using System.Text.Json.Serialization;

namespace Elternbeirat.Contracts;

/// <summary>
///     A calendar entry of the Elternbeirat, as stored in PocketBase.
/// </summary>
/// <remarks>
///     Event lists are ordered by <see cref="Start"/>. Unset optional text fields are
///     <see cref="string.Empty"/>, never <see langword="null"/>.
/// </remarks>
public record Event
{
    /// <summary>
    ///     Gets the PocketBase record id.
    /// </summary>
    /// <remarks>
    ///     <see langword="required"/>: every stored record has an id. Modeling it as
    ///     required states which fields a record must carry, independent of the store,
    ///     so a future data source has to supply them too.
    /// </remarks>
    [JsonPropertyName("id")]
    public required string Id { get; init; }

    /// <summary>
    ///     Gets the start of the event as Europe/Berlin wall-clock time.
    /// </summary>
    /// <remarks>
    ///     PocketBase stores the value in UTC; it is converted to Berlin local time on
    ///     deserialization, with daylight saving applied. An all-day event uses 00:00
    ///     as the time.
    ///     <see langword="required"/>: an event without a start has no place on the
    ///     calendar, and the field is required in PocketBase.
    /// </remarks>
    [JsonPropertyName("start")]
    [JsonConverter(typeof(LocalDateTimeConverter))]
    public required DateTime Start { get; init; }

    /// <summary>
    ///     Gets the optional end of the event as Europe/Berlin wall-clock time.
    /// </summary>
    /// <value>
    ///     The end time, or <see langword="null"/> if the event has no end.
    /// </value>
    [JsonPropertyName("end")]
    [JsonConverter(typeof(NullableLocalDateTimeConverter))]
    public DateTime? End { get; init; }

    /// <summary>
    ///     Gets the event name, e.g. <c>"Elternbeiratssitzung"</c>.
    /// </summary>
    /// <remarks>
    ///     <see langword="required"/>: an event without a name is incomplete, and the
    ///     field is required in PocketBase.
    /// </remarks>
    [JsonPropertyName("title")]
    public required string Title { get; init; }

    /// <summary>
    ///     Gets the optional location, e.g. <c>"Aula"</c>.
    /// </summary>
    /// <value>
    ///     The location, or <see cref="string.Empty"/> if none is set.
    /// </value>
    [JsonPropertyName("location")]
    public string Location { get; init; } = string.Empty;

    /// <summary>
    ///     Gets the optional note, e.g. <c>"Anmeldung erforderlich"</c>.
    /// </summary>
    /// <value>
    ///     The note, or <see cref="string.Empty"/> if none is set.
    /// </value>
    [JsonPropertyName("note")]
    public string Note { get; init; } = string.Empty;

    /// <summary>
    ///     Gets a value indicating whether the event has a wall-clock time, as opposed
    ///     to being an all-day event.
    /// </summary>
    /// <remarks>
    ///     PocketBase has no all-day flag; the convention is that a start of 00:00
    ///     means all-day. This is the single definition of that rule -- formatting and
    ///     the calendar feed both read it here instead of re-deriving it.
    /// </remarks>
    [JsonIgnore]
    public bool HasTime => Start.TimeOfDay != TimeSpan.Zero;
}