//
//  Popover.swift
//  Popover
//
//  Created by corin8823 on 8/16/15.
//  Copyright (c) 2015 corin8823. All rights reserved.
//

import Foundation
import UIKit

public enum PopoverOption {
  case arrowSize(CGSize)
  case animationIn(TimeInterval)
  case animationOut(TimeInterval)
  case cornerRadius(CGFloat)
  case sideEdge(CGFloat)
  case blackOverlayColor(UIColor)
  case overlayBlur(UIBlurEffect.Style)
  case type(PopoverType)
  case color(UIColor)
  case dismissOnBlackOverlayTap(Bool)
  case showBlackOverlay(Bool)
  case springDamping(CGFloat)
  case initialSpringVelocity(CGFloat)
  case sideOffset(CGFloat)
  case borderColor(UIColor)
}

@objc public enum PopoverType: Int {
  case up
  case down
  case left
  case right
  case auto
}

@objcMembers
open class Popover: UIView {

  // custom property
  open var arrowSize: CGSize = CGSize(width: 16.0, height: 10.0)
  open var animationIn: TimeInterval = 0.6
  open var animationOut: TimeInterval = 0.3
  open var cornerRadius: CGFloat = 6.0
  open var sideEdge: CGFloat = 20.0
  open var popoverType: PopoverType = .down
  open var blackOverlayColor: UIColor = UIColor(white: 0.0, alpha: 0.2)
  open var overlayBlur: UIBlurEffect?
  open var popoverColor: UIColor = UIColor.white
  open var dismissOnBlackOverlayTap: Bool = true
  open var showBlackOverlay: Bool = true
  open var highlightFromView: Bool = false
  open var highlightCornerRadius: CGFloat = 0
  open var springDamping: CGFloat = 0.7
  open var initialSpringVelocity: CGFloat = 3
  open var sideOffset: CGFloat = 6.0
  open var borderColor: UIColor?

  // custom closure
  open var willShowHandler: (() -> ())?
  open var willDismissHandler: (() -> ())?
  open var didShowHandler: (() -> ())?
  open var didDismissHandler: (() -> ())?

  public fileprivate(set) var blackOverlay: UIControl = UIControl()

  fileprivate var containerView: UIView!
  fileprivate var contentView: UIView!
  fileprivate var contentViewFrame: CGRect!
  fileprivate var arrowShowPoint: CGPoint!

  public init() {
    super.init(frame: .zero)
    self.backgroundColor = .clear
    self.accessibilityViewIsModal = true
  }

  public init(showHandler: (() -> ())?, dismissHandler: (() -> ())?) {
    super.init(frame: .zero)
    self.backgroundColor = .clear
    self.didShowHandler = showHandler
    self.didDismissHandler = dismissHandler
    self.accessibilityViewIsModal = true
  }

  public init(options: [PopoverOption]?, showHandler: (() -> ())? = nil, dismissHandler: (() -> ())? = nil) {
    super.init(frame: .zero)
    self.backgroundColor = .clear
    self.setOptions(options)
    self.didShowHandler = showHandler
    self.didDismissHandler = dismissHandler
    self.accessibilityViewIsModal = true
  }

  required public init?(coder aDecoder: NSCoder) {
    fatalError("init(coder:) has not been implemented")
  }

  override open func layoutSubviews() {
    super.layoutSubviews()
    self.contentView.frame = self.bounds
  }

  open func showAsDialog(_ contentView: UIView) {
    guard let rootView = UIApplication.shared.keyWindow else {
      return
    }
    self.showAsDialog(contentView, inView: rootView)
  }

  open func showAsDialog(_ contentView: UIView, inView: UIView) {
    self.arrowSize = .zero
    let point = CGPoint(x: inView.center.x,
                        y: inView.center.y - contentView.frame.height / 2)
    self.show(contentView, point: point, inView: inView)
  }

  open func show(_ contentView: UIView, fromView: UIView) {
    guard let rootView = UIApplication.shared.keyWindow else {
      return
    }
    self.show(contentView, fromView: fromView, inView: rootView)
  }

  open func show(_ contentView: UIView, fromView: UIView, inView: UIView) {
    let point: CGPoint
    
