import Foundation
import RDSpeechReaderView

/// A ready-to-use PDF speech session. It owns the controller delegate so page
/// navigation and temporary sentence highlighting stay synchronized.
@MainActor
public final class RDPDFSpeechSession: NSObject, RDSpeechReaderControllerDelegate {
    public let controller: RDSpeechReaderController
    public let contentProvider: RDPDFSpeechContentProvider
    public var onStateChange: ((RDSpeechReaderState) -> Void)?

    private weak var reader: RDPDFReaderViewController?

    init(reader: RDPDFReaderViewController, configuration: RDSpeechReaderConfiguration) {
        self.reader = reader
        contentProvider = reader.makeSpeechContentProvider()
        controller = RDSpeechReaderController(contentProvider: contentProvider, configuration: configuration)
        super.init()
        controller.delegate = self
    }

    public func start(from pageIndex: Int = 0) async throws {
        let location = RDSpeechLocation(
            bookIdentifier: contentProvider.speechBookDescriptor().identifier,
            resourceIdentifier: String(max(0, pageIndex))
        )
        try await controller.start(from: location)
    }

    public func pause() { controller.pause() }
    public func resume() { controller.resume() }

    public func stop() {
        controller.stop()
        reader?.clearSpeechHighlight()
    }

    public func speechReaderController(_ controller: RDSpeechReaderController, didChange state: RDSpeechReaderState) {
        if case .finished = state { reader?.clearSpeechHighlight() }
        if case .idle = state { reader?.clearSpeechHighlight() }
        onStateChange?(state)
    }

    public func speechReaderController(_ controller: RDSpeechReaderController, willSpeak range: RDSpeechSpokenRange) {
        guard let pageIndex = Int(range.unit.location.resourceIdentifier) else { return }
        reader?.showSpeechHighlight(
            pageIndex: pageIndex,
            normalizedRects: contentProvider.normalizedRects(for: range)
        )
    }
}

public extension RDPDFReaderViewController {
    func makeSpeechSession(
        configuration: RDSpeechReaderConfiguration = .default
    ) -> RDPDFSpeechSession {
        RDPDFSpeechSession(reader: self, configuration: configuration)
    }
}