using System;
using System.Collections.Generic;

namespace Spectre.Console;

/// <summary>
/// Represents color and text decoration.
/// </summary>
public sealed class Style : IEquatable<Style>
{
    /// <summary>
    /// Gets the foreground color.
    /// </summary>
    public Color Foreground { get; }

    /// <summary>
    /// Gets the background color.
    /// </summary>
    public Color Background { get; }

    /// <summary>
    /// Gets the text decoration.
    /// </summary>
    public Decoration Decoration { get; }

    /// <summary>
    /// Gets the link associated with the style.
    /// </summary>
    public string? Link { get; }

    /// <summary>
    /// Gets a <see cref="Style"/> with the
    /// default colors and without text decoration.
    /// </summary>
    public static Style Plain { get; } = new Style();

    /// <summary>
    /// Initializes a new instance of the <see cref="Style"/> class.
    /// </summary>
    /// <param name="foreground">The foreground color.</param>
    /// <param name="background">The background color.</param>
    /// <param name="decoration">The text decoration.</param>
    /// <param name="link">The link.</param>
    public Style(Color? foreground = null, Color? background = null, Decoration? decoration = null, string? link = null)
    {
        Foreground = foreground ?? Color.Default;
        Background = background ?? Color.Default;
        Decoration = decoration ?? Decoration.None;
        Link = link;
    }

    /// <summary>
    /// Creates a new style from the specified foreground color.
    /// </summary>
    /// <param name="color">The foreground color.</param>
    /// <returns>A new <see cref="Style"/> with the specified foreground color.</returns>
    [Obsolete("Use ctor(..) instead")]
    public static Style WithForeground(Color color)
    {
        return new Style(foreground: color);
    }

    /// <summary>
    /// Creates a new style from the specified background color.
    /// </summary>
    /// <param name="color">The background color.</param>
    /// <returns>A new <see cref="Style"/> with the specified background color.</returns>
    [Obsolete("Use ctor(..) instead")]
    public static Style WithBackground(Color color)
    {
        return new Style(background: color);
    }

    /// <summary>
    /// Creates a new style from the specified text decoration.
    /// </summary>
    /// <param name="decoration">The text decoration.</param>
    /// <returns>A new <see cref="Style"/> with the specified text decoration.</returns>
    [Obsolete("Use ctor(..) instead")]
    public static Style WithDecoration(Decoration decoration)
    {
        return new Style(decoration: decoration);
    }

    /// <summary>
    /// Creates a new style from the specified link.
    /// </summary>
    /// <param name="link">The link.</param>
    /// <returns>A new <see cref="Style"/> with the specified link.</returns>
    [Obsolete("Use ctor(..) instead")]
    public static Style WithLink(string link)
    {
        return new Style(link: link);
    }

    /// <summary>
    /// Combines this style with another one.
    /// </summary>
    /// <param name="other">The item to combine with this.</param>
    /// <returns>A new style representing a combination of this and the other one.</returns>
    public Style Combine(Style other)
    {
        if (other is null)
        {
            throw new ArgumentNullException(nameof(other));
        }

        var foreground = Foreground;
        if (!other.Foreground.IsDefault)
        {
            foreground = other.Foreground;
        }

        var background = Background;
        if (!other.Background.IsDefault)
        {
            background = other.Background;
        }

        var link = Link;
        if (!string.IsNullOrWhiteSpace(other.Link))
        {
            link = other.Link;
        }

        return new Style(foreground, background, Decoration | other.Decoration, link);
    }

    /// <summary>
    /// Implicitly converts <see cref="string"/> into a <see cref="Style"/>.
    /// </summary>
    /// <param name="style">The style string.</param>
    public static implicit operator Style(string style)
    {
        return Parse(style);
    }

    /// <summary>
    /// Converts the string representation of a style to its <see cref="Style"/> equivalent.
    /// </summary>
    /// <param name="text">A string containing a style to parse.</param>
    /// <returns>A <see cref="Style"/> equivalent of the text contained in <paramref name="text"/>.</returns>
    public static Style Parse(string text)
    {
        return StyleParser.Parse(text);
    }

    /// <summary>
    /// Converts the string representation of a style to its <see cref="Style"/> equivalent.
    /// A return value indicates whether the operation succeeded.
    /// </summary>
    /// <param name="text">A string containing a style to parse.</param>
    /// <param name="result">
    /// When this method returns, contains the <see cref="Style"/> equivalent of the text contained in <paramref name="text"/>,
    /// if the conversion succeeded, or <c>null</c> if the conversion failed.
    /// </param>
    /// <returns><c>true</c> if s was converted successfully; otherwise, <c>false</c>.</returns>
    public static bool TryParse(string text, out Style? result)
    {
        return StyleParser.TryParse(text, out result);
    }

    /// <inheritdoc/>
    public override int GetHashCode()
    {
        int? GetLinkHashCode()
        {
#if NETSTANDARD2_0
            return Link?.GetHashCode();
#else
            return Link?.GetHashCode(StringComparison.Ordinal);
#endif
        }

        unchecked
        {
            var hash = (int)2166136261;
            hash = (hash * 16777619) ^ Foreground.GetHashCode();
            hash = (hash * 16777619) ^ Background.GetHashCode();
            hash = (hash * 16777619) ^ Decoration.GetHashCode();

            if (Link != null)
            {
                hash = (hash * 16777619) ^ GetLinkHashCode() ?? 0;
            }

            return hash;
        }
    }

    /// <summary>
    /// Returns the markup representation of this style.
    /// </summary>
    /// <returns>The markup representation of this style.</returns>
    public string ToMarkup()
    {
        var builder = new List<string>();

        if (Decoration != Decoration.None)
        {
            var result = DecorationTable.GetMarkupNames(Decoration);
            if (result.Count != 0)
            {
                builder.AddRange(result);
            }
        }

        if (Foreground != Color.Default)
        {
            builder.Add(Foreground.ToMarkup());
        }

        if (Background != Color.Default)
        {
            if (builder.Count == 0)
            {
                builder.Add("default");
            }

            builder.Add("on " + Background.ToMarkup());
        }

        return string.Join(" ", builder);
    }

    /// <inheritdoc/>
    public override bool Equals(object? obj)
    {
        return Equals(obj as Style);
    }

    /// <inheritdoc/>
    public bool Equals(Style? other)
    {
        if (other == null)
        {
            return false;
        }

        return Foreground.Equals(other.Foreground) &&
            Background.Equals(other.Background) &&
            Decoration == other.Decoration &&
            string.Equals(Link, other.Link, StringComparison.Ordinal);
    }
}