import Foundation

public typealias PasteboardItem = [String: Data]

public protocol PasteboardProviding {
    func readItems() -> [PasteboardItem]
    func writeString(_ text: String)
    func writeItems(_ items: [PasteboardItem])
}

public protocol KeystrokePosting {
    func postPaste() throws
}

public struct TextInserter: TextInserting {
    private let pasteboard: PasteboardProviding
    private let paster: KeystrokePosting
    private let restoreDelay: Duration

    public init(
        pasteboard: PasteboardProviding,
        paster: KeystrokePosting,
        restoreDelay: Duration = .milliseconds(400)
    ) {
        self.pasteboard = pasteboard
        self.paster = paster
        self.restoreDelay = restoreDelay
    }

    public func insert(_ text: String) async throws {
        let saved = pasteboard.readItems()
        pasteboard.writeString(text)
        // On failure the text deliberately stays on the clipboard.
        try paster.postPaste()
        // Give the target app time to read the clipboard before restoring it.
        try await Task.sleep(for: restoreDelay)
        pasteboard.writeItems(saved)
    }
}