//
//  ViewController.swift
//  MastoSearch
//
//  Created by Shadowfacts on 12/14/21.
//

import Cocoa
import Combine
import SwiftSoup
import MastoSearchCore

class ViewController: NSViewController {

    private static let formatter: DateFormatter = {
        let f = DateFormatter()
        f.locale = .current
        f.setLocalizedDateFormatFromTemplate("yyyy-MM-dd hh:mm a")
        return f
    }()
    private static let searchThread = DispatchQueue(label: "Search", qos: .userInitiated)
    
    @IBOutlet weak var table: NSTableView!
    @IBOutlet weak var progressIndicator: NSProgressIndicator!
    
    private var dataSource: DataSource!
    private var allStatusesSnapshot: NSDiffableDataSourceSnapshot<Section, Item>?
    
    private var cancellables = Set<AnyCancellable>()
    
    private var query: String?
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        dataSource = DataSource(owner: self) { tableView, tableColumn, row, item in
            let cell = tableView.makeView(withIdentifier: tableColumn.identifier, owner: self) as! NSTableCellView

            switch cell.identifier! {
            case .date:
                cell.textField!.font = .monospacedDigitSystemFont(ofSize: 13, weight: .regular)
                cell.textField!.stringValue = ViewController.formatter.string(from: item.status.published)

            case .contentWarning:
                cell.textField!.stringValue = item.status.summary ?? ""

            case .content:
                let doc = try! SwiftSoup.parse(item.status.content)
                cell.textField!.stringValue = try! doc.text()

            default:
                fatalError()
            }

            return cell
        }
        
        table.sortDescriptors = [NSSortDescriptor(key: "published", ascending: false)]
        
        let menu = NSMenu()
        menu.addItem(withTitle: "Open in Browser", action: #selector(openURL(_:)), keyEquivalent: "")
        menu.addItem(withTitle: "Copy URL", action: #selector(copyURL(_:)), keyEquivalent: "c")
        table.menu = menu
        
        DatabaseController.shared.onInitialize
            .sink { [unowned self] in self.loadAll() }
            .store(in: &cancellables)
        
        SyncController.shared.onSync
            .sink { [unowned self] in
                self.allStatusesSnapshot = nil
                self.loadAll()
            }
            .store(in: &cancellables)
    }
    
    override func viewWillAppear() {
        super.viewWillAppear()
        
        progressIndicator.startAnimation(nil)
    }
    
    private func loadStatuses(_ statuses: StatusSequence) -> NSDiffableDataSourceSnapshot<Section, Item> {
        var snapshot = NSDiffableDataSourceSnapshot<Section, Item>()
        snapshot.appendSections([.statuses])
        snapshot.appendItems(statuses.map { Item(status: $0) }, toSection: .statuses)
        DispatchQueue.main.async {
            self.dataSource.apply(snapshot, animatingDifferences: false) {
                self.progressIndicator.stopAnimation(nil)
            }
        }
        return snapshot
    }
    
    private func loadAll() {
        self.query = nil
        
        if let snapshot = allStatusesSnapshot {
            dispatchPrecondition(condition: .onQueue(.main))
            self.dataSource.apply(snapshot, animatingDifferences: false)
        } else {
            let sortDescriptor = table.sortDescriptors.first
            ViewController.searchThread.async {
                DatabaseController.shared.getStatuses(sortDescriptor: sortDescriptor) { statuses in
                    let snapshot = self.loadStatuses(statuses)
                    self.allStatusesSnapshot = snapshot
                }
            }
        }
    }
    
    func search(_ query: String) {
        let query = query.trimmingCharacters(in: .whitespacesAndNewlines)
        self.query = query
        guard !query.isEmpty else {
            loadAll()
            return
        }
        
        let sortDescriptor = table.sortDescriptors.first
        ViewController.searchThread.async {
            DatabaseController.shared.getStatuses(query: query, sortDescriptor: sortDescriptor) { statuses in
                _ = self.loadStatuses(statuses)
            }
        }
    }
    
    func sortDescriptorsChanged() {
        guard DatabaseController.shared.isInitialized else {
            return
        }
        allStatusesSnapshot = nil
        self.dataSource.apply(NSDiffableDataSourceSnapshot(), animatingDifferences: false)
        if let query = query {
            search(query)
        } else {
            loadAll()
        }
    }
    
    @objc func openURL(_ sender: Any) {
        guard table.clickedRow != -1,
              let item = dataSource.itemIdentifier(forRow: table.clickedRow) else {
                  return
              }
        NSWorkspace.shared.open(URL(string: item.status.url)!)
    }
    
    @objc func copyURL(_ sender: Any) {
        guard table.clickedRow != -1,
              let item = dataSource.itemIdentifier(forRow: table.clickedRow) else {
                  return
              }
        NSPasteboard.general.clearContents()
        NSPasteboard.general.setString(item.status.url, forType: .string)
    }
    
}

extension ViewController {
    enum Section {
        case statuses
    }
    struct Item: Hashable {
        let status: Status
        
        static func ==(lhs: Item, rhs: Item) -> Bool {
            return lhs.status.url == rhs.status.url
        }
        
        func hash(into hasher: inout Hasher) {
            hasher.combine(status.url)
        }
    }
}

extension ViewController {
    class DataSource: NSTableViewDiffableDataSource<Section, Item> {
        unowned var owner: ViewController
        
        init(owner: ViewController, cellProvider: @escaping NSTableViewDiffableDataSource<ViewController.Section, ViewController.Item>.CellProvider) {
            self.owner = owner
            super.init(tableView: owner.table, cellProvider: cellProvider)
        }
        
        // without @objc the table view doesn't detect it, even though it overrides an NSTableViewDataSource method and so should be exposed automatically
        @objc func tableView(_ tableView: NSTableView, sortDescriptorsDidChange oldSortDescriptors: [NSSortDescriptor]) {
            owner.sortDescriptorsChanged()
        }
    }
}

extension ViewController: NSMenuItemValidation {
    func validateMenuItem(_ menuItem: NSMenuItem) -> Bool {
        if menuItem.action == #selector(copyURL) || menuItem.action == #selector(openURL) {
            return table.clickedRow != -1
        } else {
            return false
        }
    }
}

private extension NSUserInterfaceItemIdentifier {

    static let date = NSUserInterfaceItemIdentifier("date")
    static let contentWarning = NSUserInterfaceItemIdentifier("contentWarning")
    static let content = NSUserInterfaceItemIdentifier("content")

}