using Microsoft.SqlServer.TransactSql.ScriptDom;
using SQLLinter.Common;
using SQLLinter.Common.Helpers;
using SQLLinter.Infrastructure.Rules.Common;

namespace SQLLinter.Infrastructure.Rules;

public class MultiTableAliasRule : BaseRuleVisitor, IRule
{
    private HashSet<string> cteNames = new HashSet<string>();


    public override string Text => "Найдена таблица без псевдонимов при объединении нескольких таблиц: {0}";

    public override void Visit(TSqlStatement node)
    {
        var childCommonTableExpressionVisitor = new ChildCommonTableExpressionVisitor();
        node.AcceptChildren(childCommonTableExpressionVisitor);
        cteNames = childCommonTableExpressionVisitor.CommonTableExpressionIdentifiers;
    }

    public override void Visit(TableReference node)
    {
        void ChildCallback(TSqlFragment childNode)
        {
            var dynamicSqlAdjustment = GetDynamicSqlColumnOffset(childNode);
            var tabsOnLine = ColumnNumberCalculator.CountTabsBeforeToken(childNode.StartLine, childNode.LastTokenIndex, childNode.ScriptTokenStream);
            var column = ColumnNumberCalculator.GetColumnNumberBeforeToken(tabsOnLine, childNode.ScriptTokenStream[childNode.FirstTokenIndex]);

            string tableName = "";

            if (childNode is NamedTableReference namedTable)
            {
                tableName = SQLHelpers.ObjectGetFullName(namedTable.SchemaObject);
            }

            AddViolation(Name, Text, GetLineNumber(childNode), column + dynamicSqlAdjustment, tableName);
        }

        var childTableJoinVisitor = new ChildTableJoinVisitor();
        node.AcceptChildren(childTableJoinVisitor);

        if (!childTableJoinVisitor.TableJoined)
        {
            return;
        }

        var childTableAliasVisitor = new ChildTableAliasVisitor(ChildCallback, cteNames);
        node.AcceptChildren(childTableAliasVisitor);
    }

    public class ChildCommonTableExpressionVisitor : TSqlFragmentVisitor
    {
        public HashSet<string> CommonTableExpressionIdentifiers { get; } = new HashSet<string>();

        public override void Visit(CommonTableExpression node)
        {
            CommonTableExpressionIdentifiers.Add(node.ExpressionName.Value);
        }
    }

    public class ChildTableJoinVisitor : TSqlFragmentVisitor
    {
        public bool TableJoined { get; private set; }

        public override void Visit(JoinTableReference node)
        {
            TableJoined = true;
        }
    }

    public class ChildTableAliasVisitor : TSqlFragmentVisitor
    {
        private readonly Action<TSqlFragment> childCallback;

        public ChildTableAliasVisitor(Action<TSqlFragment> errorCallback, HashSet<string> cteNames)
        {
            CteNames = cteNames;
            childCallback = errorCallback;
        }

        public HashSet<string> CteNames { get; }

        public override void Visit(NamedTableReference node)
        {
            if (CteNames.Contains(node.SchemaObject.BaseIdentifier.Value))
            {
                return;
            }

            if (node.Alias == null)
            {
                childCallback(node);
            }
        }
    }
}