// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.

using System.Globalization;
using Microsoft.AspNetCore.Mvc.Core;
using Microsoft.Net.Http.Headers;

namespace Microsoft.AspNetCore.Mvc.Formatters;

/// <summary>
/// Used to specify mapping between the URL Format and corresponding media type.
/// </summary>
public class FormatterMappings
{
    private readonly Dictionary<string, string> _map =
        new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase);

    /// <summary>
    /// Sets mapping for the format to specified media type.
    /// If the format already exists, the media type will be overwritten with the new value.
    /// </summary>
    /// <param name="format">The format value.</param>
    /// <param name="contentType">The media type for the format value.</param>
    public void SetMediaTypeMappingForFormat(string format, string contentType)
    {
        ArgumentNullException.ThrowIfNull(format);
        ArgumentNullException.ThrowIfNull(contentType);

        SetMediaTypeMappingForFormat(format, MediaTypeHeaderValue.Parse(contentType));
    }

    /// <summary>
    /// Sets mapping for the format to specified media type.
    /// If the format already exists, the media type will be overwritten with the new value.
    /// </summary>
    /// <param name="format">The format value.</param>
    /// <param name="contentType">The media type for the format value.</param>
    public void SetMediaTypeMappingForFormat(string format, MediaTypeHeaderValue contentType)
    {
        ArgumentNullException.ThrowIfNull(format);
        ArgumentNullException.ThrowIfNull(contentType);

        ValidateContentType(contentType);
        format = RemovePeriodIfPresent(format);
        _map[format] = contentType.ToString();
    }

    /// <summary>
    /// Gets the media type for the specified format.
    /// </summary>
    /// <param name="format">The format value.</param>
    /// <returns>The media type for input format.</returns>
    public string? GetMediaTypeMappingForFormat(string format)
    {
        if (string.IsNullOrEmpty(format))
        {
            var message = Resources.FormatFormatFormatterMappings_GetMediaTypeMappingForFormat_InvalidFormat(
                nameof(format));

            throw new ArgumentException(message, nameof(format));
        }

        format = RemovePeriodIfPresent(format);

        _map.TryGetValue(format, out var value);

        return value;
    }

    /// <summary>
    /// Clears the media type mapping for the format.
    /// </summary>
    /// <param name="format">The format value.</param>
    /// <returns><c>true</c> if the format is successfully found and cleared; otherwise, <c>false</c>.</returns>
    public bool ClearMediaTypeMappingForFormat(string format)
    {
        ArgumentNullException.ThrowIfNull(format);

        format = RemovePeriodIfPresent(format);
        return _map.Remove(format);
    }

    private static void ValidateContentType(MediaTypeHeaderValue contentType)
    {
        if (contentType.Type == "*" || contentType.SubType == "*")
        {
            throw new ArgumentException(
                string.Format(CultureInfo.CurrentCulture, Resources.FormatterMappings_NotValidMediaType, contentType),
                nameof(contentType));
        }
    }

    private static string RemovePeriodIfPresent(string format)
    {
        ArgumentException.ThrowIfNullOrEmpty(format);

        if (format.StartsWith('.'))
        {
            if (format == ".")
            {
                throw new ArgumentException(string.Format(CultureInfo.CurrentCulture, Resources.Format_NotValid, format), nameof(format));
            }

            format = format.Substring(1);
        }

        return format;
    }
}