import AppKit
import ConjureKit

@MainActor
final class LauncherWindowController: NSWindowController, NSWindowDelegate, NSSearchFieldDelegate, NSTableViewDataSource, NSTableViewDelegate {
    private let searchField = NSSearchField()
    private let tableView = ApplicationTableView()
    private let statusLabel = NSTextField(labelWithString: "Finding applications…")
    private let emptyLabel = NSTextField(labelWithString: "Finding applications…")
    private let openButton = NSButton(title: "Open Application", target: nil, action: nil)
    private var applications: [Application] = []
    private var results: [Application] = []
    private var discoveryTask: Task<Void, Never>?
    private var isLaunching = false

    init() {
        let window = NSWindow(
            contentRect: NSRect(x: 0, y: 0, width: 640, height: 480),
            styleMask: [.titled, .closable, .miniaturizable, .resizable],
            backing: .buffered,
            defer: false
        )
        window.title = "Conjure"
        window.contentMinSize = NSSize(width: 420, height: 300)
        window.isReleasedWhenClosed = false
        window.center()
        super.init(window: window)
        configureContent(in: window)
        window.delegate = self
    }

    required init?(coder: NSCoder) {
        fatalError("Conjure creates its window programmatically")
    }

    func present() {
        searchField.stringValue = ""
        updateResults()
        window?.deminiaturize(nil)
        showWindow(nil)
        NSApp.activate()
        window?.makeKeyAndOrderFront(nil)
        window?.makeFirstResponder(searchField)
        refreshApplications()
    }

    func windowDidResignKey(_ notification: Notification) {
        guard !isLaunching, window?.attachedSheet == nil else { return }
        window?.orderOut(nil)
    }

    private func configureContent(in window: NSWindow) {
        guard let content = window.contentView else { return }
        searchField.placeholderString = "Search applications"
        searchField.controlSize = .large
        searchField.font = .systemFont(ofSize: NSFont.systemFontSize(for: .large))
        searchField.sendsSearchStringImmediately = true
        searchField.sendsWholeSearchString = false
        searchField.delegate = self
        searchField.setAccessibilityLabel("Search applications")

        let column = NSTableColumn(identifier: NSUserInterfaceItemIdentifier("application"))
        column.resizingMask = .autoresizingMask
        tableView.addTableColumn(column)
        tableView.headerView = nil
        tableView.style = .inset
        tableView.rowHeight = 44
        tableView.columnAutoresizingStyle = .uniformColumnAutoresizingStyle
        tableView.allowsMultipleSelection = false
        tableView.allowsEmptySelection = false
        tableView.dataSource = self
        tableView.delegate = self
        tableView.target = self
        tableView.doubleAction = #selector(openSelection)
        tableView.openSelection = { [weak self] in self?.openSelection() }
        tableView.dismiss = { [weak self] in self?.window?.orderOut(nil) }
        tableView.editSearch = { [weak self] event in
            guard let self, let window = self.window else { return }
            window.makeFirstResponder(self.searchField)
            self.searchField.currentEditor()?.keyDown(with: event)
        }
        tableView.setAccessibilityLabel("Applications")

        let scrollView = NSScrollView()
        scrollView.documentView = tableView
        scrollView.hasVerticalScroller = true
        scrollView.autohidesScrollers = true
        scrollView.borderType = .noBorder

        statusLabel.font = .systemFont(ofSize: NSFont.smallSystemFontSize)
        statusLabel.textColor = .secondaryLabelColor
        statusLabel.setContentCompressionResistancePriority(.defaultLow, for: .horizontal)
        emptyLabel.textColor = .secondaryLabelColor
        emptyLabel.alignment = .center
        openButton.bezelStyle = .rounded
        openButton.keyEquivalent = "\r"
        openButton.target = self
        openButton.action = #selector(openSelection)
        openButton.isEnabled = false
        openButton.toolTip = "Open the selected application (Return). Use ↑ and ↓ to select."

        let footer = NSStackView(views: [statusLabel, NSView(), openButton])
        footer.orientation = .horizontal
        footer.spacing = 12
        for view in [searchField, scrollView, emptyLabel, footer] {
            view.translatesAutoresizingMaskIntoConstraints = false
            content.addSubview(view)
        }
        NSLayoutConstraint.activate([
            searchField.topAnchor.constraint(equalTo: content.topAnchor, constant: 16),
            searchField.leadingAnchor.constraint(equalTo: content.leadingAnchor, constant: 16),
            searchField.trailingAnchor.constraint(equalTo: content.trailingAnchor, constant: -16),
            scrollView.topAnchor.constraint(equalTo: searchField.bottomAnchor, constant: 12),
            scrollView.leadingAnchor.constraint(equalTo: content.leadingAnchor),
            scrollView.trailingAnchor.constraint(equalTo: content.trailingAnchor),
            scrollView.bottomAnchor.constraint(equalTo: footer.topAnchor, constant: -12),
            emptyLabel.centerXAnchor.constraint(equalTo: scrollView.centerXAnchor),
            emptyLabel.centerYAnchor.constraint(equalTo: scrollView.centerYAnchor),
            emptyLabel.leadingAnchor.constraint(greaterThanOrEqualTo: content.leadingAnchor, constant: 16),
            emptyLabel.trailingAnchor.constraint(lessThanOrEqualTo: content.trailingAnchor, constant: -16),
            footer.leadingAnchor.constraint(equalTo: content.leadingAnchor, constant: 16),
            footer.trailingAnchor.constraint(equalTo: content.trailingAnchor, constant: -16),
            footer.bottomAnchor.constraint(equalTo: content.bottomAnchor, constant: -12),
        ])
        window.initialFirstResponder = searchField
    }

