vds_ios/VDS/Components/Buttons/ButtonGroup/ButtonGroupConstants.swift

//
//  ButtonGroupConstants.swift
//  VDS
//
//  Created by Matt Bruce on 12/1/22.
//

import Foundation
import UIKit

struct ButtonGroupConstants {
    static let defaultSpace = 12.0
    
    /// This will determine the spacing that will go between 2 ButtonBases either horizontally or vertically
    /// - Parameters:
    ///   - axis: horizontal/vertical
    ///   - primary: first ButtonBase
    ///   - neighboring: next ButtonBase based off of axis
    /// - Returns: float value
    static func getSpacing(for axis: NSLayoutConstraint.Axis, with primary: ButtonBase, neighboring: ButtonBase) -> CGFloat {

        //large button
        if let button = primary as? Button, button.size == .large {
            if let neighboringButton = neighboring as? Button, neighboringButton.size == .large {
                return axis == .horizontal ? 12.0 : 12.0
            } else if neighboring is TextLinkCaret {
                return axis == .horizontal ? 24.0 : 24.0
            } else if let neighboringTextLink = neighboring as? TextLink, neighboringTextLink.size == .large {
                return axis == .horizontal ? 16.0 : 16.0
            } else {
                return defaultSpace
            }
        }
        //large text link
        else if let textLink = primary as? TextLink, textLink.size == .large {
            if let neighboringButton = neighboring as? Button, neighboringButton.size == .large {
                return axis == .horizontal ? 16.0 : 16.0
            } else if neighboring is TextLinkCaret {
                return axis == .horizontal ? 24.0 : 24.0
            } else if let neighboringTextLink = neighboring as? TextLink, neighboringTextLink.size == .large {
                return axis == .horizontal ? 16.0 : 24.0
            } else {
                return defaultSpace
            }
        }
        //text link caret
        else if let _ = primary as? TextLinkCaret {
            if let neighboringButton = neighboring as? Button, neighboringButton.size == .large {
                return axis == .horizontal ? 24.0 : 24.0
            } else if let _ = neighboring as? TextLinkCaret {
                return axis == .horizontal ? 24.0 : 24.0
            } else if let neighboringTextLink = neighboring as? TextLink, neighboringTextLink.size == .large {
                return axis == .horizontal ? 24.0 : 24.0
            } else {
                return defaultSpace
            }
        }
        //small button
        else if let button = primary as? Button, button.size == .small {
            if let neighboringButton = neighboring as? Button, neighboringButton.size == .small {
                return axis == .horizontal ? 12.0 : 12.0
            } else if let neighboringTextLink = neighboring as? TextLink, neighboringTextLink.size == .small {
                return axis == .horizontal ? 16.0 : 24.0
            } else {
                return defaultSpace
            }
        }
        //small text link
        else if let textLink = primary as? TextLink, textLink.size == .small {
            if let neighboringTextLink = neighboring as? TextLink, neighboringTextLink.size == .small {
                return axis == .horizontal ? 16.0 : 24.0
            } else if let _ = neighboring as? Button {
                return axis == .horizontal ? 16.0 : 32.0
            } else {
                return defaultSpace
            }
        }
        //return defaultSpace
        else {
            return defaultSpace
        }
    }


    //
    
    /// Gets the tallest ButtonBases within the row
    /// - Parameter row: Row that includes the attributes
    /// - Returns: Array of [ButtonLayoutAttributes] of the tallest items
    private static func getTallestAttributes(for row: ButtonCollectionViewRow) -> [ButtonLayoutAttributes] {
        var height = 0.0
        var foundIndexes:[Int] = []
        for (index, attribute) in row.attributes.enumerated() {
            if attribute.frame.height >= height {
                height = attribute.frame.height
                foundIndexes.append(index)
            }
        }
        return foundIndexes.compactMap { row.attributes[$0] }
    }
    
    
    /// Gets the vertical spacing that will go between rows.
    /// - Parameters:
    ///   - row: Primary row that the space will go between
    ///   - neighboringRow: Secondary row that will be below the Primary
    /// - Returns: Amount of space that should live between these rows based off of the items.  The largest space will win when the comparison occurs.
    static func getVerticalSpacing(for row: ButtonCollectionViewRow, neighboringRow: ButtonCollectionViewRow?) -> CGFloat {
        // if the neighboringRow is nil, this is the last row in the collection
        // so return no space
        guard let neighboringRow else { return 0.0 }
           
        let primaryTallestAttributes = getTallestAttributes(for: row)
        let neighboringTallestAttributes = getTallestAttributes(for: neighboringRow)
        
        if primaryTallestAttributes.count > 0 && neighboringTallestAttributes.count > 0 {
            // If there is a tie for “tallest child,” the tiebreaker criteria is to refer to the child with the larger space requirement (for vertical spacing).
            var largestVerticalSpace = defaultSpace

            primaryTallestAttributes.forEach { primaryAttribute in
                neighboringTallestAttributes.forEach { neighboringTallestAttribute in
                    let space = getSpacing(for: .vertical, with: primaryAttribute.button!, neighboring: neighboringTallestAttribute.button!)
                    if space > largestVerticalSpace {
                        largestVerticalSpace = space
                    }
                }
            }
            return largestVerticalSpace
        }
        else {
            return defaultSpace
        }
    }
}