import AppKit
import ApplicationServices

public struct SystemPasteboard: PasteboardProviding {
    public init() {}

    public func readItems() -> [PasteboardItem] {
        (NSPasteboard.general.pasteboardItems ?? []).map { item in
            var dict: PasteboardItem = [:]
            for type in item.types {
                if let data = item.data(forType: type) { dict[type.rawValue] = data }
            }
            return dict
        }
    }

    public func writeString(_ text: String) {
        let pasteboard = NSPasteboard.general
        pasteboard.clearContents()
        pasteboard.setString(text, forType: .string)
    }

    public func writeItems(_ items: [PasteboardItem]) {
        let pasteboard = NSPasteboard.general
        pasteboard.clearContents()
        let restored = items.map { dict -> NSPasteboardItem in
            let item = NSPasteboardItem()
            for (type, data) in dict { item.setData(data, forType: NSPasteboard.PasteboardType(type)) }
            return item
        }
        if !restored.isEmpty { pasteboard.writeObjects(restored) }
    }
}

public struct CGEventPaster: KeystrokePosting {
    public enum PasteError: Error, LocalizedError {
        case accessibilityDenied
        case eventCreationFailed

        public var errorDescription: String? {
            switch self {
            case .accessibilityDenied:
                "Geen Accessibility-rechten: tekst staat op het klembord, plak zelf met ⌘V."
            case .eventCreationFailed:
                "Kon het plak-event niet aanmaken: tekst staat op het klembord."
            }
        }
    }

    public init() {}

    public func postPaste() throws {
        guard AXIsProcessTrusted() else { throw PasteError.accessibilityDenied }
        let source = CGEventSource(stateID: .combinedSessionState)
        let vKey: CGKeyCode = 0x09
        guard
            let down = CGEvent(keyboardEventSource: source, virtualKey: vKey, keyDown: true),
            let up = CGEvent(keyboardEventSource: source, virtualKey: vKey, keyDown: false)
        else { throw PasteError.eventCreationFailed }
        down.flags = .maskCommand
        up.flags = .maskCommand
        down.post(tap: .cgAnnotatedSessionEventTap)
        up.post(tap: .cgAnnotatedSessionEventTap)
    }
}