using System.Text.Json;
using System.Text.Json.Nodes;

namespace ZB.MOM.WW.OtOpcUa.AdminUI.Components.Shared.Drivers;

/// <summary>
///     Shared millisecond helpers for the AB forms (#576): the driver factories bind <c>*Ms</c> integers
///     while the forms edit whole seconds, so a sub-second stored value must survive an edit of an
///     unrelated field.
/// </summary>
internal static class DriverConfigMs
{
    /// <summary>Reads an integer-millisecond key at <paramref name="path"/> from <paramref name="json"/>, or null.</summary>
    public static int? Read(string? json, string path)
    {
        if (string.IsNullOrWhiteSpace(json)) return null;
        try
        {
            JsonNode? cur = JsonNode.Parse(json);
            foreach (var seg in path.Split('.'))
            {
                if (cur is not JsonObject o) return null;
                cur = o.FirstOrDefault(kv => string.Equals(kv.Key, seg, StringComparison.OrdinalIgnoreCase)).Value;
            }
            return cur is JsonValue v && v.TryGetValue<int>(out var ms) ? ms : null;
        }
        catch (JsonException) { return null; }
    }

    /// <summary>Whole seconds for display (truncating, like the pre-#576 forms).</summary>
    public static int ToSeconds(TimeSpan t) => (int)t.TotalSeconds;

    /// <summary>
    ///     The duration to save: the loaded value when the operator left the seconds field unchanged
    ///     (keeps 500 ms from collapsing to 0 s), else the edited whole seconds.
    /// </summary>
    public static TimeSpan Save(int seconds, TimeSpan? loaded)
        => loaded is { } l && ToSeconds(l) == seconds ? l : TimeSpan.FromSeconds(seconds);
}