }

        let isExpanded = self.outline.isItemExpanded(item)
        let isParentExpanded = self.outline.parent(forItem: item).map(self.outline.isItemExpanded)

        print("DELEGATE DID EXPAND", item.name, isExpanded, isParentExpanded)
    }


}