import Foundation
import Vision
import CoreVideo
import CoreGraphics

/// Thin wrapper over Vision's text recognition, used by adapters to read names /
/// initials off participant tiles. Runs on the Neural Engine; no permission
/// needed. Works on any frame, so adapters can be developed against still images.
struct TextRecognizer {
    struct Result {
        let text: String
        let confidence: Float
        /// Normalized Vision bounding box (origin bottom-left, 0…1).
        let boundingBox: CGRect
    }

    var recognitionLevel: VNRequestTextRecognitionLevel = .accurate
    var minimumTextHeight: Float = 0          // 0 = Vision default
    var usesLanguageCorrection = false        // names/initials aren't dictionary words

    /// Recognize text in `pixelBuffer`, optionally limited to a normalized region
    /// of interest (origin bottom-left, matching Vision's coordinate space).
    func recognize(in pixelBuffer: CVPixelBuffer, regionOfInterest: CGRect? = nil) -> [Result] {
        let request = VNRecognizeTextRequest()
        request.recognitionLevel = recognitionLevel
        request.usesLanguageCorrection = usesLanguageCorrection
        if minimumTextHeight > 0 { request.minimumTextHeight = minimumTextHeight }
        if let roi = regionOfInterest { request.regionOfInterest = roi }

        let handler = VNImageRequestHandler(cvPixelBuffer: pixelBuffer, options: [:])
        do {
            try handler.perform([request])
        } catch {
            return []
        }

        guard let observations = request.results else { return [] }
        return observations.compactMap { obs in
            guard let top = obs.topCandidates(1).first else { return nil }
            return Result(text: top.string, confidence: top.confidence, boundingBox: obs.boundingBox)
        }
    }

    /// Convenience for fixtures/tests: recognize text in a CGImage.
    func recognize(in cgImage: CGImage, regionOfInterest: CGRect? = nil) -> [Result] {
        let request = VNRecognizeTextRequest()
        request.recognitionLevel = recognitionLevel
        request.usesLanguageCorrection = usesLanguageCorrection
        if minimumTextHeight > 0 { request.minimumTextHeight = minimumTextHeight }
        if let roi = regionOfInterest { request.regionOfInterest = roi }

        let handler = VNImageRequestHandler(cgImage: cgImage, options: [:])
        guard (try? handler.perform([request])) != nil, let results = request.results else { return [] }
        return results.compactMap { obs in
            guard let top = obs.topCandidates(1).first else { return nil }
            return Result(text: top.string, confidence: top.confidence, boundingBox: obs.boundingBox)
        }
    }
}