using System.Text.Json.Serialization;

namespace Elternbeirat.Contracts;

/// <summary>
///     A content page of the site, as stored in PocketBase.
/// </summary>
/// <remarks>
///     Pages also drive the site navigation: <see cref="Location"/> and
///     <see cref="Order"/> decide where and in which order a page appears in the
///     header or footer menu. <see cref="Embed"/> lists dynamic blocks rendered
///     below the page body.
/// </remarks>
public record Page
{
    /// <summary>
    ///     The slug of the home page, which is served at the site root <c>/</c> rather
    ///     than at <c>/home</c>. Reserved: no other page may use it.
    /// </summary>
    private const string HomeSlug = "home";

    /// <summary>
    ///     Gets the PocketBase record id.
    /// </summary>
    [JsonPropertyName("id")]
    public string Id { get; init; } = "";

    /// <summary>
    ///     Gets the heading shown to visitors.
    /// </summary>
    /// <remarks>
    ///     Free text; may contain umlauts and spaces. For the URL, see <see cref="Slug"/>.
    /// </remarks>
    [JsonPropertyName("title")]
    public string Title { get; init; } = "";

    /// <summary>
    ///     Gets the page body as Markdown.
    /// </summary>
    [JsonPropertyName("body")]
    public string Body { get; init; } = "";

    /// <summary>
    ///     Gets the navigation menu the page appears in.
    /// </summary>
    /// <value>
    ///     Either <c>"header"</c> or <c>"footer"</c>.
    /// </value>
    [JsonPropertyName("location")]
    public string Location { get; init; } = "";

    /// <summary>
    ///     Gets the sort order within the navigation menu given by <see cref="Location"/>.
    /// </summary>
    /// <value>
    ///     The sort key; pages with smaller values appear first.
    /// </value>
    [JsonPropertyName("order")]
    public double Order { get; init; }

    /// <summary>
    ///     Gets the URL slug of the page, e.g. <c>"board"</c> for <c>/board</c>.
    /// </summary>
    /// <value>
    ///     A lowercase path segment without umlauts.
    /// </value>
    [JsonPropertyName("slug")]
    public string Slug { get; init; } = "";

    /// <summary>
    ///     Gets the dynamic blocks rendered below the <see cref="Body"/>.
    /// </summary>
    /// <value>
    ///     Any of <c>"posts"</c>, <c>"events"</c> and <c>"faqs"</c>, or an empty list
    ///     for a plain text page.
    /// </value>
    [JsonPropertyName("embed")]
    public IReadOnlyList<string> Embed { get; init; } = [];

    /// <summary>
    ///     Gets a value indicating whether the page is visible to visitors of the site.
    /// </summary>
    [JsonPropertyName("public")]
    public bool Public { get; init; }

    /// <summary>
    ///     Tests whether a slug is the home page's, ignoring case. This is the single
    ///     definition of that comparison, so every caller treats <c>home</c> and
    ///     <c>Home</c> alike.
    /// </summary>
    /// <param name="slug">
    ///     The slug to test.
    /// </param>
    /// <returns>
    ///     <see langword="true"/> if <paramref name="slug"/> is the home page's slug.
    /// </returns>
    public static bool IsHomeSlug(string slug) =>
        string.Equals(slug, HomeSlug, StringComparison.OrdinalIgnoreCase);
}