    //TODO: add left/right auto
    if self.popoverType == .auto {
        if let point = fromView.superview?.convert(fromView.frame.origin, to: nil),
            point.y + fromView.frame.height + self.arrowSize.height + contentView.frame.height > inView.frame.height {
            self.popoverType = .up
        } else {
            self.popoverType = .down
        }
    }
    
    switch self.popoverType {
    case .up:
      point = inView.convert(
        CGPoint(
          x: fromView.frame.origin.x + (fromView.frame.size.width / 2),
          y: fromView.frame.origin.y
      ), from: fromView.superview)
    case .down, .auto:
      point = inView.convert(
        CGPoint(
          x: fromView.frame.origin.x + (fromView.frame.size.width / 2),
          y: fromView.frame.origin.y + fromView.frame.size.height
      ), from: fromView.superview)
    case .left:
      point = inView.convert(
        CGPoint(x: fromView.frame.origin.x - sideOffset,
                y: fromView.frame.origin.y + 0.5 * fromView.frame.height
      ), from: fromView.superview)
    case .right:
      point = inView.convert(
        CGPoint(x: fromView.frame.origin.x + fromView.frame.size.width + sideOffset,
                y: fromView.frame.origin.y + 0.5 * fromView.frame.height
      ), from: fromView.superview)
    }

    if self.highlightFromView {
      self.createHighlightLayer(fromView: fromView, inView: inView)
    }

    self.show(contentView, point: point, inView: inView)
  }

  open func show(_ contentView: UIView, point: CGPoint) {
    guard let rootView = UIApplication.shared.keyWindow else {
      return
    }
    self.show(contentView, point: point, inView: rootView)
  }

  open func show(_ contentView: UIView, point: CGPoint, inView: UIView) {
    if self.dismissOnBlackOverlayTap || self.showBlackOverlay {
      self.blackOverlay.autoresizingMask = [.flexibleWidth, .flexibleHeight]
      self.blackOverlay.frame = inView.bounds
      inView.addSubview(self.blackOverlay)

      if showBlackOverlay {
        if let overlayBlur = self.overlayBlur {
          let effectView = UIVisualEffectView(effect: overlayBlur)
          effectView.frame = self.blackOverlay.bounds
          effectView.isUserInteractionEnabled = false
          self.blackOverlay.addSubview(effectView)
        } else {
          if !self.highlightFromView {
            self.blackOverlay.backgroundColor = self.blackOverlayColor
          }
          self.blackOverlay.alpha = 0
        }
      }

      if self.dismissOnBlackOverlayTap {
        self.blackOverlay.addTarget(self, action: #selector(Popover.dismiss), for: .touchUpInside)
      }
    }
    
    self.containerView = inView
    self.contentView = contentView
    self.contentView.backgroundColor = UIColor.clear
    self.contentView.layer.cornerRadius = self.cornerRadius
    self.contentView.layer.masksToBounds = true
    self.arrowShowPoint = point
    self.show()
  }

  open override func accessibilityPerformEscape() -> Bool {
    self.dismiss()
    return true
  }

  @objc open func dismiss() {
    if self.superview != nil {
      self.willDismissHandler?()
      UIView.animate(withDuration: self.animationOut, delay: 0,
                     options: UIView.AnimationOptions(),
                     animations: {
                      self.transform = CGAffineTransform(scaleX: 0.0001, y: 0.0001)
                      self.blackOverlay.alpha = 0
      }){ _ in
        self.contentView.removeFromSuperview()
        self.blackOverlay.removeFromSuperview()
        self.removeFromSuperview()
        self.transform = CGAffineTransform.identity
        self.didDismissHandler?()
      }
    }
  }

  override open func draw(_ rect: CGRect) {
    super.draw(rect)
    let arrow = UIBezierPath()
    let color = self.popoverColor
    let arrowPoint = self.containerView.convert(self.arrowShowPoint, to: self)
    switch self.popoverType {
    case .up:
      arrow.move(to: CGPoint(x: arrowPoint.x, y: self.bounds.height))
      arrow.addLine(
        to: CGPoint(
          x: arrowPoint.x - self.arrowSize.width * 0.5,
          y: self.isCornerLeftArrow ? self.arrowSize.height : self.bounds.height - self.arrowSize.height
        )
      )

