//
//  CommonCIImage.swift
//  PayCash
//
//  Created by Igor on 23.03.2021.
//  Copyright © 2021 AM. All rights reserved.
//

import CoreImage
import UIKit

extension CIImage {
    /// Inverts the colors and creates a transparent image by converting the mask to alpha.
    /// Input image should be black and white.
    var transparent: CIImage? { inverted?.blackTransparent }
    /// Inverts the colors.
    var inverted: CIImage? {
        guard let invertedColorFilter = CIFilter(name: "CIColorInvert") else { return nil }
        invertedColorFilter.setValue(self, forKey: "inputImage")
        return invertedColorFilter.outputImage
    }
    /// Converts all black to transparent.
    var blackTransparent: CIImage? {
        guard let blackTransparentFilter = CIFilter(name: "CIMaskToAlpha") else { return nil }
        blackTransparentFilter.setValue(self, forKey: "inputImage")
        return blackTransparentFilter.outputImage
    }
    /// Applies the given color as a tint color.
    func tinted(using color: UIColor) -> CIImage? {
        guard
            let transparentQRImage = transparent,
            let filter = CIFilter(name: "CIMultiplyCompositing"),
            let colorFilter = CIFilter(name: "CIConstantColorGenerator")
        else { return nil }
        let ciColor = CIColor(color: color)
        colorFilter.setValue(ciColor, forKey: kCIInputColorKey)
        let colorImage = colorFilter.outputImage
        filter.setValue(colorImage, forKey: kCIInputImageKey)
        filter.setValue(transparentQRImage, forKey: kCIInputBackgroundImageKey)
        return filter.outputImage!
    }
}