using System.Globalization;
using System.Text.RegularExpressions;

namespace Admin.NET.Plugin.AiDOP.DataPlatform.Executors;

/// <summary>
/// P-015：解析调度同步窗口（FULL / INCR / ROLLING），供抽数 SQL 使用。
/// </summary>
public static class MdpSyncWindowResolver
{
    private static readonly Regex DurationRegex = new(
        @"^\s*(?<n>\d+)\s*(?<u>[dDhHmM])\s*$",
        RegexOptions.Compiled);

    /// <summary>
    /// 将窗口类型落到上下文：FULL→全量；INCR→水位；ROLLING→下界时间。
    /// 显式 FullRefresh 时强制 FULL。
    /// </summary>
    public static void Apply(MdpPullContext ctx)
    {
        if (ctx.FullRefresh)
        {
            ctx.SyncWindowType = "FULL";
            ctx.WindowFrom = null;
            return;
        }

        var type = (ctx.SyncWindowType ?? "INCR").Trim().ToUpperInvariant();
        if (type is "ROLLING_WINDOW") type = "ROLLING";

        switch (type)
        {
            case "FULL":
                ctx.SyncWindowType = "FULL";
                ctx.FullRefresh = true;
                ctx.WindowFrom = null;
                break;
            case "ROLLING":
                ctx.SyncWindowType = "ROLLING";
                ctx.WindowFrom = ResolveWindowFrom(ctx.SyncWindowValue, DateTime.Now)
                    ?? DateTime.Now.AddDays(-7);
                break;
            default:
                // INCR / 其它：走 last_cursor
                ctx.SyncWindowType = "INCR";
                ctx.WindowFrom = null;
                break;
        }
    }

    /// <summary>
    /// 解析窗口参数：支持 <c>7d</c>/<c>24h</c>/<c>30m</c> 或绝对时间 <c>yyyy-MM-dd[ HH:mm:ss]</c>。
    /// </summary>
    public static DateTime? ResolveWindowFrom(string? value, DateTime now)
    {
        if (string.IsNullOrWhiteSpace(value)) return null;
        var raw = value.Trim();

        var m = DurationRegex.Match(raw);
        if (m.Success)
        {
            var n = int.Parse(m.Groups["n"].Value, CultureInfo.InvariantCulture);
            return m.Groups["u"].Value.ToUpperInvariant() switch
            {
                "D" => now.AddDays(-n),
                "H" => now.AddHours(-n),
                "M" => now.AddMinutes(-n),
                _ => null
            };
        }

        if (DateTime.TryParse(raw, CultureInfo.InvariantCulture, DateTimeStyles.AssumeLocal, out var abs)
            || DateTime.TryParse(raw, CultureInfo.CurrentCulture, DateTimeStyles.AssumeLocal, out abs))
            return abs;

        return null;
    }
}