//
//  KMWatermarkPDFView.swift
//  PDF Reader Pro
//
//  Created by tangchao on 2022/12/19.
//

import Cocoa

class KMWatermarkPDFView: CPDFView {
    
//    var watermarkModel: KMWatermarkModel!
    
    var watermark: KMWatermarkModel?
    var background: KMBackgroundModel?
    var headerFooter: KMHeaderFooterObject?
    
    override func draw(_ dirtyRect: NSRect) {
        super.draw(dirtyRect)
    }
    override func draw(_ page: CPDFPage!, to context: CGContext!) {
        if let watermark = self.watermark {
            if watermark.isFront {
                super.draw(page, to: context)
                if (self.needDraw(page)) {
                    drawWatermarkPage(page, to: context)
                }
            } else {
                if (self.needDraw(page)) {
                    drawWatermarkPage(page, to: context)
                }
                super.draw(page, to: context)
            }
        } else if let background = self.background {
//            if let context = NSGraphicsContext.current?.cgContext {
                drawBackgroundPage(page, to: context)
                super.draw(page, to: context)
//            }
        } else if let headerFooter = self.headerFooter {
            super.draw(page, to: context)
//            if let context = NSGraphicsContext.current?.cgContext {
                drawHeaderFooterPage(page, to: context)
//            }
        } else {
            super.draw(page, to: context)
        }
    }
    
    func needDraw(_ page: CPDFPage) -> Bool {
        guard let watermark = watermark else { return false}
        
        if (watermark.pageRangeType.rawValue == 0) {
            return true
        }
//        else if (self.watermarkModel.pageRangeType == 1) {
//            let array = self.watermarkModel.pagesString.components(separatedBy: ",")
//            let index: Int = Int(self.document.index(for: page))
//            if (!array.contains("\(index+1)")) {
//                return false
//            }
//        }
        else if (watermark.pageRangeType == .odd) {
            let index: Int = Int(self.document.index(for: page))
            return (index % 2 == 0)
        } else if (watermark.pageRangeType == .even) {
            let index: Int = Int(self.document.index(for: page))
            return (index % 2 == 1)
        } else if (watermark.pageRangeType == .other) {
            if (watermark.pagesString.isEmpty) {
                return false
            }
            
            let array = watermark.pagesString.components(separatedBy: ",")
            let index: Int = Int(self.document.index(for: page))
            if (!array.contains("\(index+1)")) {
                return false
            }
        }
        
        return true
    }
    
    func drawWatermarkPage(_ page: CPDFPage, to context: CGContext) {
        guard let watermark = watermark else { return}
        
        let pageBounds = page.bounds(for: .cropBox)
        let w: CGFloat = NSWidth(pageBounds)
        let h: CGFloat = NSHeight(pageBounds)
        
        let width: CGFloat = sqrt(w*w+h*h)
        let newRect: CGRect = CGRect(x: -(width-w)*0.5, y: -(width-h)*0.5, width: width, height: width)
        let new_w: CGFloat = NSWidth(newRect)
        let new_h: CGFloat = NSHeight(newRect)
        
//        NSGraphicsContext.current = NSGraphicsContext(cgContext: context, flipped: false)
        NSGraphicsContext.saveGraphicsState()
        NSGraphicsContext.current = NSGraphicsContext(cgContext: context, flipped: false)
        page.transform(context, for: .cropBox)
        if (watermark.pagesString.count > 0) {
            let array = watermark.pagesString.components(separatedBy: ",")
            let index: Int = Int(self.document.index(for: page))
            if (!array.contains("\(index)")) {
                return
            }
        }
        
        if (!watermark.text.isEmpty) {
            var font = watermark.getTextFont()
            var color = watermark.getTextColor()
            