      arrow.addLine(to: CGPoint(x: self.cornerRadius, y: self.bounds.height - self.arrowSize.height))
      arrow.addArc(
        withCenter: CGPoint(
          x: self.cornerRadius,
          y: self.bounds.height - self.arrowSize.height - self.cornerRadius
        ),
        radius: self.cornerRadius,
        startAngle: self.radians(90),
        endAngle: self.radians(180),
        clockwise: true)

      arrow.addLine(to: CGPoint(x: 0, y: self.cornerRadius))
      arrow.addArc(
        withCenter: CGPoint(
          x: self.cornerRadius,
          y: self.cornerRadius
        ),
        radius: self.cornerRadius,
        startAngle: self.radians(180),
        endAngle: self.radians(270),
        clockwise: true)

      arrow.addLine(to: CGPoint(x: self.bounds.width - self.cornerRadius, y: 0))
      arrow.addArc(
        withCenter: CGPoint(
          x: self.bounds.width - self.cornerRadius,
          y: self.cornerRadius
        ),
        radius: self.cornerRadius,
        startAngle: self.radians(270),
        endAngle: self.radians(0),
        clockwise: true)

      arrow.addLine(to: CGPoint(x: self.bounds.width, y: self.bounds.height - self.arrowSize.height - self.cornerRadius))
      arrow.addArc(
        withCenter: CGPoint(
          x: self.bounds.width - self.cornerRadius,
          y: self.bounds.height - self.arrowSize.height - self.cornerRadius
        ),
        radius: self.cornerRadius,
        startAngle: self.radians(0),
        endAngle: self.radians(90),
        clockwise: true)

      arrow.addLine(
        to: CGPoint(
          x: arrowPoint.x + self.arrowSize.width * 0.5,
          y: self.isCornerRightArrow ? self.arrowSize.height : self.bounds.height - self.arrowSize.height
        )
      )

    case .down, .auto:
      arrow.move(to: CGPoint(x: arrowPoint.x, y: 0))
      
      if self.isCloseToCornerRightArrow && !self.isCornerRightArrow {
        if !isBehindCornerRightArrow {
          arrow.addLine(to: CGPoint(x: self.bounds.width - self.cornerRadius, y: self.arrowSize.height))
          arrow.addArc(
            withCenter: CGPoint(x: self.bounds.width - self.cornerRadius, y: self.arrowSize.height + self.cornerRadius),
            radius: self.cornerRadius,
            startAngle: self.radians(270.0),
            endAngle: self.radians(0),
            clockwise: true)
        } else {
          arrow.addLine(to: CGPoint(x: self.bounds.width, y: self.arrowSize.height + self.cornerRadius))
          arrow.addLine(to: CGPoint(x: self.bounds.width, y: self.arrowSize.height))
        }
      } else {
        arrow.addLine(
          to: CGPoint(
            x: self.isBehindCornerLeftArrow ? self.frame.minX - self.arrowSize.width * 0.5 : arrowPoint.x + self.arrowSize.width * 0.5,
            y: self.isCornerRightArrow ? self.arrowSize.height + self.bounds.height : self.arrowSize.height
          )
        )
        arrow.addLine(to: CGPoint(x: self.bounds.width - self.cornerRadius, y: self.arrowSize.height))
        arrow.addArc(
          withCenter: CGPoint(
            x: self.bounds.width - self.cornerRadius,
            y: self.arrowSize.height + self.cornerRadius
          ),
          radius: self.cornerRadius,
          startAngle: self.radians(270.0),
          endAngle: self.radians(0),
          clockwise: true)
      }
      
      arrow.addLine(to: CGPoint(x: self.bounds.width, y: self.bounds.height - self.cornerRadius))
      arrow.addArc(
        withCenter: CGPoint(
          x: self.bounds.width - self.cornerRadius,
          y: self.bounds.height - self.cornerRadius
        ),
        radius: self.cornerRadius,
        startAngle: self.radians(0),
        endAngle: self.radians(90),
        clockwise: true)

