TextStyle.swift

import UIKit

public struct TextStyle: Equatable {
    
    // MARK: - Instance Properties
    public let font: UIFont?
    public let color: UIColor?
    public let backgroundColor: UIColor?
    public let strikethrough: Bool
    public let underline: Bool
    public let paragraphSpacing: CGFloat?
    public let paragraphIndent: CGFloat?
    public let lineHeight: CGFloat?
    public let letterSpacing: CGFloat?
    public let lineBreakMode: NSLineBreakMode?
    public let alignment: NSTextAlignment?
    public let link: URL?
    
    
    // MARK: - Initializers
    public init(
        font: UIFont? = nil,
        color: UIColor? = nil,
        backgroundColor: UIColor? = nil,
        strikethrough: Bool = false,
        underline: Bool = false,
        paragraphSpacing: CGFloat? = nil,
        paragraphIndent: CGFloat? = nil,
        lineHeight: CGFloat? = nil,
        letterSpacing: CGFloat? = nil,
        lineBreakMode: NSLineBreakMode? = nil,
        alignment: NSTextAlignment? = nil,
        link: URL? = nil
    ) {
        self.font = font
        self.color = color
        self.backgroundColor = backgroundColor
        self.strikethrough = strikethrough
        self.underline = underline
        self.paragraphSpacing = paragraphSpacing
        self.paragraphIndent = paragraphIndent
        self.lineHeight = lineHeight
        self.letterSpacing = letterSpacing
        self.lineBreakMode = lineBreakMode
        self.alignment = alignment
        self.link = link
    }
    
    // MARK: - Instance Methods
    private func attributes(paragraphStyle: NSParagraphStyle?) -> [NSAttributedString.Key: Any] {
        var attributes: [NSAttributedString.Key: Any] = [:]
        
        if let paragraphStyle = paragraphStyle {
            attributes[.paragraphStyle] = paragraphStyle
        }
        
        if let font = font {
            attributes[.font] = font
        }
        
        if let color = color {
            attributes[.foregroundColor] = color
        }
        
        if let backgroundColor = backgroundColor {
            attributes[.backgroundColor] = backgroundColor
        }
        
        if strikethrough {
            attributes[.strikethroughStyle] = NSUnderlineStyle.single.rawValue
        }
        
        if underline {
            attributes[.underlineStyle] = NSUnderlineStyle.single.rawValue
        }
        
        if let letterSpacing = letterSpacing {
            attributes[.kern] = letterSpacing
        }
        
        if let link = link {
            attributes[.link] = link
        }
        
        return attributes
    }
    
    // MARK: -
    public func paragraphStyle() -> NSParagraphStyle {
        let paragraphStyle = NSMutableParagraphStyle()
        
        if let lineHeight = lineHeight {
            paragraphStyle.minimumLineHeight = lineHeight
            paragraphStyle.maximumLineHeight = lineHeight
        }
        
        if let paragraphSpacing = paragraphSpacing {
            paragraphStyle.paragraphSpacing = paragraphSpacing
        }
        
        if let paragraphIndent = paragraphIndent {
            paragraphStyle.firstLineHeadIndent = paragraphIndent
        }
        
        if let lineBreakMode = lineBreakMode {
            paragraphStyle.lineBreakMode = lineBreakMode
        }
        
        if let alignment = alignment {
            paragraphStyle.alignment = alignment
        }
        
        return paragraphStyle
    }
    
    public func attributes(includingParagraphStyle: Bool = true) -> [NSAttributedString.Key: Any] {
        if includingParagraphStyle {
            return attributes(paragraphStyle: paragraphStyle())
        } else {
            return attributes(paragraphStyle: nil)
        }
    }
    
    public func attributedString(
        _ string: String,
        includingParagraphStyle: Bool = true
    ) -> NSAttributedString {
        return NSAttributedString(string: string, style: self, includingParagraphStyle: includingParagraphStyle)
    }
    
    public func mutableString(
        _ string: String,
        includingParagraphStyle: Bool = true
    ) -> NSMutableAttributedString {
        return NSMutableAttributedString(string: string, style: self, includingParagraphStyle: includingParagraphStyle)
    }
    