            var red: CGFloat = 0
            var green: CGFloat = 0
            var blue: CGFloat = 0
            color.usingColorSpaceName(NSColorSpaceName.calibratedRGB)?.getRed(&red, green: &green, blue: &blue, alpha: nil)
            color = NSColor(red: red, green: green, blue: blue, alpha: watermark.opacity)
            
            var size = NSZeroSize
            let style = NSMutableParagraphStyle()
            style.alignment = watermark.textAligement
            style.lineBreakMode = .byCharWrapping
            let dict = [
                NSAttributedString.Key.paragraphStyle : style,
                        NSAttributedString.Key.foregroundColor : color,
                        NSAttributedString.Key.font : font as Any
            ] as [NSAttributedString.Key : Any]
            size = watermark.text.boundingRect(with: NSSize(width: 1000, height: 1000), options: NSString.DrawingOptions(rawValue: 3), attributes: dict).size
            
            let radian: CGFloat = watermark.rotation*(Double.pi/180.0)
            let t: CGAffineTransform = CGAffineTransform(rotationAngle: radian)
            var rect:CGRect = CGRect(x: 0, y: 0, width: size.width, height: size.height)
            
            if (watermark.isTilePage) {
                context.translateBy(x: w * 0.5, y: h * 0.5)
                context.concatenate(t)
                context.translateBy(x: -(w/2),  y: -(h/2))
                
                let verticalWidth: CGFloat = size.width + watermark.tileHorizontalSpace
                let horizontalHeight: CGFloat = size.height + watermark.tileVerticalSpace
                let line: Int = Int(((new_h-watermark.tileVerticalSpace)/horizontalHeight)+1)
                let row: Int = Int(((new_w-watermark.tileHorizontalSpace)/verticalWidth)+1)
                
                let point: CGPoint = CGPoint(x: w*0.5-size.width*0.5+watermark.horizontalSpace, y: h*0.5-size.height*0.5+watermark.verticalSpace)
                for i in 0 ..< line {
                    for j in 0 ..< row {
                        watermark.text.draw(in: NSRect(x: point.x+CGFloat(j)*verticalWidth, y: point.y+CGFloat(i)*horizontalHeight, width: size.width, height: size.height), withAttributes: dict)
                    }
                }
                
                for i in 1 ..< line {
                    for j in 0 ..< row {
                        watermark.text.draw(in: NSRect(x: point.x+CGFloat(j)*verticalWidth, y: point.y-CGFloat(i)*horizontalHeight, width: size.width, height: size.height), withAttributes: dict)
                    }
                }
                
                for i in 0 ..< line {
                    for j in 1 ..< row {
                        watermark.text.draw(in: NSRect(x: point.x-CGFloat(j)*verticalWidth, y: point.y+CGFloat(i)*horizontalHeight, width: size.width, height: size.height), withAttributes: dict)
                    }
                }
                
                for i in 1 ..< line {
                    for j in 1 ..< row {
                        watermark.text.draw(in: NSRect(x: point.x-CGFloat(j)*verticalWidth, y: point.y-CGFloat(i)*horizontalHeight, width: size.width, height: size.height), withAttributes: dict)
                    }
                }
            } else {
                if (watermark.verticalMode == 0) {
                    rect.origin.y = pageBounds.size.height-rect.size.height
                } else if (watermark.verticalMode == 1) {
                    rect.origin.y = (pageBounds.size.height-rect.size.height) * 0.5
                } else {
                    rect.origin.y = 0
                }
                
                if (watermark.horizontalMode == 0) {
                    rect.origin.x = 0
                } else if (watermark.horizontalMode == 1) {
                    rect.origin.x = (pageBounds.size.width-rect.size.width) * 0.5
                } else {
                    rect.origin.x = pageBounds.size.width-rect.size.width
                }
                
                rect.origin.x += watermark.horizontalSpace
                rect.origin.y += watermark.verticalSpace
                