      arrow.addLine(to: CGPoint(x: 0, y: self.bounds.height))
      arrow.addArc(
        withCenter: CGPoint(
          x: self.cornerRadius,
          y: self.bounds.height - self.cornerRadius
        ),
        radius: self.cornerRadius,
        startAngle: self.radians(90),
        endAngle: self.radians(180),
        clockwise: true)

      arrow.addLine(to: CGPoint(x: 0, y: self.arrowSize.height + self.cornerRadius))
      
      if !isBehindCornerLeftArrow {
      arrow.addArc(
        withCenter: CGPoint(
          x: self.cornerRadius,
          y: self.arrowSize.height + self.cornerRadius
        ),
        radius: self.cornerRadius,
        startAngle: self.radians(180),
        endAngle: self.radians(270),
        clockwise: true)
      }

      if isBehindCornerRightArrow {
        arrow.addLine(to: CGPoint(
          x: self.bounds.width - self.arrowSize.width * 0.5,
          y: self.isCornerLeftArrow ? self.arrowSize.height + self.bounds.height : self.arrowSize.height))
      } else if isCloseToCornerLeftArrow && !isCornerLeftArrow {
        () // skipping this line in that case
      } else {
        arrow.addLine(to: CGPoint(x: arrowPoint.x - self.arrowSize.width * 0.5,
                                  y: self.isCornerLeftArrow ? self.arrowSize.height + self.bounds.height : self.arrowSize.height))
      }
        
    case .left:
        arrow.move(to: CGPoint(x: self.bounds.width, y: self.bounds.height * 0.5))
        arrow.addLine(
            to: CGPoint(
                x: self.bounds.width - self.arrowSize.height,
                y: self.bounds.height * 0.5 + self.arrowSize.width * 0.5
        ))
        
        arrow.addLine(to: CGPoint(x:self.bounds.width - self.arrowSize.height, y: self.bounds.height - self.cornerRadius))
        arrow.addArc(
            withCenter: CGPoint(
                x: self.bounds.width - self.arrowSize.height - self.cornerRadius,
                y: self.bounds.height - self.cornerRadius
            ),
            radius: self.cornerRadius,
            startAngle: self.radians(0.0),
            endAngle: self.radians(90),
            clockwise: true)
        
        arrow.addLine(to: CGPoint(x: self.cornerRadius, y: self.bounds.height))
        arrow.addArc(
            withCenter: CGPoint(
                x: self.cornerRadius,
                y: self.bounds.height - self.cornerRadius
            ),
            radius: self.cornerRadius,
            startAngle: self.radians(90),
            endAngle: self.radians(180),
            clockwise: true)
        
        arrow.addLine(to: CGPoint(x: 0, y: self.cornerRadius))
        arrow.addArc(
            withCenter: CGPoint(
                x: self.cornerRadius,
                y: self.cornerRadius
            ),
            radius: self.cornerRadius,
            startAngle: self.radians(180),
            endAngle: self.radians(270),
            clockwise: true)
        
        arrow.addLine(to: CGPoint(x: self.bounds.width - self.arrowSize.height - self.cornerRadius, y: 0))
        arrow.addArc(
            withCenter: CGPoint(x: self.bounds.width - self.arrowSize.height - self.cornerRadius,
                                y: self.cornerRadius
            ),
            radius: self.cornerRadius,
            startAngle: self.radians(270),
            endAngle: self.radians(0),
            clockwise: true)
        
        arrow.addLine(to: CGPoint(x: self.bounds.width - self.arrowSize.height,
                                  y: self.bounds.height * 0.5 - self.arrowSize.width * 0.5
        ))
    case .right:
        arrow.move(to: CGPoint(x: arrowPoint.x, y: self.bounds.height * 0.5))
        arrow.addLine(
            to: CGPoint(
                x: arrowPoint.x + self.arrowSize.height,
                y: self.bounds.height * 0.5 + 0.5 * self.arrowSize.width
        ))
        
