//
//  SVGViewBox.swift
//  react-native-drawableview
//
//  Created by Juan J LF on 9/23/21.
//

import Foundation
import UIKit



 class SVGViewBox {
    
     enum AspectRatio {
        case meet,
             slice,
             none
    }
    
     static func transform(vbRect:CGRect,eRect:CGRect,align:String,meetOrSlice:AspectRatio)->CGAffineTransform{
        
        // based on https://svgwg.org/svg2-draft/coords.html#ComputingAViewportsTransform
              // Let vb-x, vb-y, vb-width, vb-height be the min-x, min-y, width and height values of the viewBox attribute respectively.
        let vbX = vbRect.left;
        let vbY = vbRect.top;
        let vbWidth = vbRect.width;
        let vbHeight = vbRect.height;

              // Let e-x, e-y, e-width, e-height be the position and size of the element respectively.
        let eX = eRect.left;
        let eY = eRect.top;
        let eWidth = eRect.width;
        let eHeight = eRect.height;


              // Initialize scale-x to e-width/vb-width.
              var scaleX = eWidth / vbWidth;

              // Initialize scale-y to e-height/vb-height.
              var scaleY = eHeight / vbHeight;

              // Initialize translate-x to e-x - (vb-x * scale-x).
              // Initialize translate-y to e-y - (vb-y * scale-y).
              var translateX = eX - (vbX * scaleX);
              var translateY = eY - (vbY * scaleY);

              // If align is 'none'
            if (meetOrSlice == .none) {
                  // Let scale be set the smaller value of scale-x and scale-y.
                  // Assign scale-x and scale-y to scale.
                
                    scaleX = min(scaleX, scaleY);
                    scaleY = min(scaleX, scaleY);

                translateX += (eWidth - vbWidth * scaleX) / 2.0;
                translateY += (eHeight - vbHeight * scaleY) / 2.0;
              } else {
                  // If align is not 'none' and meetOrSlice is 'meet', set the larger of scale-x and scale-y to the smaller.
                  // Otherwise, if align is not 'none' and meetOrSlice is 'slice', set the smaller of scale-x and scale-y to the larger.
                if (!(align == "none") && meetOrSlice == .meet) {
                    scaleX = min(scaleX, scaleY);
                      scaleY = min(scaleX, scaleY);
                } else if (!(align == "none") && meetOrSlice == .slice) {
                      scaleX = max(scaleX, scaleY);
                      scaleY = max(scaleX, scaleY);
                  }

                  // If align contains 'xMid', add (e-width - vb-width * scale-x) / 2 to translate-x.
                  if (align.contains("xMid")) {
                      translateX += (eWidth - vbWidth * scaleX) / 2.0;
                  }

                  // If align contains 'xMax', add (e-width - vb-width * scale-x) to translate-x.
                  if (align.contains("xMax")) {
                      translateX += (eWidth - vbWidth * scaleX);
                  }

                  // If align contains 'yMid', add (e-height - vb-height * scale-y) / 2 to translate-y.
                  if (align.contains("YMid")) {
                      translateY += (eHeight - vbHeight * scaleY) / 2.0;
                  }

                  // If align contains 'yMax', add (e-height - vb-height * scale-y) to translate-y.
                  if (align.contains("YMax")) {
                      translateY += (eHeight - vbHeight * scaleY);
                  }

              }

              // The transform applied to content contained by the element is given by
              // translate(translate-x, translate-y) scale(scale-x, scale-y).
            
      

        return CGAffineTransform(translationX: translateX, y: translateY).scaledBy(x: scaleX, y: scaleY)
    }
    
     static func transform3D(vbRect:CGRect,eRect:CGRect,align:String,meetOrSlice:AspectRatio)->CATransform3D{
        
        // based on https://svgwg.org/svg2-draft/coords.html#ComputingAViewportsTransform
              // Let vb-x, vb-y, vb-width, vb-height be the min-x, min-y, width and height values of the viewBox attribute respectively.
        let vbX = vbRect.left;
        let vbY = vbRect.top;
        let vbWidth = vbRect.width;
        let vbHeight = vbRect.height;

              // Let e-x, e-y, e-width, e-height be the position and size of the element respectively.
        let eX = eRect.left;
        let eY = eRect.top;
        let eWidth = eRect.width;
        let eHeight = eRect.height;


              // Initialize scale-x to e-width/vb-width.
              var scaleX = eWidth / vbWidth;

              // Initialize scale-y to e-height/vb-height.
              var scaleY = eHeight / vbHeight;

              // Initialize translate-x to e-x - (vb-x * scale-x).
              // Initialize translate-y to e-y - (vb-y * scale-y).
              var translateX = eX - (vbX * scaleX);
              var translateY = eY - (vbY * scaleY);

              // If align is 'none'
            if (meetOrSlice == .none) {
                  // Let scale be set the smaller value of scale-x and scale-y.
                  // Assign scale-x and scale-y to scale.
                 