                let contextCenter = CGPoint(x: rect.midX, y: rect.midY)
                context.translateBy(x: contextCenter.x, y: contextCenter.y)
                context.rotate(by: radian)
                context.translateBy(x: -contextCenter.x, y: -contextCenter.y)
                
                watermark.text.draw(in: rect, withAttributes: dict)
            }
        } else if (watermark.image != nil) {
            let tiffData = watermark.image.tiffRepresentation
            let bitmap: NSBitmapImageRep!
            bitmap = NSBitmapImageRep(data: tiffData!)
            let ciImage = CIImage(bitmapImageRep: bitmap)
            var size: NSSize = (ciImage?.extent.size)!
            size.width *= watermark.scale
            size.height *= watermark.scale
            
            let radian = watermark.rotation * (Double.pi / 180.0)
            let t: CGAffineTransform = CGAffineTransform(rotationAngle: radian)
            var rect = NSMakeRect(0, 0, size.width, size.height)
            if (watermark.isTilePage) {
                context.translateBy(x: w/2,y: h/2)
                context.concatenate(t)
                context.translateBy(x: -(w/2),  y: -(h/2))
                
                let verticalWidth: CGFloat = size.width + watermark.tileHorizontalSpace
                let horizontalHeight: CGFloat = size.height + watermark.tileVerticalSpace
                let line: Int = Int((new_h - watermark.tileVerticalSpace)/horizontalHeight + 1)
                let row: Int = Int((new_w - watermark.tileHorizontalSpace) / verticalWidth + 1)
                let point = NSPoint(x: w/2 - size.width/2, y: h/2 - size.height/2)
                for i in 0 ..< (line/2+1) {
                    for j in 0 ..< row {
                        let area = CGRect(x: point.x  + CGFloat(j) * verticalWidth, y: point.y + CGFloat(i)*horizontalHeight, width: size.width, height: size.height)
                        watermark.image.draw(in: area, from: NSZeroRect, operation: .overlay, fraction: watermark.opacity)
                    }
                }
                
                for i in 1 ..< (line/2+1) {
                    for j in 0 ..< row {
                        let area = CGRect(x: point.x  + CGFloat(j) * verticalWidth, y: point.y - CGFloat(i)*horizontalHeight, width: size.width, height: size.height)
                        watermark.image.draw(in: area, from: NSZeroRect, operation: .overlay, fraction: watermark.opacity)
                    }
                }
                
                for i in 0 ..< (line/2+1) {
                    for j in 1 ..< row {
                        let area = CGRect(x: point.x  - CGFloat(j) * verticalWidth, y: point.y + CGFloat(i)*horizontalHeight, width: size.width, height: size.height)
                        watermark.image.draw(in: area, from: NSZeroRect, operation: .overlay, fraction: watermark.opacity)
                    }
                }
                
                for i in 1 ..< (line/2+1) {
                    for j in 1 ..< row {
                        let area = CGRect(x: point.x  - CGFloat(j) * verticalWidth, y: point.y - CGFloat(i)*horizontalHeight, width: size.width, height: size.height)
                        watermark.image.draw(in: area, from: NSZeroRect, operation: .overlay, fraction: watermark.opacity)
                    }
                }
            } else {
                if (watermark.verticalMode == 0) {
                    rect.origin.y = pageBounds.size.height-rect.size.height
                } else if (watermark.verticalMode == 1) {
                    rect.origin.y = (pageBounds.size.height-rect.size.height) * 0.5
                } else {
                    rect.origin.y = 0
                }
                
                if (watermark.horizontalMode == 0) {
                    rect.origin.x = 0
                } else if (watermark.horizontalMode == 1) {
                    rect.origin.x = (pageBounds.size.width-rect.size.width) * 0.5
                } else {
                    rect.origin.x = pageBounds.size.width-rect.size.width
                }
                
                rect.origin.x += watermark.horizontalSpace
                rect.origin.y += watermark.verticalSpace
                
