import AppKit
import Carbon.HIToolbox
import Foundation

/// User-chosen capture hotkey. `modifiers` are Carbon bits (`cmdKey`, `optionKey`,
/// `shiftKey`, `controlKey`), matching `HotkeyCenter.register`.
struct HotkeyPreference: Codable, Equatable, Sendable {
    var keyCode: UInt32
    var modifiers: UInt32

    static let defaultsKey = "ai.flowmaster.shotdeck.hotkey"

    /// ⌥⇧2 — kVK_ANSI_2 (19) with optionKey|shiftKey.
    static let `default` = HotkeyPreference(
        keyCode: 19,
        modifiers: UInt32(optionKey) | UInt32(shiftKey)
    )

    static func load(defaults: UserDefaults = .standard) -> HotkeyPreference {
        guard let data = defaults.data(forKey: defaultsKey),
              let decoded = try? JSONDecoder().decode(HotkeyPreference.self, from: data),
              decoded.modifiers != 0
        else { return .default }
        return decoded
    }

    func save(defaults: UserDefaults = .standard) {
        guard let data = try? JSONEncoder().encode(self) else { return }
        defaults.set(data, forKey: Self.defaultsKey)
    }

    /// ⌘⌥⇧⌃ in that order, then a name for common keycodes.
    var displayString: String {
        var s = ""
        if modifiers & UInt32(cmdKey) != 0 { s += "⌘" }
        if modifiers & UInt32(optionKey) != 0 { s += "⌥" }
        if modifiers & UInt32(shiftKey) != 0 { s += "⇧" }
        if modifiers & UInt32(controlKey) != 0 { s += "⌃" }
        s += Self.keyName(for: keyCode)
        return s
    }

    /// `nil` when the event is modifier-only or has no ⌘⌥⇧⌃ flags.
    static func fromKeyEvent(keyCode: UInt16, modifierFlags: NSEvent.ModifierFlags) -> HotkeyPreference? {
        switch Int(keyCode) {
        case kVK_Shift, kVK_RightShift,
             kVK_Command, kVK_RightCommand,
             kVK_Option, kVK_RightOption,
             kVK_Control, kVK_RightControl,
             kVK_CapsLock, kVK_Function:
            return nil
        default:
            break
        }
        var carbon: UInt32 = 0
        if modifierFlags.contains(.command) { carbon |= UInt32(cmdKey) }
        if modifierFlags.contains(.option) { carbon |= UInt32(optionKey) }
        if modifierFlags.contains(.shift) { carbon |= UInt32(shiftKey) }
        if modifierFlags.contains(.control) { carbon |= UInt32(controlKey) }
        guard carbon != 0 else { return nil }
        return HotkeyPreference(keyCode: UInt32(keyCode), modifiers: carbon)
    }

    private static func keyName(for keyCode: UInt32) -> String {
        switch Int(keyCode) {
        case kVK_ANSI_A: return "A"
        case kVK_ANSI_B: return "B"
        case kVK_ANSI_C: return "C"
        case kVK_ANSI_D: return "D"
        case kVK_ANSI_E: return "E"
        case kVK_ANSI_F: return "F"
        case kVK_ANSI_G: return "G"
        case kVK_ANSI_H: return "H"
        case kVK_ANSI_I: return "I"
        case kVK_ANSI_J: return "J"
        case kVK_ANSI_K: return "K"
        case kVK_ANSI_L: return "L"
        case kVK_ANSI_M: return "M"
        case kVK_ANSI_N: return "N"
        case kVK_ANSI_O: return "O"
        case kVK_ANSI_P: return "P"
        case kVK_ANSI_Q: return "Q"
        case kVK_ANSI_R: return "R"
        case kVK_ANSI_S: return "S"
        case kVK_ANSI_T: return "T"
        case kVK_ANSI_U: return "U"
        case kVK_ANSI_V: return "V"
        case kVK_ANSI_W: return "W"
        case kVK_ANSI_X: return "X"
        case kVK_ANSI_Y: return "Y"
        case kVK_ANSI_Z: return "Z"
        case kVK_ANSI_0: return "0"
        case kVK_ANSI_1: return "1"
        case kVK_ANSI_2: return "2"
        case kVK_ANSI_3: return "3"
        case kVK_ANSI_4: return "4"
        case kVK_ANSI_5: return "5"
        case kVK_ANSI_6: return "6"
        case kVK_ANSI_7: return "7"
        case kVK_ANSI_8: return "8"
        case kVK_ANSI_9: return "9"
        case kVK_ANSI_Equal: return "="
        case kVK_ANSI_Minus: return "-"
        case kVK_ANSI_RightBracket: return "]"
        case kVK_ANSI_LeftBracket: return "["
        case kVK_ANSI_Quote: return "'"
        case kVK_ANSI_Semicolon: return ";"
        case kVK_ANSI_Backslash: return "\\"
        case kVK_ANSI_Comma: return ","
        case kVK_ANSI_Slash: return "/"
        case kVK_ANSI_Period: return "."
        case kVK_ANSI_Grave: return "`"
        case kVK_Space: return "Space"
        case kVK_Return: return "Return"
        case kVK_Tab: return "Tab"
        case kVK_Delete: return "Delete"
        case kVK_ForwardDelete: return "Fwd Delete"
        case kVK_Escape: return "Esc"
        case kVK_Home: return "Home"
        case kVK_End: return "End"
        case kVK_PageUp: return "Page Up"
        case kVK_PageDown: return "Page Down"
        case kVK_Help: return "Help"
        case kVK_LeftArrow: return "←"
        case kVK_RightArrow: return "→"
        case kVK_DownArrow: return "↓"
        case kVK_UpArrow: return "↑"
        case kVK_F1: return "F1"
        case kVK_F2: return "F2"
        case kVK_F3: return "F3"
        case kVK_F4: return "F4"
        case kVK_F5: return "F5"
        case kVK_F6: return "F6"
        case kVK_F7: return "F7"
        case kVK_F8: return "F8"
        case kVK_F9: return "F9"
        case kVK_F10: return "F10"
        case kVK_F11: return "F11"
        case kVK_F12: return "F12"
        case kVK_F13: return "F13"
        case kVK_F14: return "F14"
        case kVK_F15: return "F15"
        case kVK_F16: return "F16"
        case kVK_F17: return "F17"
        case kVK_F18: return "F18"
        case kVK_F19: return "F19"
        case kVK_F20: return "F20"
        default: return "Key \(keyCode)"
        }
    }
}