    // MARK: -
    public func withFont(_ font: UIFont?) -> TextStyle {
        return TextStyle(
            font: font,
            color: color,
            backgroundColor: backgroundColor,
            strikethrough: strikethrough,
            underline: underline,
            paragraphSpacing: paragraphSpacing,
            paragraphIndent: paragraphIndent,
            lineHeight: lineHeight,
            letterSpacing: letterSpacing,
            lineBreakMode: lineBreakMode,
            alignment: alignment,
            link: link
        )
    }
    
    public func withColor(_ color: UIColor?) -> TextStyle {
        return TextStyle(
            font: font,
            color: color,
            backgroundColor: backgroundColor,
            strikethrough: strikethrough,
            underline: underline,
            paragraphSpacing: paragraphSpacing,
            paragraphIndent: paragraphIndent,
            lineHeight: lineHeight,
            letterSpacing: letterSpacing,
            lineBreakMode: lineBreakMode,
            alignment: alignment,
            link: link
        )
    }
    
    public func withBackgroundColor(_ backgroundColor: UIColor?) -> TextStyle {
        return TextStyle(
            font: font,
            color: color,
            backgroundColor: backgroundColor,
            strikethrough: strikethrough,
            underline: underline,
            paragraphSpacing: paragraphSpacing,
            paragraphIndent: paragraphIndent,
            lineHeight: lineHeight,
            letterSpacing: letterSpacing,
            lineBreakMode: lineBreakMode,
            alignment: alignment,
            link: link
        )
    }
    
    public func withStrikethrough(_ strikethrough: Bool) -> TextStyle {
        return TextStyle(
            font: font,
            color: color,
            backgroundColor: backgroundColor,
            strikethrough: strikethrough,
            underline: underline,
            paragraphSpacing: paragraphSpacing,
            paragraphIndent: paragraphIndent,
            lineHeight: lineHeight,
            letterSpacing: letterSpacing,
            lineBreakMode: lineBreakMode,
            alignment: alignment,
            link: link
        )
    }
    
    public func withUnderline(_ underline: Bool) -> TextStyle {
        return TextStyle(
            font: font,
            color: color,
            backgroundColor: backgroundColor,
            strikethrough: strikethrough,
            underline: underline,
            paragraphSpacing: paragraphSpacing,
            paragraphIndent: paragraphIndent,
            lineHeight: lineHeight,
            letterSpacing: letterSpacing,
            lineBreakMode: lineBreakMode,
            alignment: alignment,
            link: link
        )
    }
    
    public func withParagraphSpacing(_ paragraphSpacing: CGFloat?) -> TextStyle {
        return TextStyle(
            font: font,
            color: color,
            backgroundColor: backgroundColor,
            strikethrough: strikethrough,
            underline: underline,
            paragraphSpacing: paragraphSpacing,
            paragraphIndent: paragraphIndent,
            lineHeight: lineHeight,
            letterSpacing: letterSpacing,
            lineBreakMode: lineBreakMode,
            alignment: alignment,
            link: link
        )
    }
    
    public func withParagraphIndent(_ paragraphIndent: CGFloat?) -> TextStyle {
        return TextStyle(
            font: font,
            color: color,
            backgroundColor: backgroundColor,
            strikethrough: strikethrough,
            underline: underline,
            paragraphSpacing: paragraphSpacing,
            paragraphIndent: paragraphIndent,
            lineHeight: lineHeight,
            letterSpacing: letterSpacing,
            lineBreakMode: lineBreakMode,
            alignment: alignment,
            link: link
        )
    }
    
