//
//  DatabaseViewController.swift
//  MongoView
//
//  Created by Shadowfacts on 1/10/20.
//  Copyright © 2020 Shadowfacts. All rights reserved.
//

import Cocoa
import MongoSwift
import NIO

struct DatabaseCollections {
    let database: String
    let collections: [String]
}

struct DatabaseCollection {
    let database: String
    let name: String
}

class DatabaseViewController: NSViewController {
    
    @IBOutlet weak var collectionsOutlineView: NSOutlineView!
    @IBOutlet weak var detailContainerView: NSView!
    
    let mongoController: MongoController
    
    private var databaseCollections: [DatabaseCollections] = []
    private var selectedCollection: DatabaseCollection?

    private var placeholderLabel: NSTextField?
    private var queryViewController: QueryViewController?
    
    init(mongoController: MongoController) {
        self.mongoController = mongoController
        
        super.init(nibName: "DatabaseViewController", bundle: .main)
    }
    
    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        mongoController.client.listDatabaseNames().flatMap { (databaseNames) -> EventLoopFuture<[DatabaseCollections]> in
            let futures = databaseNames.map { (name: String) -> EventLoopFuture<DatabaseCollections> in
                let db = self.mongoController.client.db(name)
                return db.listCollectionNames().map { (collectionNames: [String]) -> DatabaseCollections in
                    let sortedNames = collectionNames.sorted()
                    return DatabaseCollections(database: name, collections: sortedNames)
                }
            }
            return EventLoopFuture.whenAllSucceed(futures, on: futures.first!.eventLoop)
        }.whenComplete { [weak self] (res) in
            guard let self = self else { return }
            
            switch res {
            case let .success(databaseCollections):
                let sortedCollections = databaseCollections.sorted(by: { $0.database < $1.database })
                self.databaseCollections = sortedCollections
                DispatchQueue.main.async {
                    self.collectionsOutlineView.reloadData()
                }
                
            case let .failure(error):
                fatalError("error getting database names: \(error)")
            }
        }

        collectionsOutlineView.dataSource = self
        collectionsOutlineView.delegate = self
        
        collectionsOutlineView.target = self
        collectionsOutlineView.doubleAction = #selector(cellDoubleClicked)
        
        updateDetailView()
    }
    
    func showCollection(_ collection: DatabaseCollection) {
        selectedCollection = collection
        updateDetailView()
    }
    
    private func updateDetailView() {
        if let collection = selectedCollection {
            if let placeholderLabel = placeholderLabel {
                placeholderLabel.removeFromSuperview()
            }
            if let oldQueryViewController = self.queryViewController {
                oldQueryViewController.view.removeFromSuperview()
                oldQueryViewController.removeFromParent()
            }
            
            let queryViewController = QueryViewController(mongoController: mongoController, collection: collection)
            self.queryViewController = queryViewController
            queryViewController.view.translatesAutoresizingMaskIntoConstraints = false
            addChild(queryViewController)
            detailContainerView.addSubview(queryViewController.view)
            NSLayoutConstraint.activate([
                queryViewController.view.leadingAnchor.constraint(equalTo: detailContainerView.leadingAnchor),
                queryViewController.view.trailingAnchor.constraint(equalTo: detailContainerView.trailingAnchor),
                queryViewController.view.topAnchor.constraint(equalTo: detailContainerView.topAnchor),
                queryViewController.view.bottomAnchor.constraint(equalTo: detailContainerView.bottomAnchor)
            ])
            
            self.title = queryViewController.title
        } else {
            if let queryViewController = queryViewController {
                queryViewController.view.removeFromSuperview()
                queryViewController.removeFromParent()
            }
            
            if self.placeholderLabel == nil {
                let label = NSTextField(labelWithString: "Select a collection to begin")
                self.placeholderLabel = label
                label.translatesAutoresizingMaskIntoConstraints = false
                detailContainerView.addSubview(label)
                NSLayoutConstraint.activate([
                    label.centerXAnchor.constraint(equalTo: detailContainerView.centerXAnchor),
                    label.centerYAnchor.constraint(equalTo: detailContainerView.centerYAnchor)
                ])
    
                self.title = "No Query"
            }
        }
    }
    
    @objc func cellDoubleClicked() {
        let item = collectionsOutlineView.item(atRow: collectionsOutlineView.clickedRow)!
        
        if item is DatabaseCollections {
            if collectionsOutlineView.isItemExpanded(item) {
                collectionsOutlineView.collapseItem(item)
            } else {
                collectionsOutlineView.expandItem(item)
            }
        } else if let collection = item as? DatabaseCollection {
            // only open a new window/tab if our own query has changed from the default, otherwise replace our query controller
            if let queryViewController = queryViewController, queryViewController.hasQueryChanged {
                (NSApplication.shared.delegate as! AppDelegate).newWindow(mongoController: mongoController, collection: collection)
            } else {
                self.selectedCollection = collection
                updateDetailView()
            }
        }
    }

    @IBAction func runQuery(_ sender: Any) {
        queryViewController?.runQuery()
    }
    
    @IBAction func refresh(_ sender: Any) {
        queryViewController?.refresh()
    }
}

extension DatabaseViewController: NSMenuItemValidation {
    func validateMenuItem(_ menuItem: NSMenuItem) -> Bool {
        if menuItem.action == #selector(runQuery(_:)) || menuItem.action == #selector(refresh(_:)) {
            return queryViewController != nil
        }
        return true
    }
}

extension DatabaseViewController: NSOutlineViewDataSource {
    func outlineView(_ outlineView: NSOutlineView, numberOfChildrenOfItem item: Any?) -> Int {
        if item == nil {
            return databaseCollections.count
        } else if let database = item as? DatabaseCollections {
            return database.collections.count
        } else {
            return 0
        }
    }
    
    func outlineView(_ outlineView: NSOutlineView, isItemExpandable item: Any) -> Bool {
        return item is DatabaseCollections
    }
    
    func outlineView(_ outlineView: NSOutlineView, child index: Int, ofItem item: Any?) -> Any {
        if item == nil {
            return databaseCollections[index]
        } else if let databaseCollections = item as? DatabaseCollections {
            let collection = databaseCollections.collections[index]
            return DatabaseCollection(database: databaseCollections.database, name: collection)
        } else {
            fatalError()
        }
    }
}

extension DatabaseViewController: NSOutlineViewDelegate {
    func outlineView(_ outlineView: NSOutlineView, viewFor tableColumn: NSTableColumn?, item: Any) -> NSView? {
        if let database = item as? DatabaseCollections {
            let cell = outlineView.makeView(withIdentifier: .databaseNameCell, owner: nil) as! NSTableCellView
            cell.textField!.stringValue = database.database
            cell.textField!.isEditable = false
            return cell
        } else if let collection = item as? DatabaseCollection {
            let cell = outlineView.makeView(withIdentifier: .collectionNameCell, owner: nil) as! NSTableCellView
            cell.textField!.stringValue = collection.name
            cell.textField!.isEditable = false
            return cell
        } else {
            fatalError()
        }
    }
}

extension NSUserInterfaceItemIdentifier {
    static let databaseNameCell = NSUserInterfaceItemIdentifier(rawValue: "DatabaseNameCell")
    static let collectionNameCell = NSUserInterfaceItemIdentifier(rawValue: "CollectionNameCell")
}