                let contextCenter = CGPoint(x: rect.midX, y: rect.midY)
                context.translateBy(x: contextCenter.x, y: contextCenter.y)
                context.rotate(by: radian)
                context.translateBy(x: -contextCenter.x, y: -contextCenter.y)
                
                watermark.image.draw(in: rect, from: NSZeroRect, operation: .overlay, fraction: watermark.opacity)
            }
        }
        NSGraphicsContext.restoreGraphicsState()
    }
    
    func drawBackgroundPage(_ page: CPDFPage, to context: CGContext) {
        guard let background = background else { return}
        
        let pageBounds = page.bounds(for: .cropBox)
        
        if let currentContext = NSGraphicsContext.current {
            NSGraphicsContext.current = NSGraphicsContext(cgContext: context, flipped: false)
        }
        
        NSGraphicsContext.saveGraphicsState()
        page.transform(context, for: .cropBox)
        
        if let backgroundColor = background.color,
           backgroundColor != NSColor.clear {
            
            var size = pageBounds.size
            size.width *= background.scale
            size.height *= background.scale
            
            let radian: CGFloat = background.rotation * (Double.pi/180.0)
            var transform = CGAffineTransform(rotationAngle: radian)
            
            var rect = CGRect(x: 0, y: 0, width: size.width, height: size.height)
            rect = rect.applying(transform)
            
            if background.verticalMode == 0 {
                rect.origin.y = pageBounds.size.height - rect.size.height
            } else if background.verticalMode == 1 {
                rect.origin.y = (pageBounds.size.height - rect.size.height) / 2.0
            } else {
                rect.origin.y = 0
            }
            
            if background.horizontalMode == 0 {
                rect.origin.x = 0
            } else if background.horizontalMode == 1 {
                rect.origin.x = (pageBounds.size.width - rect.size.width) / 2.0
            } else {
                rect.origin.x = pageBounds.size.width - rect.size.width
            }
            
            rect.origin.y += background.verticalSpace
            rect.origin.x += background.horizontalSpace
            
            let contextCenter = CGPoint(x: rect.midX, y: rect.midY)
            context.translateBy(x: contextCenter.x, y: contextCenter.y)
            context.rotate(by: CGFloat(radian))
            context.translateBy(x: -contextCenter.x, y: -contextCenter.y)
            
            var red: CGFloat = 0, green: CGFloat = 0, blue: CGFloat = 0, alpha: CGFloat = 0
            if let color = background.color?.usingColorSpaceName(NSColorSpaceName.calibratedRGB) {
                color.getRed(&red, green: &green, blue: &blue, alpha: &alpha)
            }
            
            context.setFillColor(red: red, green: green, blue: blue, alpha: background.opacity ?? 1.0)
            context.fill(CGRect(x: rect.origin.x + (rect.size.width - size.width) / 2.0,
                                y: rect.origin.y + (rect.size.height - size.height) / 2.0,
                                width: size.width, height: size.height))
            
        } else if let backgroundImage = background.image {
            var size = backgroundImage.size
            if background.imagePath.extension.lowercased() == ".pdf",
                FileManager.default.fileExists(atPath: background.imagePath) {
                // Handle PDF background image case
            } else {
                size = CGSize(width: size.width * 2, height: size.height * 2)
            }
            size.width *= background.scale
            size.height *= background.scale
            
            let radian: CGFloat = background.rotation * (Double.pi/180.0)
            var transform = CGAffineTransform(rotationAngle: radian)
            
            var rect = CGRect(x: 0, y: 0, width: size.width, height: size.height)
            rect = rect.applying(transform)
            
            if background.verticalMode == 0 {
                rect.origin.y = pageBounds.size.height - rect.size.height
            } else if background.verticalMode == 1 {
                rect.origin.y = (pageBounds.size.height - rect.size.height) / 2.0
            } else {
                rect.origin.y = 0
            }
            