    public func withLineHeight(_ lineHeight: CGFloat?) -> TextStyle {
        return TextStyle(
            font: font,
            color: color,
            backgroundColor: backgroundColor,
            strikethrough: strikethrough,
            underline: underline,
            paragraphSpacing: paragraphSpacing,
            paragraphIndent: paragraphIndent,
            lineHeight: lineHeight,
            letterSpacing: letterSpacing,
            lineBreakMode: lineBreakMode,
            alignment: alignment,
            link: link
        )
    }
    
    public func withLetterSpacing(_ letterSpacing: CGFloat?) -> TextStyle {
        return TextStyle(
            font: font,
            color: color,
            backgroundColor: backgroundColor,
            strikethrough: strikethrough,
            underline: underline,
            paragraphSpacing: paragraphSpacing,
            paragraphIndent: paragraphIndent,
            lineHeight: lineHeight,
            letterSpacing: letterSpacing,
            lineBreakMode: lineBreakMode,
            alignment: alignment,
            link: link
        )
    }
    
    public func withLineBreakMode(_ lineBreakMode: NSLineBreakMode?) -> TextStyle {
        return TextStyle(
            font: font,
            color: color,
            backgroundColor: backgroundColor,
            strikethrough: strikethrough,
            underline: underline,
            paragraphSpacing: paragraphSpacing,
            paragraphIndent: paragraphIndent,
            lineHeight: lineHeight,
            letterSpacing: letterSpacing,
            lineBreakMode: lineBreakMode,
            alignment: alignment,
            link: link
        )
    }
    
    public func withAlignment(_ alignment: NSTextAlignment?) -> TextStyle {
        return TextStyle(
            font: font,
            color: color,
            backgroundColor: backgroundColor,
            strikethrough: strikethrough,
            underline: underline,
            paragraphSpacing: paragraphSpacing,
            paragraphIndent: paragraphIndent,
            lineHeight: lineHeight,
            letterSpacing: letterSpacing,
            lineBreakMode: lineBreakMode,
            alignment: alignment,
            link: link
        )
    }
    
    public func withLink(_ link: URL?) -> TextStyle {
        return TextStyle(
            font: font,
            color: color,
            backgroundColor: backgroundColor,
            strikethrough: strikethrough,
            underline: underline,
            paragraphSpacing: paragraphSpacing,
            paragraphIndent: paragraphIndent,
            lineHeight: lineHeight,
            letterSpacing: letterSpacing,
            lineBreakMode: lineBreakMode,
            alignment: alignment,
            link: link
        )
    }
    
    public func withLink(_ stringLink: String) -> TextStyle {
        var link: URL?
        if let url = URL(string: stringLink ) {
            link = url
        }
        return TextStyle(
            font: font,
            color: color,
            backgroundColor: backgroundColor,
            strikethrough: strikethrough,
            underline: underline,
            paragraphSpacing: paragraphSpacing,
            paragraphIndent: paragraphIndent,
            lineHeight: lineHeight,
            letterSpacing: letterSpacing,
            lineBreakMode: lineBreakMode,
            alignment: alignment,
            link: link
        )
    }
}

public extension NSAttributedString {
    
    // MARK: - Initializers
    convenience init(string: String, style: TextStyle, includingParagraphStyle: Bool = true) {
        self.init(string: string, attributes: style.attributes(includingParagraphStyle: includingParagraphStyle))
    }
}


public extension NSMutableAttributedString {
    
    @discardableResult
    func withSubstringStyle(substring: String, style: TextStyle, includingParagraphStyle: Bool = false) -> NSMutableAttributedString {
        let range = self.mutableString.range(of: substring)
        self.setAttributes(style.attributes(includingParagraphStyle: includingParagraphStyle), range: range)
        return self
    }
    
    func append(_ substring: String, withStyle style: TextStyle, includingParagraphStyle: Bool = false) {
        self.append(NSMutableAttributedString(string: substring, attributes: style.attributes(includingParagraphStyle: includingParagraphStyle)))
    }
}