import AppKit
import Carbon.HIToolbox
import Localization

/// 可以绑定全局快捷键的操作
public enum HotKeyAction: String, CaseIterable, Identifiable, Codable, Sendable {
    case toggleMainWindow, showProcesses, toggleKeepAwake, purgeMemory

    public var id: String { rawValue }

    var title: String {
        switch self {
        case .toggleMainWindow: tr("显示 / 隐藏主窗口")
        case .showProcesses: tr("打开进程页")
        case .toggleKeepAwake: tr("开关防休眠")
        case .purgeMemory: tr("释放内存")
        }
    }

    /// Carbon 热键编号，从 1 开始
    var carbonID: UInt32 { UInt32(Self.allCases.firstIndex(of: self)! + 1) }
}

/// 一个快捷键：虚拟键码加修饰键
public struct HotKey: Codable, Equatable, Sendable {
    public var keyCode: UInt16
    /// NSEvent.ModifierFlags 的原始值，只保留 ⌃⌥⇧⌘
    public var modifiers: UInt
    /// 录制时按下的字符，用于显示
    public var key: String

    public init(keyCode: UInt16, modifiers: NSEvent.ModifierFlags, key: String) {
        self.keyCode = keyCode
        self.modifiers = modifiers.intersection([.control, .option, .shift, .command]).rawValue
        self.key = key
    }

    var flags: NSEvent.ModifierFlags { NSEvent.ModifierFlags(rawValue: modifiers) }

    /// 至少带一个 ⌃、⌥ 或 ⌘，避免抢走普通按键
    var isValid: Bool { !flags.intersection([.control, .option, .command]).isEmpty }

    var display: String {
        var text = ""
        if flags.contains(.control) { text += "⌃" }
        if flags.contains(.option) { text += "⌥" }
        if flags.contains(.shift) { text += "⇧" }
        if flags.contains(.command) { text += "⌘" }
        return text + Self.keyName(keyCode: keyCode, fallback: key)
    }

    var carbonModifiers: UInt32 {
        var result: UInt32 = 0
        if flags.contains(.control) { result |= UInt32(controlKey) }
        if flags.contains(.option) { result |= UInt32(optionKey) }
        if flags.contains(.shift) { result |= UInt32(shiftKey) }
        if flags.contains(.command) { result |= UInt32(cmdKey) }
        return result
    }

    private static let functionKeys: [Int: Int] = [
        kVK_F1: 1, kVK_F2: 2, kVK_F3: 3, kVK_F4: 4, kVK_F5: 5, kVK_F6: 6,
        kVK_F7: 7, kVK_F8: 8, kVK_F9: 9, kVK_F10: 10, kVK_F11: 11, kVK_F12: 12,
    ]

    static func keyName(keyCode: UInt16, fallback: String) -> String {
        switch Int(keyCode) {
        case kVK_Space: tr("空格")
        case kVK_Return: "↩"
        case kVK_Tab: "⇥"
        case kVK_Delete: "⌫"
        case kVK_Escape: "⎋"
        case kVK_LeftArrow: "←"
        case kVK_RightArrow: "→"
        case kVK_UpArrow: "↑"
        case kVK_DownArrow: "↓"
        default:
            // F1–F12 的虚拟键码不连续，逐个对照
            functionKeys[Int(keyCode)].map { "F\($0)" } ?? fallback.uppercased()
        }
    }
}

/// 用 Carbon 注册系统级快捷键：不需要辅助功能权限，应用在后台也能响应
@MainActor
final class HotKeyCenter {
    private var references: [HotKeyAction: EventHotKeyRef] = [:]
    private var handler: EventHandlerRef?
    var onAction: (HotKeyAction) -> Void = { _ in }
    /// 注册失败（被其他应用占用）的操作
    private(set) var conflicts: Set<HotKeyAction> = []

    private static weak var current: HotKeyCenter?

    func apply(_ bindings: [HotKeyAction: HotKey]) {
        installHandlerIfNeeded()
        for reference in references.values { UnregisterEventHotKey(reference) }
        references = [:]
        conflicts = []
        for (action, hotKey) in bindings where hotKey.isValid {
            var reference: EventHotKeyRef?
            let id = EventHotKeyID(signature: Self.signature, id: action.carbonID)
            let status = RegisterEventHotKey(UInt32(hotKey.keyCode), hotKey.carbonModifiers, id, GetApplicationEventTarget(), 0, &reference)
            if status == noErr, let reference {
                references[action] = reference
            } else {
                conflicts.insert(action)
            }
        }
    }

    private static let signature: OSType = 0x4F505354   // "OPST"

    private func installHandlerIfNeeded() {
        guard handler == nil else { return }
        Self.current = self
        var spec = EventTypeSpec(eventClass: OSType(kEventClassKeyboard), eventKind: UInt32(kEventHotKeyPressed))
        InstallEventHandler(GetApplicationEventTarget(), { _, event, _ -> OSStatus in
            var id = EventHotKeyID()
            let status = GetEventParameter(event, EventParamName(kEventParamDirectObject), EventParamType(typeEventHotKeyID),
                                           nil, MemoryLayout<EventHotKeyID>.size, nil, &id)
            guard status == noErr, id.signature == HotKeyCenter.signature,
                  let action = HotKeyAction.allCases.first(where: { $0.carbonID == id.id }) else { return OSStatus(eventNotHandledErr) }
            MainActor.assumeIsolated { HotKeyCenter.current?.onAction(action) }
            return noErr
        }, 1, &spec, nil, &handler)
    }
}