Connected.Components/Utilities/StyleBuilder.cs

// Copyright (c) 2011 - 2019 Ed Charbeneau
// License: MIT
// See https://github.com/EdCharbeneau

using System;
using System.Collections.Generic;

namespace Connected.Utilities
{
    public struct StyleBuilder
    {
        private string stringBuffer;

        /// <summary>
        /// Creates a StyleBuilder used to define conditional in-line style used in a component. Call Build() to return the completed style as a string.
        /// </summary>
        /// <param name="prop"></param>
        /// <param name="value"></param>
        public static StyleBuilder Default(string prop, string value) => new(prop, value);

        /// <summary>
        /// Creates a StyleBuilder used to define conditional in-line style used in a component. Call Build() to return the completed style as a string.
        /// </summary>
        /// <param name="style"></param>
        public static StyleBuilder Default(string style) => Empty().AddStyle(style);

        /// <summary>
        /// Creates a StyleBuilder used to define conditional in-line style used in a component. Call Build() to return the completed style as a string.
        /// </summary>
        public static StyleBuilder Empty() => new();

        /// <summary>
        /// Creates a StyleBuilder used to define conditional in-line style used in a component. Call Build() to return the completed style as a string.
        /// </summary>
        /// <param name="prop"></param>
        /// <param name="value"></param>
        public StyleBuilder(string prop, string value) => stringBuffer = $"{prop}:{value};";

        /// <summary>
        /// Adds a conditional in-line style to the builder with space separator and closing semicolon.
        /// </summary>
        /// <param name="style"></param>
        public StyleBuilder AddStyle(string style) => !string.IsNullOrWhiteSpace(style) ? AddRaw($"{style};") : this;

        /// <summary>
        /// Adds a raw string to the builder that will be concatenated with the next style or value added to the builder.
        /// </summary>
        /// <param name="style"></param>
        /// <returns>StyleBuilder</returns>
        private StyleBuilder AddRaw(string style)
        {
            stringBuffer += style;
            return this;
        }

        /// <summary>
        /// Adds a conditional in-line style to the builder with space separator and closing semicolon..
        /// </summary>
        /// <param name="prop"></param>
        /// <param name="value">Style to add</param>
        /// <returns>StyleBuilder</returns>
        public StyleBuilder AddStyle(string prop, string value) => AddRaw($"{prop}:{value};");

        /// <summary>
        /// Adds a conditional in-line style to the builder with space separator and closing semicolon..
        /// </summary>
        /// <param name="prop"></param>
        /// <param name="value">Style to conditionally add.</param>
        /// <param name="when">Condition in which the style is added.</param>
        /// <returns>StyleBuilder</returns>
        public StyleBuilder AddStyle(string prop, string value, bool when = true) => when ? this.AddStyle(prop, value) : this;


        /// <summary>
        /// Adds a conditional in-line style to the builder with space separator and closing semicolon..
        /// </summary>
        /// <param name="prop"></param>
        /// <param name="value">Style to conditionally add.</param>
        /// <param name="when">Condition in which the style is added.</param>
        /// <returns></returns>
        public StyleBuilder AddStyle(string prop, Func<string> value, bool when = true) => when ? this.AddStyle(prop, value()) : this;

        /// <summary>
        /// Adds a conditional in-line style to the builder with space separator and closing semicolon..
        /// </summary>
        /// <param name="prop"></param>
        /// <param name="value">Style to conditionally add.</param>
        /// <param name="when">Condition in which the style is added.</param>
        /// <returns>StyleBuilder</returns>
        public StyleBuilder AddStyle(string prop, string value, Func<bool> when = null) => this.AddStyle(prop, value, when != null && when());

        /// <summary>
        /// Adds a conditional in-line style to the builder with space separator and closing semicolon..
        /// </summary>
        /// <param name="prop"></param>
        /// <param name="value">Style to conditionally add.</param>
        /// <param name="when">Condition in which the style is added.</param>
        /// <returns>StyleBuilder</returns>
        public StyleBuilder AddStyle(string prop, Func<string> value, Func<bool> when = null) => this.AddStyle(prop, value(), when != null && when());

        /// <summary>
        /// Adds a conditional nested StyleBuilder to the builder with separator and closing semicolon.
        /// </summary>
        /// <param name="builder">Style Builder to conditionally add.</param>
        /// <returns>StyleBuilder</returns>
        public StyleBuilder AddStyle(StyleBuilder builder) => this.AddRaw(builder.Build());

        /// <summary>
        /// Adds a conditional nested StyleBuilder to the builder with separator and closing semicolon.
        /// </summary>
        /// <param name="builder">Style Builder to conditionally add.</param>
        /// <param name="when">Condition in which the style is added.</param>
        /// <returns>StyleBuilder</returns>
        public StyleBuilder AddStyle(StyleBuilder builder, bool when = true) => when ? this.AddRaw(builder.Build()) : this;

        /// <summary>
        /// Adds a conditional in-line style to the builder with space separator and closing semicolon..
        /// </summary>
        /// <param name="builder">Style Builder to conditionally add.</param>
        /// <param name="when">Condition in which the styles are added.</param>
        /// <returns>StyleBuilder</returns>
        public StyleBuilder AddStyle(StyleBuilder builder, Func<bool> when = null) => this.AddStyle(builder, when != null && when());

        /// <summary>
        /// Adds a conditional in-line style to the builder with space separator and closing semicolon..
        /// A ValueBuilder action defines a complex set of values for the property.
        /// </summary>
        /// <param name="prop"></param>
        /// <param name="builder"></param>
        /// <param name="when"></param>
        public StyleBuilder AddStyle(string prop, Action<ValueBuilder> builder, bool when = true)
        {
            var values = new ValueBuilder();
            builder(values);
            return AddStyle(prop, values.ToString(), when && values.HasValue);
        }

        /// <summary>
        /// Adds a conditional in-line style when it exists in a dictionary to the builder with separator.
        /// Null safe operation.
        /// </summary>
        /// <param name="additionalAttributes">Additional Attribute splat parameters</param>
        /// <returns>StyleBuilder</returns>
        public StyleBuilder AddStyleFromAttributes(IReadOnlyDictionary<string, object> additionalAttributes) =>
            additionalAttributes == null ? this :
            additionalAttributes.TryGetValue("style", out var c) ? AddRaw(c.ToString()) : this;


        /// <summary>
        /// Finalize the completed Style as a string.
        /// </summary>
        /// <returns>string</returns>
        public string Build()
        {
            // String buffer finalization code
            return stringBuffer != null ? stringBuffer.Trim() : string.Empty;
        }

        // ToString should only and always call Build to finalize the rendered string.
        public override string ToString() => Build();
    }
}