            if background.horizontalMode == 0 {
                rect.origin.x = 0
            } else if background.horizontalMode == 1 {
                rect.origin.x = (pageBounds.size.width - rect.size.width) / 2.0
            } else {
                rect.origin.x = pageBounds.size.width - rect.size.width
            }
            
            rect.origin.y += background.verticalSpace
            rect.origin.x += background.horizontalSpace
            
            let contextCenter = CGPoint(x: rect.midX, y: rect.midY)
            context.translateBy(x: contextCenter.x, y: contextCenter.y)
            context.rotate(by: radian)
            context.translateBy(x: -contextCenter.x, y: -contextCenter.y)
            
            backgroundImage.draw(in: CGRect(x: rect.origin.x + (rect.size.width - size.width) / 2.0,
                                             y: rect.origin.y + (rect.size.height - size.height) / 2.0,
                                             width: size.width, height: size.height),
                                  from: NSZeroRect,
                                  operation: .sourceOver,
                                  fraction: background.opacity)
        }
        
        NSGraphicsContext.restoreGraphicsState()
    }
    
    func drawHeaderFooterPage(_ page: CPDFPage, to context: CGContext) {

        guard let headerFooter = headerFooter else { return }

        let pageBounds = page.bounds(for: .cropBox)
        let xMargin = 0.0//pageBounds.origin.x * 2
        let yMargin = 0.0//pageBounds.origin.y * 2
        
        NSGraphicsContext.saveGraphicsState()

        if context != nil {
            NSGraphicsContext.current = NSGraphicsContext(cgContext: context, flipped: false)
        }

        page.transform(context, for: .cropBox)

        let color = headerFooter.getTextColor()
        let font = NSFont.boldSystemFont(ofSize: CGFloat(headerFooter.getTextFontSize()))
        var style = NSMutableParagraphStyle()
        style.alignment = .center
        style.lineBreakMode = .byCharWrapping

        var size = NSZeroSize
        var attributes: [NSAttributedString.Key: Any] = [
            .paragraphStyle: style,
            .foregroundColor: color,
            .font: font
        ]

        let index = self.document?.index(for: page) ?? 0

        var topOffset: CGFloat = 0
        var bottomOffset: CGFloat = 0

        let topLeftString = headerFooter.topLeftString
        var tString = replacingOldString(topLeftString, currentPage: Int(index))

        size = tString.boundingRect(with: CGSize(width: CGFloat.greatestFiniteMagnitude, height: CGFloat.greatestFiniteMagnitude),
                                   options: [.usesLineFragmentOrigin, .usesFontLeading],
                                   attributes: attributes).size

        var posY = min(pageBounds.size.height - CGFloat((headerFooter.topMargin)), pageBounds.size.height - size.height)
        tString.draw(in: CGRect(x: Double(headerFooter.leftMargin) + xMargin, y: posY + yMargin, width: size.width, height: size.height), withAttributes: attributes)
    

        let topCenterString = headerFooter.topCenterString
        tString = replacingOldString(topCenterString, currentPage: Int(index))

        size = tString.boundingRect(with: CGSize(width: CGFloat.greatestFiniteMagnitude, height: CGFloat.greatestFiniteMagnitude),
                                   options: [.usesLineFragmentOrigin, .usesFontLeading],
                                   attributes: attributes).size

        posY = min(pageBounds.size.height - CGFloat((headerFooter.topMargin)), pageBounds.size.height - size.height)
        tString.draw(in: CGRect(x: pageBounds.size.width/2 - size.width/2 + xMargin, y: posY + yMargin, width: size.width, height: size.height), withAttributes: attributes)
        

        let topRightString = headerFooter.topRightString
        tString = replacingOldString(topRightString, currentPage: Int(index))

        size = tString.boundingRect(with: CGSize(width: CGFloat.greatestFiniteMagnitude, height: CGFloat.greatestFiniteMagnitude),
                                   options: [.usesLineFragmentOrigin, .usesFontLeading],
                                   attributes: attributes).size

