using System.Text.RegularExpressions;

namespace YY.Admin.Services.Service.EquipmentDb;

/// <summary>
/// 设备库 SQL 白名单：仅允许访问 MCS 中间表白名单表。
/// </summary>
public static class EquipmentDbWhitelist
{
    private static readonly HashSet<string> AllowedTables = new(StringComparer.OrdinalIgnoreCase)
    {
        "MCSToMES_Alarm", "MCSToMES_MixAlarm", "MCSToMES_MixAct", "MCSToMES_Act_Mill", "MCSToMES_MixBatch",
        "MCSToMES_MixCon", "MCSToMES_MixCurve", "MCSToMES_MixStep", "MCSToMES_MixWeight",
        "MCSToMES_MixExePlan", "MCSToMES_BinToMater", "MCSToMES_AutoXLLog", "MCSToMES_CheckScaleLog",
        "MESToMCS_Material", "MESToMCS_MixPlan", "MESToMCS_Recipe",
        "MESToMCS_Recipe_MixStep", "MESToMCS_Recipe_Weight"
    };

    private static readonly Regex Dangerous = new(
        @"\b(DROP|ALTER|TRUNCATE|EXEC|EXECUTE|xp_|sp_|INTO\s+OUTFILE|OPENROWSET|OPENDATASOURCE)\b",
        RegexOptions.IgnoreCase | RegexOptions.Compiled);

    private static readonly Regex TableRef = new(
        @"\b(?:FROM|INTO|UPDATE|JOIN)\s+\[?(?<t>[A-Za-z0-9_]+)\]?",
        RegexOptions.IgnoreCase | RegexOptions.Compiled);

    public static bool IsAllowedTable(string? table)
    {
        if (string.IsNullOrWhiteSpace(table))
        {
            return false;
        }
        return AllowedTables.Contains(table.Trim());
    }

    public static void ValidateSql(string? sql, string? tableHint = null)
    {
        if (string.IsNullOrWhiteSpace(sql))
        {
            throw new InvalidOperationException("SQL 不能为空");
        }
        if (Dangerous.IsMatch(sql))
        {
            throw new InvalidOperationException("SQL 包含禁止关键字");
        }
        var trimmed = sql.TrimStart();
        var isSelect = trimmed.StartsWith("SELECT", StringComparison.OrdinalIgnoreCase);
        var isInsert = trimmed.StartsWith("INSERT", StringComparison.OrdinalIgnoreCase);
        var isUpdate = trimmed.StartsWith("UPDATE", StringComparison.OrdinalIgnoreCase);
        var isDelete = trimmed.StartsWith("DELETE", StringComparison.OrdinalIgnoreCase);
        if (!(isSelect || isInsert || isUpdate || isDelete))
        {
            throw new InvalidOperationException("仅允许 SELECT/INSERT/UPDATE/DELETE");
        }

        if (!string.IsNullOrWhiteSpace(tableHint) && !IsAllowedTable(tableHint))
        {
            throw new InvalidOperationException($"表不在白名单: {tableHint}");
        }

        foreach (Match m in TableRef.Matches(sql))
        {
            var t = m.Groups["t"].Value;
            if (string.Equals(t, "TOP", StringComparison.OrdinalIgnoreCase)
                || string.Equals(t, "SELECT", StringComparison.OrdinalIgnoreCase)
                || string.Equals(t, "SET", StringComparison.OrdinalIgnoreCase)
                || string.Equals(t, "VALUES", StringComparison.OrdinalIgnoreCase)
                || string.Equals(t, "WHERE", StringComparison.OrdinalIgnoreCase))
            {
                continue;
            }
            if (!IsAllowedTable(t))
            {
                throw new InvalidOperationException($"SQL 引用了未授权表: {t}");
            }
        }
    }
}