conjure/Sources/Conjure/TranslationController.swift

import AppKit
import ConjureKit
import Security

@MainActor
final class TranslationController: NSViewController {
    private let keyField = NSSecureTextField()
    private let provider = NSPopUpButton()
    private let credentials = NSStackView()
    private var usesMyMemory: Bool { provider.indexOfSelectedItem == 0 }
    private let output = NSTextView()
    private let status = NSTextField(wrappingLabelWithString: "")
    private let translateButton = NSButton(title: "Translate ↵", target: nil, action: nil)
    private var task: Task<Void, Never>?
    var input: (() -> String)?
    var closed: (() -> Void)?
    private static let credential: [String: Any] = [
        kSecClass as String: kSecClassGenericPassword,
        kSecAttrService as String: "Conjure.OpenAI",
        kSecAttrAccount as String: "translation",
    ]

    override func loadView() {
        view = NSView()
        let back = NSButton(title: "‹ Back", target: self, action: #selector(goBack))
        let title = NSTextField(labelWithString: "Conjure Translate · English → Japanese")
        title.font = .systemFont(ofSize: 13, weight: .semibold)
        let heading = NSStackView(views: [back, title, NSView()])
        provider.addItems(withTitles: ["MyMemory (no key)", "OpenAI · gpt-6-luna"])
        provider.selectItem(at: UserDefaults.standard.string(forKey: "translationProvider") == "openai" ? 1 : 0)
        provider.setAccessibilityLabel("Translation provider")
        provider.target = self
        provider.action = #selector(providerChanged)
        keyField.placeholderString = "OpenAI API key (saved in Keychain)"
        keyField.setAccessibilityLabel("OpenAI API key")
        keyField.widthAnchor.constraint(greaterThanOrEqualToConstant: 220).isActive = true
        let save = NSButton(title: "Save Key", target: self, action: #selector(saveKey))
        let forget = NSButton(title: "Forget Key", target: self, action: #selector(forgetKey))
        for control in [keyField, save, forget] { credentials.addArrangedSubview(control) }
        credentials.distribution = .fill
        translateButton.target = self
        translateButton.action = #selector(translate)
        translateButton.keyEquivalent = "\r"
        output.isEditable = false
        output.isSelectable = true
        output.drawsBackground = false
        output.textColor = SunsetPalette.text
        output.font = .systemFont(ofSize: 20)
        output.setAccessibilityLabel("Japanese translation")
        let scroll = NSScrollView()
        scroll.documentView = output
        scroll.hasVerticalScroller = true
        scroll.drawsBackground = false
        output.isVerticallyResizable = true
        output.autoresizingMask = [.width]
        output.textContainer?.widthTracksTextView = true
        status.textColor = SunsetPalette.secondaryText
        status.font = .systemFont(ofSize: 12)
        let stack = NSStackView(views: [heading, provider, credentials, scroll, status, translateButton])
        stack.orientation = .vertical
        stack.alignment = .leading
        stack.spacing = 12
        stack.translatesAutoresizingMaskIntoConstraints = false
        view.addSubview(stack)
        NSLayoutConstraint.activate([
            stack.leadingAnchor.constraint(equalTo: view.leadingAnchor, constant: 16),
            stack.trailingAnchor.constraint(equalTo: view.trailingAnchor, constant: -16),
            stack.topAnchor.constraint(equalTo: view.topAnchor),
            stack.bottomAnchor.constraint(equalTo: view.bottomAnchor, constant: -16),
            credentials.widthAnchor.constraint(equalTo: stack.widthAnchor),
            scroll.widthAnchor.constraint(equalTo: stack.widthAnchor),
            scroll.heightAnchor.constraint(greaterThanOrEqualToConstant: 100),
            status.widthAnchor.constraint(equalTo: stack.widthAnchor),
        ])
        updateProvider()
    }

    @objc func goBack() {
        task?.cancel()
        task = nil
        closed?()
    }

    func inputChanged() {
        task?.cancel()
        task = nil
        translateButton.isEnabled = true
        output.string = ""
        status.stringValue = usesMyMemory
            ? "MyMemory · No key · 500 bytes/request · 5,000 characters/day. Text is sent to MyMemory; avoid sensitive content."
            : "OpenAI · gpt-6-luna · Text is sent to OpenAI only when you translate."
    }

    @objc private func providerChanged() {
        UserDefaults.standard.set(usesMyMemory ? "mymemory" : "openai", forKey: "translationProvider")
        keyField.stringValue = ""
        updateProvider()
    }

    private func updateProvider() {
        credentials.isHidden = usesMyMemory
        inputChanged()
    }

    @objc private func saveKey() {
        let key = keyField.stringValue.trimmingCharacters(in: .whitespacesAndNewlines)
        guard !key.isEmpty, !key.contains(where: { $0.isNewline }) else {
            status.stringValue = "Enter a valid API key before saving."
            return
        }
        let data = Data(key.utf8)
        var result = SecItemUpdate(Self.credential as CFDictionary, [kSecValueData as String: data] as CFDictionary)
        if result == errSecItemNotFound {
            var item = Self.credential
            item[kSecValueData as String] = data
            item[kSecAttrAccessible as String] = kSecAttrAccessibleWhenUnlockedThisDeviceOnly
            result = SecItemAdd(item as CFDictionary, nil)
        }
        if result == errSecSuccess {
            keyField.stringValue = ""
            status.stringValue = "API key saved in Keychain. Press Return to translate."
        } else { showKeychainError(result) }
    }

    @objc private func forgetKey() {
        task?.cancel()
        task = nil
        translateButton.isEnabled = true
        let result = SecItemDelete(Self.credential as CFDictionary)
        if result == errSecSuccess || result == errSecItemNotFound {
            keyField.stringValue = ""
            status.stringValue = "API key removed."
        } else { showKeychainError(result) }
    }

    private func showKeychainError(_ code: OSStatus) {
        status.stringValue = "Keychain: \(SecCopyErrorMessageString(code, nil) as String? ?? String(code))"
    }

    @objc func translate() {
        guard task == nil else { return }
        let text = input?() ?? ""
        guard !text.trimmingCharacters(in: .whitespacesAndNewlines).isEmpty else {
            status.stringValue = "Enter English text in the search bar."
            return
        }
        let myMemory = usesMyMemory
        var key = ""
        if !myMemory {
            if !keyField.stringValue.isEmpty { saveKey(); guard keyField.stringValue.isEmpty else { return } }
            var query = Self.credential
            query[kSecReturnData as String] = true
            var item: CFTypeRef?
            let result = SecItemCopyMatching(query as CFDictionary, &item)
            guard result == errSecSuccess, let data = item as? Data, let savedKey = String(data: data, encoding: .utf8) else {
                if result == errSecItemNotFound { status.stringValue = "Enter and save your OpenAI API key first." }
                else { showKeychainError(result) }
                return
            }
            key = savedKey
        }
        output.string = ""
        status.stringValue = "Translating…"
        translateButton.isEnabled = false
        task = Task { [weak self] in
            do {
                let translation = try await myMemory
                    ? MyMemoryAPI.translate(text)
                    : TranslationAPI.translate(text, apiKey: key)
                guard !Task.isCancelled, let self else { return }
                self.output.string = translation
                self.status.stringValue = "Japanese · Select text to copy (⌘C)."
            } catch {
                guard !Task.isCancelled, let self else { return }
                self.status.stringValue = error.localizedDescription
            }
            guard let self else { return }
            self.task = nil
            self.translateButton.isEnabled = true
        }
    }
}