using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;

using Slugify;

namespace MfGames.Nitride.Slugs;

/// <summary>
/// A default implementation of ISlugProvider.
/// </summary>
public class SimpleSlugConverter : ISlugConverter, IEnumerable<string>
{
    private readonly List<(string, string, StringComparison)> replacements;

    public SimpleSlugConverter()
    {
        this.replacements = new List<(string, string, StringComparison)>();
    }

    public SimpleSlugConverter(
        IDictionary<string, string> replacements,
        StringComparison comparison = StringComparison.InvariantCultureIgnoreCase)
        : this()
    {
        foreach (KeyValuePair<string, string> pair in replacements)
        {
            this.Add(pair.Key, pair.Value, comparison);
        }
    }

    /// <summary>
    /// Adds a replacement for the resulting slug. This is applied before the final
    /// conversion
    /// into a slug but after any other added replacements.
    /// </summary>
    /// <param name="search">The text to search for.</param>
    /// <param name="replace">The replacement string.</param>
    /// <param name="comparison">
    /// The comparison to use, defaults to invariant ignore
    /// case.
    /// </param>
    public void Add(
        string search,
        string replace,
        StringComparison comparison = StringComparison.InvariantCultureIgnoreCase)
    {
        this.replacements.Add((search, replace, comparison));
    }

    /// <inheritdoc />
    public IEnumerator<string> GetEnumerator()
    {
        return this.replacements.Select(x => x.Item1)
            .GetEnumerator();
    }

    /// <inheritdoc />
    public virtual string ToSlug(string input)
    {
        // If we have null or whitespace, we have a problem.
        if (string.IsNullOrWhiteSpace(input))
        {
            throw new ArgumentException("Cannot have a blank or null input", nameof(input));
        }

        // We need to do the replacements before we slugify.
        // Perform any additional replacements.
        foreach ((string search, string replace, StringComparison comparison) in this.replacements)
        {
            input = input.Replace(search, replace, comparison);
        }

        // Create a slug.
        var helper = new SlugHelper();
        string output = helper.GenerateSlug(input);

        return output;
    }

    /// <inheritdoc />
    IEnumerator IEnumerable.GetEnumerator()
    {
        return this.GetEnumerator();
    }
}