import opencv2

// Show source image
let src = Mat(uiImage: image)

// Transform source image to gray if it is not already
let gray: Mat
if (src.channels() == 3) {
    gray = Mat()
    Imgproc.cvtColor(src: src, dst: gray, code: .COLOR_BGR2GRAY)
} else {
    gray = src
}

// Apply adaptiveThreshold at the bitwise_not of gray, notice the ~ symbol
let notGray = Mat()
Core.bitwise_not(src: gray, dst: notGray)

let bw = Mat()
Imgproc.adaptiveThreshold(src: notGray, dst: bw, maxValue: 255, adaptiveMethod: .ADAPTIVE_THRESH_MEAN_C, thresholdType: .THRESH_BINARY, blockSize: 15, C: -2)

// Create the images that will use to extract the horizontal lines
let horizontal = bw.clone()
let vertical = bw.clone()

// Specify size on horizontal axis
let horizontalSize = horizontal.cols() / 30
// Create structure element for extracting horizontal lines through morphology operations
let horizontalStructure = Imgproc.getStructuringElement(shape: .MORPH_RECT, ksize: .init(width: horizontalSize, height: 1))
// Apply morphology operations
Imgproc.erode(src: horizontal, dst: horizontal, kernel: horizontalStructure, anchor: .init(x: -1, y: -1))
Imgproc.dilate(src: horizontal, dst: horizontal, kernel: horizontalStructure, anchor: .init(x: -1, y: -1))

// Specify size on vertical axis
let verticalSize = vertical.rows() / 30

// Create structure element for extracting vertical lines through morphology operations
let verticalStructure = Imgproc.getStructuringElement(shape: .MORPH_RECT, ksize: .init(width: 1, height: verticalSize))

// Apply morphology operations
Imgproc.erode(src: vertical, dst: vertical, kernel: verticalStructure, anchor: .init(x: -1, y: -1))
Imgproc.dilate(src: vertical, dst: vertical, kernel: verticalStructure, anchor: .init(x: -1, y: -1))

// Inverse vertical image
Core.bitwise_not(src: vertical, dst: vertical)

// Extract edges and smooth image according to the logic
// 1. extract edges
// 2. dilate(edges)
// 3. src.copyTo(smooth)
// 4. blur smooth img
// 5. smooth.copyTo(src, edges)
// Step 1
let edges = Mat();
Imgproc.adaptiveThreshold(src: vertical, dst: edges, maxValue: 255, adaptiveMethod: .ADAPTIVE_THRESH_MEAN_C, thresholdType: .THRESH_BINARY, blockSize: 3, C: -2)

// Step 2
let kernel = Mat.ones(rows: 2, cols: 2, type: CvType.CV_8UC1)
Imgproc.dilate(src: edges, dst: edges, kernel: kernel)

// Step 3
let smooth = Mat();
vertical.copy(to: smooth)

// Step 4
Imgproc.blur(src: smooth, dst: smooth, ksize: .init(width: 2, height: 2))

// Step 5
smooth.copy(to: vertical, mask: edges)

// Show final result
let result = vertical.toUIImage()