import Foundation
import RDAIReaderView

/// Temporary speech content for an AI answer or summary. It deliberately uses
/// an in-memory identifier and disables progress persistence by default.
@MainActor
public final class RDAISpeechContentProvider: RDSpeechContentProvider {
    private let descriptor: RDSpeechBookDescriptor
    private let units: [RDSpeechTextUnit]

    public init(title: String, text: String, language: String? = nil) {
        let identifier = "rdai-speech-\(UUID().uuidString)"
        descriptor = RDSpeechBookDescriptor(identifier: identifier, title: title)
        let location = RDSpeechLocation(bookIdentifier: identifier, resourceIdentifier: "ai-result")
        units = RDSpeechTextPreprocessor.makeUnits(text: text, location: location, language: language)
    }

    public func speechBookDescriptor() -> RDSpeechBookDescriptor { descriptor }

    public func speechContentBatch(startingAt location: RDSpeechLocation?, limit: Int) async throws -> RDSpeechContentBatch {
        let start = location.flatMap { requested in units.firstIndex { $0.location.textOffset >= requested.textOffset } } ?? 0
        let batch = Array(units.dropFirst(start).prefix(max(1, limit)))
        let nextIndex = start + batch.count
        return RDSpeechContentBatch(units: batch, nextLocation: nextIndex < units.count ? units[nextIndex].location : nil)
    }
}

@MainActor
public extension RDSpeechReaderController {
    convenience init(aiTitle: String, text: String, language: String? = nil, configuration: RDSpeechReaderConfiguration = .default) {
        let provider = RDAISpeechContentProvider(title: aiTitle, text: text, language: language)
        self.init(contentProvider: provider, configuration: configuration, progressStore: nil)
    }
}