using System.Text.Json;

namespace Distribution.Features.GeneralLedger;

/// <summary>Small readers for the GL service's ApiResponse envelope ({statusCode, success, message, data}).</summary>
public static class GlJson
{
    public static JsonElement? Data(GeneralLedgerResult result) =>
        result.Body is { ValueKind: JsonValueKind.Object } body && Get(body, "data") is { } data ? data : null;

    public static string? Message(GeneralLedgerResult result) =>
        result.Body is { ValueKind: JsonValueKind.Object } body ? Get(body, "message")?.GetString()
            ?? Get(body, "Message")?.GetString() : null;

    /// <summary>Case-insensitive property lookup (GL success bodies are camelCase, its error bodies PascalCase).</summary>
    public static JsonElement? Get(JsonElement element, string name)
    {
        if (element.ValueKind != JsonValueKind.Object) return null;
        foreach (var p in element.EnumerateObject())
            if (string.Equals(p.Name, name, StringComparison.OrdinalIgnoreCase)) return p.Value;
        return null;
    }

    public static string? GetString(JsonElement element, string name)
    {
        var v = Get(element, name);
        return v is null || v.Value.ValueKind == JsonValueKind.Null ? null
            : v.Value.ValueKind == JsonValueKind.String ? v.Value.GetString() : v.Value.ToString();
    }

    public static long? GetLong(JsonElement element, string name) =>
        long.TryParse(GetString(element, name), out var n) ? n : null;
}