        arrow.addLine(
            to: CGPoint(
                x: arrowPoint.x + self.arrowSize.height,
                y: self.bounds.height - self.cornerRadius
        ))
        arrow.addArc(
            withCenter: CGPoint(
                x: arrowPoint.x + self.arrowSize.height + self.cornerRadius,
                y: self.bounds.height - self.cornerRadius
            ),
            radius: self.cornerRadius,
            startAngle: self.radians(180.0),
            endAngle: self.radians(90),
            clockwise: false)
        
        arrow.addLine(to: CGPoint(x: self.bounds.width + arrowPoint.x - self.cornerRadius, y: self.bounds.height))
        arrow.addArc(
            withCenter: CGPoint(
                x: self.bounds.width + arrowPoint.x - self.cornerRadius,
                y: self.bounds.height - self.cornerRadius
            ),
            radius: self.cornerRadius,
            startAngle: self.radians(90),
            endAngle: self.radians(0),
            clockwise: false)
        
        arrow.addLine(to: CGPoint(x: self.bounds.width + arrowPoint.x, y: self.cornerRadius))
        arrow.addArc(
            withCenter: CGPoint(
                x: self.bounds.width + arrowPoint.x - self.cornerRadius,
                y: self.cornerRadius
            ),
            radius: self.cornerRadius,
            startAngle: self.radians(0),
            endAngle: self.radians(-90),
            clockwise: false)
        
        arrow.addLine(to: CGPoint(x: arrowPoint.x + self.arrowSize.height - self.cornerRadius, y: 0))
        arrow.addArc(
            withCenter: CGPoint(x: arrowPoint.x + self.arrowSize.height + self.cornerRadius,
                                y: self.cornerRadius
            ),
            radius: self.cornerRadius,
            startAngle: self.radians(-90),
            endAngle: self.radians(-180),
            clockwise: false)
        
        arrow.addLine(to: CGPoint(x: arrowPoint.x + self.arrowSize.height,
                                  y:  self.bounds.height * 0.5 - self.arrowSize.width * 0.5))
    }

    color.setFill()
    arrow.fill()
    if let borderColor = borderColor {
      borderColor.setStroke()
      arrow.stroke()
    }
  }
}

private extension Popover {

  func setOptions(_ options: [PopoverOption]?){
    if let options = options {
      for option in options {
        switch option {
        case let .arrowSize(value):
          self.arrowSize = value
        case let .animationIn(value):
          self.animationIn = value
        case let .animationOut(value):
          self.animationOut = value
        case let .cornerRadius(value):
          self.cornerRadius = value
        case let .sideEdge(value):
          self.sideEdge = value
        case let .blackOverlayColor(value):
          self.blackOverlayColor = value
        case let .overlayBlur(style):
          self.overlayBlur = UIBlurEffect(style: style)
        case let .type(value):
          self.popoverType = value
        case let .color(value):
          self.popoverColor = value
        case let .dismissOnBlackOverlayTap(value):
          self.dismissOnBlackOverlayTap = value
        case let .showBlackOverlay(value):
          self.showBlackOverlay = value
        case let .springDamping(value):
          self.springDamping = value
        case let .initialSpringVelocity(value):
          self.initialSpringVelocity = value
        case let .sideOffset(value):
          self.sideOffset = value
        case let .borderColor(value):
          self.borderColor = value
        }
      }
    }
  }

  func create() {
    var frame = self.contentView.frame
    
    switch self.popoverType {
    case .up, .down, .auto:
        frame.origin.x = self.arrowShowPoint.x - frame.size.width * 0.5
    case .left, .right:
        frame.origin.y = self.arrowShowPoint.y - frame.size.height * 0.5
    }

    var sideEdge: CGFloat = 0.0
    if frame.size.width < self.containerView.frame.size.width {
      sideEdge = self.sideEdge
    }

    let outerSideEdge = frame.maxX - self.containerView.bounds.size.width
    if outerSideEdge > 0 {
      frame.origin.x -= (outerSideEdge + sideEdge)
    } else {
      if frame.minX < 0 {
        frame.origin.x += abs(frame.minX) + sideEdge
      }
    }
    self.frame = frame

