//
//  PhotoEncoder.swift
//  GasTankAR
//
//  Created by Dennis Nemec on 28.08.26.
//

import ImageIO
import UniformTypeIdentifiers
import CoreLocation
import UIKit

/// Kodiert einen Snapshot als JPEG und bettet dabei EXIF-Aufnahmezeit sowie – falls vorhanden –
/// GPS-Metadaten direkt in die Bilddatei ein (ImageIO). So tragen auch exportierte Bilder ihren
/// Aufnahmeort mit sich.
enum PhotoEncoder {
    /// Erzeugt JPEG-Daten mit eingebetteten Metadaten. Fällt bei Fehlern auf `UIImage.jpegData` zurück.
    static func jpegData(
        from image: UIImage,
        coordinate: CLLocationCoordinate2D?,
        date: Date,
        compressionQuality: CGFloat = 0.9
    ) -> Data? {
        guard let cgImage = image.cgImage else {
            return image.jpegData(compressionQuality: compressionQuality)
        }

        let output = NSMutableData()
        guard let destination = CGImageDestinationCreateWithData(
            output, UTType.jpeg.identifier as CFString, 1, nil
        ) else {
            return image.jpegData(compressionQuality: compressionQuality)
        }

        var properties: [CFString: Any] = [
            kCGImageDestinationLossyCompressionQuality: compressionQuality,
            kCGImagePropertyOrientation: CGImagePropertyOrientation(image.imageOrientation).rawValue,
            kCGImagePropertyExifDictionary: [
                kCGImagePropertyExifDateTimeOriginal: Self.exifDateFormatter.string(from: date),
                kCGImagePropertyExifDateTimeDigitized: Self.exifDateFormatter.string(from: date),
            ],
        ]

        if let coordinate {
            properties[kCGImagePropertyGPSDictionary] = gpsProperties(for: coordinate, date: date)
        }

        CGImageDestinationAddImage(destination, cgImage, properties as CFDictionary)
        guard CGImageDestinationFinalize(destination) else {
            return image.jpegData(compressionQuality: compressionQuality)
        }
        return output as Data
    }

    private static func gpsProperties(for coordinate: CLLocationCoordinate2D, date: Date) -> [CFString: Any] {
        [
            kCGImagePropertyGPSLatitude: abs(coordinate.latitude),
            kCGImagePropertyGPSLatitudeRef: coordinate.latitude >= 0 ? "N" : "S",
            kCGImagePropertyGPSLongitude: abs(coordinate.longitude),
            kCGImagePropertyGPSLongitudeRef: coordinate.longitude >= 0 ? "E" : "W",
            kCGImagePropertyGPSDateStamp: Self.gpsDateFormatter.string(from: date),
            kCGImagePropertyGPSTimeStamp: Self.gpsTimeFormatter.string(from: date),
        ]
    }

    /// EXIF-Zeitstempel in lokaler Zeit („yyyy:MM:dd HH:mm:ss").
    private static let exifDateFormatter: DateFormatter = {
        let formatter = DateFormatter()
        formatter.locale = Locale(identifier: "en_US_POSIX")
        formatter.dateFormat = "yyyy:MM:dd HH:mm:ss"
        return formatter
    }()

    /// GPS-Datum in UTC („yyyy:MM:dd").
    private static let gpsDateFormatter: DateFormatter = {
        let formatter = DateFormatter()
        formatter.locale = Locale(identifier: "en_US_POSIX")
        formatter.timeZone = TimeZone(identifier: "UTC")
        formatter.dateFormat = "yyyy:MM:dd"
        return formatter
    }()

    /// GPS-Uhrzeit in UTC („HH:mm:ss").
    private static let gpsTimeFormatter: DateFormatter = {
        let formatter = DateFormatter()
        formatter.locale = Locale(identifier: "en_US_POSIX")
        formatter.timeZone = TimeZone(identifier: "UTC")
        formatter.dateFormat = "HH:mm:ss"
        return formatter
    }()
}

private extension CGImagePropertyOrientation {
    init(_ orientation: UIImage.Orientation) {
        switch orientation {
        case .up: self = .up
        case .down: self = .down
        case .left: self = .left
        case .right: self = .right
        case .upMirrored: self = .upMirrored
        case .downMirrored: self = .downMirrored
        case .leftMirrored: self = .leftMirrored
        case .rightMirrored: self = .rightMirrored
        @unknown default: self = .up
        }
    }
}