import Foundation
import AppKit

class IntensityView: NSView {

    override func draw(_ rect: CGRect) {
        drawMultipleShapesWithAColorGradient()
    }

    func drawMultipleShapesWithAColorGradient() {

        let height: Double = 500
        let startingMargin = 3.5

        guard let ctx = NSGraphicsContext.current else { return }
        let cgx = ctx.cgContext
        ctx.saveGraphicsState() /// Save out the state so that we dont clip everything outside of the path        ctx.beginPath()
        cgx.move(to: CGPoint(x: 0, y: startingMargin))
        cgx.addLine(to: CGPoint(x: 25, y: startingMargin))
        cgx.addLine(to: CGPoint(x: 25, y: startingMargin + height))
        cgx.addLine(to: CGPoint(x: 0, y: startingMargin + height))
        cgx.closePath()
        cgx.clip() /// This is the clip we are referring to above.

        let locations: [CGFloat] = [0.0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0]
        let colors: [CGFloat] = [
            0.0, 0.0, 205/255, 1.0,
            0.0, 75/255, 248/255, 1.0,
            2/255, 209/255, 137/255, 1.0,
            71/255, 250/255, 55/255, 1.0,
            188/255, 255/255, 18/255, 1.0,
            253/255, 252/255, 16/255, 1.0,
            255/255, 219/255, 16/255, 1.0,
            255/255, 137/255, 0/255, 1.0,
            254/255, 61/255, 0/255, 1.0,
            241/255, 0/255, 0/255, 1.0,
            178/255, 11/255, 11/255, 1.0
        ]

        let colorSpace = CGColorSpaceCreateDeviceRGB()
        guard let gradient = CGGradient(colorSpace: colorSpace, colorComponents: colors, locations: locations, count: 11) else {
            return
        }
        cgx.drawLinearGradient(gradient, start: CGPoint(x: 0, y: 0.0), end: CGPoint(x: 0, y: height + startingMargin), options: CGGradientDrawingOptions(rawValue: 0))

        ctx.restoreGraphicsState() /// Restore the previous state. This will remove any paths, clipping, gradients, etc.

        let paragraphStyle = NSMutableParagraphStyle()
        paragraphStyle.alignment = .center

        let attributes = [
            NSAttributedString.Key.paragraphStyle: paragraphStyle,
            NSAttributedString.Key.font: NSFont.systemFont(ofSize: 12.0),
            NSAttributedString.Key.foregroundColor: NSColor.white
        ]

        (0...10).forEach { index in
            cgx.move(to: CGPoint(x: 0, y: startingMargin + Double(index) * (height) / 10))
            cgx.addLine(to: CGPoint(x: 38, y: startingMargin + Double(index) * (height) / 10))
            cgx.setLineWidth(1)
            cgx.setStrokeColor(#colorLiteral(red: 0.2549019754, green: 0.2745098174, blue: 0.3019607961, alpha: 1))
            cgx.strokePath()

            let labelText = "\(index - 3)"
            let attributedString = NSAttributedString(string: labelText, attributes: attributes)

            let stringRect = CGRect(x: 38, y: 0.0 + Double(index) * height / 10, width: 20, height: 12)
            attributedString.draw(in: stringRect)
        }

        ctx.cgContext.setFillColor(.clear)
        ctx.cgContext.setStrokeColor(.white)
        ctx.cgContext.setLineWidth(1)

        let rectangle = CGRect(x: 0, y: startingMargin, width: 26, height: height)
        ctx.cgContext.addRect(rectangle)
        ctx.cgContext.drawPath(using: .fillStroke)
    }

}