                    scaleX = min(scaleX, scaleY);
                    scaleY = min(scaleX, scaleY);

                translateX += (eWidth - vbWidth * scaleX) / 2.0;
                translateY += (eHeight - vbHeight * scaleY) / 2.0;
              } else {
                  // If align is not 'none' and meetOrSlice is 'meet', set the larger of scale-x and scale-y to the smaller.
                  // Otherwise, if align is not 'none' and meetOrSlice is 'slice', set the smaller of scale-x and scale-y to the larger.
                if (!(align == "none") && meetOrSlice == .meet) {
                    scaleX = min(scaleX, scaleY);
                      scaleY = min(scaleX, scaleY);
                } else if (!(align == "none") && meetOrSlice == .slice) {
                      scaleX = max(scaleX, scaleY);
                      scaleY = max(scaleX, scaleY);
                  }

                  // If align contains 'xMid', add (e-width - vb-width * scale-x) / 2 to translate-x.
                  if (align.contains("xMid")) {
                      translateX += (eWidth - vbWidth * scaleX) / 2.0;
                  }

                  // If align contains 'xMax', add (e-width - vb-width * scale-x) to translate-x.
                  if (align.contains("xMax")) {
                      translateX += (eWidth - vbWidth * scaleX);
                  }

                  // If align contains 'yMid', add (e-height - vb-height * scale-y) / 2 to translate-y.
                  if (align.contains("YMid")) {
                      translateY += (eHeight - vbHeight * scaleY) / 2.0;
                  }

                  // If align contains 'yMax', add (e-height - vb-height * scale-y) to translate-y.
                  if (align.contains("YMax")) {
                      translateY += (eHeight - vbHeight * scaleY);
                  }

              }

              // The transform applied to content contained by the element is given by
              // translate(translate-x, translate-y) scale(scale-x, scale-y).
            
        
        var matrix = CATransform3DTranslate(CATransform3DIdentity, translateX, translateY, 0)
         matrix = CATransform3DScale(matrix, scaleX, scaleY, 1)
        return matrix
    }
     static func transformArray(vbRect:CGRect,eRect:CGRect,align:String,meetOrSlice:AspectRatio)->[CGFloat]{
        
        // based on https://svgwg.org/svg2-draft/coords.html#ComputingAViewportsTransform
              // Let vb-x, vb-y, vb-width, vb-height be the min-x, min-y, width and height values of the viewBox attribute respectively.
        let vbX = vbRect.left;
        let vbY = vbRect.top;
        let vbWidth = vbRect.width;
        let vbHeight = vbRect.height;

              // Let e-x, e-y, e-width, e-height be the position and size of the element respectively.
        let eX = eRect.left;
        let eY = eRect.top;
        let eWidth = eRect.width;
        let eHeight = eRect.height;


              // Initialize scale-x to e-width/vb-width.
              var scaleX = eWidth / vbWidth;

              // Initialize scale-y to e-height/vb-height.
              var scaleY = eHeight / vbHeight;

              // Initialize translate-x to e-x - (vb-x * scale-x).
              // Initialize translate-y to e-y - (vb-y * scale-y).
              var translateX = eX - (vbX * scaleX);
              var translateY = eY - (vbY * scaleY);

              // If align is 'none'
            if (meetOrSlice == .none) {
                  // Let scale be set the smaller value of scale-x and scale-y.
                  // Assign scale-x and scale-y to scale.
                  
                    scaleX = min(scaleX, scaleY);
                    scaleY = min(scaleX, scaleY);

                translateX += (eWidth - vbWidth * scaleX) / 2.0;
                translateY += (eHeight - vbHeight * scaleY) / 2.0;
              } else {
                  // If align is not 'none' and meetOrSlice is 'meet', set the larger of scale-x and scale-y to the smaller.
                  // Otherwise, if align is not 'none' and meetOrSlice is 'slice', set the smaller of scale-x and scale-y to the larger.
                if (!(align == "none") && meetOrSlice == .meet) {
                    scaleX = min(scaleX, scaleY);
                      scaleY = min(scaleX, scaleY);
                } else if (!(align == "none") && meetOrSlice == .slice) {
                      scaleX = max(scaleX, scaleY);
                      scaleY = max(scaleX, scaleY);
                  }

                  // If align contains 'xMid', add (e-width - vb-width * scale-x) / 2 to translate-x.
                  if (align.contains("xMid")) {
                      translateX += (eWidth - vbWidth * scaleX) / 2.0;
                  }

                  // If align contains 'xMax', add (e-width - vb-width * scale-x) to translate-x.
                  if (align.contains("xMax")) {
                      translateX += (eWidth - vbWidth * scaleX);
                  }

                  // If align contains 'yMid', add (e-height - vb-height * scale-y) / 2 to translate-y.
                  if (align.contains("YMid")) {
                      translateY += (eHeight - vbHeight * scaleY) / 2.0;
                  }

                  // If align contains 'yMax', add (e-height - vb-height * scale-y) to translate-y.
                  if (align.contains("YMax")) {
                      translateY += (eHeight - vbHeight * scaleY);
                  }

              }

              // The transform applied to content contained by the element is given by
              // translate(translate-x, translate-y) scale(scale-x, scale-y).
            
        
    
        return [translateX,translateY,scaleX,scaleY]
    }
    

}