import Vision
import CoreGraphics

// MARK: - OCR ENGINE
class OCREngine {
    static func readCardDetails(image: CGImage, orientation: CGImagePropertyOrientation = .up) -> (setCode: String?, number: String?, year: String?, isSerialized: Bool) {
        let request = VNRecognizeTextRequest()
        request.recognitionLevel = .accurate
        request.usesLanguageCorrection = false
        let handler = VNImageRequestHandler(cgImage: image, orientation: orientation)
        try? handler.perform([request])
        guard let obs = request.results as? [VNRecognizedTextObservation] else { return (nil, nil, nil, false) }

        var possibleSetCode: String?
        var possibleNumber: String?
        var possibleYear: String?
        var isSerialized = false

        for observation in obs {
            guard let candidate = observation.topCandidates(1).first else { continue }
            let text = candidate.string.trimmingCharacters(in: .whitespacesAndNewlines)

            // Set Code: 3-5 chars, uppercase
            // FIX: Ensure it's in the bottom half to avoid reading Card Name (e.g. "FOG") as Set Code
            // FIX: Must contain at least one letter to avoid reading years or numbers as Set Codes
            if text.count >= 3 && text.count <= 5 && text == text.uppercased() && possibleSetCode == nil && text.rangeOfCharacter(from: .letters) != nil {
                // Vision coordinates: (0,0) is Bottom-Left. y < 0.5 is Bottom Half.
                // FIX: Tighten to y < 0.2 to match Collector Number and fully exclude Text Box (e.g. "FLY")
                if observation.boundingBox.origin.y < 0.2 { possibleSetCode = text }
            }

            // Collector Number & Serialized
            if text.contains("/") && text.count <= 10 {
                // FILTER: Ignore Power/Toughness in bottom-right corner (x > 0.75, y < 0.2)
                if observation.boundingBox.origin.x > 0.75 && observation.boundingBox.origin.y < 0.2 { continue }

                // FIX: Tighten standard location to bottom 20% to avoid text box stats (e.g. "10/10" token)
                let isStandardLocation = observation.boundingBox.origin.y < 0.2

                let parts = text.split(separator: "/")
                if parts.count == 2 {
                    let numStr = parts[0].trimmingCharacters(in: .whitespacesAndNewlines)
                    let denomStr = parts[1].trimmingCharacters(in: .whitespacesAndNewlines)
                    if let num = Int(numStr), let denom = Int(denomStr) {
                        if isStandardLocation {
                            if denom < 10 { continue }
                            if possibleNumber == nil { possibleNumber = numStr }
                        } else if observation.boundingBox.origin.y > 0.5 {
                            // FIX: Only consider Top Half (Art) as Serialized to avoid Text Box false positives
                            isSerialized = true
                        }
                    }
                }
            } else if text.count >= 1 && text.count <= 5, let first = text.first, first.isNumber, possibleNumber == nil {
                // FIX: Only accept simple numbers if they are at the very bottom (Collector Number location)
                // AND not in the bottom-right corner (Power/Toughness zone)
                if observation.boundingBox.origin.y < 0.2 && observation.boundingBox.origin.x < 0.75 { possibleNumber = text }
            }

            // Copyright Year (for Summer Magic detection)
            if let range = text.range(of: #"(19|20)\d{2}"#, options: .regularExpression) {
                if observation.boundingBox.origin.y < 0.15 {
                    possibleYear = String(text[range])
                }
            }
        }
        return (possibleSetCode, possibleNumber, possibleYear, isSerialized)
    }
}