        posY = min(pageBounds.size.height - CGFloat((headerFooter.topMargin)), pageBounds.size.height - size.height)
        tString.draw(in: CGRect(x: pageBounds.size.width - CGFloat((headerFooter.rightMargin)) - size.width + xMargin,
                                y: posY + yMargin,
                                width: size.width,
                                height: size.height),
                      withAttributes: attributes)
    

        let bottomLeftString = headerFooter.bottomLeftString
        tString = replacingOldString(bottomLeftString, currentPage: Int(index))

        size = tString.boundingRect(with: CGSize(width: CGFloat.greatestFiniteMagnitude, height: CGFloat.greatestFiniteMagnitude),
                                   options: [.usesLineFragmentOrigin, .usesFontLeading],
                                   attributes: attributes).size

        posY = max(CGFloat((headerFooter.bottomMargin)) - size.height, 0)
        tString.draw(in: CGRect(x: Double(headerFooter.leftMargin) + xMargin, y: posY + yMargin, width: size.width, height: size.height), withAttributes: attributes)
        

        let bottomCenterString = headerFooter.bottomCenterString
        tString = replacingOldString(bottomCenterString, currentPage: Int(index))

        size = tString.boundingRect(with: CGSize(width: CGFloat.greatestFiniteMagnitude, height: CGFloat.greatestFiniteMagnitude),
                                   options: [.usesLineFragmentOrigin, .usesFontLeading],
                                   attributes: attributes).size

        posY = max(CGFloat((headerFooter.bottomMargin)) - size.height, 0)
        tString.draw(in: CGRect(x: pageBounds.size.width/2 - size.width/2 + xMargin,
                                y: posY + yMargin,
                                width: size.width,
                                height: size.height),
                      withAttributes: attributes)
        

        let bottomRightString = headerFooter.bottomRightString
        tString = replacingOldString(bottomRightString, currentPage: Int(index))

        size = tString.boundingRect(with: CGSize(width: CGFloat.greatestFiniteMagnitude, height: CGFloat.greatestFiniteMagnitude),
                                   options: [.usesLineFragmentOrigin, .usesFontLeading],
                                   attributes: attributes).size

        posY = max(CGFloat((headerFooter.bottomMargin)) - size.height, 0)
        tString.draw(in: CGRect(x: pageBounds.size.width - CGFloat((headerFooter.rightMargin)) - size.width + xMargin,
                                y: posY + yMargin,
                                width: size.width,
                                height: size.height),
                      withAttributes: attributes)
    

        context.setStrokeColor(NSColor(red: 51.0/255.0, green: 186.0/255.0, blue: 234.0/255.0, alpha: 1.0).cgColor)
        context.setLineWidth(1.0)

        context.move(to: CGPoint(x: xMargin, y: CGFloat(headerFooter.bottomMargin) + bottomOffset))
        context.addLine(to: CGPoint(x: xMargin + pageBounds.size.width, y: CGFloat(headerFooter.bottomMargin) + bottomOffset))

        context.move(to: CGPoint(x: Int(xMargin) + headerFooter.leftMargin, y: 0))
        context.addLine(to: CGPoint(x: xMargin + Double(headerFooter.leftMargin), y: pageBounds.size.height))

        context.move(to: CGPoint(x: Int(xMargin + pageBounds.size.width) - (headerFooter.rightMargin), y: 0))
        context.addLine(to: CGPoint(x: xMargin + pageBounds.size.width - Double((headerFooter.rightMargin)), y: pageBounds.size.height))

        context.move(to: CGPoint(x: xMargin, y: pageBounds.size.height - CGFloat((headerFooter.topMargin)) - topOffset))
        context.addLine(to: CGPoint(x: xMargin + pageBounds.size.width, y: pageBounds.size.height - CGFloat((headerFooter.topMargin)) - topOffset))

        let arr: [CGFloat] = [8, 1]
        context.setLineDash(phase: 0, lengths: arr)
        context.drawPath(using: .stroke)

