LeadKit/TIUIKitCore/Sources/TextAttributes/BaseTextAttributes/BaseTextAttributes.swift

//
//  Copyright (c) 2020 Touch Instinct
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import UIKit
import TISwiftUtils

/// Base set of attributes to configure appearance of text.
open class BaseTextAttributes {

    public let font: UIFont
    public let color: UIColor
    public let paragraphStyle: NSParagraphStyle
    public let numberOfLines: Int

    private let forceAttributedStringUsage: Bool

    open var attributedStringAttributes: [NSAttributedString.Key : Any] {
        [
            .font: font,
            .foregroundColor: color,
            .paragraphStyle: paragraphStyle
        ]
    }

    public init(font: UIFont,
                color: UIColor,
                numberOfLines: Int,
                paragraphStyleConfiguration: ParameterClosure<NSMutableParagraphStyle>) {

        self.font = font
        self.color = color

        let mutableParagraphStyle = NSMutableParagraphStyle()
        paragraphStyleConfiguration(mutableParagraphStyle)

        let equator = KeyPathEquatable(rhs: mutableParagraphStyle, lhs: NSParagraphStyle.default)

        // The following attributes require to construct NSAttributedString instead of
        // using plain String + BaseTextAttributesConfigurable target
        let equalityResults = [
            equator(\.lineSpacing),
            equator(\.paragraphSpacing),
            equator(\.headIndent),
            equator(\.tailIndent),
            equator(\.firstLineHeadIndent),
            equator(\.minimumLineHeight),
            equator(\.maximumLineHeight),
            equator(\.lineHeightMultiple),
            equator(\.paragraphSpacingBefore),
            equator(\.hyphenationFactor),
            equator(\.allowsDefaultTighteningForTruncation),
            equator(\.lineBreakStrategy)
        ]

        forceAttributedStringUsage = !equalityResults.allSatisfy { $0 }

        self.paragraphStyle = mutableParagraphStyle
        self.numberOfLines = numberOfLines
    }

    // MARK: - UI elements appearance configuration

    private func configure<T: BaseTextAttributesConfigurable>(textContainer: T) {
        textContainer.set(font: font)
        textContainer.set(color: color)
        textContainer.set(alignment: paragraphStyle.alignment)
        textContainer.set(lineBreakMode: paragraphStyle.lineBreakMode)
    }

    open func configure(label: UILabel) {
        configure(textContainer: label)

        label.numberOfLines = numberOfLines
    }

    open func configure(textField: UITextField) {
        configure(textContainer: textField)
    }

    open func configure(textView: UITextView) {
        configure(textContainer: textView)
    }

    // MARK: - UI elements text configuration

    private func configure<T>(textContainer: T,
                              with string: String?,
                              appearanceConfiguration: (T) -> Void,
                              textConfiguration: (String?) -> Void,
                              attributedTextConfiguration: (NSAttributedString?) -> Void) {

        if forceAttributedStringUsage {
            let resultAttributedString: NSAttributedString?

            if let string = string {
                resultAttributedString = attributedString(for: string)
            } else {
                resultAttributedString = nil
            }

            attributedTextConfiguration(resultAttributedString)
        } else {
            appearanceConfiguration(textContainer)

            textConfiguration(string)
        }
    }

    open func configure(label: UILabel, with string: String?) {
        configure(textContainer: label,
                  with: string,
                  appearanceConfiguration: configure(label:),
                  textConfiguration: { label.text = $0 },
                  attributedTextConfiguration: {
            label.attributedText = $0
            label.numberOfLines = numberOfLines
        })
    }

    open func configure(textField: UITextField, with string: String?) {
        configure(textContainer: textField,
                  with: string,
                  appearanceConfiguration: configure(textField:),
                  textConfiguration: { textField.text = $0 },
                  attributedTextConfiguration: { textField.attributedText = $0 })
    }

    open func configure(textView: UITextView, with string: String?) {
        configure(textContainer: textView,
                  with: string,
                  appearanceConfiguration: configure(textView:),
                  textConfiguration: { textView.text = $0 },
                  attributedTextConfiguration: { textView.attributedText = $0 })
    }

    open func configure(button: UIButton, with string: String? = nil) {
        if #available(iOS 15, *) {
            var configuration = button.configuration ?? UIButton.Configuration.plain()

            if let title = string {
                button.setTitle(nil, for: .normal)
                button.setAttributedTitle(nil, for: .normal)

                configuration.attributedTitle = attributedString(for: title)
                button.configuration = configuration
            }
        } else {
            button.setTitle(string, for: .normal)
            button.setTitleColor(color, for: .normal)

            if let label = button.titleLabel {
                configure(label: label)
            }
        }
    }

    // MARK: - Attributed string manipulation

    @available(iOS 15, *)
    open func attributedString(for string: String) -> AttributedString {
        AttributedString(attributedString(for: string))
    }

    open func attributedString(for string: String) -> NSAttributedString {
        NSAttributedString(string: string, attributes: attributedStringAttributes)
    }

    open func apply(in attributedString: NSMutableAttributedString, at range: NSRange? = nil) {
        attributedString.addAttributes(attributedStringAttributes,
                                       range: range ?? NSRange(location: 0, length: attributedString.length))
    }

    // MARK: - Size calculation

    open func size(of string: String?,
                   with size: CGSize,
                   options: NSStringDrawingOptions = [.usesFontLeading, .usesLineFragmentOrigin],
                   context: NSStringDrawingContext? = nil) -> CGSize {

        guard let string = string else {
            return .zero
        }

        let attributedString = NSAttributedString(string: string,
                                                  attributes: attributedStringAttributes)

        return attributedString
            .boundingRect(with: size,
                          options: options,
                          context: context)
            .size
    }

    open func height(of string: String?,
                     with width: CGFloat,
                     options: NSStringDrawingOptions = [.usesFontLeading, .usesLineFragmentOrigin],
                     context: NSStringDrawingContext? = nil) -> CGFloat {

        size(of: string,
             with: CGSize(width: width, height: .greatestFiniteMagnitude),
             options: options,
             context: context).height
    }
}

public extension BaseTextAttributes {
    typealias FigmaPercent = CGFloat

    convenience init(font: UIFont,
                     color: UIColor,
                     alignment: NSTextAlignment,
                     isMultiline: Bool,
                     lineHeight: FigmaPercent? = nil) {

        self.init(font: font,
                  color: color,
                  alignment: alignment,
                  lineHeightMultiple: lineHeight?.dividing(by: 100),
                  numberOfLines: isMultiline ? 0 : 1)
    }

    convenience init(font: UIFont,
                     color: UIColor,
                     alignment: NSTextAlignment,
                     lineHeightMultiple: CGFloat?,
                     numberOfLines: Int) {

        self.init(font: font,
                  color: color,
                  numberOfLines: numberOfLines) {

            if let lineHeightMultiple = lineHeightMultiple {
                $0.lineHeightMultiple = lineHeightMultiple
            }

            $0.alignment = alignment
        }
    }
}

private extension BaseTextAttributes.FigmaPercent {
    func dividing(by other: Self) -> Self {
        self / other
    }
}