import AppKit
import SwiftUI

// MARK: - Shortcut Action

/// All configurable keyboard shortcut actions in MixBoard.
enum ShortcutAction: String, CaseIterable, Identifiable, Codable {
    // Playback
    case playPause      = "Play / Pause"
    case stop           = "Stop"
    case nextTrack      = "Next Track"
    case previousTrack  = "Previous Track"
    case skipForward    = "Skip Forward 10s"
    case skipBackward   = "Skip Backward 10s"
    case toggleShuffle  = "Toggle Shuffle"
    case toggleRepeat   = "Toggle Repeat"
    // Mix
    case addToMix1      = "Add to Mix 1"
    case addToMix2      = "Add to Mix 2"
    case addToMix3      = "Add to Mix 3"
    // General
    case nowPlaying     = "Now Playing"
    case search         = "Search All Playlists"
    case newPlaylist    = "New Playlist"
    case exportToDAW    = "Export to DAW"
    case importFromiPhone = "Import from iPhone"

    var id: String { rawValue }

    var group: ShortcutGroup {
        switch self {
        case .playPause, .stop, .nextTrack, .previousTrack,
             .skipForward, .skipBackward, .toggleShuffle, .toggleRepeat:
            return .playback
        case .addToMix1, .addToMix2, .addToMix3:
            return .mix
        case .nowPlaying, .search, .newPlaylist, .exportToDAW, .importFromiPhone:
            return .general
        }
    }
}

/// Grouping for display in the Shortcuts settings tab.
enum ShortcutGroup: String, CaseIterable {
    case playback = "Playback"
    case mix      = "Mix"
    case general  = "General"

    var actions: [ShortcutAction] {
        ShortcutAction.allCases.filter { $0.group == self }
    }
}

// MARK: - Shortcut Binding

/// A stored keyboard shortcut: key + modifier flags.
struct ShortcutBinding: Codable, Equatable {
    var key: String          // Character or special key: "space", "right", "left", etc.
    var command: Bool  = false
    var shift: Bool    = false
    var option: Bool   = false
    var control: Bool  = false

    /// Convert to SwiftUI `KeyEquivalent`.
    var keyEquivalent: KeyEquivalent {
        switch key.lowercased() {
        case "space":  return .space
        case "right":  return .rightArrow
        case "left":   return .leftArrow
        case "up":     return .upArrow
        case "down":   return .downArrow
        case "return": return .return
        case "tab":    return .tab
        case "delete": return .delete
        case "escape": return .escape
        default:
            if let char = key.first {
                return KeyEquivalent(char)
            }
            return KeyEquivalent("?")
        }
    }

    /// Convert to SwiftUI `EventModifiers`.
    var eventModifiers: EventModifiers {
        var mods: EventModifiers = []
        if command { mods.insert(.command) }
        if shift   { mods.insert(.shift) }
        if option  { mods.insert(.option) }
        if control { mods.insert(.control) }
        return mods
    }

    /// Human-readable display string, e.g. "⇧⌘1".
    var displayString: String {
        var parts: [String] = []
        if control { parts.append("⌃") }
        if option  { parts.append("⌥") }
        if shift   { parts.append("⇧") }
        if command { parts.append("⌘") }

        let keyDisplay: String
        switch key.lowercased() {
        case "space":  keyDisplay = "Space"
        case "right":  keyDisplay = "→"
        case "left":   keyDisplay = "←"
        case "up":     keyDisplay = "↑"
        case "down":   keyDisplay = "↓"
        case "return": keyDisplay = "↩"
        case "tab":    keyDisplay = "⇥"
        case "delete": keyDisplay = "⌫"
        case "escape": keyDisplay = "⎋"
        default:       keyDisplay = key.uppercased()
        }
        parts.append(keyDisplay)
        return parts.joined()
    }

    /// Build a `ShortcutBinding` from an `NSEvent`.
    static func from(_ event: NSEvent) -> ShortcutBinding {
        let key: String
        switch event.keyCode {
        case 49:  key = "space"
        case 124: key = "right"
        case 123: key = "left"
        case 126: key = "up"
        case 125: key = "down"
        case 36:  key = "return"
        case 48:  key = "tab"
        case 51:  key = "delete"
        default:
            key = event.charactersIgnoringModifiers?.lowercased() ?? "?"
        }
        let mods = event.modifierFlags
        return ShortcutBinding(
            key: key,
            command: mods.contains(.command),
            shift:   mods.contains(.shift),
            option:  mods.contains(.option),
            control: mods.contains(.control)
        )
    }
}

// MARK: - Config Singleton

/// Manages all keyboard shortcut bindings, persisted to UserDefaults.
final class KeyboardShortcutConfig: ObservableObject {
    static let shared = KeyboardShortcutConfig()

    @Published var shortcuts: [ShortcutAction: ShortcutBinding] {
        didSet { save() }
    }

    /// Factory defaults.
    static let defaultShortcuts: [ShortcutAction: ShortcutBinding] = [
        .playPause:       ShortcutBinding(key: "space"),
        .stop:            ShortcutBinding(key: ".", command: true),
        .nextTrack:       ShortcutBinding(key: "right", command: true),
        .previousTrack:   ShortcutBinding(key: "left", command: true),
        .skipForward:     ShortcutBinding(key: "right", command: true, shift: true),
        .skipBackward:    ShortcutBinding(key: "left", command: true, shift: true),
        .toggleShuffle:   ShortcutBinding(key: "s", command: true, shift: true),
        .toggleRepeat:    ShortcutBinding(key: "r", command: true, shift: true),
        .addToMix1:       ShortcutBinding(key: "1", command: true),
        .addToMix2:       ShortcutBinding(key: "2", command: true),
        .addToMix3:       ShortcutBinding(key: "3", command: true),
        .nowPlaying:      ShortcutBinding(key: "p", command: true, shift: true),
        .search:          ShortcutBinding(key: "f", command: true),
        .newPlaylist:     ShortcutBinding(key: "n", command: true, shift: true),
        .exportToDAW:     ShortcutBinding(key: "e", command: true),
        .importFromiPhone: ShortcutBinding(key: "i", command: true, shift: true),
    ]

    init() {
        shortcuts = Self.load()
    }

    /// Get the binding for an action (with fallback to default).
    func binding(for action: ShortcutAction) -> ShortcutBinding {
        shortcuts[action] ?? Self.defaultShortcuts[action]!
    }

    func resetToDefaults() {
        shortcuts = Self.defaultShortcuts
    }

    // MARK: - Persistence

    private func save() {
        let stringKeyed = Dictionary(uniqueKeysWithValues: shortcuts.map { ($0.key.rawValue, $0.value) })
        if let data = try? JSONEncoder().encode(stringKeyed) {
            UserDefaults.standard.set(data, forKey: "keyboardShortcuts")
        }
    }

    private static func load() -> [ShortcutAction: ShortcutBinding] {
        guard let data = UserDefaults.standard.data(forKey: "keyboardShortcuts"),
              let stringKeyed = try? JSONDecoder().decode([String: ShortcutBinding].self, from: data) else {
            return defaultShortcuts
        }
        // Merge with defaults so new actions added in updates get their fallback
        var result = defaultShortcuts
        for (key, value) in stringKeyed {
            if let action = ShortcutAction(rawValue: key) {
                result[action] = value
            }
        }
        return result
    }
}