        NSGraphicsContext.restoreGraphicsState()
    }


    func replacingOldString(_ oldString: String?, currentPage page: Int) -> String {
        guard let oldString = oldString else {
            return ""
        }
        
        var newString = oldString
        let startString = self.headerFooter?.startString ?? ""
        var newPage = ""
        
        if let isBates = self.headerFooter?.isBates, isBates {
            let pattern = "<<#\\d*?#\\d*#.*?>>|<<#\\d*?#\\d*?>>"
            if let dates = match(pattern, in: oldString) {
                for result in dates {
                    let resultStr = (oldString as NSString).substring(with: result.range) 
                    let newResultStr = (resultStr as NSString).substring(with: NSMakeRange(2, resultStr.count - 4))
                    let array = newResultStr.components(separatedBy: "#")
                    
                    if array.count > 1 {
                        let batesDigits = array[1]
                        
                        if array.count > 2 {
                            let firstString = array[2]
                            newPage = String(format: "%0*ld", batesDigits.count, page + (firstString as NSString).integerValue)
                        }
                        
                        if array.count > 3 {
                            newPage = "\(array[3])\(newPage)"
                        }
                        
                        if array.count > 4 {
                            newPage += array[4]
                        }
                        
                        newString = newString.replacingOccurrences(of: resultStr, with: newPage)
                    }
                }
            }
        } else {
            newPage = "\(page + (startString as NSString).integerValue)"
            
            if !startString.isEmpty {
                newString = KMWatermarkPDFView.convertViewPageFormat(newString, currentPage: newPage, pageCount: "\(self.document?.pageCount ?? UInt(0 + (startString as NSString).integerValue - 1))")
            }
        }
        
        newString = KMWatermarkPDFView.convertDateFormat(newString)
        return newString
    }

    func match(_ pattern: String, in testString: String) -> [NSTextCheckingResult]? {
        do {
            let regex = try NSRegularExpression(pattern: pattern, options: [])
            let results = regex.matches(in: testString, options: [], range: NSRange(location: 0, length: testString.count))
            return results
        } catch {
            return nil
        }
    }

    static func convertDateFormat(_ oldString: String) -> String {
        var newString = oldString
        
        for dateFormat in KMHeaderFooterManager.defaultManager.dateFormatArray {
            if newString.contains(dateFormat) {
                let formatString = dateFormat.replacingOccurrences(of: "m", with: "M")
                let replace = "<<\(dateFormat)>>"
                
                let date = Date()
                let dateFormatter = DateFormatter()
                dateFormatter.dateFormat = formatString
                let dateString = dateFormatter.string(from: date)
                
                newString = newString.replacingOccurrences(of: replace, with: dateString)
            }
        }
        return newString
    }

    static func convertViewPageFormat(_ oldString: String, currentPage: String, pageCount: String) -> String {
        var newString = oldString
        let pageFormatArray = ["1", "1 of n", "1/n", "Page 1", "Page 1 of n"]
        
        for pageFormat in pageFormatArray {
            let pageFormat = "<<\(pageFormat)>>"
            
            if newString.contains(pageFormat) {
                var tString: String?
                
                switch pageFormat {
                case "<<1>>":
                    tString = currentPage
                case "<<1 of n>>":
                    tString = "\(currentPage) of \(pageCount)"
                case "<<1/n>>":
                    tString = "\(currentPage)/\(pageCount)"
                case "<<Page 1>>":
                    tString = "Page \(currentPage)"
                case "<<Page 1 of n>>":
                    tString = "Page \(currentPage) of \(pageCount)"
                default:
                    break
                }
                
                if let tString = tString {
                    newString = newString.replacingOccurrences(of: pageFormat, with: tString)
                }
            }
        }
        return newString
    }
}