    let arrowPoint = self.containerView.convert(self.arrowShowPoint, to: self)
    var anchorPoint: CGPoint
    switch self.popoverType {
    case .up:
      frame.origin.y = self.arrowShowPoint.y - frame.height - self.arrowSize.height
      anchorPoint = CGPoint(x: arrowPoint.x / frame.size.width, y: 1)
    case .down, .auto:
      frame.origin.y = self.arrowShowPoint.y
      anchorPoint = CGPoint(x: arrowPoint.x / frame.size.width, y: 0)
    case .left:
        frame.origin.x = self.arrowShowPoint.x - frame.size.width - self.arrowSize.height
        anchorPoint = CGPoint(x: 1, y: 0.5)
    case .right:
        frame.origin.x = self.arrowShowPoint.x
        anchorPoint = CGPoint(x: 0, y: 0.5)
    }

    if self.arrowSize == .zero {
      anchorPoint = CGPoint(x: 0.5, y: 0.5)
    }

    let lastAnchor = self.layer.anchorPoint
    self.layer.anchorPoint = anchorPoint
    let x = self.layer.position.x + (anchorPoint.x - lastAnchor.x) * self.layer.bounds.size.width
    let y = self.layer.position.y + (anchorPoint.y - lastAnchor.y) * self.layer.bounds.size.height
    self.layer.position = CGPoint(x: x, y: y)

    switch self.popoverType {
    case .up, .down, .auto:
        frame.size.height += self.arrowSize.height
    case .left, .right:
        frame.size.width += self.arrowSize.height
    }
    
    self.frame = frame
  }

  func createHighlightLayer(fromView: UIView, inView: UIView) {
    let path = UIBezierPath(rect: inView.bounds)
    let highlightRect = inView.convert(fromView.frame, from: fromView.superview)
    let highlightPath = UIBezierPath(roundedRect: highlightRect, cornerRadius: self.highlightCornerRadius)
    path.append(highlightPath)
    path.usesEvenOddFillRule = true

    let fillLayer = CAShapeLayer()
    fillLayer.path = path.cgPath
    fillLayer.fillRule = CAShapeLayerFillRule.evenOdd
    fillLayer.fillColor = self.blackOverlayColor.cgColor
    self.blackOverlay.layer.addSublayer(fillLayer)
  }

  func show() {
    self.setNeedsDisplay()
    switch self.popoverType {
    case .up:
      self.contentView.frame.origin.y = 0.0
    case .down, .auto:
      self.contentView.frame.origin.y = self.arrowSize.height
    case .left, .right:
      self.contentView.frame.origin.x = 0
    }
    self.addSubview(self.contentView)
    self.containerView.addSubview(self)

    self.create()
    self.transform = CGAffineTransform(scaleX: 0.0, y: 0.0)
    self.willShowHandler?()
    UIView.animate(
      withDuration: self.animationIn,
      delay: 0,
      usingSpringWithDamping: self.springDamping,
      initialSpringVelocity: self.initialSpringVelocity,
      options: UIView.AnimationOptions(),
      animations: {
        self.transform = CGAffineTransform.identity
    }){ _ in
      self.didShowHandler?()
    }
    UIView.animate(
      withDuration: self.animationIn / 3,
      delay: 0,
      options: .curveLinear,
      animations: {
        self.blackOverlay.alpha = 1
    }, completion: nil)
  }

  var isCloseToCornerLeftArrow: Bool {
    return self.arrowShowPoint.x < self.frame.origin.x + arrowSize.width/2 + cornerRadius
  }

  var isCloseToCornerRightArrow: Bool {
    return self.arrowShowPoint.x > (self.frame.origin.x + self.bounds.width) - arrowSize.width/2 - cornerRadius
  }

  var isCornerLeftArrow: Bool {
    return self.arrowShowPoint.x == self.frame.origin.x
  }

  var isCornerRightArrow: Bool {
    return self.arrowShowPoint.x == self.frame.origin.x + self.bounds.width
  }
  
  var isBehindCornerLeftArrow: Bool {
    return self.arrowShowPoint.x < self.frame.origin.x
  }

  var isBehindCornerRightArrow: Bool {
    return self.arrowShowPoint.x > self.frame.origin.x + self.bounds.width
  }

  func radians(_ degrees: CGFloat) -> CGFloat {
    return CGFloat.pi * degrees / 180
  }
}