    private func refreshApplications() {
        guard discoveryTask == nil else { return }
        statusLabel.stringValue = "Finding applications…"
        discoveryTask = Task { [weak self] in
            let applications = await Task.detached(priority: .userInitiated) {
                ApplicationCatalog.discover()
            }.value
            guard let self else { return }
            self.applications = applications
            self.discoveryTask = nil
            self.updateResults()
        }
    }

    private func updateResults() {
        results = ApplicationSearch.results(for: searchField.stringValue, in: applications)
        tableView.reloadData()
        if !results.isEmpty {
            tableView.selectRowIndexes(IndexSet(integer: 0), byExtendingSelection: false)
            tableView.scrollRowToVisible(0)
        }
        emptyLabel.isHidden = !results.isEmpty
        if discoveryTask != nil {
            emptyLabel.stringValue = "Finding applications…"
            statusLabel.stringValue = "Finding applications…"
        } else {
            emptyLabel.stringValue = applications.isEmpty ? "No applications found" : "No matching applications"
            statusLabel.stringValue = results.count == 1 ? "1 application" : "\(results.count) applications"
        }
        updateOpenButton()
    }

    func controlTextDidChange(_ notification: Notification) {
        updateResults()
    }

    func control(_ control: NSControl, textView: NSTextView, doCommandBy commandSelector: Selector) -> Bool {
        switch commandSelector {
        case #selector(NSResponder.moveDown(_:)):
            moveSelection(by: 1)
        case #selector(NSResponder.moveUp(_:)):
            moveSelection(by: -1)
        case #selector(NSResponder.insertNewline(_:)):
            openSelection()
        case #selector(NSResponder.cancelOperation(_:)):
            window?.orderOut(nil)
        default:
            return false
        }
        return true
    }

    private func moveSelection(by offset: Int) {
        guard !results.isEmpty else { return }
        let row = min(max(tableView.selectedRow + offset, 0), results.count - 1)
        tableView.selectRowIndexes(IndexSet(integer: row), byExtendingSelection: false)
        tableView.scrollRowToVisible(row)
    }

    private func updateOpenButton() {
        openButton.isEnabled = !isLaunching && results.indices.contains(tableView.selectedRow)
    }

    func tableViewSelectionDidChange(_ notification: Notification) {
        updateOpenButton()
    }

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

    func tableView(_ tableView: NSTableView, viewFor tableColumn: NSTableColumn?, row: Int) -> NSView? {
        let identifier = NSUserInterfaceItemIdentifier("applicationCell")
        let cell = (tableView.makeView(withIdentifier: identifier, owner: self) as? NSTableCellView)
            ?? makeCell(identifier: identifier)
        let application = results[row]
        cell.textField?.stringValue = application.name
        cell.imageView?.image = NSWorkspace.shared.icon(forFile: application.url.path)
        cell.toolTip = application.url.path
        return cell
    }

    private func makeCell(identifier: NSUserInterfaceItemIdentifier) -> NSTableCellView {
        let cell = NSTableCellView()
        cell.identifier = identifier
        let icon = NSImageView()
        icon.imageScaling = .scaleProportionallyDown
        icon.setAccessibilityElement(false)
        let label = NSTextField(labelWithString: "")
        label.lineBreakMode = .byTruncatingTail
        cell.imageView = icon
        cell.textField = label
        for view in [icon, label] {
            view.translatesAutoresizingMaskIntoConstraints = false
            cell.addSubview(view)
        }
        NSLayoutConstraint.activate([
            icon.leadingAnchor.constraint(equalTo: cell.leadingAnchor, constant: 8),
            icon.centerYAnchor.constraint(equalTo: cell.centerYAnchor),
            icon.widthAnchor.constraint(equalToConstant: 28),
            icon.heightAnchor.constraint(equalToConstant: 28),
            label.leadingAnchor.constraint(equalTo: icon.trailingAnchor, constant: 12),
            label.centerYAnchor.constraint(equalTo: cell.centerYAnchor),
            label.trailingAnchor.constraint(equalTo: cell.trailingAnchor, constant: -8),
        ])
        return cell
    }

    @objc private func openSelection() {
        guard !isLaunching, results.indices.contains(tableView.selectedRow) else { return }
        let application = results[tableView.selectedRow]
        isLaunching = true
        updateOpenButton()
        Task {
            do {
                try await AppLauncher.launch(application.url)
                window?.orderOut(nil)
            } catch {
                let alert = NSAlert(error: error)
                alert.messageText = "Couldn’t open \(application.name)"
                if let window {
                    await alert.beginSheetModal(for: window)
                }
            }
            isLaunching = false
            updateOpenButton()
        }
    }
}

@MainActor
private final class ApplicationTableView: NSTableView {
    var openSelection: (() -> Void)?
    var dismiss: (() -> Void)?
    var editSearch: ((NSEvent) -> Void)?

    override func keyDown(with event: NSEvent) {
        switch event.keyCode {
        case 36, 76:
            openSelection?()
        case 53:
            dismiss?()
        default:
            let isEditing = event.keyCode == 51 || event.keyCode == 117
                || (event.characters?.unicodeScalars.contains { !CharacterSet.controlCharacters.contains($0) } ?? false)
            if isEditing && event.modifierFlags.intersection([.command, .control]).isEmpty {
                editSearch?(event)
            } else {
                super.keyDown(with: event)
            }
        }
    }
}